DOT-TSC-RSPA-81-13

0S82184961 ~.

S -t- -t- !, III 11111111111111111111 IIII!III - ~ensl IVI les t,-.-'.-.-"~.-I lUI--

Combustion AutomotiveEngines to Variations inFuel Prope.rties

- - " --;

N.A. Henein

Center for Automotive.ResearchWayne State UniversityDetroit MI 48202

February 1982Final Repon

This document is available to the publicthrough the National Technical InformationService. Springfield. Virginia 22161.

ous. DeporTmenf of TronsporTOtiOn

IIesearch and Special Pn:9UftbAdministratIon

Transportation Programs BureauOffice of Systems Engineering'~:=C-~-=-====_NTSIWashington DC 20500 .~EPRODUCEOBY: Nos.

u.s. Oepartmen1 of Commerce _Nal;onal TeChnic:al.lnf~r:matlonService

Springfield, Virginia 22161

... '

NOTICE

This document is disseminated under the sponsorshipof the Department of Transportation in the interestof information exchange. The United States Govern­ment assumes no liability for its contents or usethereof ..

NOTICE

The United States -Government does not endorse pro­ducts or manufacturers. Trade or manufacturers'names appear herein solely because they are con­sidered essential to the object of this report.

GENERAL DISCLAIMER

This document may be affected by one or more of the following statements

• This document has been reproduced from the best copy furnished bythe sponsoring agency. It is being released in the interest of makingavailable as much information as possible.

• This document may contain data which exceeds the sheetparameters. It was furnished in this cODdition by-the sponsoringagency and is the best copy available.

• This document may contain tone-on-tone or color graphs, chartsand/or pictures which have been reproduced in black and white.

• This document is paginated as submitted by the original source.

• Portions of this document are not fully legible due to the historicalnature of some of the material. However, it is the best reproductionavailable from the original submission.

1. ~.,.." No. .-

DOT-TSC-RSPA-81-13

Tec:hnical R.,ort Documentation Page

3. ~.cipi_t·. C.'olov No.

SENSITIVITIES OF INTERNAL COMBUSTIONAUTOMOTIVE ENGINES TO VARIATIONS INFUEL PROPERTIES

S. Report Oot.

February 19826. P.,fo""inv o'V...; 10"0" Cod.

DTS-321

DOT-TSC-RSPA-8l-13~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~8.P..~_i~O~_il~_~~"N~

7........or'sl

N.A. Henein

C~nter for Automotive Research*Wayne State UniversityDetroit MI 48202

.12, 5.-......inv "'v_c., N_ ..d ...dd,o..if.S. l'epartment of TransportationResearch and Special Programs AuministrationTransportation Programs BureauOffice of Systems EngineeringWashington DC 20590

10. w... Uni' No. CTRAISI

RS2l2/R25l711. ContrMt 0' G,., No.

.~ DTRS-57-80-P-80733

Final ReportApr-Dec 81

14. s,-....inv ....one., Cocl.

DPB-25

*Under contract to:

16. ...• .,r.ct

U.S. Department of TransportationResearch and Special Programs AdministrationTransportation Systems CenterCambrir=rop MA 02;47

" An assessment of the sensitivity of the automotive gasoline anddiesel engines to variations in fuel propertie's has been made. Thevariables studied' include H/C ratio, distillation range, aromatic content,ignition quality as determined by the octane number, and. the auto­ignition quality as determined by the cetane number. The sensitivity ofthe engine is 'measured' against its power output, fuel economy, emis-

~ sians, and degradation of lubricants. The sensitivity to the. use ofalternate fuels such as neat fuels or fuel extenders is discussed. Thealternate fuels studied include shale oil derivatives, coal liquefactionderivatives, and alcohols. The impact of using emergency fuels inautomotive gasoline and diesel engines is discussedo:;-f--"~'

.. 17. 1C0., Words

Sensitivity of Gasoline Engines;Sensitivity of Diesel Engines;Alternate Fuels; Fuel Character­istics.

DOCUMENT IS AVAILABLE TO THE PUBLICTHROUGH THE NATIONAL TECHNICALINFORMATION SERVICE. SPRINGFIELD.VIRGINIA 22161

19. s.a,n,., Clouif. (0' ",i. ,~"l

Unclassified

Fo"" COT F 1700.1 (8-72)

20. S.cu,i ,., Closs. I. <01 'hi. P0901

Unclassified

Reproduction of comple,ed pave au'horized

21. No. 01 Pov.. 22. P"".

240

•

•

"

PREFACE

• The purpose of this report is to assess the sensitivity ofautomotive gasoline and diesel engines to variations in fuel

properties. Engines have different degrees of sensitivity to the

different fuel properties. This report discusses the fuel

properties which have major effects on engine sensitivities.

Published results of past work in this area are included and

analyzed. Areas which need new or additional research are also

identified in this report .

..

iiiPreceding page blank

..

'.

o BI

... 0"', ... 'or:' :-

.1It.

:•·•

."

..

.. 1-:: III= Sf•....•..•

i __ ......

I.

.. I i aliIII JlilU

.~-

•C•

i ....If

liB

......... I

::s ' .. _ ..c

I •• t i

n iJIj jj

1111 J

llJti

I •• -~.......

I•

J

•i !·~t••I ~ •

! I =: . =· . -'!i•u !:! •I ':: ~;. .~ i

•CI;;lSI­~•DU

U•=•

­cCI~UC...

'I

t•sed ........".1 I iii ..'., ....

i !: =•

IIt..y

••...a

:!.: ::c

. ~~ ...::; ..... -•..-

I•I~

J•

Do•

1II

~

~••..C

:!riiu

:i•a

'S

t• .J • '11 aa ..

iv

Section

TABLE OF CONTENTS

1. SU~Y••••••••••••••••• o.lleo ••• e •• CI ••••••••••••••• 1-1

1.1 Introduct.ion ·· oo.D •• o 1-11.2 Probable Future Alternate Fuels ..•••••.•••••.• 1-21.3 Sensitivity of Gasoline Engines ••••••••••••••• 1-2

" 1.3.1 Gasoline Engine Alternate Fuel Options. 1-2

1.4 Sensitivity of Diesel Engines................. 1-6

1.4.1 Diesel Engine Alternate Fuel Options .•• 1-6

1.S Emergency Fuels ••••.••••••.•• o~ ••• o.OQ ••• ••••• 1-81.6 Recommendations II ~ ••• 0". 11 •• 0 •• 0 •• 0.0 1-9

1.6.11.6.21. 6.3

Future Fuel Characterization ••.•••••.•.Gasoline Engines 0000 ••••••••

Die 5 e 1 En gin e s. II 0 II • .. II II • .. • • • .. • II • • • .. II • • • •

1-91-91-10

2. INTRODUCTION AND BACKGROPND........................ 2-1

3. FUEL PROPERTIES AND THEIR EFFECTS ••.•••"............ 3-1

3. 1 Fu t ur e Fue Is II • II ••• 0 II • e .. II II • II •• II •• 0 • 0 e 0 ill II • 3-1

3.1.1 General ooo.•••••••• " ••••• e •• o. 3-13.1.2 Properties of Future Fuels............. 3-3

3.2 Sto ichiometry and Combustion.................. 3 - 5

3.2.1 Effect of HIC Ratio on Stoichiometry ••• 3-83.2.2 Effect of HIC Ratio on the Adibatic

Flame Temperature ••.........•.•.•..••.. 3-113.2~3 Effect of HIC Ratio on the (F-A)

Standard Cy~le .......•••...•.........•. 3-11

3.3 Gasoline Engine Fuels ...•....•....•........••. 3-11

3.3.1 Volatility and Distillation Range .•..•. 3-143.3.2 Detonation and Preignition .

Characteristics .•.•.•.••...•.....•..... 3-173.3.3 Energy Density ...............••.....•.• 3-193.3.4 Latent Heat of Evaporation............. 3-20

3.4 Diesel Engine Fuels ...............•..•...••.•. 3-21

3.4.1 Augoignition Quality ................•.. 3-213.4.2 Volatility and Distillation Range...... 3-29

v

TABLE OF CONTENTS (CONTINUED)

4.2 ~1ethanol Neat." 0 0 00" ••• 11 •• 0.

4.1 Alcohol-Indolene Blends ...•.....•••.•••••..•.•

4.3 Shale-Derived and Coal Derived Gasoline in

Section',,--

Page

3-293-29

4-1

4-1

4-14-1

4-5

4-13 ,.

4-16

4-23

4-314-32

4-34

4-34

4-36.4-40

4-46

4-514-51

4-534-664-664-664-674-674-67

Effect of Blending on a 3-Way CatalystCar with Closed Loop Emission ControlSystem at Constant Speed .Effect on a 3-Way Catalyst Car withClosed Loop Control System on FTPeye1e .. 0 0 CI ••• 0 CII •• 0 •• CI II •• 0 ••••••

Effect of Exhaust Aldehydes and AcetoneEmissions II ••••••••••••••••

Phase Separation .....•...............•.

-Effect of Blending Gasoline and Alcoholson Octane Number •....... ~ •.•.•.•••....•Effe ct on Fl arne Speed .........•.•.....•Effect on a Single Cylinder Engine'sPerformance, Thermal Efficiency andEffi'i S 5 ion S 0 0 • • • 0 !t II • • • • G • • • eo. II • • • • 0 ct 0 D • 00

Effect of Alcohols on a Non-CatalyticCar,. .•• CI •••••••••••••••••••••••••••••••

Effect on Reid Vapor Pressure ......•...Effect on API Gravity ...............•..Effect on Octane Number .............•..Effect on Power Index .Effect on Conservation Index .Effect on Tradeoff Index .Effect on Emissions Index .

Single Cylinder Engine Sensitivity .....Comparison Between the Single CylinderEngine Results and Cycle Computations ..Mu1ticy1inder Engine Sensitivity .•.....Sensitivity of a Vehicle to NeatAlcohol G ••••••••••

4.1. 7

4.1. 8

4.1. 6

4.1.1

4.1. 24.1. 3

4.1. 4

4.1. 5

4.2.14.2.2

4.2. 34.2.4

4.4.14.4.24.4.34.4.44.4.54.4.64.4. 7

Gasoline Engines.ooo CI ••••••

4.4 Gasoline Emergency Blends ...•....•.••..•.•.••.

3.4.3 ViscosityooCl.ra ....•.•... G •••••••••••••••

3.4.4 Specific Gravity .....•..•..•.•..•••.••.

4. ()SENSITIVITY OF AUTOMOTIVE GASOLINE ENGINES ItOVARIATIONS IN FUEL PROPERTIES •.•••.•.•.••.••.•.••.•

vi

Section

TABLE OF CONTENTS (CONTINUED)

5. SENSITIVITY OF AUTOMOTIVE DIESEL ENGINES TOVARIATIONS IN FUEL PROPERTIES...................... 5-1

5.1 D.I. Four-Stroke-Cyc1e Diesel Engine .••••••.•• 5-1

5.1.15.1. 25.1. 3

5.1. 4

5.1. 55.1. 6

5.1. 75.1.8

5.1.9

Effect of Cetane Number ..•••.••••••••••Effect of Aromatic Content •••.•.•••.•••Effect of Mixing DF-2 with ShaleDistillates a ••••••••••••••••••••••• a II ••

Effect of Mixing DF2 with CoalDistillates 0 ••••

Effect of' Using Alcohols ••.•.•.••.••..•Effect of Mixing DF-2 wit~ VegetableOils c •• a ••••••••

Effect of Mixing DF-2 with Gasoline •••.Effect of Using Two Separate InjectionSystems in a Diesel/Gasoline FueledEngine II ••••

Effect of Using Wide Cut Distillates ...

5-15-2

5-2

5-45-8

5-185-18

5-245-24

.. '

5.2 D.I. Two-Stroke-Cyc1e Diesel Engine ••••••••••• 5-26

5.2.1 Effect of Using Off-Specification DieselFuels 5-26

5.2.2 Effect of Using Fuels Derived from TarSands and Shale Oil ...•..••.••.....•.•. 5-36

5.3 I.D.I. Swirl Type 4-Stroke-Cycle Engine ......• 5-50

5.3.1 Effect of Fuel Properties on FuelEconomy and on Particulates andOther Emissions........................ 5-50

5.3.2 Effect of Fuel Properties onParticula tes 0 0 ••• 0 • 0 II III' 5 - S4

5.4 Diesel Emergency Blends ........... 0 •••• 0 ••• II e II 5-59

5.4.1 Effect on Cetane Number .•.•..• II ........ o- S-595 . 4• 2 Effect on API Gravity ........ o. C1 ••••••• 5-595.4. 3 Effect of Heat on Combustion ..•.•...•.. 5-595.4.4 Effect on Viscosity .................... 5-635.4. 5 Effect on Power I nde x .................. 5~63

5.4. 6 Effect on Conservation Index ....... 0 • Il • 5-635. 4. 7 Effect on Tradeoff I n de x ............... 5-635.4. 8 Effect on Emissions Indexe s ............ 5-63

vii

TABLE OF CONTENTS (CONTINUED)

7 • 2 Die 5 e 1 En gin e 5" 0 0 • II " III Q (I • 0 iii • • • 0 ••• 0 • 0 •• CI III III • • • • 0

7 e CONCLUSIONS •.• II •••••• 0 ••• II ••• 0 0 ••• 0 0 II 0 ...... 0 •••• 0 ••

6 • 3 Die 5 e 1 En gin e s. 0 0 0 • 0 0 tI ••• 0 0 • e g •••••••••••• e eo.

...Page

6-1

6-16-b

6-26-2

6-26-36-4

6-4

6-5

6-56-5

7-1

7-1

7-37-37-5

7-7

7-9

7-15

7-157-15

8-1

8-18-18-2

A-I

B-1

Alternate Fuel Option~......•..•.......Gasoline - Alcohol Blends ......•....•..Neat Alcohols.Cl.o CI.ee.IIl." .

Ni trogen Oxides o ••••••••••••••••

Sulfur Compounds ~ .Partial and Complete OxidationProducts .- 0 0 .

Hydrocarbons. 0 ••••••••• 0 •••••••••••••••

Corrosion .................•. e ••••••• o ••

Effect of Alcohol Fuels on Lubricationand Engine Wearae'oaooDoo.ao.oo ••••••••

Gasoline Engine Emergency Fuels .....•.•Diesel Engine Emergency Fuels .

7.1. J_7.1. 27.1. 3

6.2.16.2.26.2.3

6.2.46.2.56.2.6

7.3.17.3.2

6 . 3• 1 Soot Par t.i cuIate s .....•.....•••. '•..•.••6.3.2 Sulfur .

7.2.1 Alternate Diesel Fuel Options •.•••.•••.

701 Gasoline Engines ...•. o ••••••••••••••••••••••••

6.1 Introduction oo •••••••••• t1 •••• o ••••

6.2 Gasoline Engines ...........•.........•.•..•...

APPENDIX A - REFERENCES .......................•....

APPENDIX B - REPORt OF INVENTIONS .

8.1 Future Fuel Characteristics ..............•....8.2 Gasoline Engines " o •••• o ••• e •••••••

8.3 Diesel Engines o ••• ooc.Il.II •••• ooooo •••••••

8 • RE COrvn·lENDATION Sill •. e •••••••• III • III " • 0 • 0 • III •• 0 0 III • II •••••••

6. SENSITIVITY OF ENGINE LUBRICATION TO VARIATIONSIN FUEL PROPERTIES ...••.•••.••.•••••••••••.••••.•••

Section

viii

LIST OF ILLUSTRATIONS

Figure.

3.1 TRENDS OF THE END-POINT AND CETANE NUMBER FOR U.S.AND EUROPEAN-PRODUCED DIESEL FUEL.................. 3-6

3.2 TRENDS OF THE CLOUD-POINT OF U.S. AND EUROPEANPRODUCED DIESEL FUELS ...••••.•..•...••••..•.• ~ .•••• 3-7

3.3 EFFECT OF HYDROGEN-TO-CARBON RATIO ON THEORETICALAIR-FUEL RATIO..................................... 3-9

3.4 EFFECT OF FUEL STRUCTURE fu~D NUMBER OF CARBON ATOMSON THEORETICAL AIR-FUEL RATIO...................... 3-10

3.5 EFFECT OF HIC RATIO ON ADIABATIC FLAME TEMPERATURE. 3-12

3.6 EFFECT OF HIC RATIO ON (F-A) STANDARD CONSTANTVO LUME C'lCLE....................................... 3-13

3~7 TYPICAL ASTM DISTILLATION CURVES ....••.•.......•..• 3-15

3.8 EFFECT OF DISTILLATION RANGE ON ENGINE PERFORMANCE. 3-16

3.9 VAPOR-AIR VERSUS FUEL-AIR RATIOS FOR OCTANE(C8H1S) AT 1 ATM................................... 3-18

3.10 RELATIONSHIP BETWEEN THE C.N. AND C.R. IN THE CFRENGINE WITH HMN AND XMN AS REFERENCE FUELS 3-23

3.11 CORRELATION BETI~EEN THE C.N. AND O.N. OF DIFFERENTFUE LS 0 •• 0 u a .. • • 3 - 2 5

3.12 A ·MODIFIED CETANE SCALE FOR RATING LOW IGNITIONQUAL I TY FUE LS II • 0 •••••• 0 • • • • 3 - 26

3.13 CYCLE-TO-CYCLE VARIATION IN THE AUTOIGNITION OFFUELS OF DI FFERENT CETANE NUMBERS.................. 3-27

3.14 PROBLEMS ASSOCIATED WITH VARIATIONS IN DIESEL FUELVOLATILITy 0 0.. 0...... 3,-30

3.15 PROBLEMS ASSOCIATED WITH VARIATIONS IN DIESEL FUELVI S COS I TY a II • • • • • .. • • 3 - 30

3.. 16 RELATIVE PERFORHANCE OF A DIESEL ENGINE AT CONSTANTFUEL-PUMP SETTINGS VERSUS SPECIFIC GRAVITY OF FUEL. 3-31

4.1 OCTANE CHARACTERISTICS OF GASOLINE HETHANOL BLENDS. 4-2

4.2 CORRELATION BETWEEN OCTANE INCREMENT AND BASE FUELOCTANE NUf\lRER..•.•...••.••...••...•.•.•.•.•• III •••••• 4-3

1.X

LIST OF ILLUSTRATIONS (CONTINUED)

Figure

4.3 EFFECT OF BLENDING METHANOL WITH INDOLENE ON THE

4.10

FL.Al\1E SPEED. II • • • • • • • • • • • • • • • • 0 • • • a • • • • • • • • • • • • • • • • • 4 .. 4

4.4 EFFECT OF MIXING METHANOL WITH INDOLENE FUEL ONBHP AND MBT •.••.....•••••...•..•••.•••• &I • e-. • • • • • • • • 4 - 6

4.5 EFFECT OF MIXING METHANOL WITH INDOLENE ON BRAKESPECIFIC FUEL CONSUMPTION.......................... 4-7

4.n EFFECT OF MIXING METHANOL WITH INDOLENE FUEL ONBRAKE SPECIFIC ENERGY CONSUMPTION 4-8

4.7 EFFECT OF MIXING METf~NOLWITH INDOLENE FUEL ONBRAKE SPECIFIC UNBURNED HyDROCARBONS ..•.....•. :.... 4-10

4.8 EFFECT OF MIXING METHANOL WITH INDOLENE FUEL ONBRAKE SPECIFIC CARBON MONOXIDE .............•...•... 4-11

4. 9 EFFECT OF }.1! XI NG METHANOL WI Tf-! IlmOLENE FUEL ONBRAKE SPECIFIC NITRIC OXIDES 4-12

EFFECT OF MIXING METHANOL WITH INDOLENE FUEL ONPEAK BRAKE SPECIFIC NITRIC OXIDES.................. 4-14

4.11 OfANGES IN FTP RESULTS FOR 10% METHANOL-ADDED TOINDOLENE IN A NON-CATALYTIC CAR 4-15

4.12 EFFECT OF REID VAPOR PRESSURE ON THE TOTALEVAPORATIVE EMISSIONS.............................. 4-21

4.13 EFFECT OF METHANOL ON. THE PERFORMANCE AND EMISSIONSOF A 3-WAY CATALYST CLOSED LOOP CAR AT CONSTANTSPEED ......••...........•.......••.•..•.••..•..•••. 4-22

4.14 ISO FUEL-ENERGY CONTOURS FOR METI-IANOL-GASOLINEBLENDS 4-24

4.15 3-WAY CATALYST CONVERSION EFFICIENCY FOR HC, CO ANDNOx AS A FUNCTION OF LAMBDA........................ 4-25

4.16. OXYGEN SENSOR MILLIVOLT OUTPUT AS A FUNCTION OFEXHAUST GAS COMPOSITION (LAMBDA)................... 4-25

4.17 EMISSIONS ON THE FTP AS A FUNCTION OF ETHANOL IN ANETHANOL/GASOLINE BLEND 4-29

4.18 CLOUD POINT FOR VARIOUS METHANOL-GASOLINE BLENDS 4-33

x

LIST OF ILLUSTRATIONS (CONTINUED)

Figure

4.19 EFFECT OF C.R. ON POWER AND EFFICIENCy ..•.......... 4-35

4.20 EFFECT OF C.R. ON SAVINGS IN FUEL-ENERGY, AT37 MPH AND AT 62 MPH ROAD LOADS 4-37

4.21 PERCENTAGE DECREASE IN FUEL-ENERGY IN A METHAl'JOLFUELED ENGINE IN RELATION TO A PRODUCTION GASOLINEENGINE ' . . -e.................. 4-37

4.22 HC AND NOx EMISSIONS VERSUS C.R ; 4-38

4.23 HIXTURE TEMPERATURE WITH METHANOL AND GASOLINE 4-41

4.24 ENGINE OUTPUT WITH METHANOL AND GASOLINE 4-41

4.25 BRAKE THERNAL EfFICIENCY WITH METHANOL ANDGASOLINE · 4-43

4.26 EXHAUST NOx WITH METH.ANOL Al'JD GASOLINE 4-44

4.27 EXHAUST CO WITH METHAt'JOL AND GASOLINE.............. 4-45

4.28 EXHAUST HC WITH METHANOL AND GASOLINE 4-45

4.29 EXHAUST ALDEHYDES WITH METHANOL AND GASOLINE 4-47

4.30 EFFECT OF WATER ADDITION TO METHANOL ON EXHAUSTEMISSIONS AND ENGINE POWER......................... 4-48

.4.31 PNA HYDROCARBONS WITH METHANOL AND GASOLINE 4-49

4.32 EXHAUST EMISSIONS WITH METHANOL AND GASOLINE ATFULL THROTTLE ................•..' •......•...•.•.•... 4-StJ

4.33 EFFECT OF GASOLINE EXTENDERS ON RVP 4-54

4.34 EFFECT OF GASOLINE EXTENDERS ON API GRAVITy 4-55

4.35 EFFECT OF GASOLINE EXTENDERS ON OCTANE Nill1BER 4-56

4.36 EFFECT OF GASOLINE EXTENDERS ON POWER INDEX 4-57

4.37 EFFECT OF GASOLINE EXTENDERS ON CONSERVATION INDEX. 4-58

4.38 EFFECT OF GASOLINE EXTENDERS ON TRADEOFF INDEX ..... 4-59

4.39 EFFECT OF GASOLINE EXTENDERS ON THE HYDROCARBONSINDEX AT IDLE...................................... 4-60

Xl

LIST OF ILLUSTRATIUNS (CUNTINUED)

Figure

4.40 EFFECT OF GASOLINE EXTENDERS ON CO INDEX AT IDLE ... 4-61

4.41 EFFECT OF GASOLINE EXTENDERS ON NOx INDEX AT IDLE.. 4-62

4.42 EFFECT OF GASOLINE EXTENDERS ON HYDRC~ARBON INDEXAT ROAD LOAD....................................... 4 - 63

4.43 EFFECT OF GASOLINE EXTENDERS ON CO INDEX AT ROADLOAD 4-64

4.44 EFFECT OF GASOLINE EXTENDERS ON NOx INDEX AT ROADLOAD............................................... 4-65

5.1 PREDICTED WEIBULL FAILURE PROFILE FOR ENGINESOPERATING ON DILUTED DIESEL FUELS.................. 5-5

5.2 CETANE NUMBER VERSUS PERCENTAGE OF CETANOX INr"IETHAN,O L••••••••••.•..... ". • . . • . • . . . • • • • . • • • • • . • • • • • 5 -1 0

5.3 EFFECT OF THE AMOUNT OF CENTANOX IN HETHANOL ON HCEM! 55 IONS II •• • ' • ~ •••• 0 ••••••• 0 0 II • II II ••••••• I!I ••• II • • • • • • 5 -1 0

5.4 EFFECT OF THE BACK PRESSURE ON HC EMISSIONS 5-13

5.5 PERCENTAGE NEEDED OF CETANOX IN METHANOL AND CETANENUMBER TO MINIMIZE HC EMISSIONS TO 400 PPM 5-13

5.6 HC-EMISSIONS VERSUS DRIVING TIME AT NO-LOAD AFTERFULL LOAD AT ENGINE SPEED 1500 RPM................. 5-15

5.7 EFFECT OF DIESEL DYNAMIC INJECTION TIMING ON SMOKEAND HC EMISSIONS WITH FIXED METHANOL TIMING 5-15

5.8 COMPARISON OF PART LOAD PERFORMANCE BETWEEN STANDARDDIESEL AND DIESEL/METHANOL ENGINES AT 1500 RPM ..... 5-17

5.9 PART LOAD PERFORMANCE WITH DIESEL/ETHANOL ENGINEAT 1500 RPM........................................ 5-1 7

5.10 CETANE NUMBER OF DIESEL-GASOLINE MIXTURES.......... 5-20

5.11 EFFECT OF MIXING GASOLINE WITH DIESEL FUEL ONIGNITION DELAy , 5-21

5.12 TYPICAL DIESEL FUEL AND GASOLINE LOAD RANGE CURVESFROM A 6 CYLINDER 300 CID DIESEL ENGINE 5-i2

5.13 COMPARISON OF PART LOAD PERFORMANCE WITH DIESEL/CRUDEGASOLINE AND CRUDE GASOLINE AT 900 RPM ' 5-25

Xll

LIST OF ILLUSTRATIO~S (CONTINUED)

Figure

5.14, EFFECT OF C.N. VARIATIONS ON LD. AND RATE OFPRESSURE RISE (2-CYLINDER ENGINE).................. 5-27

,5.15 EFFECT OF C. N. ON ENGINE PERFORMANCE (2 - CYCLEENGIN E) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 • • • • • • 5 - 2 8

5.16 EFFECT OF C.N. ON EMISSIONS IN A 2-CYCLE ENGINE .... 5-30

5.17 EFFECT OF VISCOSITY ON EMISSIONS IN A 2-CYCLEENGINE ....................................•· .••..... 5-31

5.18 EFFECT OF C.N. ON LD. FOR VARIOUS DISTILLATIONRANGE FUELS........................................ 5-33

5.19

5.20

EFFECT OF C.N. ON RATE OF PRESSURE RISE-DISTILLATIONRANGE· SERI ES -. . . . . . . . . . . 5 - 33

EFFECT OF API GRAVITY ON BRAKE THERr·1AL EFFICIENCYDISTILLATION RANGE SERIES ...............•.......... 5-34

5.22

5.21

~.

.=

EFFECT OF API GRAVITY ON BRAKE HORSEPOWER -DISTILLATION RANGE SERIES 00 ~....... 5-34

EFFECT OF VISCOSITY ON BRAKE THEID·1AL EFFICIENCYDISTILLATION RANGE SERIES 5-35

5.23 EFFECT OF VISCOSITY ON BRAKE HORSEPOWERDISTILLATION RANGE SERIES 00_...... 5-35

5.24 RELATIONSHIP BETWEEN VISCOSITY AND API GRAVITY FORDIFFERENT DISTILLATES 5-37

5.25. EFFECT OF API GRAVITY ON BRAKE SPECIFIC HC -DI STI LLATI ON RANGE SERI ES. . . . . . . . . . . . . . . . . . . . . . . . . . 5- 38

5.26 EFFECT OF VISCOSITY ON BRAKE SPECIFIC HC -DISTILLATION RANGE SERIES 5-38

5.27 EFFECT OF TOTAL BTU INPUT ON BRAKE SPECIFIC CARBONMONOXIDE EMISSIONS - DISTILLATIO~ RANGE SERIES ..... 5-39

5.28 EFFECT OF C. N. ON BRAKE SPECI FI C CARBON ~1ONOXI DE -DISTILLATION RANGE SERIES 5-39

5.29 COMPARISON OF I.D. WITH REGULAR DIESEL FUEL ANDFUELS DERIVED FROM SHALE AND TAR SANDS 5-42

xiii

LIST OF ILLUSTRATIONS (CONTINUED)

Figure

5.30 COMPARISON OF MAXIMUM RATE OF PRESSURE RISE WITHREGU~AR DIESEL FUEL AND FUELS FROM SHALE AND TARSANDS .....••.•••••.•.••••• 0 0 ••••••• " • 0 •• II •• 0 ••••• II II 5- 43

5.31 BSFC WITH SHALE AND TAR SANDS FUELS RELATIVE TORE GU LAR FUEL •• Cl • ,.:) ••••••••••••• 0 •• 0 •••• II •• II II II II • • • • • 5- 44

5.32 COMPARISON OF SMOKE WITH REGULAR DIESEL FUEL ANDFUELS DERIVED ,FROM SHALE AND TAR SANDS............. 5-45

5.33 NOx EMISSION BY MASS WITH SHALE AND TAR SANDS FUELSRELATIVE TO REGULAR DIESEL FUEL 5-47

5.34 HC EMISSIONS BY ~~SS WITH TAR SANDS FUEL RELATIVETO REGULAR DIESEL FUEL............................. 5-48

5.35 CO EMISSION BY MASS WITH SHALE AND TAR SANDS FUELSRELATIVE TO REGULAR DIESEL FUEL 5-49

5.36 CONTRIBUTION OF VARIOUS COMPONENTS OF DIESEL FUELTO PARTICULATE EMISSIONS •.......................... 5-53

5.37 DISTILLATION RANGE OF SONE OF THE FUELS TESTED .•... 5-53

5.38 PARTICULATE INDEX IN ARBITRARY UNITS VS. FUELAROMATIC CONTENT................................... 5-57

5.39 PARTICULATE INDEX IN ARBITRARY UNITS VS. FUEL 90%BOILING POINT...................................... 5-57

5.40 EMISSIONS AND ECONO~~ VARIATION WITH FUEL BLENDS OFINCREASING AROMATICITY fu~D SPECIFIC GRAVITYSTARTING WITH D-2 FUEL 5-58

5.41 EMISSION AND ECONOMY VARIATION WITH FUEL BLENDS OFINCREASING AROMATICITY AND SPECIFIC GRAVITYSTARTING WITH LOW-AROMATIC NARROW CUT PRODUCT 5-58

5.42 EFFECT OF DIESEL EXTENDERS ON C.N 5-61

5.43 EFFECT OF DIESEL EXTENDERS ON API GRAVITy 5-62

5.44 EFFECT OF DIESEL EXTENDERS ON THE HEAT OFCOMB US TION II .... 0 •• I ••••••• II •• II •• 0 • 0 • Cl •• 0 • 0 •• II 0 •• 0 CI • e 5 - 64

5.45 EFFECT OF DIESEL EXTENDERS ON VISCOSITY 5-65

XIV

LIST OF ILLUSTRATIONS "(CUNTINUED)

Figure Page

5.46 EFFECT OF DIESEL EXTENDERS ON POWER INDEX .....•.... 5-66

5.47 EFFECT OF DIESEL EXTENDERS ON CONSERVATION INDEX ... 5-67

5.48 EFFECT OF DIESEL EXTENDERS ON TRADEOFF INDEX...•.... · 5-68

"5.49 EFFECT OF DIESEL EXTENDERS ON HC I N'DEX ...... 0 ••••• III 5-69

5.50 EFFECT OF DIESEL EXTENDERS ON CO INDEX ............. 5-70.

5.51 EFFECT OF DIESEL EXTENDERS ON NO x INDEX............. 5-71

5.52 EFFECT OF DIESEL EXTENDERS ON SMOKE INDEX ..•....... 5-72

6-l. EFFECT OF SULFUR CONTENT ON WEAR................... 6-7

LIST OF TABLES

c.- Table

1.l.

1. 2.

3.1

3.2

3.3

3.4

3.5

4.1

4.2

4.3

4.4

Page

PROBABLE FUTURE ALTERNATE FUELS ................•... 1-3

SOURCES OF ALCOHOLS i-4

PROPERTIES OF SYNTHETIC MOTOR FUELS PRODUCED FROMSI-I~I\.LEO I L. • • • • • • • • • • III .. • • III II • • III • • • • • • • • • • • • .' • • • • III .. III • • 3 - 4

PROPERTIES OF U.S. AND NON-U.S. DIESEL FUELS 3-8

OCTANE RATING METHODS .. ;........................... 3-19

SPECIFIC GRAVITY AND ENERGY-DENSITY FOR DIFFERENTFUELS. It •••••••••• o. -II 0.0 III III II ••• CI III 3-20

LATENT HEAT OF EVAPORATION OF DIFFERENT FUELS 3-21

COMPRESSION RATIOS CORRESPONDING TO VARIOUSINDOLENE-METHANOL BLENDS........................... 4-5

PROPERTIES OF THE DIFFERENT FUELS 4-17

PROPERTIES OF BLENDS OF INDOLENE AND ALCOHOLS 4-18

SUMMARY OF THE EXHAUST EHISSIONS, EVAPORATIVEEMISSIONS, AND FUEL ECONOMY 4-19

xv

LIST OF TABLES (CONTINUED)

Table

4. 5 FUEL ECONOMY WI TH DI FFERENT BLENDS BASED ON THEI RENERGY CONTENT g •••••••••••• oc ••••••••• 4-20

(\

4.6 EMISSIONS FOR FTP PROCEDURE WITH ETHANOL -GASOLINE BLENDS ...•....•.• ".....•.....•.•••.•..••. C1 4-28

4.7 EMISSIONS OF FTP PROCEDURE FOR A 3-WAY CATALYST CARWITH CLOSED LOOP CONTROL, WITH BLENDS OF GASOLINE,DIESEL FUEL AND WATER ..•........................... 4-30

4.8 CHART CALCULATIONS OF CYCLE CHARACTERISTICS 4-39

4.9 PROPERTIES OF SHALE OIL-DERIVED GASOLINE 4-52

4.10 EMISSIONS AND FUEL ECONO~~ RESULTS WITH SHALE- .DERIVED GASOLINE 00 4-52

4.11 EMERGENCY GASOLINE EXTENDERS....................... 4- 66

5.1 TYPICAL PERFOR~~NCE DEGRADATION OF SHALE OILDI LUT ION •• II'. 0 • 0 ••••••• 0'•••• II • • e.•••• Cl •• 0 • 0 0 • II 0 •••• e e 5 - 3

5.2 SELECTED PROPERTIES OF COAL DISTILLATES 5-6

5.3 TYPICAL PERFORMANCE DEGRADATION WITH TAR OIL ANDHYDROGENATED CREOSOTE OIL~ 5-7

5.4 POUR POINT (ASTM D975) OF DIESEL OILS DILUTED WITHCOAL DERIVED CRUDE................................. 5-9

S. 5 PERFOro.~NCE IMPACT OF ETHANOL FUELING.............. 5-12

5.6 PERFORMANCE IMPACT OF EXTENSION WITH VEGETABLE OIL. 5-19

5.7 PERFORMANCE IMPACT OF COTTON-SEED OIL EXTENSION 5-19

5.8 NO.2 DIESEL. FUEL PROPERTIES 5-29

5.9 PROPERTIES OF REGULAR DF-2 FUELS DERIVED FROM SHALEAND TAR SANDS ... G ••••••••• o ••••••••••••••• o .. eo ••• IiIG 5-41

5.10 PERFORMANCE IMPACT OF ETHANOL FUELING 5-51

5.11 PHYSICAL PROPERTIES OF G.M. STUDY FUELS 5-52

XVl

Table

5.12

5.13

5.14

7.1

7.2

7.3

7.4

7 ~ 5

7.6

2: 7. 7

LIST OF TABLES (CONTINUED)

Page

PROPERTIES OF D-1, D-2 &C-40 .....................• ~-55

PARTICULATES WITH D-2 AND C-40 FUELS - FTP CYCLE 5-56

EMERGENCY DIESEL EXTENDERS 5-60

IMPORTANT FUEL PROPERTIES FOR GASOLINE ENGINES 7-2

GASOLINE ENGINE ALTERNATE FUELS: GASOLINE - ALCOHOLBLENDS 7-4

GASOLINE ENGINE NEAT ALCOHOLS COMPARED TOIr~DOLENE........................................... 7-6

IMPORTANT FUEL PROPERTIES FOR DIESEL ENGINES 7-8

DP-2 GASOLINE BLENDS 7-11

DIESEL ENGINE ALTERNATE FUELS (DF-2/SYNFUELS'B LENDS) .......................•.............. .' ....' .' . 7 -12

DF-2/ALCOHOL BLENDS 7-13

xvii/xviii

1. SUMMARY

1.1 INTRODUCTION

The properties of automotive fuels are expected to change

in the future as efforts continue~to extend the petroleum reserves

and produce alternate fuels to replace the petroleum derived

fuels. These efforts are being made to reduce imports and achieve

energy self reliance. Automotive engines are sensitive to many

of the fuel properties which are expected to change. This report

deals with the sensitivities of the present, mass produced internal

combustion, automotive gasolini and diesel engines to variations

in fuel properties. Other types of automotive engines, such as

stratified charge or gas turbine, are still in the research anddevelopment stage and are not included in this report.

The introduction of alternate fuels may take one of the

following forms:

1. Varying the distillation range of currently produced

fuels (gasoline and diesels) in order to increase the

yeild of crude petroleum.

2. Mixing gasoline and diesel fuels with liquid synthetic

fuels such as shale oil derivatives, coal derivatives

or biomass derivatives.

3. Replacing gasoline and diesel fuels with alternate

fuels.

The gradual shift from regular automotive fuels to alternate

fuels in any of the above forms will result in variations in fuel

properties which affect combustion, lubrication, engine performance~

fuel economy,· emissions and reliability. This report emphasizes

the projected impact of those alternate fuels which are expected

to be available in the future on automotive engines.

1-1

1.2 PROBABLE FUTURE ALTERNATE FUELS

A pDssible scenario for future automotive fuels is given in

Table 1.1. This table is a result of studies made of reports

published by DOE, oil refining companies, research institutions

and automotive companies. For the immediate term (1980-1990),

current types of mass produced automotive fuels will be available

and are expected to be extended by alcohols or alcohol based

additives. For the near term (1990-2000), in addition to alcohols,it is probable that syncrudes derived from shale oil and coal

derivatives will be mixed with feedstocks of the refineries. For

the midterm future (2000-2020), the production of syncrudes is

expected to increase and reach about 10 percent of the U.S.

petroleum demand. For the long term future (2020-2040), new

engines may be mass produced to match the fuels which will then be

available. The contribution of syncrudes in the production of

these fuels is expected to reach 30 to 40 percent. For the far­future (2040-2060),syncrude production is expected to equal that

of natural petroleum ~rude and gradually replace it. For post

2060, fuels (such as hydrogen) produced using inexhaus"tible energysources (such as solar energy or fusion energy) are expected to be

introduced. The use of hydrogen in automotive engines is con­

tingent on the development of safe and economically competitivedistribution and storage systems.

1.3 SENSITIVITY OF GASOLINE ENGINES

Gasoline engines are mainly sensitive to the following fuel

properties: volatility, octane number, Hie ratio, latent heat of

evaporation, volumetric energy content, and sulfur and nitrogen

content.

1.3.1 Gasoline Engine Alternate Fuel Options

1.3.1.1 Synthetic Gasoline - Synthetic gasoline can be produced

from oil shale or coal derivatives. Synthetic gasoline from shale

oil is mainly paraffinic and is low in octane number. Synthetic

1-2

TABLE 1.1 PROBABLE FUTURE ALTERNATE FUELS

IMMEDIATE­TERM

NEAR-TERN

MID-TERN

LONG-TERN

FAR-TERM

POST-2060

1980

1990

12000

12020

12040

12060

Adequate supply of petroleum derived gasoline anddiesel fuels.Introduction of ethanol as octane improver or asa blend in gasohol (10%), and introduction ofmethanol.Production of gasoline from methanol (Mobil Pro­cess)Production of MTBE octane improver from methanol(Arco Process)

Introduction of syncrudes from shale oil and coalderivatives in the feedstocks of the refineries.The product depends upon the amount and composi­tion of the syncrude and the degree of refinipg.

Production of syncrudes equivalent to about 10%of the -potential U. S'. petroleum demand.

Possible production of new engines to match thenew fuels.Production of sy~crudes equivalent to about 30%or 40% of the potential U.s. petroleum demand.

Possible introduction of hydrogen from inexhaust­able energy sources.Production of syncrudes equivalent to more than50% of the potential U.S. petroleum demand.

Alternate non-petroleum fuels dominate.

1-3

gasoline from coal derivatives is rich in aromatic content and is

high in octane numb.er. It is expected that the a1 ternate fuels

will be introduced in the form of syncrude added to the refinery

feedstock. The quality of the produced fuel will depend upon the

quality of the feedstock, and energy expenditure in the refinery.

The increase in the octane number of the fuel (by using more

coal derived fuels) will allow the use of higher compression

ratios and improve the thermal efficiency of the gasoline engine.

The control of sulfur and nitrogen content of the final product

is crucial for limiting the emission of NO· and sulfates from the. xgasoline engine. In addition to emissions, the nitrogen ,and sul-

fur content of the gasoline from syncrude should be reduced to

avoid oil contamination, with resulting engine wear and'deterior­

tion.

1.3.1.2 Alcohols - Alcohols are practical extenders or substitutes

for petroleum fuels. Methanol and ethanol, which are the least

expensive alcohols, can be produced from many sources as indicated

in Table 1.2.

TABLE 1.2 SOURCES OF ALCOHOLS

!t Source

! Methanol CoaljJ ! Natural gasII

,I \ Wood biomassi ~

I Municipal waste•

Ethanol Biomass: grain

sugar cane

other plants

Ethanol is currently marketed as an extender to gasoline in

gasohol which consists of 90 percent gasoline and 10 percentethanol. In a recent study. by T. Austin and G. Rubenstein (3.26)*,

*References are listed in Appendix A.

1-4

..--,:':: '.....~~!~. ,

the use of gasohol manufactured from u.s. grown corn was found to

be uneconomical from an energy point of view, and will increase,

rather than decrease the dependence of the United States on crude

oil. This is an alarming finding and requires immediate action

for further research.

The use of alcohols can take one of the following forms:

a. Alcohol-Gasoline Blends

Blends with a methanol content ?f up to 20 percent have

been found by VW (4.18) to require only minor engine

and vehicle modifications. The high octane number of

the blend allows the use of a higher compression ratio

(C.R.) resulting in a higher thermal efficiency. Using

methanol without increasing the C.R. or optimizing the

spark advance has no effect on the thermal efficiency.

The disadvantages are:

Drop in fuel economy measured in miles per gallon,

caused by the lower volumetric energy content of

the alcohols.

Increase in evaporative emissions, caused by the

increase in the volatility of the alcohol - gasoline

blends.

Increase in NOx exhaust emissions caused by the

leaning of the charge due to blending with alcohols.

(Alcohols have a lower stoichiometric air - fuel

ratio.)

Other problems related to lack of compatibility of

the engine and vehicle materials with alcohol-gasoline blends, and phase separation of the methanol ­

gasoline blends.

b. Neat Alcohols

Neai alcohols allow the use of a high compression ratioresulting in high thermal efficiency. Also, neat alcohols

1-5

with MBT (minimum advance for best torque); spark

timing, and optimum C.R. can produce less NO , HC and CO.x

Problems associated with the use of neat alcohols are:

A cold starting aid is absolutely essential for

starting the engines at temperatures below goC (46°F).

The fuel economy measured in miles per gallon, drops.

1.4 SENSITIVITY OF DIESEL ENGINES

Automotive diesel engines are mainly sensitive to the follow­ing fuel properties: cetane number (which affects every aspect

of the diesel combustion process), distillation range, aromaticity,

viscosity, sulfur content, nitrogen content, and energy density.

1.4.1 Diesel Engine Alternate Fuel Options

1.4.1.1 Broad or Wide Cut Distillates from Petroleum Crude ­

The increa.se in demand for jet fuel and heating oil is puttingpressure on refineries to produce wide cut distillates or diesel

fuels with more, heavier compounds. DF-3, which is heavier and

has a lower cetane number than diesel fuel (DF-2), is being con­sidered for transportation diesel engines. The anticipated main

problems with DF-3 are related to increase in smoke information

and the resulting limitation on power to keep smoke emissions

within bounds.

The wide cut distillates contain lighter compounds than DF-2,

which cause a drop in cetane number and an increase in volatility.No work has been done to study the sensitivity of automotive

diesel engines to broad or wide cut distillates.

1.4.1.2 Synthetic Diesel Fuel from Oil Shale or Coal - Very

limited studies have been made on blends of DF-2 and synfuels

derived from shale oil and coal derivatives.

1-6

1.4.1.3 Alcohols in Diesel Engines - The use of alcohols in

diesel engines may take one of the following forms:

a. Alcohol - Diesel Blends

Mixing alcohols with diesel fuel has been found to re­

ducethe smoke emission, and increase the smoke limited

power. It increases the BSFC, and the hydrocarbon,

aldehyde and noise)emissions.~~

Problem areas are related to:

.Co1d starting caused by the low cetane number of

alcohols,

Lubricating oil contamination by alcohols and their

combustion products, which causes engine wear, and

injection system wear.

b. Alcohol - DF-2 Emulsions

The cold starting problems experienced in the DF-2

alcohol blends, may be reduced by using alcohols as

emulsions. Pure DF-2 is used for cold starting. The

, concentration of the emulsified alcohol increases with

load. This will increase the smoke-limited power.

Problem areas are related to:

The need for an emulsifier and an extra tank.

Complicated techniques needed to control the two

fuels, particularly under transient modes.

c. Alcohol Carburet ion or Manifold Injection and Autoigni­

tion of Diesel Fuel

The engine starts on diesel fuel. Alcohols are intro­

duced into the intake manifold by carburetion or manifold

injection. The fraction of alcohols increases with load.

Problem areas are related to:

Misfiring at light loads,

Self-ignition at high loads,

1-7

The need for elaborate control systems to optimize

the timing and metering of the two fuels,

Excessive increase in the hydrocarbon and aldehyde

emissions.

d. Two Separate Injection Systems

The engine starts on diesel fuel. The alcohol injection

starts after warm up, the amount increasing with load.

Problem areas are related to:

The need for two high pressure injection systems.

The need for elaborate control systems.

e. Neat Alcohols

Neat alcohols have very low cetane numbers and need to

be mixed with two additives: i) cetane improvers to

increase their cetane number, and ii) lubricating oil to

improve their lubricity.

Problem areas are related to:

The absolute need for a starting aid. The aid can

be in the form of an intake air heater, or starting

on diesel fuel. The research work conducted so faron the use of alcohols in automotive diesel engines

has been very limited, and definite conclusionscannot yet be reached in this area. Further workis needed.

1.5 EMERGENCY FUELS

In case of a national emergency, vehicles to conduct certain

essential services would be required. Automotive gasoline and

diesel engines would be required to run on emergency fuels formed

from the available stock of basic fuels, extended with other liquid

fuels. One program was conducted on the use of emergency fuelsin automotive engines in a very limited number of vehicles. The

results of this program showed the following.

1-8

o

) .

a. Only alcohols can be used in automotive gasoline engineswithout the need to reduce the engine compression ratio

in order to avoid knock. The other emergency blends

studied are DF-2, marine diesel fuel, kerosene and

maphtha and their blends with alcohols.

b. For diesel engines: jet fuels, kerosene, medium naphtha

and No.4 fuel oil were used without any significant

()differences in engine operation being observed. Blend­

ing with gasoline and alcohols decreased cetane number,

and smoke. This would probably increase the engine noise,

dilution of lubrication oil, and wear, particularly in the

injection system.

1.6 RECOMMENDATIONS

1.6.1 Future Fuel Characterization

Develop the following:

a. Scenarios for probable future fuels based on the availa­

bility ·of new technologies and energy sources.

b. Data base for the variations in fuel properties caused by

blending the base fuels with different extenders.

c. Data base for the effect of variations in the fuel

properties on cetane number and octane number.

d. Information on the impact of alternate fuels on the

lubrication. of automotive engines.

1.6.2 Gasoline Engines

a. Investigate the sensitivity of gasoline engines to varia­

tions in base fuel properties.

b. Assess tradeoffs in economy, performance and emissions

with variations in the fuel properties which affect cost

and energy savings in the refinery.

1-9

c. Assess the impact of mass-producing gasohols on the U.S.

energy situation, and the U.S. dependence on importedcrude.

d. Study of the use of neat alcohols, and their blends with

gasoline, in automotive gasoline engines. Engines should

be optimized for the alcohols.

e. Find techniques to solve the cold starting problems of

gasoline engines wi!h alcohols.

1.6.3 Diesel Engines.

a. Investigate the sensitivity of diesel engines to varia­

tions in the base DF-2 by varying the fractioni of ~he

1ight and heavy c.ompounds.

b. Assess the tradeoffs in economy, performance, emissions

and variations in fuel properties which have an impact

on cost and energy savings in the refinery.

c. Develop a cetane scale suitable for rating the alternate

fuels.

d. Study the problem of instability of the autoignition

process of low-ignition-quality alternate fuels in dieselengines. Develop techniques to reduce its effect on

engine reliability.

e. Determine techniques to improve the cetane number of

alcohols.

f. Investigate the use of neat alcohols and their blends in

automotive D.I. and I.D.I. diesel engines.

The above recommendations are made to develop basic technicalinformation which is currently lacking.. This information is

essential for utilizing future alternate fuels in automotive

gasoline and diesel engines.

1-10

.,....~.

2. INTRODUCTION AND BACKGROUND

The future supply of automotive fuels, and changes that may

occur in their properties are matters of concern. While today

there are ample supplies of automotive fuels derived from petroleum,

the rate at which the world petroleum demand is increasing is such

that adequate supplies can only reasonably be assured until approxi­

mately 1990 (2.1). Beyond 1990, it will be necessary to introduce

alternative sources of liquid automotive fuels in increasing

quantities. It will also be necessary for the United States to

produce alternative automotive fuels from the more plentiful

domestic energy sources available in order to reduce imports, and

achieve greater energy independence.

Coal and oil shale are the most promising sources in the

United States for the supplemental crude materials (syncrude)

needed for automotive fuel production. The syncrudes may either

be used separately as, refinery feedstock, or fed to the refinery

as part of a mixed charge of natural and synthetic crudes. The

product characteristics will depend on the applicable refining

- technology, as well as on the material in the feedstock.

Alcohols such as methanol and ethanol represent another type

of alternate fuel, which can be produced from coal or biomass.

Fermentation of biomass has been used for thousands of years to

produce methanol and ethanol. More recently, enzymes have been

used to convert cellulose to sugar, which is then processed intoethanol.

The criteria which will affect the future automotive fuels

concern the energy source, conversion technology, environmental

concerns, energy,efficiency, fuel distribution and storage costs,

and certain properties of fuels which control their compatibility

with future automotive engines.

The present types of gasoline and diesel engines are expected

to power vehicles for the rest of the 20th century. The gasolineengine is the most widely used engine for passenger cars.

2-1

The diesel engine, the most efficient transportation engine, is

used in heavy duty trucks and is penetrating the medium duty

truck and passenger car field. Other alternative types of engines

are being considered but are not currently in mass production.

Alternative engines include various types of stratified charge

engines, the gas turbine, the Stirling engine, and the steam

engine.

This report will deal only with the sensitivity of the

currently produced gasoline and diesel engines to variations in

fuel properties. The sensitivity of alternative engines to

variations in fuel properties is beyond the scope of this report.

2 - 2

3. FUEL PROPERTIES AND THEIR EFFECTS

3.1 FUTURE FUELS

3.1.1 General

There is no clear picture of what the future automotive

fuels will be. Published reports by DOE, oil companies, and

automotive companies indicate that the properties of future fuels

might change with time according to the availability of the energy

resources and refining technologies. A possible' scenario of

future automotive fuels, developed from the available information

in the literature is as follows:

1. Immediate term (1980-1990): Alcohols represent the

first alternate fuels which are expected to be introduced in

limited amounts. The currently mass produced au'tomotive fuels

will be available and are expected to be extended by alcohols or

alcohol-derived additives.

Alcohols have been used as fuels for internal combustion

engines for many decades. Methanol and ethanol have been con­

sidered as motor fuels more so than other alcohols because they

are less expensive to manufacture from a numher of different raw

materials. Isopropanol has been used in fuels primarily as an

icing inhibitor and for ~ater scavenging during cold seasons.

Tertiary butanol is currently added,to gasoline by one company as

an octane booster (3.24).

Gasohol, which is a mixture of 10 percent ethanol and 90

percent gasoline, has already been consider.ed by many workers arid

DOE officials as a viable alternative gasoline engine fuel which

can reduce the reliance on imported foreign crude petroleum. In

fact, the price of gasohol has been subsidized by the Federal

Government to make it competitive with the price of gasoline

(3.25). In a recent study (3.26) made hy T. Austin and G.

Rubenstein of California Air Resources Board, questions were

3-1

raised about the validity of the use of gasohol as a more econom­

ical alternate fuel. Austin and Rubenstein indicated that the

use of gasohol manufactured from u.s. grown corn has increased

rather than decreased the nation's dependence on crude oil. Also,they considered that it is more econOmical to make synthetic

fuels from coa~)than to use the same amount of coal to run an

ethanol production facility.

It is clear that a detailed study is rieeded to evaluate the

validity of the arguments used in the Austin/Rubenstein paper,

and to evaluate the economy of the production of eth~nolcand its

use as a gasoline extender.

2. Near-term future (1990-2000): In addition to al~ohols,

. i~ is probable that syncrudes derived from shale oil and coal

derivatives will be mixed with the feedstock of refineries (3.23).The quality of the final product depends on the fraction of

alternate syncrude in the feedstock, the properties of the basic

feedstock and the degree of refining. (3.23)

3. Mid-term future (2000-2020): The production of syncrudesis expected to increase and reach about 10 percent of the u.s.petroleum demand. (2.1)

4. Long-term future (2020-2040): New engine technologies

may be developed in the future to match the fuels which will than

be available. New engine candidates are the gas turbine and

Stirling engine. These engines utilize continuous combustionsystems which have different sensitivities to variations in fuel

properties: These new engines are not covered in this report.

It is expected that the syncrude contribution at the end of thistime frame will reach up to 30 or 40 percent.

5. Far Future (2040-2060): The syncrude production is

expected to equal that of the natural petroleum crude, and grad­

ually replace it. Fuels such as hydrogen, produced using in­

exhaustible energy sources, are expected to be introduced. Cur­

rently, the use of hydrogen as an alternate automotive fuel IS

3-2

contingent on the development of safe and economically competi­

tive distribution and storage systems.

6. Post 2060: Alternate fuels from inexhaustible energy

sources are expected to dominate.

3.1.2 Properties of Future Fuels

The fuel properties important to engine operation are octane

quality (for gasoline engines), cetane quality (for diesel

engines), volatility, viscosity, volumetric energy density, and

impurity content, e.g., sulfur and/or nitrogen.

Establishing the properties of future alternate fuels

is very difficult. However, general trends may be establishedbased on the currently available data on the properties of dif­

ferent sources of fuels. For example, distillates derived from

coal are highly aromatic in nature (3.1) (3.2) (3.3) (3.23) and

are of a high octane quality. But, distillates derived from oil­shale are highly paraffinic in nature (3.4) (3.5) (3.6)

(3.7) (3.23) and would likely have high cetane quali ty and low

octane quality. The less-refined fuels from coal and oil shale

are likely to have high nitrogen and/or sulfur contents (3.4)

(3.6) (3.7) (3.8) (3.9) (3.10) (3.23). The presence of nitrogencompounds can lead to instability resulting in the formation of

gums and ~articulate matter in storage, and the formation of dele­terious deposits in vehicle engines (3.23). The coal-derived

fuels, such as solvent-refined coal and synthetic oils, may also

contain appreciable amounts of ash (3.8) (:L9) (3.11).

Table 3~1 gives the properties of automotive gasoline, diesel,

and jet fuels, processed from shale oil, by Laramie Energy ResearchCenter, Energy Research and Development Administration (3.12).

Gary (3.12) indicated that technology is available to producemotor fuels meeting existing motor fuel specifications from

Western oil shale, but more severe and extensive processing isrequired than for fuels produced from conventional crude oils.

As a result, the synthetic motor fuels will be more costly and their.production more energy consuming than todays petroleum based fuels.

3-3

TABL

E3

.1.

PRO

PER

TIES

OF

SYN

THET

ICM

OTOR

FUEL

SPR

OD

UCE

DFR

OMSH

ALE

OIL

,_..

......_

----

----

Dis

till

ati

on

,O

F

10%

20%

50%

9U%

EP

Dis

t.R

esi

du

e,

%~

IRV

P,

psia

(Max

)~

RON

l-10N

Cu

Str

ipC

orr

osio

nG

um,

mg

/lO

Om

lS

ulf

ur,

ppm

Nit

rog

en

,pp

mF

lash

po

int,

OF

Po

ur

po

int,

OF

Gra

vit

y,

°AP

IC

arb

on

Resi

du

eo

n10

%R

esi

dA

sh,

Wt%

Vis

.@

10

0o

P,

cst

Ceta

ne

Ind

ex

Net

heat

of

co

mb

ust

ion

,B

tu~romatics,

Vo

l%

Ole

fin

s,

Vo

l%

I'.~

Die

sel

Fu

el

Jet

Fu

el

---,---~._.._

_._...

Gaso

lin

e1

-02

-D4

-0JP

5/

JP

4/

Jet

AJet

~

----1

-0-._

_•••••-

.......--

----

13

04

00

422"

45

03

76

23

21

48

40

94

54

46

83

87

25

02

15

42

24

84

50

74

22

29

23

26

46

95

37

60

54

82

36

83

85

51

75

54

62

85

18

40

5

1.0

2.0

1.0

2.0

1.0

1.0

,8

.82

.08

29

1[)

lAIB

lB2

.83

01

00

20

0~

20

02

71

31

41

16

62

02

18

82

12

~2

65

14

0<

00

Ii2

0-2

6-9

14

1.9

39

.8II

39

.04

4.0

57

.00

.14

0.1

60

.36

<0

.00

1<

0.0

01

<0

.00

11

.6

62

.40

2.9

648

54

56

/Ib

18

,16

0_

18

,34

02

1.0

11

.7.

40

30

.4--

Ref

.3

.12

~.}

1,~~~

..!

Figure 3-2 shows that the minimum values for cl?ud-point for

u.s. produced No.2 diesel fuels have been consistently lower than

for diesel fuels produced in Europe. The maximum values, however,

are appro~imately the same. According to EMA (2.1), diesel No.1

~""" fuel or kerosene have been added to No.2 diesel fuel to achieve

the necessary filterability. rhe importation of No. 2 fuel pro­

duced abroad, a trend toward higher end-point for u.s. producedfuel, and diminishing availability of No. lifuel suggest increas­

ing winter operational pro~lems.

Table 3-2 from reference (2.1) summarizes the important

characteristics of u.s. and non-U.S. produced diesel fuels. The

information in Table 3-2 reflects, primarily, the difference in the

refining procedures used. U.S. refiners crack heavy residuals to

increase gasoline yield, whereas cracking is not as prevalent

abroad. The difference in practice accounts for the difference

in cloud-points and cetane numbers.

3.2 STOICHIOMETRY AND COMBUSTION

Stoichiometry and" combustion are related to the HIC ratio of

the fuel. For Indolene, HIC is 1.86, for diesel fuel, HIC is

3-5

360 -- --- - TYPICAL---- EUROPEAN-340

,/

c.J ./ ('j/'

,.: /'

z 320 ,/

- ;I'0 U.S. PR 0 OUCED ;I'a.. /'

Q./

./·z ,/14.1

~/300

NO.2 DIESEL FUEL

70

o'Z

60 .

50

40·

U.S. PROD UCEO

30 ..,....---""":I~---_----r----_----1960 1970 1980 1990 2000

Ref 2-1

YEARFIGURE 3.1. TRENDS OF THE END-POINT AND CETANE NUMBER FOR

U.S. AND EUROPEAN-PRODUCED DIESEL FUEL

3-6

60

40

20 o

uV

I..

Ir

---J

z-2

0- 0 Q

.

0 :> 0 .J-4

0\,

)

.:'.

-6~91o

r19~O

I1

9h

oI

19~O

I2

0b

O

Ref.

2-1

FIG

UR

E3

.2.

YE

AR

TREN

DS

OF

THE

CLO

UD

-PO

INT

OF

U.S

.AN

DEU

ROPE

AN

PRO

DU

CED

DIE

SEL

FUEL

S

G

TABLE 3.2. PROPERTIES OF'U.S. AND NON-U.S. DIESEL FUELSUSE. . uropean

Gravity, API 30-36(31) 36-47(38)

Cetane No. 39-60(47) 55-65

Distillation Range °C 175-332 175-371

Cloud Poi~t °C -16 to -9(-15) -20 to -7~

Pour Point °C -40 to -15(-23) -20 to ~9

( ) = typical value

1.875. The H/C ratio of the fuel may change with the introduction

of alternative fuels.

3.2.1 Effect of H/C Ratio on Stoichiometry

The stoichiometric air-fuel ratio depends upon the H/C ratio

of the fuel. The theoretical AIF ratio varies from 11.491 for

pure carbon to 17.233 for H/C = 4, as shown in Figure 3-3.

Figure 3-4 is a replot of Figure 3-3 showing the stoichiometric

AIF ratio plotted against the number of carbon atoms for different

types of hydrocarbons. For the same number of carbon atoms,

aromatics have the lowest theoretical AIF ratio. Therefore, an

increase in the percentage of aromatics in a distillate fuel

results in an increase in its density, and a reduction in its

stoichiometrIc AIF ratio. The use of such a fuel in an engine

designed for low aromatic fuels may affect fuel metering, the

mixture strength, and the exhaust emissions (3.14).

Figure 3-4 also shows that the stoichiometric AIF ratio drops

at a decreasing rate with the increase in the number of carbon

atoms, n , in the paraffins CnH Zn + Z' For olefins, CnH Zn ' thestoichiometric AIF ratio is the same for all values of n. For the

diolefins, C H2 2' and aromatics, C HZ 6' the theoretical AIFn n- n n-ratio increases at a decreasing rate with the increase in n.

Figure 3-4 shows that the difference between the AIF ratio for the

several hydrocarbon families diminishes as n increases.

3-8

,'tI-~

12

17

16

I 0 'n +-J

C\j~

15

I-I-L

;.., -<

Hr-

iC

Th

eo

r.A

IrC

\j u 'n0

11

."9

1+-

J

14\]

0.7

51

2.-

86

1V

II

11

3.2

76

U)

f-<2

1".7

86

~

16~090

:r3

f-o1

3~

..1

7.2

33

HIC

11

I,

B,

,,

Ie

I,'

o1

23

..

FIG

UR

E3.

3.EF

FEC

TO

FH

YD

ROG

EN-T

O-C

ARB

ON

RA

TIO

ONTH

EOR

ETIC

AL

AIR~FUEL

RA

TIO

18

•

Cnl

l:>

n•

2

Cn"2

n

Cn"2

n-6

/

17 1'-

r-~ c-J U ·rl~ Q

) 81

5Q

) ...c:

E-<o 'rl~ CO ~ ~

16

......... «

'J'l I t--' o

13

II

II

II

~_

IL

",

o5

10

15

20

NUM

BER

orCA

RBO

NA

TOM

S

jl~

:w:1

5

FIG

UR

E3

.4.

EFFE

CT

OF

FUEL

STR

UC

TUR

EAN

DNU

MBE

RO

FCA

RBO

NAT

OMS

ONTH

EOR

ETIC

AL

AIR

-FU

EL

RA

TIO

t J.j

!r

Theoretically, at n = 00, the theoretical AIF ratio for all the

hydrocarbons is that of olefins, which is 14.786.

3.Z.Z Effect of H/C Ratio on the Adiabatic Flame Temperature

Figure 3-5 shows the adiabatic flame temperature calculated

for the stoichiometric mixture at the end of a constant volume

combustion, with chemical equilibrium (3.15). The original pres-~ dsure before combustion is 10 atmospheres, and the original tem-

perature is 77°C. It is clear that the adiabatic flame tempera­

ture increases w!th the de~rease in H/C ratio.

3.Z.3 Effect of H/C Ratio on the (F-A) Standard Cycle

The effect of H/C ratio on the (F-A) standard constant-volume

cycle is shown in Figure 3-6 (3.16). The cycle conditions are as

follows: compression ratio = 8.5, equivalence ratio ¢=l, initialtemperature = Z94.3°K (Zl.3°C), initial pressure = 1 atm.

Figure 3-6 shows that, for the hydrocarbon fuels, the

decrease in H/C ratio has the following general effects: increases

the maximum cycle temperature, decreases the thermal efficiency,

increases the maximum cycle pressure, and increases the meaneffective pressure. Most of these effects are the results of the

variations in the stoichiometric A/F ratio, which decreases with

the drop in the H/C ratio.

For alcohols (CH 30H and CZHsOH) the increase in H/C ratro has

effects similar to those on the hydrocarbons, except that the

stoichiometric AIF ratio increases with the decrease in H/C ratio.

For example, methanol, CH30H, with an H/C ratio of 4, has a

stoichiometric A/F ratio of 6.45, while ethanol, CZHSOH, with anH/C ratio of 3, has a stoichiometric A/F ratio of 9.0

3.3 GASOLINE ENGINE FUELS

Automotive gasoline engines are sensitive to many fuel pro­perties particularly the following:

1. Volatility and distillation range,

3-11

3000

2900VOLUME COMBUSTIONCONSTANT

2800INITI AL PRESSURE - 10 ATM

u INITIAL TEMP. - 70·C•a: '-12 2700&&J~

l.IJ 2600:&<.J

2500......a:J< 2400-Q<

2'300

2 3 4

Hie

Re f. 3. IS.

FIGURE 3. S. EFFECT OF HIC RATIO ON ADIABATIC FLAME TEMPERATURE

3-12

16

%o•%v1

---. - - ""'It ALCOHOLS15

CaL 14-~

~- 13

HYDROCARBONS

,..----'llo~ 7u.-CL'"

44 _::::lc( -I.,..---

~ 42 3000f'..

~

40 2900 :..c(I

""--- 2800 ~- ..... '"p

2700

20u......

ISc(

~u 10 .-0 --~ -....\I) 5

2 3 4

Ref. 3.16

FIGURE 3.6. EFFECT OF HIC RATIO ON THE (F-A)STANDARD CONSTANT VOLUME CYCLE

3-13

2. Detonation and preignition characteristics,

3. Energy Density on both a mass and volume basis,

4. Latent heat of evaporation.

Other fuel properties which affect engine performance, and

which will not be discussed in this report are: chemical

stability, corrosiveness, safety and cost.

Gasoline engines are sensitive to many fuel properties

particularly the following:

3.3.1 Volatility and Distillation Range

Volatility is measured by the Reid Vapor Pressure (RVP) , the

lighter part of the fuel on the ASTM distillation curve, or theEquilibrium Air Distillation (EAD).

Ideally, the fuel shou1~ be equally distributed among thecylinders of the engine, and completely evaporated before ignition.During cold starting, only the volatile portion of the supplied

fuel will evaporate. At the .same time the mass ratio of theevaporated fuel to the total supplied fuel is low. Choking is

applied to increase the mass ratio of the "total fuel supplied"

to the "air" (FT/A), which, in turn, will bring the ratio of

evaporated fuel to air (Fv/A) above the lean ignition limit.

Figure 3-7 shows the distillation curves -for the differentfuels produced from the petroleum crude for use in automotive

engines. Wide cut fuels will have a distillation range which

combines that of gasoline and diesel fuels. The shape and level

of the distillation curve affect gasoline engine performance. The

characteristic indicating the starting quality of a fuel is gen- ­

eral1y considered to be represented by the percentage vaporized at

a fixed temperature of 158°F. The warm-up characteristic isrelated to the temperature at which SO percent of the fuel isvaporized. Fuel economy is related to the temperature at which

90 percent of the fuel is vaporized, because the heavy ends havehigher heating values. Figure 3-8 shows the relationship betweenthe different portions of the distillation curve and the engine

3-14

lO 40 10 .._., ••11' g,.foll.' ..., V.._o

00 ~

y V

l.--~t.,.......oo00

~V

0/......

~2,

~P' '"- :.-- I

~~ ~..- VI.J""'" l--l--

l~V Y VV 1/ )/

00

./[..7'V 6V

V '--"~I,....--

.-00

.J' -:::;;.- i,....o"'" 7't/Y --7 ../' R

r./

- -0

2

l'

•

1. Heavy Diesel oil2. Distillate3. Kerosene4. Summer gasolinp

5. Wintp.T gasoline6. Aviatinn ~asoline .7. Ethyl ~lcohol

8. BPozr>nE'

Ref. 3.17.

FIGURE 3.7. TYPICAL ASTM DISTILLATION CURVES

3-15

- lONG ntIP fCOtto.' -----

DR"'''''DI'O"'I

-- U"""TOI C"Nor IfAlUNO ---

- G"M­_._•.__ WAI",.U' _ __ _ - 'tUO -

'OULING•.- ACCIU .... '.OH & 'own -----• .• - $MOO'HNUI -----­

---- SHOIt 'I., ICONO"" ----

VA'OI- LOCI •

fE.....,

o 10 20--' ,40 ..J~---J'80 90 100

" EVAPORATED

Re f. 3.18.

FIGURE 3.8. EFFECT OF DISTILLATION RANGE ONENGINE PERFORMANCE

3-16

problems.

In gasoline engines, the unburned hydrocarbons and carbon

monoxide emissions are reduced with more volatile fuels, because

leaner mixtures can be used during warm-up. The lower the whole

range of temperatures on the ASTM curve, the shorter is the warm­

up period.

The heavy portions of the fuel, which are represented by

temperatures above the 90 percent point on the distillation curve,

may be deposited on the cylinder wall, and get mixed with the

lubricating oil in the crankcase, affecting its lubricity. Wide

cut fuels, which contain a larger portion of the heavy compounds,

can cause more crankcase oil dilution. This will be discussed in

Section 6 of this report.

For single compound fuels such as methanol and ethanol, the

ratio of (Fv/FT) depends only on the temperature, and cannot be

increased by increasing (FT/A) beyond the point of complete

evaporation. This is illustrated in Figure 3-9. and explains the

difficulty in cold starting with single compound fuels (such as

alcohols) which have low vapor pressure at the low starting

temperatures.

3.3.2 Detonation and Preignition Characteristics

3.3.2.1 Octane Rating - The tendency of any fuel to produce knock

in a gasoline engine depends upon many design and operating

parameters. The knock rating of a fuel is determined by measure­

ments on a standard engine (CFR) , under standard operating condi­

tions (motoring or research conditions), using a standard knock

intensity (measured by a standard knock meter) and a pair of

standard reference fuels (100 for isooctane, and zero for n­

heptane). The octane number of the fuel is equal to the percentage

of isooctane in a mixture of isooctane and n-heptane which pro­

duces the same knock intensity as the tested fuel under the

standard operating conditions. The different standard conditions

for the two octane methods are given in Tahle 3-3.

3 -17 ..

.0

.5

o

0.300.20F

0.\0o

V tJI 100·~

14

/ 2

II

.12

11-t 90°F10

.~I..

8.06 80·F,

/ I.roOF.06

/

/ 60 OF

II ""'OF ore

2 I 30·F

/oV

Q

QO

0.

o

o

a:.~'0:0.~

&A

~o

Re f. 3.19.

FIGURE 3.9. VAPOR-AIR VERSUS FUEL-AIR RATIOSFOR OCTANE (C 8H18 ) AT 1 ATM

3-18

TABLE 3.3. OCTANE RATING METHODS

Motor Method Research Method(MaN) (RON).

Inlet Temperature 300°F 125°F

Speed 900 R.P.M. 600 R.P.M.. I

The motor method is considered more severe because of its higher

inlet temperature and speed requirements.

3.3.2.2 Fuel Sensitivity - The fuel sensitivity is defined as

equal to (RON-MaN). The paraffins show near zero sensitivity

because they are similar in structure to the two reference fuels.

Therefore, the more the paraffinic content of the fuel, the lower

~ts sensitivity. For alternate fuels, the sensitivity depends on

the fuel sources. For example, fuels from coal-derived-liquids

will have a higher percentage of aromatic compounds and a higher

sensitivity than those derived from shale oil. At the same time,

the octane number of the coal derived fuels is higher than that of

the 5hale oil derived fuels. Sensitive fuels tend to knock sooner

= as the inlet temperature is increased.

The use of high octane fuels will not improve the performanceand efficiency of the gasoline engine unless the compression ratio

is raised, or the -spark timing is advanced. It should be noted

that increasing the compression ratio and/or advancing the timing

may increase the NOx and the hydrocarbon emissions.

·3.3.3 Energy Density

Fuel economy is usually expressed in terms of BSFC for

engines, and kilometers per liter or miles per gallon for vehicles.The BSFC is a function of the energy-mass density in 8ddition to

other thermodynamic parameters which affect the efficiency of

- conversion of the chemical energy of comhustion to useful mech­

anical work. The energy-mass density of sever~l fuels is given In

3-19

Table 3-4. Table 3-4 shows that methanol has 49 percent of the

energy-volume de~sity of gasoline, and ethanol has 65.6 percent

of the energy-volume density of gasoline.

TABLE 3.4. SPECIFIC GRAVITY AND ENERGY-DENSITYFOR DIFFERENT FUELS

SpecifiG Ener~-Mass Energy-VolumeGravi ty') . De sity Density

(Dens i ty) * ,I BTU/Ibm BTU/Gallon

High Low . Low

Gasoline 0.739 20,300 19,070 117,400(6.156)

Kerosene 0.825 19,750 18,510 127,200(6.872)

Light Diesel Fuel 0.876 19,240 I 18,250 133,200(7.297) I

! I!

Medium Diesel Fuel 0.920 I 19,110 , 18,000 138,000(7.663) ! I, I ,

Methanol 0.796 9,750 8,570 56,800(6.630)

Ethanol 0.794 12,800 11,500 76,100(6.614)

i

* IDensity-Pound/U.S. Gallon. '-

The energy-volume density is directly proportional to the

product of the energy-mass density and the specific gravity.

Diesel fuel has the highest energy volume density, followed by

gasoline, ethanol and methanol.

The energy density of the fuel affects the storage and

transportation related costs which contribute to the final market

price of the fuel.

3.3.4 Latent Heat of Evaporation

Table 3-5 shows the latent heat of evaporation for several

fuels, and the drop in the inlet air temperature (6T) with

3-20

..

complete evaporation of the fuel in ait to a stoichiometric A/F

ratio.

TABLE 3.5. LATENT HEAT OF EVAPORATION OF DIFFERENT FUELS

H BTU I~T of,)

fg Ibm

Gasoline 150 40

Ethyl Alcohol 361 I 153 !I

I

Me'thyl Alcohol 474 ! 300I

Light Diesel 115 30

3.4 DIESEL ENGINE FUELS

Automotive diesel engines are sensitive to many fuel proper­

ties, in particular the following:

1. Autoignition Quality

2. Volatility

3. Viscosity

4. Specific Gravity

3.4.1 Autoignition Quality

3.4.1.1 Centane Rating - The autoignition quality of the fuel is

related to the rates of the preignition processes which take place

in the period of time between fuel injection and combustion.

These processes can be divided into two major types: physical and

chemical processes. The physical processes are: (1) spray dis­

integration and droplet formation, (2) heating of the liquid and

evaporation, and (3) diffusion of the vapor into air to form a

combustible mixture. The chemical .processes are: (1) the decom­position of the fuel molecule to lighter compounds, and (2) the

oxidation reactions which release the chemical energy. These

processes overlap, but the early processes are mainly physical and

3-21

the latter processes are chemical. The fuel properties affect

both the physical and chemical preignition reactions.

The autoignition quality of the fuel is measured by theperiod of time between the start of injection and the start of

pressure rise or illumination due to combustion. In diesel

engines, the start of pressure rise due to combustion is the cri­

teria used to indicate combustion. The autoignition quality is

indicated by the cetane number of the fuel wH)ch is measured in

a standard engine (CFR) , under standard operating conditions(RPM = 900, T. = 150°F), by using a pair-of standard reference. a J.rfuels (100 for cetane, and 15 for hepta-methyl-nonane). In the

CPR engine, the C.R. is varied to produce an ignition delay of

l3°C.A., with the dynamic injection timing at l3°C.A. BTDC. Therelationship between the C.R. and C.N. is given in curve 1 of

F'igure 3-10. The cetane nlDTIber of the fuel, according to the

ASTM D-6l3 method, is given by the following equation:

C.N. = % n-cetane + 0.15 (%I1MN)

According to the above ASTM method, fuels can be rated between

C.N. 100 and C.N. 15. But below C.N. 15, fuels cannot be ratedby this standard method.

3.4.1.2 Problems Related to the Autoignition of Some Aiternate

Fuels

a. ASTM D-6l3 Rating Method

Alternate fuels which have cetane nlDTIbers less than IS can­

not be rated by using the ASTM D-6l3 method. These fuels includegasoline, ethanol and ethanol. For such fuels, the low standardreference fuel should have a C.N. of zero rather than the C.N. of

15 used in ASTM D-6l3. In earlier methods, alpha-methyl­

naphthalane (ctMN) was used as a zero C. N. reference fuel. Curve

number 2 of Figure 3-10 is a scale obtained by using n-centaneand aMN as reference fuels. It is noted that a C.R. higher

3-22

10 20 30 40 SO 60 70 80 eo 100CETANE NUMBE~

RELATIONSHIP BETWEEN THE C.N. AND C.R. IN THE CFRENGINE WITH HMN AND XMN AS REFERENCE FUELS

CETANE SCALE BASED ON BLENOS2 OF n-CETANE 8 aMN, lj= I~OoF,

1.0.• 13 0

o

CURRENT ASTMCETANE SCAl.E RANGE

i n -CETANEa HMN, T II 150°F

1.0.• 13°

:IiU1ft

30.0

29.0

2B.0

21.0

26.0

2e.0

24.0

23.0

22.0

21.0

20.0

0 19.0-t:tQ: 18.0

ZQ 17.0tntn 16.0UJa::Q.:E 15.00U

14.0

'3.0

12.0

11.0

10.0

~.O

8.0

7.00

Ref. 3.2l.

FIGURE 3.10.

3-23

than 29:1 is needed for C.N. = 10. For lower cetane fuels, aC.R. exceeding the highest C.R. of the CFR engine is needed.

Many attempts have been made by the U.S. Army Fuels and

Lubricants Research Laboratory to extend the scale to lower than

C.N. = 15. These are summarized in a comprehensive SAE paper by

Urban and Gray (3.20) a~tl include the following:

i. Blend normal cetane with the sample, and then, calcu­~)

late the sample cetane number from the cetane number

of the blend.

11. Correlate the cetane and octane numbers of the sampleas shown in Figure 3-11.

iii.. Use an I.D. = l7 C C.A. instead of the standard I.D. of

l3°C.A.

All these methods proved to be unsatisfactory. In a more recent

study (3.21), a modified cetane scale was developed by increasing

the inlet air temperature from 150°F to 350°F, which allowed fuels

of C.N. as low as zero to be rated at a C.R. of 19.5:1. This

modified scale is shown in Figure 3-12.

There is a need for an extensive study of the modified scale

by using inlet temperatures between the standard temperature of

150°F and 350°F. This study is needed to determine the most

suitable inlet air temperature for the cetane rating of fuels in

the CFR engine.

b. Cycle-to-Cycle Variation in the Ignition Delay

Low ignition quality fuels having C.N. <20 have been observed

to produce cycle-to-cycle variations in the ignition delay asindicated in the pressure traces shown in Figure 3-13. It should

be noted that for all the fuels shown in Figure 3-13, the start

of needle lift was at 13° BTDC according to the ASTM D-6l3method, and cycle-to-cycle variations in the needle lift were not

observed. The cycle-to-cycle variations in the pressure trace,

at the point of pressure rise due to combustion, increased with

the decrease in the cetane number of the fuel from 20 to zero.

3-24

20

•

•

eN = 146. 0 - 1. 48 (ON)

SEE = =1.6

.'•

••

8

6

16

18

14

1 2

10

...1/

.D

E::lZI/'CIII...&I

L>

84 86 88 90 9Z 94 96

Motor Octane Number

Each point represents the average of several determinations.

FIGURE 3,11. CORRELATION BETWEEN THE C.N. ANDO.N. OF DIFFERENT FUELS

3-25

!C.O

29.0

2e.o

21.0

26.0

2~.0

24.0

23.0

22.0

21.0

20.0

19.0

C- Iaoi=it(

17.0a::zQ 18.0VIU')

I~OL&Ja::0- 14.0:t0U I~O

12.0

1/.0

10.0

8.0

8.0

Ref. 3. 21. 7.00

FIGURE 3. 12.

o AVERAGE OF :s RUNS USINGBLENDS OF n-C£TANE a ALPHA­METHYLNAPHTHALENEC.MH)REF'ERENCf: FUELS.

CETANE SCALE BASED ON Bl.ENDSOF n-CETANE 8 QtMH, T1.1~OoF,I.D. lII3 o. .~.. .

~ EXPEnEMENTAl. CETANESCALE BASED ON BL.ENDSOF n-CETANE 8exMN

1j • 3~0OF , I.D.= 13~

Cl..~ "".. er.uc....--- Ic..u..r; • .uta ---......

_ ..l... L I I I

10 20 ::Ie 40 ~ GO TO 80 eo 10c)

CETANi: NUMBERA MODIFIED CETANE SCALE FOR RATING LOWIGNITION QUALITY FUELS

3-26

(b)

(e)

(d)

,",,:n,§

.~

_~(L

1P

/L1

t)p

re

"""~:

;:,,.j=

jP

inj

(a)

~ I N ----I

(c)

Ref.

3.2

1.

(f)

FIG

UR

E3

.13

.CYCLE~TO-CYCLE

VA

RIA

TIO

NIN

THE

AU

TOIG

NIT

TON

OF

FUEL

SOF

DIF

FER

ENT

CETA

NE

Nill

1BER

S

"-J

This cycle-to-cycle variation in the I.D. explains the erratic

operation of the I.D. meter used in the ASTM D-613 method, reported

by Urban and Gray (3.20), during the rating of low C.N. fuels.

There is a need to study the source of the cycle-to-cycle

variation in the autoignition of low C.N. fuels~ and methods to

control it.

3.4.1.3 Ignition Delay Correlations - Many correlations have been

developed between the ignition delay and the air properties in

diesel engines for the regular fuels. These" correlations are

reviewed in reference (3.22).

There correlations are of the general form

I •D D =

E

AeRT

np

where

1. D. is in units of time

A is a pre-exponential factor

E is the global activation energy-R is the universal gas constant

T is the absolute temperature

p is the absolute pressure

n is an exponent

There is a need to develop such correlations for the other"alter­

nate fuels which might be used in the future in diesel engines.

The effects of increasing the aromaticity and the distillation

range of the petroleum fuels, and blending the diesel fuel with

alcohols, and coal and shale derived distillates, need to be

determined. These correlations will be needed in the future to

3-28

determine the sensitivity of the I.D. to fuel properties and the

most effective techniques to reduce the ignition delay.

3.4.2 Volatility and Distillation Range

The sensitivity of the diesel engine to variations in fuel

volatility are summarized in Figure 3-14.

3.4.3 Viscosity

The sensitivity of diesel engines to variations in the fuel

viscosity are illustrated in Figure 3-15.

3.4.4 Specific Gravity

Figure 3-16 shows the relative performance versus fuel

specific gravity, and BTU per gallon when operated in a particular

engine at constant fuel pump setting. The increase in efficiency

as the -fuel becomes lighter is due to reduced F/A ratio. At a

constant efficiency, the effect on power is due entirely to t~e

changes in heat of combustion per unit volume.

3-29

- Low rates of mass diffusionresulting in poor mixingand exhaust smoke.

:; .-l

High content of heavy ~polycyclic aromatics .~

which are slow in burning~~__ o~and produce exhaust smoke. ~

cl1J1-41-4:lU

- Long ignition delayscausing high rates ofpressure rise, noise,and vibrations.

Vapor lock on the lowpressure side of theinjection pump.

- Excessively high diffusionrates resulting in poorcombustible mixtures andincreased He anc aldehydeemissions.

Volatility

FIGURE 3. 14. PROBLEMS ASSOCIATED WITH VARIATIONSIN DIESEL FUEL VOLATILITY

~

Eoor lubrication and ~fuel leakage I particularly .~at low speeds. _ ..-.....,.::0 ~

~ l1JC :ll1JtL.1-41-4::lU

- Poor handling by thefuel injection pump

__~.-requiring heating.

- Poor spray atomization.

Viscosity

FIGURE 3.15. PROBLEMS ASSOCIATED WITH VARIATIONSIN DIESEL FUEL VISCOSITY

3-30

SOtt,1 'e ,raw",Q 090 08~ 080

1..'_.......I.__L.-_...L..._...J.._---J'I-..._...L..._.....L._--1__.L-__'L.-_...L...__

~18.~00 18.600Qe , Blu/lDm

111.100 111,1100 111.900

I • I I, • Full 'ood -I

!~ - ~/."

I I I ~ r--::: " 11z'\ 00 I I

II' r-r-~I II I" : r1I I

Oil ,7~ ~

,5 I

,2 'II F..., ""mh',

0ii

II0

oc

..•o0.

" 8.e<C~ 7

! I I !....J I II "'_-------- ---

I.--~~ i II.... I i

II

I

1-D,fc •

027

026 .,

o 2~

O~O

28 30 32 3<1 36 38

API "OW",40 42 44 46

13~ 130Blu oe' 90110" llllOullO""')

NOTE: BSFC Points are average for all loads

Re f. 3.19.

FIGURE 3.16. RELATIVE P~RFORMANCE OF A DIESEL ENGINE ATCONSTANT FUEL-PUMP SETTINGS VERSUS SPECIFICGRAVITY OF FUEL.

3-31/3-32

4. SENSITIVITY OF AUTOMOTIVE GASOLINE ENGINESTO VARIATIONS IN FUEL PROPERTIES

4.1 ALCOHOL-INDOLENE BLENDS

4.1.1 Effect of Blending Gf~oline and Alcohols on Octane Number

Figure 4.1 sh~ws the effect on the octane number of addingmethanol to Indo1ene (4.1). Methanol improved RON more than MON.

This observation has been made by many investigators. Johnsonand Riley (4.1) developed the following correlation to describe

the effect of methanol on fuel octane rating:

ONB = Nt + 6N[1-exp(-Kx)]

where

ONB = octane number of blend

x = volume % methanol in blend

Nt = RON or MaN of base fuel

liN = octane increment from addition of methanol

K = base fuel response factor

6N is fixed for any given base fuel and indicates how effectivemethanol will be in raising the O.N. of the base fuel. The varia­

tion in 6N with the base fuel O.N., obtairied by Johnson (4.1), is

given in Figure 4.2. This Figure shows that the higher the octanenumber of the base fuel, the lower the antiknock achieved by add­ing methanol. Also, the MaN curve shows significantly smaller

octane increases than those found for the RON. Base fuels with aMaN greater than 83 gave virtually no change in MaN when blendedwith methanol.

4.1.2 Effect on Flame Speed

The effect of blending Indo1ene and methanol on the flamespeed in a CFR engine is shown in Figure 4.3. The flame speed 1S

measured by using an ionization gap probe. This figure shows that

4-1

120,..---.,..-----------.-.---

lASE FUEL' D (".llItON. I.,., MON)METHANOL.' (.09.5 IlION. '6.0 WON)

110

_OTOR

61li1 e 0.66". 0.0345

• RESEARCH

6N • 12.00K·00ZI'6

10020 40 60 80VOLUME % METHA,NOL.

10-_--1__.........__........__.-1-__""""

o

Ref. 4.1.

FIGURE 4.1. OCTANE CHARACTERISTICS OF GASOLINE METHANOL BLENDS

4-2

oL-_-.J..__J......_.-L.--==--...L-_--.l.__~

- 70 80 90 100lASE FUEL OCTANE NUMBER

Ref. 4-1.

FIGURE 4.2. CORRELATION BETWEEN OCTANE INCREMENT AND BASEFUEL OCTANE NUMBER

4-3

)(3

0%

ME

TH

AN

OL

04

0%

ME

TH

AN

OL

.9

00

RPI

,,1.

C.R

.:5

toI

SP

AR

I(T

IMIN

G:

180

BT

OC

oB

AS

ELI

NE

.v10

%M

ETH

AN

OL

21

00

-1!3

200/

0M

ETH

AN

OL

18

00

. u w Ul

17

00

".~ U1

90

0,

N'7

~"",..-

)f

...

0+>

-W

I .j::

.W 0

-1

50

0U

l

W11

00~ <

t-J lL

10

0

1.00

1.80

_2D

O

Ref.

4.2

EQ

UIV

ALE

NC

ER

AT

IOFI

GU

RE

4.3

EFFE

CT

OFBL

END

ING

MET

HANO

LW

ITH

IND

OLE

NE

ONTH

EFL

AME

SPEE

D

t~L

a blend, having 20 percent methanol, produced the highest maximum

flame speed.

4.1. 3 Effect on a Single Cylinder Engine's Performance, Thermal

Efficiency and Emissions

4.1.3.1 Power Output and Minimum Advance for Best Torque - Add­

ing methanol to Indo1ene allowed higher compression ratios to beused without knock and resulted in a horsepower increase as shownin Figure 4.4. The maximum gain in power output is with 25 per­

cent methanol; higher percentages of methanol do not further in­crease the power output. In fact, the output with 40 percent

methanol is less than that with 25 percent methanol. The MBT

(minimum advance for best torque) for each blend is also shown in

Figure 4.4. The compression ratio that corresponds to each ofthe Indo1ene-methanol blends is given in Table 4.1.

TABLE 4.1. COMPRESSION RATIOS CORRESPONDING TO VARIOUSINDOLENE-METHANOL BLENDS

PERCENT 0 5 10 15 20 25 40METHANOLI

jCOMP. 7.2:1 7.5: 1 7.62:1 7.73:1 8.1: 1 8.0:1 8.0:1jRATIO

4.1.3.2 Fuel Economy - Brake specific fuel consumption resultsare given in Figure 4.5, and show an increase in fuel consumption

with the addition of methanol. This is caused by methanol's lowerheat of combustion (4800 k cal/kg) as compared to Indolene

(10,600 k cal/kg).

On an energy basis, the brake specific energy consumption inK cal/BHP hr is plotted in Figure 4.6 for different blends. Add­ing methanol to Indolene has a definite effect on decreasing the

4-5

WIDE OPEN THROTTLE 900 RPM

c 25~oMETHANOL

.to 40/o METHANOL

•o

...\l

•

c:w~0~

w(f.l

c:0:I:

w...::.:::c::{Q::.CD

3.6 .-u0

3.4 ~

a:l

3.20w0..."

3.0 wuz

2.8 ~0c::{

2.6 ::.:::Q::.

~2.4 (/)

402.2

302.0

20

10

0

.7

. Ref. 4.2.

.8 .9 1.0 1.1 1.2

EQUIVALENCE RATIO q,1.3

FIGURE 4.4. EFFECT OF MIXING METHANOL WITH INDOLENE FUEL ONBHP AND MBT

4-6

SPARK ADVANCE MBT

WIDE OPEN THROTTLE 900 RPM

1.3.8 .9 1.0 /.1 1.2

EQUIVALENCE RATIO P

• INDOLENEo 5%METHANOL

~ 10% METHANOL

v 15% METHANOL

• 20% METHANOLc 25/0 METHANOL

z .9o-.....a..~ .8(f)

zou .7-1W~I.J... .6

u~

u .5wQ..(f)

w .4-t----,r---r---r-..,..---,.-.,......--r--,..-...,...-,.-....,......-.

~ .7c::coRef. 4.2.FIGURE 4.5. EFFECT OF MIXING METHANOL WITH INDOLENE ON

BRAKE SPECIFIC FUEL CONSUMPTION

4-7

.,

WIDE OPEN THROTTLE

900 RPMSPARK ADVANCE MBT

• INDOLENEo 5 °h METHANOL'Y 10% METHANOL~ 15% METHANOL

"• 20"0 METHANOLo 25% METHANOL

4000a::~,~

~

m"--J<U~

z3500o-~Cl.:E:::>CJ)

zou

G 3000a::I.LJZ~

U-IJ..-ULLJ£l.fI) 2500

1.20 1.301.101.00.90.80

2000 --L.__--L..__........__""""-- ~

.70

Ref. 4.2. EQUIVALENCE RATIO

FIGURE 4.6. EFFECT OF MIXING METHANOL WITH INDOLENE FUEL ONBRAKE SPECIFIC ENERGY CONSUMPTION

4-8

specific energy consumption or improving the brake thermal effi­

ciency for equivalent ratios between the lean limit and the stoi­chiometric. This is attributed to many factors including the in­

crease in the allowable compression ratio with methanol, the

lower time losses caused by the higher flame speeds, and the

lower heat losses caused by the lower combustion temperatures.

4.1.3.3 Hydrocarbons - The effect of adding methanol to Indoleneon the brake specific hydrocarbons (HC) is shown in Figure 4.7for different equivalence ratios. It is noticed that, in general,

the HC emissions tend to increase with methanol, particularly inthe lean mixtures. This increase is expected to be more signi­ficant if the response of the HFID (Heated Flame Ionization De­

tector) to methanol is into consideration.

The increase in (HC) emissions with methanol is attributedto the higher volatility of the methanol-Indo1ene blend (as com­

pared to that of pure Indo1ene) and to the presence of more fuel

per pound of air for a given blend. These factors lead to higherconcentrations of HC in the quench layers and crevices.

4.1.3.4 carbon Monoxide - Figure 4~8 shows emissions of carbonmonoxide as a function of ¢ for various blends. This follows the

expected trend that (with and without methanol) very little CO is

emitted on the fuel-lean side down to ¢ = 0.7, and the concentra­tion of CO increases as ¢ increases on the fuel-rich side. At a

given fuel-air equivalence ratio, the brake specific CO slightlyincreases with methanol.

4.1.3.5 Nitrogen Oxides - The effect of methanol on the brakespecific NO emissions is shown in Figure 4.9 for different meth-

xano1 ratios as a function of the equivalence ratio. It is noticed

that the specific NO x emissions increase with methanol for richmixtures having ¢ more 1.1. For leaner mixtures, the specific

NO x is reduced to different degrees with methanol content. The

brake specific NO x peaks at richer mixtures with the addition ofmethanol.

4-9

1.31.21.1

RATIO <p.8 .9 1.0

EQUIVALENCE

--

.7

5

10

WIDE OPEN THROTTLE 900 RPMSPARK ADVANCE MBT

"1"')

• rNDOLENEo 5 % METHANOL• 10% METHANOLV 15% METHANOL

20 • 20% METHANOL

C 25% METHANOL15 & 40 rio METHANOL

a:::Id..:r:~(j)

~«a:<.9

UI

UlJ..

UWa..(f)

. _w.~

«a::.CD

. Ref. 4.2.

FIGURE 4.7. EFFECT OF MIXING METHANOL WITH INDOLENE FUEL ONBRAKE SPECIFIC UNBURNED HYDROCARBONS.

4-10

EFFECT OF MIXING METHANOL WITH INDOLENE FUEL ONBRAKE SPECIFIC CARBON HONOXIDE.

.8 .9 1.0 1.1 1.2 1.3

EQUIVALENCE RATIO <p

"

900 RPMWIDE OPEN THROTTLE

SPARK ADVANCE MBT

420 • INDOLENEo 5 ~o METHANOL~ I 0 % MET HAN aLv I 5 % MET HAN 0 L

• 20 0/ 0 'METHANOL

c 25;to MET HAN 0 L

A 40% METHANOL

:/0::I

I

§:340OJ

"(/)

~300<t:0::0

2400u

u l801...l--U

~ 120(J)

w~ 60<t:0:::.co

0.7

Ref. 4.2.

FIGURE 4.8.

4-11

. 1.3

900 RPM

METHANOLMETHANOLMETHANOL.,METHANOLMETHANOLMETHANOL

o 5 %

... 10 %

V 15 %

• 20/0·0·25/0

40%

.8 .9 1.0 1.1 1.2

EQUIVALENCE RA TIO <P

WIDE OPEN THROTTLESPARK ADVANCE MBT

elNDOLENE

.7

40

350

0:::I:

30ICl..ICD

~ 25~<!a::e,:) 20

x0z

15u-lJ....-Uw 100...enw~ 5<x:cr.C!J

Ref. 4.2.

FIGURE 4.9. EFFECT OF MIXING METHANOL WITH INDOLENE FUEL ONBRAKE SPECIFIC NITRIC OXIDES.

4-12

The peak values of the specific NO x curves are plotted in

Figure 4.10, and show a definite reduction in specific NO x withthe increase in percentage methanol up to about 30%.

4.1.4 Effect of Alcohols on a Non-Catalytic Car

The effect of using a blend of 10 percent methanol/gasolinefuel in a non-cat~lytic car has been reported by Johnson and Riley

and is given in Figure 4.11. The baseline fuel is Indolene. Based

on this figure and other results reported by Wigg and Lung (4.3)

and Brinkman et al (4.4), the following conclusions are made:

(i) Adding 10 percent methanol to unleaded gasoline will

reduce the CO emissions by approcimeately 30 percent.

(ii) Adding 10 percent methanol to unleaded gasoline does

not substantially change the HC or NO x emissions.

(iii) The miles per gallon of fuel is less forblends than for the unmodified gasoline.caused by the low energy content per unit

methanol as compared with Indolene.

the methanol

This isvolume of

(iv) However, there was a slight increase in the milestraveled per million BTU's, indicating a slight in­

crease in the energy efficiency.

4.1.4.1 Effect of Alcohols on 1978 Catalytic Cars - Naman and

Allsup (4.15) of DOE reported the results of~hassis dynamometer

test on eight 1978 vehicles. Five vehicles had oxidation catalystsand 49-state emission control systems, and three vehicles were

equipped with 3-way catalysts and California emission control sys­tems. The spark timing and idle speeds were adjusted to the manu­facturer's specifications (which probably were optimized for In­

dolene fuel). The extenders were 10 percent ethanol, 10 percent

methanol, 7 percent methyl tertiary butyl ether, and 7 percenttertiary butyl alcohol. The exhaust emissions and fuel economies

were measured on the 1978 Federal Test Procedure (FTP), using achassis dynamometer. Fuel economy was measured using the carbon

4-13

c

Q,

.•~=

.B65

•<{

>=.8

85<1

>=.8

95-

16-1

.~=.970

28

2040

32

24

36

1015

20

25

30

35

40

Ref.

4.2

.P

ER

CE

NT

ME

TH

AN

OL

.FIG

UR

E4

.10

.EF

FEC

TO

FM

IXIN

GM

ETHA

NOL

WIT

HIN

DO

LEN

EFU

ELON

PEA

KBR

AK

ESP

EC

IFIC

NIT

RIC

OX

IDES

0:: :r I 0... :r m ~.

en ~ <{ a: 0

x 0 Z U - l.L. -

+:>

0I

·wt-

'+:

>Q

.. en w ~ <{

0:: m ~ <{

·w n..

Q,

""-JCD<ir<[

>-20

Z

38.5

4.2

CIPfMJ9Jf MR FlPRflS: IrcxuNE eN),

JICD.EJ£ • lei Pnwo..\tMJQ£:

JDJ Ct~ AInt.1\10 WI'" 6ltJa.J lIE.

, 275C La IIG'TIA ItT.M. D'USSI~. ~ A.£L.:

I( -1.99~,

m- 36.6 PI"',Illx - 2.70 ew~,

~-17.2

. 1)(;7(;

Ref. 4.1-FIGURE 4.11. CHANGES IN FTP RESULTS FOR 10% HETHANOL ADDED

TO INDOLENE IN A NON-CATALYTIC CAR

4-15

balance method. The evaporative emissions were measured usingthe 1978 Sealed Housing for Evaporative Determination (SHED).

The properties of the fuel and alcohols used in this inves­

tigation are given in Table 4.2. The properties of the blends

are given in Table 4.3. The results 'reported by Naman (4.15) aregiven in Table 4.4). These results show the following:

,

1. The fuel economy, on a mpg basis, decreased from 2,7

to 7.6 percent with each blend from that of the base

fuel. But from an energy point of view the miles per

million BTU decreased from 0.5 to 2.02 percent from

that of the base 'fuel. In one case, the ethanol ex­

tender increased the miles per million BTU by 0.5percent. The results computed on an energy basis are

given in Table (4.5).

2. CO emissions decreased from 8 to 46 percent dependingon the emissions control syst~m used.

3. HC emissions decreased from 5 to 32 perc~nt.

4. NO x emissions were either unaffected or increased.

5. Evaporative emissions increased proportional to the in­crease in RVP as shown in Figure 4.12. The 10 percentmethanol blend has the highest evaporative emissions

and RVP.

4.1.5 Effect of Blending on a 3-Way Catalyst Car with Closed

Loop Emission Control System at Constant Speed

The effect of' blending gasoline with methanol was determi~ed

by Lawson, et. a1. (4.5) in a Volvo 244 DL car, with ~-sond

emission control system. The sensor is designed to control the

F/A ratio at the stoichiometric value. The effect of increasingthe percentage of methanol in the gasoline/methanol blend on

engine performance and emissions is shown in Figure 4.13. Theoxygen sensor was found to continue to maintain stoichiometric

F/A control with increasing methanol content in the blend up to

4-16

TABLE 4.2. PROPERTIES OF THE DIFFERENT FUELS

Indo1ene Ethanol Methanol !'!TBE TBAC8H15 C2H6O CH 40 C5H12O C4H10O

Molecular Weight 99.65 46.07 32.04 88.14 74.12

Specific Gravity 0.739 0.794 0.791 Q 0.741 0.784

Density 1b/gal. 6.15 6.62 6.60 6.18 6.54

Heat of Combustion 18,558 11,613 8,495 ·15,100 14,025BTU/lb

Heat of Combustion 114,132 76,878 56,067 93,318 91,724BTU/gallon

Stoichiometric A 14.8/1 9.0/1 6.45/1 11. 7/1 11/1F

Ref. 4. IS.

4-17

TABLE 4.3. PROPERTIES OF BLENDS OF INDOLENE AND ALCOHOLS

2 3Fuel No. 1

Specific gravity, @ 60 o /60 o F••••

API gravity, degrees ••••..••••••

Sulfur, wt pct •. ~ ..•••••.•.•..••

F.I.A., pct:Aromatics••.......•••••....••.01efins ••.••......••••......••Saturates .•..•....••••...• : •••

Reid vapor pressure, psi •••..•..

Hydrogen/carbon ......•••••••.••.

Oxygen/carbon•••....•••••••.•••.

Distillation, OF:

I ElP •••••••••••••••••••••••••••5%•••••••••••••••••••••••••••

10% .•..........•.......••.•••.20 %•••••••••••••••••••••••••••30 %•••••••••••••••••••••••••••40\.g._ ••••••••••••••• ~ ••••••••50\ 0 •••••••••

60% •••.•••••••••••••• e ••••••••

70% .•....•••.....••.••.•.•.•..80 %•••••••••••••••••••••••••••90% ..................•........ '95% ..•...............•........End point .

Recovery, pet .........•....•....

Residue, pct ....•........••••.•.

Loss, pct ••......•••......••••..

1

0.739

60.0

.002

251

74

8.6

1.90

9212213816719'3214229242259294326335356

98.0

1.0

1.0

0.744

58.7

.002

251

74

9.7

1. 97

.034

102120130143152182222238250284320334346

98.0

1.0

1.0

0.744

,58.7

.002

251

74

11. 9

2.00

.049

96110116123131191219235252283321332345

98.0

1.0

1.0

4

0.740

59.7

.001

241

75

8.7

1. 93

.012

93120133157178200228238252282322330348

98.5

.5

1.0

5

0.741

59.5

.002

241

75

9.1

1. 93

.014

96123131\153172195218234250284322331350

98.0

1.0

1.0

IFuel No.1 = Indolene (base fuel}.Fuel No. 2 = Fuel No. 1 + 10% ethanol.Fuel No. 3 = Fuel No. 1 + 10% methanol.Fuel No. 4 = Fuel No. 1 + 7% MTElE.Fuel No. 5 = Fuel No. 1 + 7% TEA.

Ref. 4.15.

4-18

f:{

TABL

E4

.4.

SUM

MAR

YO

FTH

EEX

HA

UST

EM

ISSI

ON

S,EV

APO

RA

TIV

EE

MIS

SI6N

S,AN

DFU

ELEC

ONOM

Y

Fu

el

Descri

pti

on

Fu

el

Eco

no

my

,m

pgU

rban

Em

issio

ns,

gm

/mil

eH

CC

O.

NO

xA

ldeh

yaes

.m

g/m

ile

To

tal

Ev

ap

ora

tiv

eE

mis

sio

ns,

gm

OX

IDA

TIO

NC

AT

AL

YST

VE

HIC

LE

S(5

-CA

RA

VE

RA

GE

)----------------------

Fu

el

No

.1

(In

do

len

e)

18

.60

.85

8.5

61

.6

31

82

.8

Fu

el

No

.2

(In

do

len

e+

10%

eth

an

ol)

17

.9.5

84

.66

1.

63

18

4.0

Fu

el

No

.3

(In

do

len

e+

10%

meth

an

ol

17

.5.6

24

.64

1.

89

27

5.4

Fu

el

No

.4

(In

do

len

e+

7%M

'I'B

E)

18

.0.6

85

.78

1.6

21

43

.5

Fu

el

No

.5

(In

do

len

e.j:

::.

+7

%'I'

SA)

18

.0.7

87

.88

1.

75

17

3.0

I f-'

I.Q

)-W

AY

CA

TA

LY

STV

EH

ICL

ES

(3-C

AR

AV

ER

AG

E)

-----------

Fu

el

No

.1

(In

do

len

e)

18

.5.4

36

.23

0.4

84

2.0

Fu

el

No

.2

(In

do

len

e+

10%

eth

an

ol'

18

.0.3

94

.55

.59

82

.3

Fu

el

No

.3

(In

do

len

e+

10%

meth

an

ol)

17

.1.4

14

.47

.71

43

.8

Fu

el

No

.4

(In

do

len

e+

7%M

TB

E)

17

.9.

31

4.5

1.6

57

2.2

Fu

el

No

.5

(In

do

len

e+

7%T

BA

)1

7.7

.32

4.8

9.5

89

2.1

D

TABLE 4.5. FUEL ECONOMY WITH DIFFERENT BLENDS BASED ONTHEIR ENERGY CONTENT

Blend1 2 3 4 5

Heat of Combustion c)BTU/gallon 114132 110407 108326 112675 112564

% Change in Heatof Combustion 0 -3.26 -5.09 -1.3 -1.4

Miles per millionBTU(a) Oxidation ca-

talyst cars(average o.f 5) 163 162.1 161. 6 159.8 159.9

(b) 3-way catalystcars (averageof 3) H2.1 163 157.9 158.9 157.2

% Cnange in milesper million BTU(a) Oxidation ca-

talyst cars 0 -0.5% -0.9% -1.96% -1. 9%

(b) 3-way catalystcars 0 0.56~ -2.59% -1. 97% -3.02%

4 -2 0 .

3-W

ayC

ata

lyst

Veh

icle

__

_

/o/.'

o./'

./'

./

:ft'"

/

.,0

gm•

60

,I

II

,I

IOx

idat

ion

Cata

lyst

Veh

icle

.---

To

tal

Ev

apo

rati

ve

Em

issi

on

s5

0

.j::> I N f-'

30~

20

1-

,.

~0

/0

/.

o/e

0/0

/"

,/'

CJ

1°1

I,

,,

'I

7.0

R.O

'1.0

I0.0

1.0f2

bp

si

Rei

dV

apor

Pre

ssu

re

FIG

UR

E4

.12

.EF

FEC

TO

FR

EID

VA

POR

PRES

SUR

EON

THE

TOTA

LEV

APO

RA

TIV

EE

MIS

SIO

NS.

!)fISSIONS M!AStTRlIl AT 2800 !.PM. SO rr. US. TORQUE

. _ 100Fr. LIS. I

1St - 95 MAX.I

90 TORQUE.J1,r.OO I AI

14 85 2800- .,II

,80_I

1.lOO 13 ~ J 75, jI

\.1,~00 12 ' 4.300~

I I

I,I

1.100I

11 ;. - 4.200

I10 lI,ROO 11.0 _ 4.100

!I BTUI !I

TBC JOO 9 ~I I

1.9 KIN. 4. OOO~.:, "."PPM

: % C02l!OO 8 .8 3.900

; % O2

! 1I II I:zoo :r

,.7 3.800-

I % CO

~ 3.700I

600 I .6- J -~OO J I

.5 i

of

I

I!!oo

,I I

.4 I

]I,I,

;loo 3: .3- I r I

I

1~OO 2 .2

i.100 1O2 .1

o 15 25 35 45 65

I I!m'BAJIOL ~Ref. 4-.5. •

FIGURE 4.13. EFFECT OF METHANOL ON THE PERFORMANCE AND EMISSIONSOF A 3-WAY CATALYST CLOSED LOOP CAR AT CONSTANTSPEED.

4-22

about 30 percent. Up to this point, there was no change in maxi­

mum torque, but the energy required to achieve this maximum power

decreased, as did the CO and hydrocarbon emissions. Between 30

and 55 percent methanol blend, the limit of the increased volu­metric fuel injection was reached, and a leaning-out of the F/A

ratio became evident in the form of decreased power output and

increased oxygen content of the exhaust. Lawson reported that"the

engine continu~9 to perform well as the efficiency continued to

improve. At methanol concentrations greater than 55 percent, it

was apparent, from the increas~d hydrocarbons that the lean .mis­

fire limit had been reached. Figure 4.14 is a plot of iso-fuelenergy contours obtained from operating the engine on zero to 55

percent methanol blends. This figure indicates that as the

methanol content of the blend increases up to 45 percent, less

BTU/min were re~uired to achieve the same load/speed conditions.

Similar results have been obtained on VW cars fueled with 15

percent methanol and 85 percent gasoline, as reported by Bernhardtand Lee (4.13). A reduction in energy consumption of 12 percent

was achieved during the ECE cold start test as compared to the

gasoline operation.

4.1.6 Effect on a 3-Way Catalyst Car With Closed Loop Control

"System on FTP Cycle

Three-way conversion catalyst systems provide control of

three types of emissions: hydrocarb6ns, carboR monoxide, and

oxides of nitrogen. The conversion efficiency depends on theair-fuel ratio (4.6) as shown in Figure 4.15." A conversionefficiency of 80 percent or higher is possible if the A/F ratio

remains, on the average, within a narrow band around the stoichio­metric ratio mixture. Although the A/F ratio may vary considerablyover very short periods, the average A/F within each interval of

a few seconds duration must lie within a band of 1 or 2 percentagepoints on either side of the stoichiometric to achieve high con­version efficiency. The A/F ratio control can be achieved by a

closed loop control system by which the oxygen content of the

4-23

VOLVO ENGINE. ISO nJEL~!!tCY CONTOUKS (ITU/MIN)POR 0 - )SI METHANOL IL!MDS

IIUT CiASOLIRE____ MJS

MlS

IISS

~M41bs~ MJS

~H2S KlSHEAT

6700 BTU/MIN

"

20

70

30 •

10

90 •

80

40

'0

60

TORQUEft. 1.15.

1500 zoooSIlEO IPK

3000 noo

Ref. 4. S.FIGURE 4.14. ISO FUEL-ENERGY CONTOURS FOR METHANOL-GASOLINE

BLENDS.

4-24

fUEL. RICH

0.99FUEL. L.EAN

1.00 1.01

A: TOTAL Oz IN EXHAUST

STOICHIOMETRIC 02 .

Ref. 4.6.

FIGURE 4.15. 3-WAY CATALYST CONVERSION EFFICIENCYFOR HC, CO AND NO x AS A FUNCTION OFLAMBDA.

__ J.. .._~

I II__~_-J

II I

- -:--...,, I

-~--""'1,

1000 .~--",t_-:.J-_l _!°rl-!·~4. , • ,I

I I I100 r---....--

I , I800 L.. - _1- - -t - -

I I I.I I

400 t---- _.L_I I ,I I ,

100 r- -- t - -t-­I , I

o L._.I __ L_~ o..M OM ·tOO Htl t.&4

. 'UIL RICH 'UlL LEAN

Ref. 4.6.

FIGURE 4.16. OXYGEN SENSOR MILLIVOLT OUTPUT AS AFUNCTION OF EXHAUST GAS COMPOSITION(LAMBDA) .

4-25

exhaust is continuously monitored and the A/F ratio adjusted to

maintain the stoichiometric A/F ratio. For unleaded gasoline,

the average A/F ratio is controlled between 14.45:1 and 14.75:1.The oxygen content of the exhaust, which is related to the A/F

ratio, is determined by an oxygen sensor placed in the exit ofthe exhaust manifold (4.7) (4.8). The oxygen sensor producesa signal of a to 500 mv when the A/F ratio is slightly lean,and

'SOO to 800 mv when slightly rich as shown in Figure 4.16. Theresponse of the oxygen sensor is very rapid, detecting changes

in the exhaust gas within a few milliseconds and responding with

a very steep voltage characteristic at ¢=1. The response of theoxygen sensor to the stoichiometric mixture is independent offuel composition (4.6).

The effect of blending gasoline with alcohols on the type

'of emission control using a 3-way catalyst was studied by Mooneyet al .(4.6), on a Volvo 244 car. The car had a 4-speed manual

transmission and a 2.1 liter, 4-cylinder engin~, without EGR.

The fuel-metering was by a R. Bosch K-Jetronic fuel injectionsystem contro"lled by a closed-loop system with an oxygen sensor.

The fuels used in Mooney's tests were:

Ethanol:

Ethyl Alcohol. Ethyl Acetate

Methyl Iso-Butyl Ketone

Aviation Gasriline

Methanol:

Reagent Grade

97%

1.%1%

1%

99.9%

Unleaded Gasoline

Research Octane NumberAPI Gravity 60/60°F

Vapor Pressure (100°F)

LeadSulfurPhosphorous

Distillation ASTMD-86

IBP50%

EP

91.8%648.4 psi

0.023gm/gal.

300 ppm0.5 ppm

4-26

The results of the emissions produced from the vehicle with

the baseline gasoline fuel, and with different 'blends of gasoline

and alcohols are given for FTP in Table 4.6, and plotted in

Figure 4.17. The FTP results indicate the following:

(a) For Ethanol-Gasoline Blends

(i) At 10 percent ethanol, HC and CO increased signifi­cantly from the baseline while NO remained constant., x

(ii) At higher ethanol concentrations, the emissions be­

haved in different ways: (a) the CO emissions de­

creased to values lower than the baseline, 3.19gm/mile, and reached a minimum of 0.78 gm/mile at

40% ethanol, (b) the HC emissions decreased andreached a minimum of 0.11 gm/mile at 30% ethanol,

(c) the NO x emissions increased from 0.11 gm/mile

at the baseline to 0.14 gm/mile with 20 percentethanol, after which it dropped to 0.07 gm/mile at

30 percent ethanol and reached 1.55 gm/mile at

50 percent ethanol.

The emissions results indicate that the 3-way catalyst withthe closed loop control system was able to produce a high conver­

sion efficiency for HC/CO/NO for ethanol mixtures of 30 percent.,xFor higher percentage mixtures, it appears that the closed-loopsystem (as set) could not maintain maximum conversion efficiency

for HC/CO/NO x .

(b) For Methanol-Gasoline Blends

Mooney's (4.6) tests on methanol-gasoline mixtures demon­strated that the system can operate satisfactorily with blends of

up to 20 percent methanol. Similar results have been recentlyreported by Seiffert of VW (4.18).

(c) For Ethanol-Diesel-Gasoline Blends

The results of tests conducted with blends of gasoline,ethanol, diesel fuel, and water are given in Table 4.7. These

results indicate that adding 30 percent ethanol increased the RON

4-27

TABLE 4.6. EMISSIONS FOR FTP PROCEDURE WITH ETHANOL ­GASOLINE BLENDS

HC CO NOr) x

gm/mi gm/mi gm/mi Blend

Baseline No C;:atalyst

0.93 13.68 2.47 100% Gasoline

Ethanol/Gasoline Blends

0.14 3.19 0.11 100% Gasoline

0.31 3.90 0.11 10% Eth./90% Gas

0.24 2.77 0.14 20% Eth./BO% Gas

0.11 2.61 0.07 30% Eth./70% Gas

0.14 0.78 1. 77 40% Eth./60% Gas

0.22 0.90 1. 56 50% Eth./50% Gas

Methanol/Gasoline Blends

0.14

0.16

.0.15

3.19

3.20

3.20'

0.11

0.09

0.05

100% Gasoline

10% Meth./90% Gas

20% Meth./80% Gas

Note: Data for car having 3-way catalyst with closed loop con­trol.

Ref. 4.6

4-28

"

./.~"----

i I....••c'"

J0 10 10

o

i...o. 1

•cz

o

Ref. 4.6.

FIGURE 4.17. EMISSIONS ON THE FTP AS A FUNCTION OF ETHANOL INAN ETHANOL/GASOLINE BLEND.

4-29

TABL

E4

.7.

EM

ISSI

ON

SO

FFT

PPR

OCE

DU

REFO

RA

3-W

AY

CATA

LYST

CAR

WIT

HCL

OSE

DLO

OP

CON

TRO

L,W

ITH

BLEN

DS

OF

GA

SOLI

NE,

DIE

SEL

FUEL

AND

WAT

ER

HC

CO

·N

OR

ese

arc

hx

Octa

ne

Fu

el

Vis

co

sit

yg

m/m

ig

m/m

ig

m/m

iB

len

dN

um

ber

(Cen

tip

ois

e)

0.3

25

.74

0.0

810

0%G

aso

lin

e9

2.9

0.4

1

Wit

ho

ut

Cata

lyst

1.

221

7.9

92

.70

100%

Gaso

lin

e9

2.9

0.4

1

0.3

33

.55

0.1

070

%G

aso

lin

e°9

8.6

0.5

7.j

O.

23%

Eth

an

ol

I Vl

7%D

iesel

Fu

el

0

- Wit

ho

ut

Cata

lyst

I

1.

391

5.8

72

.34

Sam

eas

Ab

ov

e9

8.6

0.5

7

0.3

85

.76

0.0

970

%G

aso

lin

eN

AN

A25

%E

than

ol

.2.5

%D

iesel

Fu

el

2~%

Wate

r

0.3

03

.83

0.1

670

%G

aso

lin

e1

02

.60

.57

30%

Eth

an

ol

Refe

ren

ce

4.6

.

:~l~ "

.j~;

~l1t

:

of gasoline from 92.9 to 102.6. Also, 23 percent ethanol could

offset the poor octane characteristics of 7 percent diesel fuel.

Mooney concluded from his studies that the closed loop con­trol system automatically provided a stoichiometric A/F ratio .of

12.8 for the 30 percent ethanol/gasoline blend and a 14.6 A/F

ratio for the 100 percent gasoline. Also, methanol/gasoline fuelblends containing up to 20 percent methanol provided excellent 0

vehicle operation and l~w HC, CO and NOx exhaust emissions.

4~1.l Effect of Exhaust, Aldehydes and Acetone Emissions

The effect of blending gasoline with methanol or ethanol on

the individual aldehydes and acetone was reported by Harrenstein,.et al (4.9). The engine used was a 1963, four-cylinder Pontiac

engine, which had been modified to simulate a modern engine, using

a 1974 cylinder head and camshaft. The C.R. was 8.1:1. Duringexhaust sampling, the engine was operated at steady-state condi­

tions, 2000 rpm, MBT spark advance, and with F/A equivalence

ratios (t) of 0.9~, 0.90 and 0.82. During operation at ~ = 0.82,

the engine experienced lean-limit misfiring. The DNPH method with

a gas chromatographic finish was employed to obtain exhaust gasconcentrations of aldehydes and acetone.

Harenstein's experiments indicated that the use of alcohol­

gasoline blends results in the following effects:

i. An increase in total aldehydes (including acetone)levels. The increase is 25 percent for 20 percentethanol, 10 percent for 20 percent methanol, and

30 percent for 30 percent methanol.

11. The aldehyde emissions are generally a strongerfunction of fuel blend-than of equivalence ratio.

iii. Formaldehyde is the -largest cQmponent of the total

aldehydes; up to 70-90 mole % of the total.

iv. The emissions of formaldehyde and acetaldehyde_arestrongly controlled by the content of methanol and

ethanol in the fuel respectively.

4-31

v. Acetone concentration increases as the lean misfire

limi t is approached. (rt> = 0.82).

vi. Acrolein concentration decreases slightly with in­creasing alcohol blend level.

vii. Aldehydes and acetone are partially destroyed in the

exhaust system and virtually completely destroyedin the catalyst.

4.1.8 Phase Separation

4.1.8.1 Nature of the Problem - A study of the methanol/gasoline.

phase separation problem was conducted by Lawson et al (4.5).Reagent grade methanol was dried and used in various proportions.

Mixtures of dry gasoline, dry methanol and water were mixed in a

'sealed conical flask, fitted with a thermometer and a magneticstirring bar. This flask was cooled until the cloud point temper­

ature was reached as observed by the eye. Figure 4.18 shows the

cloud point expressed as grams of water added per 100 g'rams fuelto reach cloud point (or onset of phase separation) at selected

temperatures and for various methanol contents. Figure 4.18 indi­

cates that at above-freezing temperatures, the presence of moremethanol imparts a greater water tolerance to the mixture. At

lower temperatures in the range -10°C to -20°C, there is rela­tively little difference in the behaviour of blends with methanolcontent of up to 45 perc.ent. The cloud point is approximately

at 0.05 gram per 100 grams of fuel. Lawson attributed this separa­tion at 30 percent and 45 percent methanol to the drop in tempera­

ture rather than to the presence of water. For example, a 30

percent methanol blend will phase separate at approximately -20°Ceven if no water is present. Increasing the methanol content to

4S percent provides greater phase separation, increasing that tem­

perature to -15°C. Lawson, et. al., concluded that phase separa­tion phenomena below the freezing point is controlled by the com­bined tendency toward immiscibility exhibited by both the waterand the methanol.

4-32

20

~-til10c

~CICIII~ 02III~

-10

-20

0'1 0'2 0·3 0·4 O'~ 0'6 0·7 o·aGRAMS OF WATER PER 100Q OF FUEL

0·9 1·0

Ref. 4.5.

20.~

u 10 .../• ./.

/r"'" 7~ "0WII:

0;:) •I- ./4II:III -10~

./:tw...

-20

.// , I •2 3 4

GRAMS OF' WATER PER 1009 OF FUEL

FIGURE 4.18. CLOUD POINT FOR VARIOUS METHANOL-GASOLINE BLENDS

4-33

At higher methanol contents of 60 percent and 70 percent,

there is a reversal towards more miscibility which can be inter­preted as the solubility of the gasoline in the methanol. This

solubility becomes relatively insensitive to the water content asis illustrated by the low slopes of the 60 and 70 percent curves.

The "crossover" temperature at which methanol insolubilityequals that of wa;er (where the cloud point lines intersect) is

0etween -10°C and -15°C. This has been found by Lawson et al toagree well with the range -12 to -18°C reported by Ecclestonand Cox (4.10) for 30 percent aromatic gasoline.

4.1.8.2 Effect of Aromatic Contents on Phase Separation - Lower­

ing the aromatic content tends to induce more phase separation,i.e., the same effect occurs at a higher temperature. Ecclestonand Cox (4.10), found that a 25 percent aromatic gasoline had a

crQ...ss~ver at 0 to SoC, and IS and 20 percent aromatic gasoline at7 to 13°C. The presence of aromatics causes a marked increase in

solubility of methanol in gasoline and of gasoline in methanol.

4.2 METHANOL NEAT

The main differences in the fuel properties of neat methanolas compared to the current production gasoline are:

(i) high octane number

(ii) low heating value

(iii) high latent heat of evaporation

(iv) low vapor pressure

4.2.1 Single Cylinder Engine Sensitivity

The high octane number of methanol allows the engine to runat compression ratios higher than 8:1 to 9:1 used in the current

production gasoline englne. This results in higher brake thermalefficiency and mean effective pressure. Figure 4.19 shows theeffect of increasing the C.R. in a single cylinder engine, with

4-34

Pe 60HP!

I i

5.8 1~i1, I

0 I I II

Itil

56/: ,

I .,..._.-. ....- ! I- -~ .....- -...,-

51. ' ,.' ,....I ",, ",

I /I ""5.2 ' •

I x-x AFER 1.0I .--- AFER '12;

E ILO .

I , .% I

! I38

I,I

36

1

I II

i I: i

34 , f-J8 10 12 11.

COMPRESSION RATIO l

Ref. 4.11-

FIGURE 4.19. EFFECT OF C.R. ON POWER AND EFFICIENCY

4-35

MBT spark timing and full throttle opening, on the power outputand brake thermal efficiency. The results are shown for A/F

equ~valence ratios of 1.0 (stoichiometric) and 1.12 (lean). For

both the A/F ratios, best brake thermal efficiency is at a C.R.

between 12:1 and 13:.1. The power output of the lean mixture peaks

at about 12:1. For the stoichiometric mixture, the power output

increases at a decreasing rate as the C.R. increases. The savingin specific energy consumption with the increase in C.R. is given

(';J in Figure 4.2 a aft loads equivalent to 37 mph and 62 mph road loads.

At 37 mph load, the fuel consumption can be reduced up to 5 percentby increasing'the C.R. from 8.2:1 to 13:1. At a 62 mph equivalent

load, the saving in fuel consumption amounts to 11 percent.

Figure 4.21 shows the improvement in specific energy consumption

at a load equivalent to that of 37 mph, with increasing compres­sion ratio for methanol fueled engines in comparison to ,the current

production gasoline engine. The gain in efficiency ranges from

18 to 23 percent according to compression ratio.

The effect of C.R. on the emissions was reported by Meurad(4.11) as follows:

(i) CO is mainly a function of A/F ratio and not on

the C.R.

(ii) HC (UBF) increased with C.R. as indicated in Figure4.22. This increase is a result of the increase in

the effective 5/V ratio which results in more HC in

the quench zone, and the drop in the exhaust temper':l­ture which results in a reduction in the oxidationreactions during exhaust.

(iii) The increase in NO x /with C.R. was insignigicant.

4.2.2 Comparison Between the Single Cylinder Engine Results and

Cycle Computations

The increase in power output of gasoline engines has beencalculated for methanol as compared to isooctane by 'detailed com­puter analysis. An example of the cycle analysis results is shown

4-36

y • 100 1rnI'I'l162mphl

~SEC:ao'o

-s

--0

-15

Ref. 4.11.

10 11 E

FIGURE 4.20. EFFECT OF C.R. ON SAVINGS IN FUEL-ENERGY, AT37 MPH AND AT 62 MPH ROAD LOADS.

Ref. 4. 11.

~SEC

-

18 1DID

·2C

- 22

8 10

'V = 60 km/h

I 37mph I

FIGURE 4.21. PERCENTAGE DECREASE IN FUEL-ENERGY IN A METHANOLFUELED ENGINE IN RELATION TO A PRODUCTION GASOLINEENGINE.

4-37

A

• 1.. 11 tpo,r~"

5OJ: \\wi• SO lr",',.

27 rr.:po

c;

c

c

'IiII ... .... ..-. .... --.11I

I£I-I

JII

2~

II

o ,-I_--:-__--:-:- _

10 1~

B

Ref. 4.11-

FIGURE 4.22. HC AND NO EMISSIONS VERSUS C.R..x

4-38

TABLE 4.8. CHART CALCULATIONS OF CYCLE CHARACTERISTICS

Cu. Ft.Peak Peak of Mixture Compression

Temperature Pressure per 1b of WorkOR psia 0 Air BTU/1b

Isooctane 5200 1240 13.92 130

Methanol' 4870 1300 13.92 101 .

Ethanol 5000 1255 14.09 111

C.R. = 9.1, Intake Air = 1000F14.7 psia, ¢ = 1

4-39

in Table 4.8. This example shows that at equal equivalence ratio

(¢ = 1) and C.R. =.9:1 the calculated compression work for methanolis 101 BTU/1b as compared to 130 BTU/1b for isooctane. The peak

combustion temperature is lower: 4870 0 R for methanol compared

to 5200 0 R for isooctane. The peak pressure is higher: 1300 psiafor methanol as compared to 1240 psia for isooctane. Thus, it

follows that a methanol-fueled engine can achieve power boostover a gasoline-fueled engine at the same equivalence ratio, orequal power at a leaner equivalence ratio. e)

These computed results agree with the experimental work on

the single cylinder engine discussed earlier.

4.2.3. Mu1ticy1inder Engine Sensitivity

Berhardt and Lee of VW (4.13) reported the results of labora­tory and road tests on a number of VW product~on vehicles whichhave been converted to methanol operation through the use of a

modified carburetor and an exhaust-heated intake manifold com­bined with a heating feature using engine coolant. The enginesused were water-cooled 4-cy1inder, 1.6 liter VW engines. The

standard carburetor was modified to improve the atomization of thefuel-air spray. The intake manifold was heated by a constant

flow of hot exhaust gases, and, in addition, by hot engine coolant

after warm-up. In spite of this heating, Bernhardt reported thatit was impossible to get completely identical mixture temperatureswith methanol and gasoline. Figure 4.23 shows the results reported

by Berhardt for the intake charge temperature for methanol andgasoline.

4.2.3.1 Effect on Power Output ~ Figure 4.24 shows the enginebrake power with methanol and with gasoline at different enginespeeds. The methanol engine had about 10% higher output than

the gasoline engine, both with MBT spark. This is related to theincrease in the mass of the fuel-air charge with methanol caused

by its higher latent heat of evaporation. This results in lower

charge temperatures as indicated in Figure 4.22.

4-40

o

6000

--- GASOLINE-METHANOL

\«\\\\\\\\.b

\\ ..

\\ ..

\.\

\\

\

'" '"............... 0-''''

CR =9.7. WOT.MA): POWERSPARK TIMINGI

I

o1_--J-._...I-.....-~_-.l.I_......l...._o 2000 4000

ENGINE SPEED - RPM

u30o

Ref. 4.13.

FIGURE 4.23. MIXTURE TEMPERATURE WITH METHANOL AND GASOLINE

-·"J;.:<'~I· - 60

.~--- GASOLINE~"'~ -METHANOL

50 ?'"

~ 40

//

I'~

~

~ 30~ j"0w~

/<t 20a:::l%l

10 CR = 9.7. WOT.I MAX POWER

~ SPARK TIMING

01000 2000 3000 4000 5000

Ref. 4. 13. ENGINF. SPEED - RPM

FIGURE 4.24. ENGINE OUTPUT WITH METHANOL AND GASOLINE

4-41

4.2.3.2 Effect on Brake Thermal Efficiency - Berhardt comparedthe brake thermal efficiency of the gasoline engine with that of

methanol engine,. both having the same compression ratio ~f 9.7:1.

The results are shown in Figure 4.25 for a speed of 2000 rpm, andWOT, at different air-fuel equivalence ratios, and show that themethanol engine is more efficient than the gasoline at the same CoRo

Because of the high octane rating of methanol (RON ~ 110,

MaN ~ 92) (21), the C.R. could be boosted to 14.0, resulting in 0higher brake thermal efficiency as indicated in Figure 4.25.

4.2.3.3 Cold Start Problems - With methanol, a cold startingaid is absolutely essential for starting the engine at tempera­tures below BOC (4.13). Cold start aids could be in the form of

volatile starting additives (such as butane, methyl ether, or

gasoline) to be sprayed into the intake air during startinG. Asmall methanol-fueled flame preheater may be used in the intake

manifold to solve the cold starting problem.

4.2.3.4 Effect of Methanol on Emissions

Figure 4.26 shows the effect, as reported by Bernhardt, ofair-fuel equivalence ratio on the NOx emissions of the gasoline

a~d methanol-fueled cars, at 2000 rpm, WOT, and MBT spark. The

methanol cars, with C.R. = 9.7:1, or C.R. = 14.1 had lower NOx

than the gasoline car. The reduction in NO is caused by the lowerxpeak temperature with methanol than with gasoline.

The CO emissions from the methanol-fueled engine correspondedI

approximately to those from the gasoline-fueled engine as indicatedby Bernhardt as shown in Figure 4.27. At 2000 rpm and a stoichio­metric mixture ratio between ~ = 1 and ¢ = 0.9, methanol produced

less CO emissions.

The hydrocarbons In the methanol-fueled car consisted of theoriginal fuel, aldehydes and other hydrocarbons. The hydrocarbons

~

in the methanol-fueled car were found to be less than those from

the gasoline-fueled car as shown in Figure 4.28.

4-42

o

/ (I

;' ..LMETHANOI.........e CR = 9.7

:2000 RPM, WOT i14 CYL. ENGINE I

,,,--~---e,... ...."'. ...., ...

/~ e , ...... c

~/ GASOLINE "",o / CR =9.7 ',;

I • 0I ;

<;I~

35

JrMETHANOL

..,;;-_~I CR = 14.0

I

t; 30zwU~....ww

~ 25c:cc

20

~. LEAN LIMIT

RICH~-LEAN

0.8 , .0 , .2 , .4AIR-FUEL EQUIVALENCE RATIO

Ref. 4.13.

FIGURE 4.25. BRAKE THERMAL EFFICIENCY WITH METHANOL ANDGASOLINE.

4-43

:2000 RPM, WOT ',4 CYL ENGINE

RICH--LEAN-O .......... ...l....-__---"-__---J

0.8 1.0 1.2 1.4AIR· FUEL EQUIVALENCE RATIO

4000· .- \.

I .- ,\ GASOLINE

IJ. \

CR = 9.7J \

iI

I I.I

~\

METHANOLI

I II \

3000~I I, \

~ II ,

CR = 9.7 IJ Ia. ) \

1a. I , ~

~20j, i

II \

I!

,\ I\

\.

I"(/) , "--~--:

~

.1wlI(

0

. z 1000L

Ref. 4.13.

FIGURE 4.26. EXHAUST NO WITH MET[~NOL AND GASOLINE.x

4-44

4.---------------,- METHANOL--_. GASOLINE

3-

\\\~

1-

\\,

a ""'-_l...-I__~J,;;;"_~..:.... =---::.Q.IJ........__:-.-.J08 1 0 1 2 1 4

RICH --:- LEAN

AIR.FUEL EQUIVALENCE RATIORef. 4.13.

FIGURE 4.27. EXHAUST CO WITH METHANOL AND GASOLINE.

9 600

800 ,-----\------------,

~ --- GASOLINE\ -- METHANOL\\\.\-,,,,, .,-

\\.~,"" \

\ ~, ~

..... _-.;'

~ 400--:<,...-c:::o?; 200

O'--........ .....L...__---' ......._

Ref. 4.13.

FIGURE 4.28.

08 10 1.2 1 4

AIR·FUEL EQUIVALENCE RATIO

EXHAUST HC WITH METHANOL AND GASOLINE.

4-45

The total aldehydes emitted from the methanol-fueled engine

were higher than from the gasoline-fueled engine when the same C.R.

(C.R. = 9.7) was used, as shown in Figure 4.29. The total alde­

hydes of the methanol-fueled car were reduced by increasing the

C.R. from 9.7:1 to 14:1 as shown in Figure 4.29. Bernhardt re­ported that the total aldehydes may be reduced by adding water to

methanol. This resulted in a NOx reduction as shown in Figure

4.30, with some sacrifice in power output.

Polynuclear aromatics (PNA) obtained from a gasoline-fueled

car were compared with those from a methanol-fueled car by

Bernhardt (4.13), on the European Test Procedure. The results

are shown in Fig. 4.31 and indicate a much lower level of PNAs

when methanol is used.

Figure 4.32 shows the variation in the emissions, withengine speed, at WOT, for methanol and for gasoline.

4.2.4 Sensitivity of a Vehicle to Neat Alcohol

VW reported the results of tests conducted on a number of

standard production vehicles which were converted from gasolineto methanol operation. To improve cold starting, gasoline orother volatile fuel was injected into the intake manifold.

Vehicle evaluation has been conducteft mainly under simulatedroad conditions using the CVS cold-hot emissions tests and theECE Test Procedure. The results for ~ethanol-fueled cars indi­

cated an improvement in energy consumptiori of 4 percent when com­pared with gasoline operation during the ECE cold-start test,

and 12 percent for the hot start.

The effect of using methanol on the ECE cold test cycle is

to reduce the CO emissions by 25 percent, but to increase (HC)by 22 percent. In the hot-start test, the CO emissions were re­

duced by 68 percent and HC by 28 percent (24), and NO by 20 per­

cent.

4-46

,,I

METI'fANOLCR = 140

(j

300 ,..---------------------,

METI'fANOLCR = 97

I200 ~ I

~ /J(1..-_-lY(j--a()r';....-~I)r----

~~~ 100 to- I~_:.... _.-.--_...~-::~::-:==~::::-. ~~::~.==:2 40:=' !:-o-----

- • • -~---~ 'GASOLI~Ea-.....::r- eR = 97

."

I ." RICH --+,-- LEAN IO~.L. ..L- .._._ ~

oe 1 0 1.2 1 4

AIR-FUEL EOUIVALENCE RATiO

Ref. 4.13.

FIGURE 4.29. EXHAUST ALDEHYDES WITH METHANOL AND GASOLINE

4-47

2000

2

-OUTPUT

---- .... ... ... .... .... ....,,-,,,,,",-ALDEHYDES

....,,,....

....,....,

15

~ CO25-.,---------....;...-....::.;::..,

80KW

20

20

60

lJ')I.lJo>~40I.U

.9 10c::

o t:o

-HC FlO

5 10WATER - VOL ~o

co- l:::::7 0

. , 5 .

Ref. 4.13.

FIGURE 4.30. EFFECT OF WATER ADDITION TO METHANOL ONEXHAUST EMISSIONS AND ENGINE POWER.

4-48

TOTAL PNAWITH GASOLINE 2777035 ... \i:ll5 f '//i

WITH METHANOL. 303 ~g res:ENGINE· 15 ~ WATER COOLED

2400

O~~~~~~~~~~~~.a:.;:~.LJ,;~~~~LJPER IND BGHIP COR

-DAH ATC

~ 1200<z 800

400

(/l 2000z

O. '"' TEST2800r-------~------------.

Ref. 4.13

FIGURE 4.31. PNA HYDROCARBONS WITH f>1ETHANOL AND GASOLINE.

4-49

NO

NO

I ~ .III,,,

~.

(f',...... '-CO

~_:~-_:.._- ....... .. --·~HC ~FiD-

1000 2000 3000 4000 5000ENGINE SPEED - RPM

o

3000

1000

NO. HC5000 r----:---------..PPM ---GASOLINE ......v...

-METHANOL ,'7 '.a- ...vI ......

I v'I

II

II

II

III1.,­

I .I~

I1

1I

2

o

CO10 4000%

~6o~ 2000

~4w

Ref. 4.13.

FIGURE 4.32. EXHAUST EMISSIONS WITH METHANOL AND GASOLINEAT FULL THROTTLE.

4.3 SHALE-DERIVED AND COAL DERIVED GASOLINE IN GASOLINE ENGINES

Hurn (4.14) reported experimental data concerning physical

properties and engine performance characteristics for a gasoline

derived from oil shale -and for a gasoline containing a coal­derived component. The properties of gasoline derived from

shale oil are given in Table 4.9.° The emissions and fuel economy

results with shale-derived gasoline are compared with Indoleneand given in Table 4.10. Hurn reported that the differences be­

tween the results with the shale-derived gasoline and the regulargasoline were mainly related to poor octane quality which resulted

in engine knock.

Hurn reported the results of tests on gasoline produced

from blends of coal derivative components and refinery stocks.The naphtha from catalytic reacting (51 percent yield) of a

coal syncrude, was blended with refinery stocks. The naphtha

was usable as 44 percent by volume of a finished, 96 RON, un­leaded gasoline.

The results showed no significant differences between the

emissions and fuel economy characteristics of reference andtest fuels. The data show somewhat elevated CO and HC emissionsfor the fuel containing coal-derived components. Hurn indicated

that the differences may be attributable to a slight differencein the stoichiometry of the fuel mixtures.

4.4 GASOLINE EMERGENCY BLENDS

In case of a national emergency, the available gasolinefuel may need to be extended in order that gasoline engines pro­

viding essential services continue operation. Under such

emergency conditions, blends of_gasoline and other fuels may beformed to stretch-out the base gasoline fuel. Russell, et al

(4.16) of Southwest Research Institute (SWRI) conducted an

extensive study of such emergency blends and published the re­sults in a guidebook. Several blends of gasoline and extenders

were tested in single and multicylinder engines and in a very

4-51

TABLE 4.9. PROPERTIES OF SHALE OIL-DERIVED GASOLINE

API Gravity, 60°F.................................... 87ASTM Distillation, of:

IBP. D. II ••• a II 0 ••••••••••• II. II ••••• 11 ••••••••••••••••• 0.

10 percent ~ .30 percent .SO percent ' .70 percent o ••••••••• ~ ••••••••••••••

90 percent .End poin t .

Reid V.apor Pressure, psia .

Sulfur, wt. percent .

Nitrogen, wt. percent .

oxy gen, wt. perc en t. . . . . . . . .'. . . . . . . . . . . . . . . . . . . . . . . . .

Hydrocarbon types (FIA) , vol. percent:

Aromatics .Olefins ; : .Saturates ' .

Motor Octane No. (MON) .

Research Octane No. (RON) .

114125158194261328387

10.5

0.024

0.03

0.52

28.01L1 .n58.0

76.0

81.1Stability data:

ASTM induction period, min 1140-*ASTM existent gum. mg/100 mI. 25Accelerated gum (4 hr.) mg/IOO m1:

2 . 0 1b s DMD per 1. 000 bb 1 . . . . . . . . . . . . . . . . . . . . . . . . . . 32

*40 lbs of pressure was lost during the entire 24-hr period:however, at no time did it lose 2 lbs in a l5-minute period.

Ref. 4.14.

TABLE 4.10. EMISSIONS AND FUEL ECONOMY RESULTS WITHSHALE-DERIVED GASOLINE

Fuel VehicleEmissions, g/rnile

CO HC NO x Aldehydes

Fuel Econorny,mpg

UrbanCycle Highway

Shale gasoline 1974 Model, 25.8 2.2 2 . 6 0.14 11. 2 17.4Indolene 351-CID 25.9 2.3 2.7 0.15 10.9 17.7

Shale gasoline 1975 Model, 7.4 1.3 2 . 7 0.18 12.3 21.1Indo1ene* 3l8-CID 8.7 1.2 2 . 5 0.17' 12.2 20.6

*Represents one analysis, all other data represent the average of 3replicates.Ref. 4.14. 4-52

limited number of vehicles, both on the road and by chassis

dynamometers. SWRI developed "Tradeoff Charts" for engine per­formance, fuel economy and emissions for each of the emergency

blends. Figures 4.33 to 4.44 are compiled from the charts de­veloped by SWRI. The following indexes are used:

1. BSGC = BSFC x w gasoline

. where

a

BSGC = brake specific gasoline ~onsumption

BSFC = brake specific fuel (blend) consumption

m gasoline = mass fraction of gasoline

2 •

= mass of gaSOlinemass of lend

C t " I d l_BSGC (blend)onserva Ion n ex = B5Ft (base)

3. Power Index = BHP(blend)BHP(base)

4. Tradeoff Index = Conservation Index + Power Index

Russell et al (4.16) indicated that the tradeoff index re­

flects the balance between increase in base fuel conservation anddrop in power (if any) with increasing extender concentration. Amaximum in the Tradeoff Index curve indicates a maximum advis­

able extender concentration. Beyond this concentration, there

is reason to believe base fuel may be wasted.

5. Emission Index _ Emission (blend)- Emission (base)

The emergencey gasoline ,extenders tested by SWRI are shown inTable 4.11.

4.4.1 Effect on Reid Vapor Pressure

Figure 4.33 shows the effect of blending. gasoline with dif­ferent extenders on the Reid Vapor Pressure CRVP). Alcohols

are the only extenders which result in an increase in the RVP atconcentrations less that 42 percent for methanol and 30 percent

4-53

REID VAPOR PRESSURE PSI

10 20 30 40 50 60 70 80 90 100

VOLUME %

1 Extender = No. 2 Diesel Fuel

2 = Marine Diesel Fuel

3 = Ethanol

4 = Methanol

5 = Naphtha

6 = Kerosene

:3

4 I I I I

_I I III

2 f ,

~I 1,-"""""'"r---I I

'. I I I

0; :

;

~ ---~·4 I

I -f--..- I8 , I ~r---.. 1-2-5-6~ I

I I

6 : I I ........i

!II

~i4

I

I

, , I I I~i&. ! , 1 I I

,

i i !i

Ioo

Ref 4.16.

FIGURE 4.33. EFFECT OF GASOLINE EXTENDERS ON RVP.

4-54

API GRAVITY 60/60F70 r---...,.....-~--,.--....,----r--,.--...,.--.....,...----..,

I.6 51----+--~---+---+--+---+----+--+--~--i

:3 0 40 50 60 70 80 90 10 0

VOLUME %10 20

4 0 ~_...:__ ___" __..I__"""'__ ___'___"__ ___Io __

o

.,'- 1 Extender = No. 2 Diesel Fuel..._-2 = Marine Diesel Fuel

3 = Ethanol

4 = Methanol

5 = Naphtha

6. = Kerosene

Reference 4.16.

FIGURE 4.34. EFFECT OF GASOLINE EXTENDERS ON APIGRAVITY.

4-55

6 01------+--4--..=.....::~...,....._--=~~-~--------__I

50 t----+------'---......-----I------>=r__--+-------............---!iI40 I--_.....I..-_....;..l.__"'--_--'-__"""-_......._--I.__..:..- ..-

o 10 2.Q :30 40 50 60 70 80 90 100

8 0 I--~t:=--~~........,~-_+_--r__-_+_-____:'------__;

OCTANE NUMBER12 0 r----:-----I-~-___r-_~-,.__-~-..,..._-~-...., :3

I I0 1--+----:.1----'+---+--+---+------1r--=:::::P-'~~-___::::13

.j

JPOI=:t~~Ft=1-4~~·.--r·::1-,,-- ~-, I• '4 I i

9 O~~+--~--d---=~--P--+--~--..;...---~

RON

MON

VOLUME %

1 Extender = No. 2 Diesel Fuel2 = Marine Diesel Fuel (DF1'1)3 = .Ethanol4 = Methanol5 = Naphtha6 = Kerosene

Reference 4.16.

FIGURE 4.35. EFFECT OF GASOLINE EXTENDERS ON OCTANE NUMBER

4-56

'-12

5045403530252015105

~ I II I! II, IiiI i

6-7- 8- 9,I

I -......... , i 4"'I . II

I:--:::- I

"- i I z

~. I "10

I

2.01.8

1.61.4

1.21.0

0.80.60.4

0.20.0o

POWERINDEX

VOLUME %

= Ethanol= Methanol

No. 2 Deisel Fuel

= Marine Diesel Fuel

= MBTE

= ,Naphtha-Ethanol

= DFM-Ethanol

= No. 2 Diesel Fuel­Ethanol

1 Gasoline Emergency Blend Extender =2

3

4

5

6

7

8

9

10

1112

= Kerosene-Ethanol

= Ethanol Extendedwith Water

= Naphtha

= Kerosene

Reference 4.16.

FIGURE 4.36. EFFECT OF GASOLINE EXTENDERS ON POWER INDEX.

4-57

00

15

5040 453525 302015105

II I I

I Ii

. ,I

I

I " I~J:I

I III I I !;

Ii I ~ (I.C?.:.!,;

I ; I.I r ! (0.45,t i 3I

i "1 6 - 7- 8- 911-12

:'.:1 2

I I

i , I I,i

i! I II . 10

CONSERVATION INDEX2.0

1.81.61.4

1.2

1.0

0.80.60.4

0.20.0

"VOLUME %

1 Extender = Noo 2 Deisel Fuel

2 = Marine Diesel Fuel

3 = Ethanol

4 = Methanol

5 = MTBE

6 = Naphtha-Ethanol

7 = DFM-Ethanol

8 = No. 2 Diesel Fuel-Ethanol

9 = Kerosene-Ethanol

10 = Ethanol Extended with Water

11 = Naphtha

12 = Kerosene

Reference 4.16.

FIGURE 4.37. EFFECT OF GASOLINE EXTENDERS ON CONSERVATIONINDEX.

4-58

I2

3I

504540353025.2015105

I I I

I I,

I I _1 6 - 7 - 89

,4.~

·1 I: I i I

1 '" --i

j t'--. I

II "10

ii

2.01.81.6

1.4

1.2\.0

0.80.60.4

0.20.0

o

TRADE-OFFINDEX

VOLUME %

1 Extender = No. 2 Diesel Fuel

2 = l1arine Diesel Fuel

3 = Ethanol

4 = Methanol

5 = MTBE

6 = NaphthaEthanol

7 = DFM-Ethanol

8 = No. 2 Diesel Fuel-Ethanol

9 = Kerosene-Ethanol

10 = Ethanol Extended with Water

11 = Naphtha

12 = Kerosene

Reference 4.16.

FIGURE 4.38. EFFECT OF GASOLINE EXTENDERS ON TRADEOFF INDEX.

4-59

4 r-----.,I----.,I-----r---I---

I I Ii I I

·31-----~----_+_----+_---__l_----._.j

III; ! I

Me INDEX 2t-------- I 4

; -----~ -,-'-- ~j~~~ 1--- :5

- --7

i2

00 5 10 15 20 25 30 35 40 45 50

' "'T~~<-J

VOLUME %

1 Extender = No. 2 Diesel Fuel

2 = Marine Diesel Fuel

3 = Ethanol

4 = Methanol

5 = Naphtha-Ethanol

6 = DFM-Ethanol

7 = Naphtha

Reference 4.16

FIGURE 4.39. EFFECT OF GASOLINE EXTENDERS ON THE HYDROCARBONSINDEX AT IDLE.

4-60

I I

I IIi ,

I II i

, I I:I

!,

I !,. ' ,'-2-7 5- 3"'-4

I

II I"

Ii iI I

4

3

CO INDEX 2

oo 5 10 15 20 25

VOLUME %30 35 40 45 50

Reference 4.16.

1 Extender = No. 2 Diesel Fuel

2 = Marine Diesel Fuel

3 = Ethanol

4 = Methanol

5 = Naphtha-Ethanol

6 = DFM-Ethanol

7 = Naphtha

FIGURE 4.40. EFFECT OF GASOLINE EXTENDERS ON CO INDEX AT IDLE.

fII

II

i II!

,

"I I

_/7,I

,

i

- i ,-=' I

!3

I·S

I -,~

4

o

NOX INDEX 2

oo 5 10 15 20 25

VOLUME %30 35 40 45 50

Reference 4.16.

1 Extender = No . . 2 Diesel Fuel2 = Marine Diesel Fuel3 = Ethanol4 = Methanol5 = Naphtha-Ethanol6 = DFM-Ethanol7 = Naphtha

FIGURE 4.41. EFFECT OF GASOLINE EXTENDERS ON NO INDEXAT IDLE. x

4-62

4,.....----.,------..,.....--~-~----~----__.

He INDEX 2t-------:~----___:: =---"-----i__---__t

Olo---_--'-__"'O"-_-""' -...010--~~-~-__=:"=_-~~~:"=_-""='o 5~ 10 15 20 25 45 50

VOLUME %

1 Extender = No. 2 Diesel Fuel2 = Marine Diesel Fuel3 = Ethanol

4 = Methanol

5 = Naphtha-Ethanol

6 = DFM-Ethanol

7 = Naphtha

Reference 4.16.

FIGURE 4.42. EFFECT OF GASOLINE EXTENDERS ON HYDROCARBONINDEX AT ROAD LOAD.

4-63

I I II .I I ii

, l II0

I

\

II

,i

II I

I I !,

! 14I. " I 7

- - --- 5""- 2...... 1I

II

4

3

2CO INDEX

oo 5 10 15 20 25 30 35 40

VOLUME %45 50

Reference 4.16.

1 Extender"= No. 2 Diesel Fuel2 = Marine Diesel Fuel3 = Ethanol4 = Methanol

5 = Naphtha-Ethanol6 = DFM-Ethanol

7 = Naphtha

FIGURE 4.43. EFFECT OF GASOLINE EXTENDERS ON CO INDEXAT ROAD LOAD.

4-64

I

III

I

IIIII III!

I ,!

iI

I

II II I

'1 17I :I

.2 I·

!1-

'5, :-=164 3

4

3

NO X INDEX 2

'0o 10 15 20 25 ~O

VOLUME %35 40 45 50

Reference 4.16.

1 Extender = No. 2 Diesel Fuel2 = Marine Diesel Fuel3 = Ethanol4 = Methanol5 = Naphtha-Ethanol6 = DFM-Ethanol7 = Naphtha

FIGURE 4.44. EFFECT OF GASOLINE EXTENDERS ON NO x INDEXAT ROAD LOAD.

4-65

for ethanol. Higher concentrations of alcohols cause a ~rop in

the RVP.

TABLE· 4.11. EMERGENCY GASOLINE EXTENDERS

(I)

(II)

(I I I)

(IV)

(V)

(VI)

(VI I I)

(IX)

(X)

(XI)

(XI I)

No. 2 Diesel Fuel 0

Marine Diesel Fuel (DFM)

EthanolMethanol

MTBE (Methyl Tert Butyl Ether)

Naphtha - EthanolNo. Z Diesel Fuel - Ethano1

Kerosene - Ethanol

Ethanol Extended with WaterNaphtha

Kerosene

Diesel

Alcohol

Ether

Complex Extender

(Lower Proof Ethanol)Solvent

(Solvent)

4.4.2 Effect on API Gravity

Figure 4.34 shows the effect of extender concentration onAPI gravity. All extenders used in this figure result in a

drop in the API gravity, or an increase in the blend specificgravity.

4.4.3 Effect on Octane Number

Figure 4.35 shows that only alcohols produce an increase in

the octane number of a blend. Blending with diesel fuel No. 2

has the worst effect on octane number of all the extenders shown.

4.4.4 Effect on Power Index

Figure 4.36 shows that gasoline extenders have either no

effect on, or decrease the power index of the blend.

4-66

4.4.5 Effect on Conservation Index

Figure 4.37 indicates that the conservation index increases

with the increase in the concentration of all the extenders ex­cept ethanol extended with water.

4.4.6 Effect on Tradeoff Index

Figure 4.37 indicates that all extenders, other than ethanolmixed with water, increase the tradeoff index, up to a volume

ratio of 25 percent. At higher volume ratios of diesel fuels,

naphtha and kerosene the tradeoff index decreases.

4.4.7 Effect on Emissions Index

The effects of the volume percent of the extenders on theemissions at idle are shown in Figure 4.39 for the unburned hydro­

carbons, Figure 4.40 for CO, and Figure 4.41 for NO x .

The effects on the emissions at road load are shown in

Figure 4.42 for the unburned hydrocarbons, Fig~re 4.43 for CO,and Figure 4.44 for NO .x

4-67/4-68

,,,(,,

5. SENSITIVITY OF AUTOMOTIVE DIESEL ENGINES TO VARIATIONSIN FUEL PROPERTIES

5.1 D.I. FOUR-STROKE-CYCLE DIESEL ENGINE

5.1.1 Effect of Cetane Number

Tne major effect of cetane number is related to the length~

of the ignition delay. Lower C.N. fuels result in longer igni­tion delays, more fuel injected before autoignition, more premix­

ing of the fuel with air, and higher rates of pressure rise. The

increased premIxIng results in more fuel in the lean flameout

region of the spray and increased unburned hydrocarbon exhaust

emissions. The increase in the HC emissions with the drop in C.N.has been observed by Bertodo (5.1) in tests on a 3.86 liter, 4

cylinder, 0.1., high swirl toroidal engine. The higher rates of

pressure rise resulting from the longer 1.0., result in higher

temperatures and more premixed combustion, which increase the NOxemissions. This effect has been observed by Bertodo (5.1).

Bertodo reported the sensitivity of the engine to variations inparameters which control the 1.0. as follows:

a. Delaying injection timing by 10°C.A. reduced the 1.0. by

about 30 percent, and allowed operation do~n to C.N. 40,

but resulted in increased smoke equivalent to a derate

requirement of 2.5 percent.

b. Increasing C.R. from 16:1 to 18:1 reduced the I.D. by

about IS percent, and allowed operation down to about

C.N. 45, but increased the NO x level by 5.7 percen~ to

9.5 percent.

~. Changing the mixing rate by using a "Squish Lip" combus­tion chamber design instead of the high swirl toroidal

design: (a) reduced the I.D. from 0.75 to 0.5 ms whentuned for best fuel economy, which allowed the operationdown to C.N. 42, and (b) reduced the r.D. by 50 percentwhen tuned for minimum emissions, and allowed operation

down to C.N. = 35.5-1

Bertodo (5.1) reported that reducing the C.N. from 55 to Z2

resulted in the following:

a. Acceptable operation down to C.N. 48, at which point,

severe white smoke and light load misfire occurred. This

trebled the HC level.

b. C.N. lower than 48 led to severe roughness and piston

erosion.

5.l.Z Effect of Aromatic Content

Aromatics are known to be low cetane number fuels, and to

contribute to the smoke particulate emissions. Bertodo (5.1)

reported that as the aromatic contents were raised from 15 to 30

percent, black smoke levels became unacceptable, and particulate

concentrations doubled. Similar effects are reported in I.D.I.

engines, which will be discussed later.

5.1.3 Effect of Mixing DF-Z With Shale Distillates

Bertodo (5.1) reported tests conducted on a D.I. high swirl,

toroidal diesel engine, with DF-Z mixed with shale distillates.The shale distillates had the following approximate split:

Light Distillates

Kerosenes

M~ddle Distillates

IBP < ZOO°C

IBP < 315°C

IBP < 375°C

10%ZO%

20%

The rest of the shale distillates were heavy fractions with IBP >

375°C and were not mixed with the DFZ. The cetane rating of shale

distillates with IBP < 375°C is about CN 25. The ASTM gums levelwas in the range 27-35 mg/ml. The DF2 was obtained from a refinerypracticing extensive cracking to maximize gasoline production.

The fuel contained 35 percent aromatics, and had the following

properties:

C6 - 190°C Raffinates 2%200 - 300°C Kerosenes 70%

200 - 300°C Hydrocrackates 4%300 - 350°C Distillates 24%

5-2

~;,:

i1

TABL

E5

.1.

TYPI

CA

LPE

RFO

RMA

NCE

DEG

RAD

ATI

ON

OF

SHA

LEO

ILD

ILU

TIO

N

En

gin

eB

aseli

ne

En

gin

e1

6:1

Co

mp

ress

ion

Rati

o2

2°

BTD

CD

yn

.In

j.T

imin

g

Baseli

ne

En

gin

e1

8:1

Co

mp

ress

ion

Rati

o8

°R

eta

rded

Po

wer,

KW

*un I

s/f

/c/.

ml/

Kw

hLN

Bla

ck

Sm

ok

e,%

USP

HS

.s

Part

icu

late

s,

mg

/m-5

No

ise,

dBre

-2

xl0

Fu

el

Sp

ecif

icati

on

Dil

uti

on

Aro

mati

cC

on

ten

t.,

%

Cen

tan

eR

ati

ng

AST

MD

97

5N

o.2

20%

Sh

ale

Oil

32

CN

39

-4

5

60

.3

28

2

14

.3

2.4

11

.7

91

/4

26

7

10

2

13

.1

2·.

6

10

.2

91

/4

22

0.

10

0

BS

28

69

Cla

ss

Al

Nil

-2

0

)C

N5

0

61

.6

28

1

N/m

2

g/K

wh

+

g/K

wh

+

g/K

wh

+

NO

,x

HC

,

CO

,

* +

~t

25

00

rev

/min

an

dB

S.A

ul4

la:

19

71

co

nd

itio

ns

~t

CA

RB

13

-mo

de

cy

cle

co

nd

itio

ns

The C.R. of the baseline engine had to be increased from 16:1 to

18:1, and the injection retarded by 8°C.A., in order to account

for the lower C.N. of the DF2-shale distillate mixture. The

results are given in Table 5.1, and indicate the following trends:

a. The power had to be derated by 2 percent from 61.6 kW

to 60.3 kW in order to keep black smoke at a constant

level of 9.25 percent USPHS opacity.

b. The specific fuel consumption was almost constant.

c .. NOx ' CO, particu~ates and noise increased ..d. HC decreased slightly

The operating problems experienced, after testing for 250 hours

on a mixed duty cycle, were restricted to lacquering and sticking

of precision components exposed to high temperatures, notably

injectors and needles. This was attributed to the high gum content

of the fuel.

5.1.4 Effect of Mixing DF2 With Coal Distillates

Bertodo (5.1) conducted tests on coal distillates-DF2 mixtureson a D.r. high swirl torodial type diesel engine. Two types of

coal distillates were used: low pressure pyrolysis tar oil, and

hydrogenated creosote oil. The properties of these coal distillates

are'shown in Table 5.2. The test results with blends of 25 perc~nt

coal distillates~and 75 percent BS2869 Class A2 diesel oil are

shown in Table 5.3. The results indicate the following:

a. Blending with 25 percent coal distilates lowered the

C.N. of the fuel. This results in a longer 1.5.

Operation with dilution above 25 percent straight tar

oil or above 50 percent hydrogenated creosote oil was

impossible.

b. Derating of the power was necessary to keep the blacksmoke at 10 percent US PHS capacity.

c. The NOx ' HC and CO increased.

5-4

~'

IBase Line Eng!.2!

and Fuel,_: ~I-

Witl'fShale Oil ==,=Dilution~ ~.

. ~'I -IWith Syncrude 4 ' /

Dilution I 7~"~?~65- -,

I

.-'........ B,·O-BO·75

Extrapolated from Ref. (13)(14)99·9

95

80

60

:! 40I

V'l 20l.LJc::: 10~-oJ

5Lt 3l.LJ 2>- ,~

<{-oJ 0·5~

~ 0·3~u

:. ....0·1

.,~~ - 0·05~ .-'.."':' ...

0·03

0·010·01 .0·1 '·0 10

OPE RAT ING LIFE - YEARS

Reference 5.1.

FIGURE 5.1. PREDICTED WEIBULL FAILURE PROFILE FORENGINES OPERATING ON DILUTED DIESEL FUELS.

5-5

TABLE 5.2. SELECTED PROPERTIES OF COAL DISTILLATES

PremiumDiesel

Oil

Low PressurePyrolysis

Tar Oil

HydrogenatedCreosote Oil

Specific Gravity 0.857 1. 06 0.87

Cetane Rating SO <20 40

Conradson Carbon, on 10%

residue, % wt. 0.05 0.26 0.19

Distillation temperature,

°C for 90% volume recovery 273 260 264

Flash point, closed cup Pensky-

Martens °C 90 112 107

Benzole Insolubles, % 0.05 4.8

Hard asphalt, % 0.11 2.5

Reference 5.1.

5-6

1<

.\

TABL

E5

.3.

TYPI

CA

LPE

RFO

RMA

NCE

DEG

RAD

ATI

ON

WIT

HTA

RO

ILAN

DH

YD

ROG

ENA

TED

CREO

SOTE

OIL

"Base

lin

eE

ng

ine

16

:1C

om

pre

ssio

nR

ati

o22

°BT

DC

Dy

n.

Inj.

Tim

ing

Str

ati

fie

dD

iesel

18

:1C

om

pre

ssio

nR

ati

o8°

BT

DC

Dy

n.

In

j.T

imin

g

Baseli

ne

En

gin

e1

8:1

Co

mp

ress

ion

Rati

ol4

°BT

DC

Dy

n.

Inj.

Tim

ing

Fu

el

Sp

ecif

icati

on

BS

28

69

Cla

ssA

lB

S2

86

9C

lass

A2

BS

28

69

Cla

ss

A2

Dil

uti

on

Nil

25%

Tar

Oil

25

%H

yd

rog

enat

edC

reo

sote

Oil

Aro

mati

cC

on

ten

t,%

-20

N/A

N/A

Ceta

ne

Rati

ng

>CN

5036

41

*P

ow

er,

Kw

61

.6

58

.45

5.1

s.

f.c.,

m1/

Kw

h2

81

33

63

23

+1

4.8

NO

,g

/Kw

h1

3.1

16

.3x

+2

.64

HC

,g

/Kw

h2

.9+

CO

,g

/Kw

h1

0.2

12

11

.7

Bla

ck

Sm

ok

e,%

USP

HS

91

/41

01

0"

-52

10

0N

/AN

/AN

ois

e,

dBre

-2

xlO

N/m

*at

25

00

rev

/min

and

BS

Au

14

la:

19

71

co

nd

itio

ns

+at

CA

RB

1]-

mo

de

cy

cle

co

nd

itio

ns

Ref

eren

ce5

.1.

Ref

eren

ce5

.1.

d. The specific fuel consumption increased.

Problems reported by Bertodo are related to nozzle fouling,

lubricating oil sludging, and consequent wear. This resulted in

poorer reliability and durability as shown in Figure 5.1. The

low pour point of the coal-derived liquids, typically 4°C on the

a ASTM 975 test, made it nOcessary to introduce some fuel line

heating to minimize waxing, filter plugging and line blockage.

Table 5.4 shows the pour point of diesel oils diluted with coal­derived crudes.

5.i.5 Effect of Using Alcohols

Alcohols can be utilized as fuels for diesel engines by using

the following techniques:

1. Neat alcohols mixed with a cetane improver.

2. Emulsion of alcohols with diesel fuel.

3. Carburetion of alcohols and ignition by diesel injection.

4. Two separate injection systems.

5. Spark ignited alcohols injected in diesel engines.

5.1.5.1 Neat Alcohols Mixed With a Cetane Improver

An improvement of the ignition quality of some alternate fuels

can be achieved by using cetane improving additives (5.2).Figure 5.2 shows the effect on cetane number of adding cetanox to

methanol. Cetane num~er increased linearly from 3 to 24 with the

addition of up to 10 percent cetanox. ' The rate of increase ofC.N. decreased as cetanox was 'added above 10 percent. FIgure 5.3

shows the effect of the additive on the hydrocarbon emissions at

part load in an automotive turbocharged direct injection dieselengine (displacement = 10 liters, C.R. = 15:1). At any BMEP, theincrease in the percentage additive resulted in a reduction in

the hydrocarbon emissions. This is probably due to the shorterignition delay periods and the decrease in the amount of fuel inthe lean flame-out regions. The probl~m.; associated with this

5-8

TABLE 5.4. POUR POINT (ASTM D975) OF DIESEL OILS DILUTED WITHCOAL DERIVED CRUDE

BS 2869 A2 Diluted Diluted DiluentDiesel Oil OnlY 2526 50'6 OnlY

Lov Pressure PyTo1ysis_17°C _12°C _6°C 4°CTar Oil as Diluent

Hydrogenated Creosote-17°C _14°C _9°C OOCOil as Diluent

Reference 5.1.

5-9

''0

10

Test on aCFR engine with equal con­tents of energy in themixed methanol and in the

,reference fuel.

°o::----""'!""""--T------,..--5 10 15 20

u-Ionox in. rr4':~n:')1 Yol %

Reference 5.2.

FIGURE 5.2. CETANE NUMBER VERSUS PERCENTAGE OF CETANOX IN METHANOL

Part loadat engine speed 2220 rpm.

1000 \ '. .\ '.

500

20 ~ol S Cet~no.

lS ~ol S •

10 ~ol S •S yo] : •

Reference 5.2.

FIGURE 5.3. EFFECT OF THE AMOUNT OF CENTANOX IN METHANOL ON HCEMISSIONS.

5-10

approach are related to low durability due to excessive wear.

The amount of additive needed can be reduced by preheating

the intake air by engine coolant. At partial loads, when the

coolant is relatively cool, the exhaust gases can be recirculated

by increasing the back pressure. This may reduce the hydrocarbon

emissions.

Cold starting represents a problem and calls for preheating

the intake air by an electrical element orJby using an intake air

burner.

The effect of increasing the back pressure on the hydrocarbon.

emissions at partial load is shown for the engine of Figure 5.2

in Figure 5.4. These results are for methanol with 5 percent

centox by volume. The reduction in the HC at any BMEP can be

attributed to two factors. The first is the reduction in the

ignition delay period caused by the increase in the gas tempera­

ture. The second factor is th~ improvement ·in the oxidation

.. reactions caused by the higher mass average temperature.

Bertodo {5.1) conducted two types of tests with ethanol.

The first consisted of ethanol neat mixed with 8 percent ethyl

nitrate ~nd 2 percent lubricating oil. Mixing with ethyl nitrateincreased the C.N. to 45. In the second type, blends containing 30

percent ethanol were used, either premixed or manifold injected

with the injection timing retarded by 10cC.A. The results are

shown in Table 5.5 and indicate the following trends:

a. Mixing with ethanol ~educed the C.N.

b. Power decreased very slightly

c. Specific fuel consumption on a vo1ume/kW basis increased

due to the lower energy content of ethanol. On an

energy basis, the fuel economy did not change.

u. NO, CO, black smoke, decreased.x

e. HC increased.

5-11

TABLE 5.5. PERFORMANCE IMPACT OF ETHANOL FUELING

~ne

PUel Specification

DilutionAromatic Content. %Cetlllle Ra till8

. Power. ",.,.s.f.c •• ml/Kwh

NO • g/Kwh +BC~ g/Il:wh+CO. g/Kwh+Black smoke. " USPHS5 2Mohle, cill re - 2zl 0- !11m

Basel1ne ~e16:1 Compreeeion Ratio

220 M'DC D)m. Inj. TimJ.lljJ

BS 2869 Clan Al

!Iil- 20>CH 50

61.6281

l}.12.6

10.2en

100

Basel1ne &!gine16:1 Compreesion Ratio

120 BTDC Dyn. Inj. TiDlilljJ

9O'J' Ethanol'"' Ethyl !Iitrate2'J{, Lub. OU

C!I 40

60.1411

10.24.16.94~

Baseline ~e1611 Compreseion Ratio

120 M'DC 11).0. Inj. T1JIL1ng

BS 2869 Class Al

}OJ' Ethano1-15

CH }8 - 4}

60.4}40

12.82.99.01

•+

at 2500 rev/min and BS Au 141a I 1971 conditions

at CARS 1}-lDode cycle conditions

Reference 5.1.

Aldehydes were reported to increase. Bertodo reported problems

related to lubricating oil contamination by organic acids (mainly

formic) and unidentified aldehydes. This resulted in higher wear

in critical engine parts such as bearings.

5.1.5.2 Emulsions of Alcohols With Diesel Fuel - Injecting

methanol or ethanol under high pressure in diesel fuel was found

by Holmer, et.al. (5.2) to form an emulsion, which remains stable

long enough to be uniform until injected. This results in a dropin the cetane number of the fuel. The cetane number demand is

much lower at full load than at low load as as shown in Figure5.5. Therefore, a load-dependent emulsion can be used, which in­

creases the amount of emulsified methanol with load. One such

system was developed in which the emulsion was produced. It was

found that with this system, emulsions of methanol and ethanol

5-12

Part--load at 1500rpm. Methanol ·~th 5 1 %

W.L VO •• centanox.

500

h"'"5thCilPP'essllre

250 175 0 kP., :. I

, P. ,\ ~. .'\ ~. ,

\ ". .., ....o~~~~"""-"--"""'::::;:::i==;:::::;:.-o 0.5 to

Bflol(P ~

1500e&:

1000(,)::I:

Reference 5.2.

FIGURE 5.4. EFFECT OF THE BACK PRESSURE ON HC EMSSIONS.

.""'", ...1 ~ ~art load at engine speed

2220, ambient air temperature25 C.

Reference 5.2.

2~~

• ~ -.oJ• - C'2

Ie ~....~

FIGURE 5.5. PERCENTAGE NEEDED OF CENTANOX IN METHANOL AND CETANENUMBER TO MINIMIZE HC EMISSIONS TO 400 PPM.

5-13

-with diesel fuel are only useful under steady state, full load

conditions. Under transient conditions, the capacity of thegallery of the injection pump does not allow the quick adjustment

of the methanol/diesel ratio to meet the cetane requirements at

different loads. Figure 5.6 shows the variation of the hydro­

carbon emissions with time after unloading the engine. Holmer,

et.al. found that only 32 percent diesel fuel could ·be substituted

by methanol ~nder full load con8itions to avoid piaks of HC above~

1000 ppm. Holmer stated that with such e~ulsions, the diesel fuel

will give reasonable wear protection of the injectors and fuel

pump providing the alternative 1uel has a low·acid content ..

5.1.5:3 Carburetion or Manifold Injection of Alcohols and Ignitionby Diesel Injection - Alcohols have a latent heat of evaporation

much higher than gasoline. Therefore, carburet ion of alcohols re­

sults in a larger drop in the intake air temperature which af­

fects the autoignition process and tends to cause misfire at low

loads. At high loads the carburetted mixture tends to self-ignite

(5.3, 5.4, 5.5). Manifold injection of ethanol was found by

Bertodo (5.1) to require elaborate and expensive control ofthe metering and timing of the two fuels.

5.1.5.4 Two Separate Injection Systems - The methanol, ethanolor gasoline is injected, separate from the diesel fuel, by a

separate injection system. The relative timing of the start ofinjection in the two injection systems has a great effect on

performance and emissions. The effect of the dynamic injection

timing of diesel fuel on the HC and smoke is shown in Figure 5.7,

at a fixed injection timing for methanol. It is clear from this

figure that earlier diesel injection results in lowering the HC

at light loads and the smoke at the higher loads.

5-14

7000

e6000a5000

~LOOO

3000

~ooo

'000

. I [ng1n. lIissfirinQ, r... ll I.::a~ e;,;\;hilJlII, {33 vel I dill.1 In ~thlnelI - --- S4 .n'''91 I: !3~ vol Idiesel 1n ~thlnol

I - 59 ,n,,,S1 $, ~9 vol. dlu,l in _thlnel, _.- 68 enel'91 II

•,,,

PU"e diesel f ...el

Ref. 5-2.

FIGURE 5.6. HC-EMISSIONS VERSUS DRIVING TIME AT NO-LOAD AFTERFULL LOAD AT ENGINE SPEED 1500 RPM.

­I

e't<:::>~\.,

0.5

ot-------C"'Part load

at engine speec 900 rpm.

os

- Oblt"Sfl - 7SaTDr- - - o.OIt Sf l =101:3'DC_. - otvl!SEL : 15BTDC20()O

~'H>J

E~~

~ 0 ~--_...L-_-";;;:-='==-_o6N[.P\ Mf'a

Ref. 5.1

FIGURE 5.7. EFFECT OF DIESEL DYNAMIC INJECTION TIMING ON SMOKEAND HC EMISSIONS WITH FIXED METHANOL TIMING.

5-15

The relative amounts of fuel injected can be varied accord­

ing to the cetane requirements at the different loads. At idling

and light loads the fuel should be diesel fuel in order to reduce

He emissions and improve ·the cold starting characteristics.

A comparison between the performance of the standard diesel

engine and the diesel/methanol engine is given in Figure 5.8.

This figure also shows curves for methanol with 15 percent water,

which represents an alcohol distilled at a low concentration andrelatively lower cost. Figure 5.8 indicates that with methanol,

there is a slight improvement in thermal efficiincy, low load

hydrocarbons, and high load smoke.

Figure 5.9 is for.a diesel/ethanol engine and is similar to

the corresponding figure for methanol.

5.1.5.5. Spark Ignited Alcohols in Diesel Engines - A commercial

spark ignited diesel engine running on diesel fuel was used by

Vo1ve (5.2). To make a light engine, a low compression ratio (12:1)

was used. The prob1~ms with this engine were cold starting, high

emission of hydrocarbons at idling, and low reliability, as thespark plug could be wetted by the fuel, thus causing misfire.

Spark ignited diesel engines running on gasoline, methanol,

and ethanol have been developed (5.6) (5.7), but are not commer­

cially available. In these engines, a much higher voltage isneeded for the spark because of the high compression ratio.

The effect of using methanol on the endurance of diesel

engines during two lOOO-hour cycling bench tests was reported by

Holmer, et.a1., (5.2). Wear was observed between the injection

needle and the spring washer causing the opening pressure to fallfrom 14.7 MPa to between 4.1 and 11.8 MPa. An attempt was made

to solve the wear problem in the injector by increasing the back

pressure in the fuel leakage pipe in order to maintain the

methanol in a liquid phase at the temperatures which exist in theinjector. This attempt did not solve the problem. Other problems

reported by Holmer are related to cracked plunger liners.

5-16

"

- ." ,'I.IJ: ,.~.(;) 1'/:'\.' l l '''6i'li-'.- - ,':!. '1/';'''[1/

- M~- ill.e.l\'Ol • 7!J % .....M [R

400

40~

30 •~

~~

70 ""'........0 "'"7,0

-'.e

~VI 0 "---~-....:::=r.;__.J

0.58,.t-P MPd

Reference 5.2.

FIGURE 5.8. COMPARISON OF PART LOAD PERFORMANCE BETWEEN STANDARDDIESEL AND DIESEL/METHANOL ENGINES AT 1500 RPM .

._- [7H""OL- - -nHAI...Ol .30"" hl.7l I(

- - [T HANOL 050 % 1''''',"[ R

7,0

Reference 5.2.

)0,

~ ~e ~~ W ~~ SMOKE ~

5, 0 '-----'---~.,....,,--~, ~o 0.58,.,£P !'1Pa

FIGURE 5.9. PART LOAD PERFORMANCE WITH DIESEL/ETHANOL ENGINE AT1500 RPM.

5-17

5.1.6 Effect of Mixing DF-2 With Vegetable Oils

Results of tests on blends of DF2 and several types of

vegetable oils are given in Table 5.6. The vegetable oils tested

are:

a Soya Oil

a Babco Oil

0 Palm Oil0 Peanut Oil

o

The results with 10 percent and 20 percent ~otton seed oil aregiven in Table 5.7. Bertodo concluded that:

i. Most vegetable oils except castor oil are directlymiscible with middle distillates.

ii. High viscosity and acidity were general problems with

all vegetable oils.

iii. Castor oil, readily mixed up to 2 percent concentration,

was too viscous (297.5 CS at 37.8°C) and tended to cause

fOUling (carbon residue 44 percnet), and proved

excessively acidic.

5.1.7 Effect of Mixing DF-2 with Gasoline - The main problem of

using gasoline as an alternate fuel in diesel engines is related

to its very poor ignition property resulting, in very long ignitiondelays. This results in late start of combustion at low speeds

and misfire at high speeds. Techniques to reduce ignition delayare heating the inlet air, raising the compression ratio, or

mixing a high ignition quality additive with the gasoline such as

diesel fuel or lubricating oil. Figure 5.10 gives the cetane

number drops from 50 to 32 as the percentage gasoline in the mix­

ture increases from 0 to 50 percent. The effect of mixinggasoline and diesel fuels on the ignition delays is shown in

Figure 5.11. This figure shows that an inlet air temperature of

100°F, mlxlng with 30 percent gasoline increased the I.D. by 50

percent. Figure 5.12 shows results reported hy Scott for testsof a 300 cu. in., 6 cylinder D.I. truck engine, with diesel fuel·

5-18

TABLE 5.6. PERFORMANCE IMPACT OF EXTENSION WITH VEGETABLE OIL

lloaBeline Enginel§:l Compression Ratio

22 !'l'DC llyn. Inj. T1m1.:lg

BS 2869 Class Al lIS 2869 Class Al BS 2869 Class Al lIS 2869 Class Al BS 2869 Class AlNil 20% Soya Oil 2~ Baba~o Oil 20% Palm Oil 20% Peanut Oil

_20 -15 _15 _15 _15>C!l 50 CB 4S C!l 48 C!l 47 C!l 47

!Zlgine

Fuel SpecificationExtenderAromatic Content, ~

Cetane Rating..Power. Itws.I.c •• ml/Kwh

NO • gjKwr.+BC~ g/Kwo­CO. g/Kwh+B:acx SmoKe. ~ OSP~5 2Noise. dB re - 2xlO H/m

61.6261

13.12.6

10.2~

100

61.1286

8 - 9

61.1284

e - 9

61.1281

e - 9

61.0280

e - 9

• a~ 2;00 rev/min and BS Au 141a 1971 conditions

at C~ l}-mode cycle conditions

Reference 5.1.

TABLE 5.7.

Ec.gine

PERFORMANCE IMPACT OF COTTON-SEED OIL EXTENSION

Baseline Engine16:1 Compression Ratio

220 BTIlC' Dyn. Inj. Timing

Fuel SpecificationExtenderAromatic ContentCetane Rating

Power. K"'"s. f. c.. ml/Kwh

1:IS 2869 Class AlNil

-20>CN 50

61.6281

1:IS 2869 Class All~ Cotton Seed Oil

-18CN 49

61.0280

E5 2869 Class Al20% Cotton Seed Oil

...... 16CN 47

60.9278

NO • g/Kwh+ l~.lHC~ g/Kwh+ 2.6CO, g/Kwh+ 10.2Elack Smoke, %USPH§5 2 ~Noise, dll re - 2xlO N/m 100

• at 2500 rev/Min and 1:IS Au 141a : 1971 conditions

+ at CARE 13-mode cycle conditions

Reference 5.1.

5-19

8 - 9 8 - 9

60

50

40

0:30LIJm

2:;)

Z

IIJ20z

et....LLIU

10

o 10 30I

40I

50Percentage of Gasoline in Mixture

FIGURE 5.10. CETANE NUMBER OF DIESEL-GASOLINE MIXTURES

5- 2 a

4.0

3.6

03.2I.IJV')

~~

0 2.8Qa::t:2.4

~...J~2.0ozo;= 1.6ZL?-

1.2

.8

BLENDS OF DIESEL # 2AND GASOLINE

Pm=600 PSIO

<> CN-44e CN - 30I2J CN - 22CD CN- 6

50 100 150 200 250 300 350 400 450 500INLET AIR TEMPERATURE (OF)

FIGURE 5.11. EFFECT OF MIXING GASOLINE WITH DIESEL FUEL ONIGNITION DELAY.

5-21

- __ KUWdlt YdS oli 23· E SlanG;.!r,: n:~_: on t,m,n-,;_._.- Es~c, rl:'yulilr yasol,n", 32 E s:"nc:,,~:: ,n!"C!lon t,mlny---- -- MT8036 yilsolln" 32 E S:ii nn:: r:: '1 ',:,l tIOr"· (,m,ny

30 40 50 60 70 se 90 10C' 1 10Brit'·· M .. iln Etlt:'C!III.. Pr",ssu'," 'ps"

---,--- ._- ------ --- - .._---\

7r---~ -- --­\ 2600 r\:l1'

~~__ \ :JV /- 61

~ __... >

- 5:'-, J V --=!"--=-=_--, \ .... J\''I \ - '- -\ - 1_·/

4;~- ----- ---6-, \ I _

j' 'So " 2000 ro", I _

; 3-~ __ J~ -~:~ ;5 ~6' .__ ._=::::..,.~-=?Ij(: I 4

JV i51--00'<..-----1500 rp,,·--J\ : 3 ~

~IV '\' I )~ oJ ~--"'::::::~SC;;~=_--I'--""::::':::"'::;-'~' -,/~-

----.~ ="=i .....

'.J13~~-""""-""'"

Reference 5.18.

FIGURE 5.12. TYPICAL DIESEL FUEL AND GASOLINE LOAD RANGE CURVESFROM A 6 CYLINDER 300 CID DIESEL ENGINE.

5-22

and two types of gasoline. TheC.R. was raised from 17 to 19:1.

The BMEP at which just visible smoke is indicated by the symbol

JV on the figure for each fuel. Figure 5.13 sho~s very clearly

that gasoline produced higher BMEP at the smoke limit. This is

caused by the incre~se in the portion of the fuel which is

injected during the longer ignition delay, and the increase in the

pre-evaporated and pre-mixed part of the charge. The deteriora­

tion in fuel economy at high speed and light load is due tr.·) mis-~

firing due to the long ignition delays of gasoline. Combustion

photographs taken by Scott (5.8) indicated the occurenc~ of pre­

mixed burning with long ignition delays.

One of the problems associated with the use of gasoline in

direct injection diesel engines is the formation of pockets of

ena gas outside the combustion.bowl, which detonate causing

damage to the piston crown.

The use of additives can reduce the ignition delay period.

Adding,S percent lubricating oil to the gasoline was found to

increase the cetane number of a primary reference fuel 'from 19

to 22 and to decrease the R.O.N. of gasoline from 93.1 to 89.5

(5.8). Adding 5 percent lubricating oil was found by Scott (5.8)

to eliminate the damage in the piston caused by detonation, and to

provide necessary lubricity to the gasoline in the fuel injection

pump.

Another problem associated with the use of highly volatile

fuels in'diesel engines is vapor lock in the fuel injection pump.

This may be avoided by using pressurized recirculating feed to the

pump gallery (5.8).

The use of gasoline in divided chamber automotive engines

was reported by Scott (5.8) to be far less successful than in D.!.

engines. This is attributed to the high rate of evaporation and

premixing, coupled with high rates of heat loss, which result in

excessive delay and unreliable ignition, particularly at partialloads.

5-23

5.1.8 Effect of Using Two Separate Injection Systems in a Diesel/

Gasoline Fueled Engine

A comparison between the partial load performance of a diesel/

·crude low octane gasoline engine and a diesel engine running on

gasoline has been reported by Holmer et.al., (5.2) and is given(j

in Figure 5.13. This figure shows an increase in the thermal

efficiency and reductioQ in smoke in the diesel engine when runon low-octane gasoline. However, the HC emissions are much higher

with pure gasoline, particularly at light loads. To reduce these

emissions and improve the cold starting characteristics, pilotinjection of diesel fuel is used at light loads and atstarting. At high loads, the pilot injection is stopped as the

cetane requirements are less.

5.1.9 Effect of Using Wide Cut Distillates

Holmer (5.2) indicated that wide cut fuels can be obtained

by mixing crude gasoline with diesel fuel, and can be produced at

the refinery with less energy than that required to produce highoctane gasoline. Broadening the distillation range of the fuel,

by including both lighter and heavier fractions than those nor­

mally associated with DF2, is the simplest and most expedientmethod to increase the diesel fuel stocks (5.1). According to

Bertodo (5.1), the benefits f~om such a fuel are:

a. Reduce the refinery losses by 17-25 percent.

b .. Increase crude barrel yield as "road fuel" by 5-25

percent.

c. Improve the mileage potential per barrel of crude by

11-21 percent.

d. Raise crude to drive-wheel conversion efficiency by

about 30 percent.

5-24

- - (/(I.'Of" u':'$JL IN! :."'0 DlfSEL

- - - (t;uDf GtSOLII£

,1£.

Reference 5.2.

.k-'Q.

~OO....(XHAUS 7

­,

o 0; 0,4BM[P MP.

0,6

FIGURE 5.13. COMPARISON OF PART LOAD PERFORMANCE WITH DIESEL!CRUDE GASOLINE AND CRUDE GASOLINE AT 900 RPM.

5-25

5.2 0.1. TWO-STROKE-CYCLE DIESEL ENGINE

5.2.1 Effect of Using Off-Specification Diesel Fuels

Baker (5.9) performed tests on a two-stroke-cycle medium­

speed diesel engine by using off-specification diesel fuels. One

or more properties of these fuelscdid not lie in the currently

accepted range of specifications for Number 2 dies.el fuel. The

fuel properties ~aried were cetane number, viscosity and dis­

tillation range.

The engine used was a'two-~ylinder version of the Electro­

Motive Division (EMD): 8.5" bore, 10.0" stroke, 2-stroke-cycle,blower scavenged, maximum governed speed of 835 rpm, 16:1 C.R.

Fuels were produced by blending various components, and

compared to No.2 diesel fuel which met all requirements of ASTM

0-975 shown in Table 5.8.

Effect of Cetane Number. The effect of cetane number was to reduce

the 1.0. and rate of pressure rise as shown in Figure 5.14. For

fuels with a C.N. above 30, the decrease in 1.0. was not sufficient

to result in a significant penalty in engine performance, brakehorsepower, thermal efficiency, BSFC, and rate of pressure rise as

shown in Figure 5.15. Below a C.N. of 30, rate of pressure rise

increased dramatically. The effect of the variation in C.N. onthe emissions is shown in Figure 5.16. In this 'figure, Notch 8

indicates .full load rated speed and load. All other notches

indicate partial load conditions.

Effect of Viscosity. The viscosity was varied independently of

the other fuel properties by heating an extremely viscous lube

stock. Probably, heating the oil resulted in variations indensity. Engine power, fuel consumption, thermal efficiency, and

combustion characteristics were almost constant. The effect of

viscosity is shown in Figure 5.17. Brake specific particulatesincreased as viscosity increased from 38 to 65, at the high load.

(This load was limited by the inability of the injection system

to supply sufficient fuel for normal operation). At partial loads,

5-26

160

140 FUEL 8LENOS

120HAN/OIESEL FUEL

·,SOOCTANE/OIESEL FUEL··SECONOARV REF FUELS

100...IZ:::l 80'""'-"'1:'IZ: ... 60"'c... -Ou;... ~ 40~

«IZ: +-

20

0

12

"10

,.~~:.. 6 NOTCH 89

+ NOTCH 6.~":'~. > 8 C NOTCH 40<

~ 0 NOTCH 2... -co<ZU01:'- ...~c 6Z -~

5

4

315 20 25 30 35 40 45 50 55

CETAIIolE IIolUM8ER

Reference 5.9.

FIGURE 5.14. EFFECT OF C.N. VARIATIONS ON I.D. AND RATE OFPRESURE RISE (2-CYLINDER ENGINE).

5-27

Z 0750i=...~::::l

'"Z0 0.5 ....'-'-~CI: .e;g =6 • Co G"':r •:l .... !:'-'Ill- -"'11I 0.25- ..J'-'-'"...'"'":It«a:

0III

~

no A"· :0:""""4

~.Co6

200

180

a: 160...~0 140......

FU~L BLENOSIII 120a:0 MAN/OI ESE L I' UE L:r 100 -rSOOCTANE/OIESEL FUEL...lI: 80 ··SECONOARY REF FuELSCa:III 60

40

f20

0

30'

> 32'-' A"Z A'" A·· ~ :6q 30

/~...... 2B..J«~

26ct A NOTCH 8...:r~

'" 24lI:~ctIII 22

20

1815 20 25 30 35 40 45 50 55

CETANE NUMBER

Reference 5 _9.

FIGURE 5.15. EFFECT OF C.N. ON ENGINE PERFORHANCE (2-CYCLE ENGINE)

5-28

TABLE 5.8. NO. 2 DIESEL FUEL PROPERTIES

Reference: 5.9.

Bas~lin~

Fuel ASTM D975 No. 2 Dies~1 (IProperty Specifications Fuel

Celane Number min. 40 55API GravilY no spec:. 37.7

Kinemalic Viscosil)' min. - maA.(esl. al 40°C) 2.0 4.3 3.3

Heal of Comb.(BTU/lb) no sp~" 1968~

DisliJIalion (0 F)10'7. no spec:. 4609017. min. - maA,

540 675 64Q

Sulfur ('7. mass) 1.0 0.15Ash (llio mass) omWain. Sed. (17. voL) 0.10Flash PI. (OF) min.I:!5 161

5 - 29

Reference 5.9.

".==~

··..·

D •

,:~~

t•.. .;

. . .:::......." :::::::;;~: -

FIGURE 5.16. EFFECT OF C.N. ON EMISSIONS IN A 2-CYCLE ENGINE.

5-30

2

0.75

6 NOTCH B

+ NOTCH 6

o NOTCH 4o 'NOTCH 2

II!!:.;;....---+---~~-o

0.5

1.5

i:r 1.25~

:r~

~<IIZo=a:;5 0.75oc::Q>::t OS

0.25

o

.,y' .~.-------+

10

95

9

~ 8.5~

:rCIl

~ 8...!:ll( 7.50uit 70-

i

63D .a SO 60 70 SO 90 100 110

6.5

Ref erenc e 5.9. VISCOSITY (CST}

FIGURE 5.17. EFFECT OF VISCOSITY ON EMISSIONS IN A 2-CYCLE ENGINE

5-31

the brake specific particulates increased with viscosity up to 65

CS, after which they decreased. This variation in particulate

emissions is related to the change in the spray characteristicsand the degree of premixing of the fuel and air.

Brake specific hydrocarbons generally increased

particularly at the lightest loads (Notch 2). Brake

nitrogen oxides decreased with increased viscosity.

"oxide and sulfates did not show a definable relation

with viscosity,

specific

Carbon mon-

to viscosity.

Effect of Distillation Range. Fuels of different distillation

range were prodnced by blending various combinations of unleaded

gasoline, a lube stock, and No.2 diesel fuel. This resulted invariations in the other fuel properties, and a multi-variate

statistical analysis was used to find the effect of each fuel.property. This analysis indicated that the distillation range

was not a primary factor in B.H.P. and BSFC, but rather, the C.N.,

API gravity and the heating value are the major factors. In a

second analysis, each of the performance parameters was plotted

in terms of each fuel property, and the results were then cross­

referenced to isolate the pertinent properties. The effect ofC.N. on I.D. is shown in Figure 5.18, and on the rate of pressure

rise in Figure 5.19. Below a C.N. of 30, the increase in I.D.resulted in a high rate of pTessuwe rise. The effect of API

gravity on brake thermal efficiency is shown in Figure 5.20. The

effects of API gravity on the brake horsepower are shown in

Figure 5.21. It should be noted that the engine was not optimized

for fuels of different distillation ranges. Accordingly, it is

expected that the engine thermal efficiency and power output are

not optimized for these fuels. Baker (5.9) observed that the

maximum brake horsepower and brake thermal efficiency resulted from

the use of fuels whose properties approximated those of the base­line diesel fuel.

The effect of viscosity on the brake thermal efficiency is

shown in Figure 5.22. The effect on brake horsepower is shown in

Figure 5.23. The relationship between the API gravity and theviscosity for the different blends used by Baker is given in

5-32

~i~

l~

\.<~

I.'.

,,

,'

~o

q

12

_I

lIiO

I

A.

l:l.

...."

14

0

"41

too..

....1/

1

10J.

411

20

41II

I'n

4110

0

:.o"'"}

c::l

'nli

t-•

c::l

1IO

.l•

t6

06

l~

•....

•4

0•

•••

••

••

•2

0:..

....

4L

160

12r

•1

40

NO

TC

H6

10t

•12

0t

NO

TC

H6

•1

00

IIL

..I

•0

lIQ•

0

6f

••:

f,

••

>-•

.•

C"

:.,...

. ••

...•

20w

_J

0«

ZU

160

IV

I0

"12

~•

-w

1t:

O1

40

Vl

Z-

NO

TC

H4

Vl

£'10

12

0 I:t•

..II

l-••

100

•6~

•ee

:~H

OT

CH

"

,.I.

,....

••

••4

L2

Q

12r

16

0

10L

14

0I

HO

TC

H2

120

NO

TC

H2

IL

10

0•

'01

0•

•L

••6

0•

eee

•o

·4

0e

e.

4,..

e•

••

"~

:10

010

010

:10

JO4

06

01

070

20

JO4

06

06

0

Ref

eren

ce5

.9C

UA

NE

HU

UII

ER

Ref

eren

ce5

..9

FIG

UR

E5

-1

8.

EFFE

CT

OFC

.N.

ONI.

D.

FOR

FIG

UR

E5

.19

.EF

FEC

TO

FC

.N.

ONRA

TEO

FV

ARI

OU

SD

IST

ILL

AT

ION

RANG

EPR

ESSU

RE

RIS

E-D

IST

ILL

AT

ION

FUE

LS.

RANG

ES

ER

IES

.

35 JO 2!i

20

......

C1l

<:I"

III

IC1

l

t:..·t

••

NO

TC

H8

•22

!i

200

<:I" I l:l. .. r· · ••

••

• •

rl C1l

III

C1l

l~

•N

OT

CH

8

•

D

35 JO

••

".

'rI.,

.•

••

IJIi

(Jl

I VI

(Jl

> u Z w ~ ... ... w .. « :I II: w :r .. w "« II: ID

21i

20 Jli

JO 2!i

20

,...

.•

eII

••

•

NO

TC

H6

•N

OT

CH

4

•

II: ~ ... '"II: o :r w "... II:

ID

1!iO

12!i

100

J!i

•.e

,•••

• •• •

•..~

..••

• •

•N

OT

CH

6

.J •N

OT

CH

4

o •

21i

20

15 10

• •,..

..•

• •

••

NO

TC

H2

•!iO 2!

i

e••

,••••

•• •

e

NO

TC

H2

•6

II

•I

II

I,

II

,

o2

J4

56

89

10o

!i10

VIS

CO

SIT

YfC

ST~

4O"C

IR

efe

ren

ce

5.9

FIG

UR

E5

.22

EFFE

CT

OFV

ISC

OSI

TYON

BRAK

ETH

ERM

ALEF

FIC

IEN

CY

DIS

TIL

LA

TIO

NRA

NGE

SER

IES

Refe

ren

ce

5.~

FIG

UR

E5

.23

.

VIS

CO

SIT

YIC

ST

fil4

o"C

I

EFFE

CT

OF

VIS

CO

SIT

YON

BRAK

EH

ORS

EPO

WER

DIS

TIL

LA

TIO

NRA

NGE

SER

IES.

Figure ~.24. This figure shows that heavy fuels are more viscous.

Accordingly, high viscosity fuels have more BTU per unit volume

and, in general, should produce more power for the same volumetricrate of fuel injection.

Effect of Fuel Properties on Emissions. The effect of API, gravity

on the brake specific hydrocarbons. is shown in Figure 5.25. In

general, lighter fuels produced more hydrocarbon emissions'. This

is caused by the longer I.D. of th~ lighter fuels~ i~ addition to

their higher vapor pressure and results in more HC in the lean

flame-out region of the spray.

The effect of viscosity on the brake specific hydrocarbon

emissions is given in Figure 5.26. This figure shows that the

fuel which has a viscosity slightly lower than diesel fuel pro­

duced less BSHC. For less viscous fuels, BSHC were higher than for

diesel fuel. Fuels which are more viscous than diesel fuel produced

less BSHC, particularly at the lighter loads.

The effect of viscosity on the BSHC is related to the lean

flame-out region of the spray and to the fuel in the sac volume

of the nozzle.

Baker reported that neither particulates nor nitric oxide

emissions could be specifically defined in terms of the infl~ence

of a single fuel property. However, carbon monoxide displayed a

dependence on both cetane number and total BTU input; in both

cases, the trends observed were also a function of load (or notch

position), as indicated in Figures 5.27 and 5.28.

Baker concluded that no single fuel property could be classi­

fied as the primary variable which affected performance and

emissions when all fuel properties were allowed to vary simultan­eously; rather it was the combined influence of several variables

that ultimately determined engine behavior~

5.2.2 Effect of Using Fuels Derived From Tar Sands and Shale Oil

Tuteja and Clark (5.11) studied the sensitivity of a D.I.,

2-stroke-cycle diesel engine to variations in fuel source. Diesel

5-36

60

50 .

>t- 40-><a::

~

C)

CL 30ca:

20

o 2 4 6 8 10 12 14 16

VISCOSITY (CST,40·C)

18 20 22 24

FIGURE 5.24. RELATIONSHIP BETWEEN VISCOSITY AND API GRAVITY FORDIFFERENT DISTILLATES.

5-37

Q

oIi~

I:[.:

.l

12 10 II Ii 4 2 o

..... III III

NO

TC

HII

III 'M Q ,.1•

•

'1 10 8

..... III III

III OM QN

OT

CH

II

••

11 10

44 1 •

.. ..••

NO

TC

H4

NO

TC

HIi

• • II·

• ..'" •

4II Ii 8o1 • 1 oi '010 1111

". z o ~ a:_ Oa:

~%

J:...

UJ:

-'"

...-

-0

u_ ... ll; ... W <f a: '"

••.0• •

••

0• •

/I

•II

••

• o

NO

TC

HIi

NO

TC

H4

II Ii 12r

.0~

2 o

'" ~ : ~0

o ~it

11~

J:

~~

'0-",

...~

u!a

II... :; ... W <f a: '"

In I VI

00

oI

•,

I,

II

I

NO

TC

H2

16

•1

0

, •16

'0

NO

TC

H1

6

•

4

,I

,,

o!

II

30

8 Ii

".

1I-

•

JO~~

r.o

•

40

• ..• 30

•

20

10

II Ii 4

AP

IG

RA

VIT

YR

efer

ence

5.9

FIG

UR

E5

.25

.R

efe

ren

ce

5.9

EFFE

CT

OF

API

GRA

VIT

YON

BRAK

EFI

GU

RE

5.2

6.

SPE

CIF

ICHC

-D

IST

ILL

AT

ION

RANG

ESE

RIE

S

VIS

CO

SIT

YIC

ST

.40

"C

I

EFFE

CT

OF

VIS

CO

SIT

YON

BRA

KE

SP

EC

IFIC

HC-

DIS

TIL

LA

TIO

NRA

NGE

SER

IES

,n

•~ IB

•III

16

•14

••

~I~

•2

01

0•

••

B"

16

•6

••

••

I~

~N

OT

CH

B

•0

B.

4N

OT

CH

.

~fN

OT

CH

60

18 16

14 :~[~O

i•

•1

6,

NO

TC

H8

...0

.••

0I)

c•

iII

I•

0~

••

z

:~•

0...

~•

•0 K

z•

•0

•0

n:-

•z

00

~e

ll:

(Jl

~N

OT

CH

4u~

z18

!:!~

I0

16

",Ill

VI

III

ua~

II:

14lD

C...-

UI~

.. ...1

6t

D10

... "8

CU

II:

~N

OT

CH

.6

••

8)

•Ill••

Ie

••

0

ot-.

,.••

~) :zo 18

NO

TC

H~

:zo1

6 14e

16

12 10U

rN

OT

CH

)8

B6

:~•

4•

o••

,.•

..•

••

~

•,

I,

•,

,0

010

20

JO4

0W

60

10

8~

90

9~

10

0IO~

11

0

CE

TA

NE

NU

M8

ER

Ref

eren

ce5

.9F

RA

CT

ION

OF

BA

SH

IIII

EB

TU

INP

UT

Ref

eren

ce5

.9FI

GU

RE

5.2

7.

EFFE

CT

OFTO

TAL

BTU

INPU

TON

FIG

UR

E5

.28

.EF

FEC

TO

FC

.N.

ONBR

AK

ES

PE

CIF

ICBR

AKE

SPE

CIF

ICCA

RBON

MO

NO

XID

ECA

RBON

MO

NO

XID

E-

DIS

TIL

LA

TIO

NEM

ISSI

ON

S-

DIS

TIL

LA

TIO

NRA

NGE

RANG

ES

ER

IES

.SE

RIE

S

fuels derived from oil shale and tar sands were compared with

the commercial DF-Z diesel fuel derived from crude petroleum. The

properties of these fuels are shown in Table .5.9. The DF-Z hasthe lowest viscosity and distillation range, while shale fuel has

the highest. Tar sands fuel has the lowest cetane number, sulfur

content and atomic HIe ratio while sha~~ fuel has the highest.

The fuel nitrggen content was low for regular DF-Z and tar sands

fuel, but substantially higher for the shale fuel. ~

The engine used was a three cylinder, D.I., 18.7 C.R.,

naturally aspirat~d, Z13 CID, Z-stroke-cycle diesel engine~ The

injectors used were of the N-60 needle valve type modified to

maintain constant beginning of injection. In this work, NO was

measured by using an NDIR analyzer, and NO Z by using a long path

NDUV. These values were corrected for temperature and humidity.

The effect of load on I.D. for the three fuels is shown in

Figure 5.Z9 for three different speeds. The I.D. decreased with

the increase in cetane number.

The maximum rates of pressure rise,shown in Figure 5.30followed a trend similar to the ignition delay.

The BSFC relative to DF-Z fuel is shown in Figure 5.31 and

shows a slight loss in fuel economy with the alternate fuels,

particularly at the high loads. This is believed to be caused by

the injection and combustion systems which were developed for the

DF-Z and not for the other two fuels. For example, in this work,the injection timing was kept constant and corresponds to the I.D.

of DF-Z fuel. The I.D.s for the alternate fuels are longer than

for the diesel fuel and a slight advance of the injection timingwould have improved the engine fuel economy.

The exhaust smoke obtained for the three fuels is given in

Figure 5.32. Tar sands fuel showed the highest smoke, followed

by regular DF-2, and shale fuel respectively. The differencesare generally small and possibly not significant at lower speeds.

At higher speeds, the fuel from tar sands produced the highestsmoke. In general, smoke is related to the injection timing,

5-40

DERIVEDFUELSREGULAR DF-2SANDS

OFAND TAR

PROPERTIESFROM SHALE

5', 9 ,TABLE

TAlI.!!m

!!!.....LsICR

Ar..utaa,IUM'M1Olaf I".....1111'11••h

0.160.0%2.7....U.'6'J.6'J. ~0.0U.7

0.2'0.010'7. J6U.87'2.6%0.00.5J2.3.0016

D.SO0.2'16.0ZU.79J).7

.001

\'.....C.R

'b

0.2O. J0.9O. :

CO. I<0.1

C.OI0.60.10.10.10.5

0.2J .•0.71.2

<0.1<0.1

mill:

AII111... 't. ('C)"/Cteta. Ikl.liP 'r1(1: or~ ·F~ 'rEP 'r'.,1

'uca.tt, CI .. 100" ,. J5

57.!I. 76'1.015 I425509605649J6. :

%.50

L.awer lIe.t1na Vel ...Un:flbl

11131 11:61 11107

~

PIO.tIl~lt5 Dr r~c.s ~SCl I' ~. OOPI.' TEns

5

•C

•Arcmel Joe

"'~P1I"""'"Oloh,..'.r.' t lnau.

.1,..ArOMt H

~

o. =~

0.0:. CO.9t1'­!'. I_ll.. E''2 .•2•. 00.\J2. J.001t

Lo.ArOUt1:

~

0.250.01! (0.9:,16 IJ1~ 6:J5. \25.30.0".1.000..

OF';

.0:',001 (;.0:1It. C:11.1'IJ. C'2LlO. C61 ;.DOO.

Jp.eel.".

.OHoc .0... : (l ~:

8~ . ]..1. tl~

t.IH.C0.'6: .\.0008

nACE !lETAll.'

!'''''\'

••...CoIPb

•. 010.60.10.10.10.1

•. 011.20.010.23D. OJ0.25

c. C5. 1\.01.09.a~0.3'

O. :1. D:.~~.o~

.01

.11

""111M ... ('C)RICee,..,. Ie.liP 'r101 'r'01 "9ll'I "EP 'r'.,1

ST.81.76'J.OH7025

'09601649h.1

'02'7~

551

102. 01n.916!236)!I

51.IH1).6

5-41

- TAR SANDS FVEI.- REGULAR DIESEL FUEL- ~ FUEL FROM SHALE 01.

15 ... .• •

10 121DRPM

·I'-----------~

nDOIIPM

1100IIPM

.. I ....-.

~-.....------ -.---

10

•iii=15,.-------------Wc~ 1D

ii ·5

II 15,.---~~~-----......;.--....

. ~---....._-~s~~~-~- ......- .....- ....-..J

ZD .eo 10 -10 100%LOAD

Reference 5.11.

FIGURE 5.29. COMPARISON OF I.D. WITH REGULAR DIESEL FUEL ANDFUELS DERIVED FROM SHALE AND TAR SANDS.

5-42

--.J REGULAR DIESEL FUEL-- TAR SANDS FUEL-- SHALE FUEL

zoo

150

..•."',/~, .---~- .•" ....

----~--

1Z60RPM

. .

2100RPM

'100RPM

................-_ .. .

'OO'-_-'-_......_--I._-""_--I_~a .ao 10 10 100

" LOAD

150

c~~ 100'--------- ....1III..,E

§ 200..,..,III

~ 150 ............................1:1 fIf""" ......__•.$ 100~-----------"'"KIeC

• ZOO

Reference 5.11.

FIGURE 5.30. COMPARISON OF MAXIMUM RATE OF PRESSURE RISE WITHREGULAR DIESEL FUEL AND FUELS FROM SHALE, AND TARSANDS.

5-43

e __•• TAR SANDS FUEL-- SHALE AIEL1JU.------.....;,;.-------,

12&0RPM

fe:= 1.02w

!ciZ 1.00II:

fe1.02 ::

w

!1.00 ~

wII:

O.98~;::::========~,... 1.0.

~/" _-0,"............ 1100'

....•. RPM.'

-==='-'========:0.111JUOr-

fe:h.020w!~1.000

*

Reference 5.11.

.'..'................;;;;.

RPM

20 .to 10% LOAD

.­.'........

100

FIGURE 5.31. BSFC WITH SHALE AND TAR SANDS FUELS RELATIVE TOREGULAR FUEL.

5-44

- REGULAR DIESEL FUEL...- •.•• TAR SANDS FUEL .~)

--FUEL FROM SHALE2

1~

~12&0RPM

..~O~

Z...-.:CI 1&00•III 1 RPMz

~~CIt

i 0..............::.:.:.:... ~

2 2100RPM

1

0

0

Reference 5.11.

FIGURE 5.32. COMPARISON OF SMOKE WITH REGULAR DIESEL FUEL ANDFUELS DERIVED FROM SHALE AND TAR SANDS.

5-45

injection pressure, 95 percent, and aromatic contents. Table 5.9

indicates that the fuel from tar sands has an aromatic content

slightly higher than DF-2 and much higher than the shale-derived

fuel. The 95 percent point does not indicate a trend in these

tests. It appears that the reason for the highest smoke with the

fuel from tar sands is related to the unoptimized injection timing.

The longer ignition delay with this fuel, without advancing thev 0

timing allows the combustion to take part later in the expansion

stroke and result in higher smoke concentrations.

The ~Ox emissions are given in Figure. 5.33 for the two fuelsrelative to DF-2 fuel. In general, over the speed range, NOxemissions were highest with tar sands fuel, and least with the

shale-fuel, except at full load at the 'highest speed. The

difference between DF-2 and shale fuel is small. However, the

difference between NO emissions from regular DF-2 and. tar sands

fuels is significant. The differences between the two fuels which

contribute to the high NOxemissions are: (i) the lower cetane

number of tar sands fuel, which results in longer I.D., and pre­mixed combustion, (ii) the slightly higher aromatic content of thetar sands fuel as compared to that of DF-2 and the resulting

higher combustion temperature, (iii) the higher nitrogen content

of the tar sands fuel as compared to that of DF-2.

The unburned hydrocarbons from the tar sands fuel and shale

fuel are given by Tuteja and Clark· (5.11) in Figure 5.34, relative

to the hydrocarbons from DF-2. The HC emissions with tar sands

fuel are about 60-70 percent of HC emissions with regular DF-2,

whereas, with shale fuel, these emissions are about 30-40 percentof those with regular DF-2, over all the speed and load ranges.

The factors that might have contributed to the lower HC emissions

from the alternate fuels are related to the higher viscosity and

SO percent points of these fuels, which reduces the HC related

to the volume of fuel in the sac and injection nozzle.

The CO emissions are shown in Figure 5.35 for the alternate

fuels relative to the CO from the regular DF-2. In general, tarsands fuel shows the highest CO followed by regular DF-2 and shale

5-46

-- SHALE FUEL- TAR SANDS RIEL• • EXPECTED RELATIVE NOX EMISSION BASED ON TOTAL

CONVERSION OF .24% N IN REGULAR DIESEL RIEL1.20r-------------­-1.00 -0.10..•Ii..

I...Ie 1.00a•...~ 0.10c.......e

1:l0-~

...".'

1.D0,~ ....

0.80

Reference 5.11.

~..............--...............-

,--e-_.....~.­--

20 40 10 ID 1DC% LOAD

12&0RPM

1100'RPM

2100RPM

FIGURE 5.33. NOx EMISSION BY MASS WITH SHALE AND TAR SANDS FUELSRELATIVE TO REGULAR DIESEL FUEL

5-47

1&00 RPM

2100 RPM

- TAR SANDS FUEl.-- SHALE RIEL

,,·1 I., 12&0 RPM-.,I 0.7-w

!I!.w 0.5-!~ ------ _..-.=O.3'---------------_...J

r--------------O.l-zIi!..

0.7;w

• Ur--------------...I! 0.7'" .... --------.....'"

~ ?! 0.5- /c /~ '--1--'-/1 I~ 0.3"-_......._ ......._ ...._---......._ ....._ ...

20 40 60 10 100% LDAD

Reference 5.11

FIGURE 5.34. He EMISSIONS BY MASS WITH TAR SANDS FUEL RELATIVETO REGULAR DIESEL FUEL.

5-48

1210 RPM

10 100,

11G0 RPM

---'TAR SANDS FUEL.--- SHALE RIEL.. Ur-------~....,;.----;.,

11.51M

8! 1.0c-~ 0.5;==============Ui

.5i1M

8.oi

c

~-----------""'D.5$.. z.ar----------~--I.,• 1.51Moc.a

~ 1.0~ ------~c·........ .-.i:l '--c 0.51.--~-....--.l.-....l--'----l

Reference 5.11.

FIGURE 5.35. CO EMISSION BY MASS WITH SHALE AND TAR SANDS FUELSRELATIVE TO REGULAR DIESEL FUEL.

5-49

fuel. The factors which contributBd to this behaviour are

related to the cetane number of the fuel. According to Broering

and Holtman (5.12), and Gross and Murphy (5.13), CO increases

with the increase in the 90 percent distillation point.

Tuteja, et. al., observed no significant contribution duea

to fuel bound nitrogen in NO emissions. Their tests were conducted

at an injection timing of 18:6 0 BTDC, and they attributed theinsignificant N conversion due to NO attaining its equilibrium

concentration in the main NO producing regions. However, at

relatively retarded timing necessary for low emission engines,

significant conversion of fuel bound nitrogen might take place.

5.3 I.D.I. SWIRL TYPE 4-STROKE-CYCLE ENGINE

5.3.1 Effect of Fuel Properties on Fuel Economy and on

Particulates and Other Emissions

Many attempts have been made to find out which constituents

of the fuel (i.e. paraffins, aromatics or olefins) were mostresponsible for particulates.

Burley and Rosebrock (5.14) reported the results of a carbon­14 fuel tracer study, in which radioactive C-14 tagged fuel

constituents were blended, one at a time, with the standard base­

line D-2 fuel. These fuels were run in a 2.1 liter I.D.I. 4

. cylinder Opel engin~, modified to run on one cylinder. All theparticulates were collected on an 8 x 10 inch filter mounted in a

tunnel and analyzed for the presence of C-14. Tests were at the

equivalent of 25 mph road load and 55 mph road load for each fuel.

The petroleum compounds used in C-14 fuel tracer· studies are

shown in Table 5.10. The quantity of C-14 compound added to the

test fuel was so small that the general physical properties of the

fuel were unchanged. The results of these tests, given inFigure 5.36, show the following:

1. Each of the compounds (paraffins, olefins and aromatics)made a contribution to particulates.

5-50

TABLE 5.10. PERFORMANCE IMPACT OF ETHANOL FUELING

CA~ION

CCMI'OUND ~ FORMULA. STIUJC'TURE

DECANE Co1O CltrCC"2~ 14cH,

MEXADECANE Co1l CMJ-ICHzI1"McH,

OC'TADECANE Co1l CMrlCHzl1r~

DKENE Co10 CM:z"'CM-ICHzlrMcHzC?43

ORTHO IIETHYL XYL.ENE C·I $=14cH,Ci"2

1~ETH"LIlUMTNALDlE Con

@J;~(lUIIfG LAaE LI

'~ETH"LNAI'KTHALINE Con"'ETHYL. LAlELI

00

Reference 5.1.

5-51

2. Particulate emissions from the paraffins were independent

. of boiling point over the range 174°C to 317°C.

3. Aromatics, as a group, were the greatest contributors to

particulates. The ring-labeled I-methyl naphthalene was thelargest contributor.

()

4. Most of the C-14 appeared in the insoluble fraction. Less

than 20 percent appeared in the soluble fraction.

In another extensive study, Burley and Rosebrock found the

effect of fuel composition on fuel economy and emiss~.o~s. Forty­

six fuels including D-l and D-2 fuels were tested. The range of

distillation characteristics of these fuels is shown in Figure 5.37.The engine used was an Oldsmobile, 5.7 liter, I.)n.I. V-8, 4-stroke­

cycle, C.R. = 22.5:1 light duty diesel, with C.A.V. poppet-type

injectors. Each fuel was tested at the standard timing, 5 engine

degrees advance, and 5 engine degrees retard. The tests were con­

ducted under steady state conditions at 5 speed-torque points in the

FTP cycle, and a weighting factor applied to calculate the per­formance and emission parameters. Particulates were collectedfrom the exhaust of one cylinder diluted in a 300 CHI constant

volume tunnel. The sampling time was 20 minutes at each point.The HC and NO emissions and the fuel economy were also measured.x

The physical properties of the fuels and their range are

shown in Table 5.11.

TABLE 5.11. PHYSICAL PROPERTIES OF G.M. STUDY FUELS

'.

Physical Property Range of Test Fuels

Specific Gravity 0.678 - 0.879

Viscosity O. 50 - 3.5 CS at 40°C

10% Boiling Point 48 - 233°C

50% Boiling Point 71 - 267°C

90% Boiling Point 92 - 365°C

Cetane Number 21 - 80

Aromatic Con tent 0 - 95%

API Gravity 27.13 77.20

Sulfur Con tent O. 002 - 1. 25~5-52

G _

--,

I

--

-

Reference 5.14.

FIGURE 5.36. CONTRIBUTION OF VARIOUS COMPONENTS OF DIESEL FUEL, TO PARTICUL.ATE EMISSIONS.

,.._->-5..

II • • • • _

fWICDff I'IA1'GM....

Reference 5.14.

FIGURE 5.37. DISTILLATION RANGE OF SOME OF THE FUELS TESTED.

5-53

A multiple linear stepwise regression analysis was employed

to relate the fuel properties to the various emissions, and fuel

economy.

5.3.2 Effect of Fuel Properties on Particulates

The regression analysis sho~~d the following:

1. Aromatic content and 90 percent boiling point were the

fuel properties most closely related to particulates, as shown in

Figures 5.38 and 5.39.

2. Fuel volatility factors such as the 10 percent and SO per­

cent boiling point showed a weaker correlation to particulates

than the 90 percent boiling point.

3. Particulate emissions increased with addition of cetane

improvers to the light fuels.

4. A typical D-l fuel produces 25 percent less particulate

emissions than D-2 fuel.

Burley and Rosebrock tested a light,narrow distillation

range, low aromatic fuel (C-40) in two vehicles on the FTP cycle.The vehicles were equipped with 5.7 liter engines similar to the

ones used in the fuel test program· conducted on the dynamometer.

The injectors in the engines were conventional two-hole pencil

injectors rather than the CAV poppet type injectors previously

used. The properties of the C-40 fuel are given in Table 5.12

together with those for D-l and D-2 fuels. The particulates formedon the FTP cycle from the C-40 fuel are reduced to 57.4 percent

of those from the reg~lar D-2 fuel (Table 5.13).

Burley and Rosebrock. (5.14) studied the effect of aromaticson the 5.7 liter Oldsmobile diesel engine on a dynamometer under

5 different steady load-speed points with the.two-hole, pencil­type injectors. The armoatic contents of the fuel were changed

5-54

TABLE 5.12. PROPERTIES OF D-l, D-2 &C-40

5-55

TABLE 5.13 PARTICULATES WITH D-2 AND C-40 FUELS ­FTP CYCLE.

Diesel No.2

C-40

0.826 grams/mile

0.474 grams/nile

by blending various amount~ of 95 percent aromatic fuel (C-42:

solvent #150) to D-2 fuel. The results given by :b~ur1ey and Rose­

brock are shown .in Figure 5.40. From this figure, it is noted

that:

1. Increase in the aromatic contents up to 55 percent had

little effect on the particulates and. hydrocarbons. Above

55 percent, the particulates and hydrocarbons increasedat a very high rate. .

2. NOx increased continuously with the increase in the

aromatic contents.

3. The increase in aromatic contents improved the fuel

economy (on a volume basis) up to an aromatic content of

45 percent, above which there was no effect.

In another test, Burley and Rosebrock (5.14) found the effect

of increasing the aromatic content o~ the fuel by blending the95 percent aromatic product (C-42) with the low aromatic narrow

distillation range fuel (C-40). The tests were at steady state at

5 sFeed-torque points of the FTP cycle. The results are shown in

Figure 5.41.

The NOx ' HC and particulates increased steadily with increas­ing aromaticity, while the fuel consumption remained relatively

constant on a volume basis in spite of a density change.

Burley and Rosebrock concluded that the soluble content of theparticulates did not correlate well with fuel properties. Soluble

contents tend to decrease as cetane number increases. Also, the

hydrocarbons decrease with the increase in specific gravity,

viscosity, 90 percent boiling point and cetane number. The NO didxnot correlate well with the fuel properties, but appeared to

decrease with the drop in the aromatic content, specific gravity,and 90 percent boiling point. The fuel economy, on a work done per

5-S6

•

u

I• • •• I •• • •-. I .-• • • •u ,- w- I.-•... • •u • •

u

" I •_1S__.•

Reference 5.14.

FIGURE 5.38. PARTICULATE INDEX IN ARBITRARY UNITS VS. FUELAROMATIC CONTENT.

-7.:,-"

-- a, .. ...U I I II I

• e ...'C'.' •u •.. -t::.

• • II,.. • II~ft •• • '10-.a • •r •,.. •

U

I, - - - -...... ..-r.~

Reference 5.14.

FIGURE 5.39. PARTICULATE INDEX IN ARBITRARY UNITS VS. FUEL 90%BOI LING POINT.

5-57

•N

O.

•IN

DEX

7

HeIN

DEX

..PA

RnC

ULA

TEIN

DEX

a

,.. 0' ..

He

PA

Rl1

CU

UT

EI

7 ..• • •

HCIN

DEX

3

NO

.IN

DEX

IPA

RTI

CU

LATE

IND

EX

U1 I U1

00

2I

EC

ON

OM

Y

EC

ON

OM

YIN

DEX

"(B

YV

OLU

ME. 0

'L

9I

11,

P15

4555

15A

RO

MA

TIC

S.%

EC

ON

OM

Y

(BYl~g~~ME)

1J.

EC

O;)

YY

V--

--

o·,

,,

,9

o10

20ao

4010

AA

OM

AT

,tS

.%

Refe

ren

ce

5.1

4.

Refe

ren

ce

5.1

4.

FIG

UR

E5

.40

.E

r.lIS

SIO

NS

AND

ECON

Gr.lY

VA

RIA

TIO

NFI

GU

RE

5.4

1.

WIT

HFU

ELBL

END

SOF

INC

REA

SIN

GA

RG

r.lA

TIC

ITY

AND

SPE

CI

FIC

GRA

VIT

YST

AR

TIN

GW

ITH

D-2

FUEL

.

EMIS

SIO

NAN

DEC

ONOM

YV

AR

IATI

ON

WIT

HFU

ELBL

END

SO

FIN

CR

EASI

NG

AR

OM

ATI

CIT

YAN

DS

PE

CIF

ICG

RAV

ITY

STA

RTI

NG

WIT

HLO

W-A

ROM

ATI

CNA

RROW

CUT

PRO

DU

CT:>

unit volume basis, improved with the increase in specific gravity,

90 percent boiling point, cetane number and viscosity.

5.4 DIESEL EMERGENCY BLENDS

Similar to the gasoline emergency blends discussed in section

4.4 of this report, diesel blends were tested by Russell et.al.

(4.16) and the :?results reported in the "Emergency Fuels Utiliza­

tion Guidebook". The tests were conducted on a DD4-53 Detroit

diesel 2-stroke~cycle engine, and LD-465-l multifuel "engine. The

diesel extenders are listed in Table 5.14. The indexes used in

this section are the same as those in Section 4.4 except for the

BSDC.

BSDC = BSFC x wdiesel

whereBSDC = Brake specific diesel consumption

wdiesel = mass fraction of diesel fuel

mass of diesel fuel= mass of blend

5.4.1 Effect on Cetane Number

The effect of blending diesel fuel with different extenders

on C.N. is shown in Figure (5.42). All the extenders useddecreased the C.N. except"No. 4 fuel oil which resulted in a slight

increase in C.N. The worst extender is gasoline which resulted in

a sharp decrease in C.N.

5.4.2 Effect on API Gravity_

Figure 5.43 shows that all the extenders used by Russell et.al.,

(4.16), except No.6 fuel oil and South Texas sour crude, increased

the API gravity of the blend.

5.4.3 Effect of Heat on Combustion

Figure 5.44 shows that all the extenders used increased the

heat of combustion except No. 6 fuel oil.

5-59

TABLE 5.14. EMERGENCY DIESEL EXTENDERS

l. Gasoline

2. Ethanol Alcohol3. Medium Naphtha

4. Heavy Naphtha Solvent

5. Jet A Jet Fuel6. Jet A-I

7. Kerosene Kerosene (Solvent)8. No. 4 Fuel Oil Heating Oil

9. No. 5 Burner Oil

10. No. 6 Fuel Oil Residual Fuel

11. TX Sour

12. LA Sweet

13. CA Sour Crude Oil

14. UT Sweet

15. Peanut Oil

16. Soy Oil

17. Sunflower Oil Vegetable Oil

18. Corn Oil

The reference fuel used is neat baseline fuel (CAT 1 H reference

diesel fuel).

Reference 4.16.

5-60

CETANE NUMBER6 0 r---r---.,--~-~----,r----:---~-----.---

I 0 &--_-I-_--"__...l...--_-J..__.l........;_...... ......_-J;.._----'

o

Reference 4.16.

FIGURE 5.42. EFFECT OF DIESEL EXTENDERS ON C.N.

5 - 61

"

API GRAVITY 60/60F80

II

70 i

60 . , III

iI 2

50 4

5

403

S

30 ~"'-

B .~,_.

20

100I

10 20 30 40 50 60 70 90 100 -.VOLUME %

1 Extender = Gasoline

2 = Medium Naphtha

3 = Jet A

4 = Jet A-I

5 = Kerosene. 6 = No. 4 Fuel Oil

7 = No. 6 Fuel Oil

8 = South Texas Sour Crude

Reference 4.16.

FIGURE 5.43. EFFECT OF DIESEL EXTENDERS ON API GRAVITY

5-62

5.4.4 Effect on.Viscosity

Figure 5.45 shows that all the extenders used reduced the

viscosity of the blend except No. 6 fuel oil and South Texas sour

crude.

5.4.5 Effect on Power Index

Figure 5.46 shows that all the extenders used reduced thepower index at concentrations highe~ than 65 percent. The gasoline

and ethanol caused the sharpest drop in power index at all con­

cent~ations. Some extenders, such as No.6 fuel oil resulted ina slight increase in the power index at concentrations less than

65 percent.

5.4.6 Effect on Conservation Index

Figure 5.47 indicates that extending the diesel fuel with any

extender results in an increase in the conservation index.

5.4.7 Effect on Tradeoff Index

Figure 5.48 indicates that the tradeoff index increases withall the extenders~ except with gasoline "at concentrations higher

than 60 percent.

5".4.8 Effect on Emissions Indexes

The effect of blending diesel fuel with different extenders

is shown in Figure 5.49 for hydrocarbons, Figure 5.50 for CO,

Figure 5.51 for NO , and Figure 5.52 for smoke. It is clear fromxthese figures that the hydrocarbons are the most sensitive, and

increase with the use of extenders. The CO increases when heavier

fuels such as No.6 fuel oil, No.5 burner oil, No.4 fuel oil,and heavy naphtha fuels, are used. The NO x index increases with

the lighter fuels, and remains almost constant with the heavier

fuels. The smoke index decreases with gasoline and ethanol, and,

tends to increase with the heavier fuels.

5-63

BTU/LB

21 000 __-~-----r-----r---:----:---~--"'-""'"

2 0 500 t----T---+--..-..----T----+-----!---I-----r-:---+-~::I'f

4200 0 Ot--------l...--~-"'"""----+--~---±=;;...".e.---___:~~ 3

~~__+:~~~::::~~~tt=_:J 2

19000 ,., I

i

185007

180000 10 20 30 40 50 60 70 80 90 100

VOLUME %

I Extender = Gasoline2 = Medium Naphtha3 = Jet A4 = Jet A-I5 = Kerosene6 = No. 4 Fuel Oil7 = No. 6 Fuel Oil

Reference 4.16.

FIGURE 5.44. EFFECT OF DIESEL EXTENDERS ON THE HEAT OF COMBUSTION

5-64

7

90 10070 8030 40 50 60

VOLUME %2010

CENTISTOKES 40c4---"""-~----""""-------~-----+--'

o

30

90

120

• .l~...

1 Extender = Gasoline

2 = Medium Naphtha

3 = Jet.A

4 = Jet A-l

·5 = Kerosene

6 = No. 4 Fuel Oil

7 = No. G Fuel Oil

8 = South Texas Sour Crude

Reference 4.16.

FIGURE 5.45. EFFECT OF DIESEL EXTENDERS ON VISCOSITY

5-65

2.0

-s7 -II

! I II : ij !

II

i

iI

frog-IO

II !I ! ~eI

I :7 4

Ij I

:z

~~ I 3'I , II

I j !II

I1---

,

I I I II I'

i

I I

I I II I II I I

I

1.2

1.6

0.8

0.4

cPOWERINDEX

10 20 30 40 50 60 70 80

VOLUME %90 100

1 Diesel Emergency Blend Extender = Gasoline

2 = Ethanol (Dieselhol)3 = Medium Naphtha

4 = Heavy Naphtha

S = Jet A

6 = Jet A-l

7 = Kerosene

8 = No. 4 Fuel Oil

9 = No. S Burner Oil

10 = No. 6 Fuel Oil

11 = South Texas Sour Crude

Reference 4.16.

FIGURE 5.46. EFFECT OF DIESEL EXTENDERS ON POWER INDEX.

5-66

CONSERVATION INDEX

50 60 70 80 90 10030 4010 20

! I II

I- I

I iI

I I

, I

I i II I I II

I

I I

/ II

I !

II

I I I ____L.---I

i

I I, 9-10

I I

II I,~!

I I

I~............ r-....... 2

.-J.--::::I ....... ,o

O.

12

1.6

0.4

2.0

0.8

tilVOLUME 10

1 Extender = Gasoline.~

2 = Ethanol (Dieselhol)3 = Medium Naphtha4 = Heavy NaphthaS = Jet A

6 = Jet A-I7 = Kerosene8 = No. 4 Fuel Oil9 = No. S Burner Oil10 = No. 6 Fuel Oil11 = South Texas Sour Crude

Reference 4.16.

FIGURE 5.47. EFFECT OF DIESEL EXTENDERS ON CONSERVATION INDEX.

5-67

90 10040 50 60 70 80

VOLUME %302010

: Ir4-10

:::J:jl

!i 4i ---c--- 3-6

, i~!I

I .i , I I I

I I ~ ! I

II

I i I "'J 2, I I I

I ,,

I I !""" .I ,I II , I

i I II i I I I

i I I

! Ii I I

II

I , I j IIoo

1.2

.1.6

0.8

0.4

2.0

TRADEOFFINDEX

..1 Extender = Gasoline2 = Ethanol3 = Medium Naphtha4 = Heavy NaphthaS = Jet A6 = Jet A-l7 = Kerosene8 = No. 4 Fuel Oil9 = No. S Burner Oil10 = No. 6 Fuel Oil11 = South Texas Sour Crude

Reference 4.16.

FIGURE 5.48. EFFECT OF DIESEL EXTENDERS ON TRADEOFF INDEX

5-68

HeINDEX

4-------.-----...,.--~-___r--r___:::~-_:_-....,

3~----l___-~--4~::.....-+.,...c::::::..._+--~-_+_-_+-___f6

oL---J_--L_--!..._~_~_...;..I_~_~_~~o 10 20 "30 40 50 60 70 80 90 100

VOLUME %

.. 1 Extender = Gasoline2 = Ethanol

.~._-

3 = Medium Naphtha4 = Heavy NaphthaS = Jet A

6 = Jet A-I7 - Kerosene8 = No. 4 Fuel Oil9 = No. S Burner Oil10 = No. 6 Fuel Oil

Reference 4.16.

FIGURE 5.49. EFFECT OF DIESEL EXTENDERS ON HC INDEX

5-69

COINDEX

4~-r--r--.,.......-.,...---r---r---------

103t---+--+--+-+----+--~-___,,~~~-..l--__J

2r--r---t--b~T_-+_-+=:=_~~~-+_~

VOLUME %

..1 Extender = Gasoline

2 = Ethanol

3 = Medium Naphtha

4 = Heavy Naphtha

5 = Jet A

6 = Jet A-17 = Kerosene

8 = No. 4 Fuel Oil

9 = No. S Burner Oil10 = No. 6 Fuel Oil

Reference 4.16.

FIGURE 5.50. EFFECT OF DIESEL EXTENDERS ON CO INDEX.

5-70

Ii j Ij I ,

I :

i

:\

"

2.

I! .

I ~ : ! ,I

,

II

i i I , I : I, I ; I j

4

N\)x 2INDEX

oo 10 20 30 40 50 60 70 80 90 100

VOLUME %

1 Extender = Gasoline.• ' 2.,\<Vo.'" = Ethanol

3 = Medium Naphtha

4 = Heavy Naphtha

5 = Jet A

6 = Jet A-I7 = Kerosene

8 = No. 4 Fuel Oil

9 = No. S Burner

10 = No. 6 Fuel Oil

Reference 4.16.

FIGURE 5.51. EFFECT OF DIESEL EXTENDERS ON NO INDEX.x

5-71

-6·7

e

40 50 60 70- 80 90 100

VOLUME %20 3010

I!

II, I

I I !

I I I II

I!

I

II

II

I

I!i

!I I

I,,

iI !I I

I, ! ;I

I II I I IOi:

----':::::i5

--2l1

4

i---r--...- I - 9 I 3

II i!

3

oo

4

SMOKEINDEX 2

I Extender

2

3

4

5

6

7

8

9

10

= Gasoline

= Ethanol

= Medium Naphtha

= Heavy Naphtha

= Jet A

= Jet A-I

= Kerosene

= No. 4 Fuel Oil

= No. 5 Burner Oil

= No. 6 Fuel Oil

Reference 4.16.

FIGURE 5.52. EFFECT OF DIESEL EXTENDERS ON SMOKE INDEX.

5- 72

6. SENSITIVITY OF ENGINE LUBRICATION TOVARIATIONS IN FUEL PROPERTIES

6.1 INTRODUCTION

Variations in fuel properties might result in increased oil

contamination and intensify some of the lubrication problems such

as lubricant de grarl"ation, depos its, corro s i on and wear. Crankcase'J

oil contamination is caused by one or a combination of the

following:

a. Direct contact of the combustion products with the lub­

ricating oil film on the cylinder walls past the piston ring or

along the valve stems. This contaminated oil returns to the

crankcase.

b~ Blow-by gases in contact with the lubricating oil in the

crankcase. The blow-by gases, during the compression stroke ingasoline engines, contain fuel vapors. During the expansion

stroke the blow-by ~ases contain combustion products.

c. Exhaust gas recirculation.

d. In some engine models, the fuel vapors are vented in the

crankcase.

The PCV valve directs the crankcase gases into the intake mani­

fold, which reduces the lubricant contamination problems.

The fuel properties which affect the concentration of con­

tanimants are related to nigrog'en and sulfur contents, and the

incomplete and complete combustion products. The type of contam­ination depends on the combustion process, and is different in

gasoline and diesel engines.

6.2 GASOLINE ENGINES

The main lubricating oil contaminants in gasoline engines arelisted in paragraphs 6.2.1 and 6.2.5. Effects of alcohol fuelson lubrication and engine wear are described in paiagraph 6.2.6.

6-1

6.2.1 Nitrogen Oxides

The nitrogen oxides are formed as a result of the high tem­

peratures reached in the combustion process, from the atmospheric

nitrogen, or from nitrogen in the fuel. Most of the nitrogenoxides are in the form of nitric oxide, and the rest is nitrogen

dioxide. The latter is more reactive than nitric oxide, in con­

taminating the' oil (6.1).

If the nitrogen content of the fuel increases, the nitrogen

oxides concentration in the blow-by gases and in the exhaust gases

use~ for EGR will increase, resulting in more oil contaminatiori.

6.2.2 Sulfur Compounds

The sulfur compounds are mainly sUlf~r dioxide (S02) and

sulfur trioxide (S03). These are formed during the combustion

process, and depend mainly on the sulfur content of the fuel arid

the air-fuel ratio. The sulfur content of the conventional

crude petroleum based gasoline is 0.07 percent.

The sulfur compounds contribute to the corrosive wear causedby the condensation of acids on the cylinder walls with subsequent

chemical attack of the metal and removal of corrosion productsby the wiping action of the rings. The corrosive wear ,is dif­

ferent from abrasive or rubbing wear caused by mechanical inter­

action between two metallic surfaces with relative sliding motion.

The corrosive wear is significant during low temperature opera­

tion.

Syncrudes are known to contain more sulfur than conventional

crudes. Reducing the sulfur content of gasoline made from syn­

crude will require the expenditure of more energy and money in

the refinery.

6.2.3 Partial and Complete Oxidation Products

The partial oxidation products consist of aldehydes, RCHO(mainly formaldehyde, HCHO) , ketones (R 2C=O) and acids (RCOOH).These are products of preflame reactions and partial comhustion

6-2

problems in the form of depositsof the engine is not achieved,

These deposits appear as "varnish"

which takes place as a result of flame quenching near the walls

or of incomplete flame propagation.

The complete combustion products, water and carbon oxides,

are, of course, present in higher concentrations in the blow-by

and EGR contaminants.(j

It is expected that the partial and complete oxidation pro-

ducts of future fuels will be nearly the same as those of conven­("

tional gasoline. J

6.2.4 Hydrocarbons

The higher boiling point hydrocarbons of fuels represent a

major contaminant because of their lower molecular weight as com­

pared with that of the lubricating oil molecules. These higher

boiling point hydrocarbons adhere to the cylinder wall, particu­larly under cold starting and warmup periods, and are mixed with

the lubricating oil film.

If the end-point of future gasolines is increased, more oil

contamination can be expected--:z: .-.';&~~'.. ' Low temperature operat ion

occur whenever complete warmupparticularly in cold weather.

and sludge.

Varnishes which coat various engine parts such as valve­lifters, pistons, piston rings, and pev valves, may cause trouhle­

some adhesion of parts or interference between close-fitting

parts. These varnishes have been found to contain significant

amounts of nitrogen, sulfur and oxygen.

Sludge is colloidal in nature and separates from the crank­case oil in the more stagnant regions of the engine, or is

deposited in places critical to oil supply and distribution, suchas the piston oil control ring or the oil screen in the sump.The sludge forms as a water-in-oil emulsion, stabilized andthickened by finely divided solids, such as lead salts, soot, and

resin forming surfactants.

6-3

6.2.5 Corrosion

Corrosion occurs on ferrous surfaces, particularly if gaso­

line engines are operated under light-duty conditions and with

frequent shut-down periods. The factors favoring corrosion are

a dispersed water phase in the oil, the presence of sulfur com­

pounds in the fuel, and high dilution of the crankcase lubricant

wi th raw fuel.

The high temperature operation problems result from exposing

the lubricant to high temperatures and to high nitrogen oxide

concentration, in the combustion chanber or as a result of contractwith the blow-by gases. Oil oxidation under high temperature oper­

ation result in carbonyl-type compounds, which are acidic incharacter and may attack and dissolve corrodible metals. Also,

nitrogen oxides can be involved in high temperature accelerated

oxidative degradation. This is particularly true with increased

blow-by rates (6.1).

6.2.6 Effect of Alcohol Fuels on Lubrication ~nd .Engine Wear

Owens and co-workers (6.6) of the U.S. Army Fuels and Lub­ricants Research Laboratory at S.W.R.I. investigated the effects

of methanol fuel on spark ignition engine wear and deposits. Theengine used was a 2-3 liter Ford overhead cam, four-cylinder

design and was tested on a dynamometer, according to a modified

ASTM sequence V-D test procedure. Owens, et al., indicated thatthe use of pure methanol as a fuel can result in large increases

in engine wear and wear-metal accumulation during low temperature

operating periods. This increased wear occurs primarily in the

piston ring and upper cylinder bore area. In addition to wear,

methanol was found to form rust. The extent of rust formation is

dependent on the materials present and the metal and lubricanttemperatures during engine operation. Therefore, this rusting

phenomena would be design dependent and vary in intensity from

engine to engine. Owens, et al indicated that the blow-by producedfrom methanol contains at least formaldehyde and formic acid,

which are capable of corrosive attack within the ring zone, the

6-4

......; ..

area of highest concentration. The methanol, or its intermediate

combustion products, directly attack the piston ring and cylinder

bore area rather than first degrading the lubricant.

6.3 DIESEL ENGINES

Diesel lubrication problems are mainly related to the oil

contamination by soot particulates, in addition to the factorsdescribed in 6.2., Gasoline Engines. ()

6.3.1 Soot Particulates

The soot particulate formation is one of the characteristics

of the diffusion type flame in heterogeneous, combustible mixtures.The particulates formed during the different stages of co~bustion

can be picked up by the lubricating oil and contaminate the crank­

case lubricating oil by the approaches discussed in Section 6.2.

The lubricating oil can be contaminated by soot particulates,

even when the final engine exhaust is clear (6.2).

The fuel properties which affect the soot particulates havebeen explained in detail in another part of this report.

The soot contrihutes to the formation of different types of

deposits in the engine, such as piston groove carbon, piston

lacquer, and crankcase sludge. The piston groove carbon and

lacquer are the result of combinations between the soot particu­lates and resins. The sludge is the result of combinations between

soot, oil, oxygenates and water (6.3). Formation of deposit

resins arises both from partial combustion products of the fuel,and from oxidative-thermal degradation of the luhricating oil and

its additives.

6.3.2 Sulfur

The problem of the contamination of the lubricating oil with

sulfur is much more serious in the diesel engines than in gasolineengines because of the much higher sulfur content of diesel fuels.

6-5

There is some evidence that formation of deposit resins is

favored by increases in fuel sulfur except at very high tempera­

tures where thermal effects predominate. Increasing the fuelsulfur content from 0.4 to 1.0 percent was reported to. increase

the level of piston deposits by 100 percent, in Caterpillar L-1

Test procedures by Deen and Schetelich (6.4).

Figure 6-1 shows the effect of sulfur on wear, obtained by

Moore and Kent (6.5), using a single cylinder 5-3/4 inch bore,

4-inch stroke, Caterpillar test engine. The sulfur content of

the fuel was varied from a to 1.3 percent by adding di£ferent

amounts of thiophene to the light commercial fuel of originallylow sulfur content. Figure 6-1 also shows the wear rates of two

heavy diesel fuels, and it is seen that the points fall reason­

ably well on the curve. Figure 6-1 shows that, with all. otherconditions constant, the rate of wear with a diesel fuel of 100

percent sulfur content is approximately 400 percent greater than

that with a fuel of a percent sulfur content.

6-6

1200

.(/)

~ 1000oto0:::W 800a..z0::o 600~

(f)

~<r 400::-~-....J--l-~ 200

o 0.2 0.4 0.6 0.8 1.0 1.2 1.4

Ref. 6.5. PERCENT SULFUR

FIGURE 6 -1. EFFECT OF 'SULFUR CONTENT ON WEAR

6-7/6-8

7. CONCLUSIONS

Automotive gasoline and diesel engines are sensitive to

certain fuel properties. Currently, the baseline automotive

gasoline and diesel fuels are highly processed to the American

Society of Testing Material (ASTM) specifications from natural

crude petroleum. The ~rrent a~tomotive engines are tailored to

meet certain performance and emission goals when run on these

fuels. Some variations in the properties of the baseline automo-

·tive fuels are anticipated in the future because of the expected

depletion of natural crude resources, the increase in the price ofimported crude and the desirability of reducing the nation's

reliance on foreign fuels. In the United States, alternate fuels

can be produced from the abundant coal and shale oif reserves, or

from biomass. At the present time, the properties of futurealternate fuels cannot be well defined, because they have not

been established; although, it is known that the distillates from

shale oil are highly paraffinic in nature while those from coal

are highly aeromatic in nature. Also, syncrudes from coal and

shale oil contain impurities such as nitrogen and sulfur.

Reducing these impurities in the final product will require ex­penditure of energy and ~ollars at the refinery. Less refined

fuels are likely to have high nitrogen and sulfur contents.

The following conclusions are based on the available datapublished in the literature. The areas which need further

research are noted.

7.1 GASOLINE ENGINES

The important fuel properties which affect gasoline engines

are summarized in Table 7-1. The gasoline engines are sensitive

to the fuel volatility, octane number, HIC ratio, latent heat of

evaporation '. energy content, and sulfur and ni trogen contents.The engine parameters which are sensitive' to each of the aboveproperties are also listed in Table 7-1.

7=1

TABLE 7-1. IMPORTANT FUEL PROPERTIES FOR GASOLINE ENGINES

Fuel economy

Acceleration.~;'

Power

Fuel Property

1 - Distillation range

o - 20% point

20 - 80% point

80 - 100% point

2 -·Octane number

3 - Hie ratio

4 - Latent heat of

evaporation

5 - Gravimetric energy

content

6 - Volumetric energy

content7 - Nitrogen content

8 - Sulfur content

Dependent Engine Parameter

Cold starting

Hot starting

Vapor lock

Evaporative emissionsWarm up

Hot stalling

Carburetor icing

Crank-case oil dilutionDeposits -

Gum

Plug fouling

Hydrocarbon emissionsCompression rat1u

Enpine efficiency

Stoichiometry

Combustion temperatureCold starting

Volumetric efficiency and powerBrake specific fuel consumption

Storag~ costTransportation cost

NO emissionsxLubricating oil contamination

Corrosion and wearSulfates emissions

Lubricating oil contamination

Corrosion and wear

7 -2

,­". '~.

7.1.1 Alternate Fuel Options

The gasoline engine alternate fuel may be one of the follow­

ing options, or their blends with gasoline:

1. Synthetic gasoline from syncrude produced from oil shale

or coal

2. Alcohols:

,) i. methanol produced from coal, biomass or wastes

ii. ethanol produced from biomass.

3. Hydrogen produced from coal.

The synthetic gasoline in the first option is expected to be pro­

duced at specifications close to those of baseline gasoline. The

synthetic gasoline produced from shale is low in octane number

a~d needs to be improved by high octane extenders such as MTBEor TBA. The synthetic gasoline produced from coal is highly

aromatic and has a high octane number. Gasoline engines can bedesigned to run on these gasolines with relatively higher compres­

sion ratios. in order to improve their fuel economy. The effect.. - of the use of the extenders MTBE and TBA will be stnnmarized in the

following item.

The hydrogen in the third option is ~onstrained in its use

as an alternate fuel by the development of safe and economically

competitive distribution and storage systems. Hydrogen is not

expected to be a viable alternate fuel in the near term (1980­

2000), or mid-term time frame (2000-2020). This report has notdealt with hydrogen as a fuel for automotive engines.

7.1.2 Gasoline - Alcohol Blends

The effects of blending gasoline with methanol, ethanol,

MTBE and TBA on the fuel physical properties, and the performance

of gasoline cars is summarized in Table 7-2. This table indicatesthe fo llowing:

7-3

TABLE 7-2. GASOLINE ENGINE ALTERNATE FUELS:GASOLINE - ALCOHOL BLENDS

Fuel or Engine Parameter Gasol~ne ExtenderMethanol Ethanol MTBE* TBA*

Volat~l~ty:10% 10% 7% 7%

RVP t t t t

10% point .j. .j. 1- 1-

t/) Specific gravity III t t t t(1)

~,,.,j H/C ratio t t t tra~

tJ lo.l.,.,j (1) Volumetric Energy content 1- i- 1- i-en Q.>'0 Octane number t

.t-= lo.l t t

c..c..Latent Heat of evaporation t t t t

Miles per gallon 1- 1- 1- 1-

~ Miles per BTU 1- 1- 1- 1-en>, Emissions g/m~

rac.. HC i- .j. .j. .j.-.lE-;rar:..U CO ..j.. i- .j. i-..C tr.l NO "t t i- ta lo.l -~,.,j ra x~u

Aldehydes N/A N/A N/Ara N/A"Ceo'.-1 I"'- Acetone N/A N/A N/A N/Ax 0'1o~

Evaporative g t t t t

Miles per gallon i- i- .j. .j.

Miles per BTU i- t .j. ..j..

Emissions g/m-.lc..mE-; HC .j. .j. .j. .j.>.r:..~

ra .. CO 1- .j. i- .j.~ enra lo.l NO t t t tU ra

U x>,

Aldehydes N/A. N/A N/A N/Araeo~I"'-I 0'1 Acetone N/A N/A N/A N/AM~

Evaporative t t t t

':".-

* MTBE:

TBA:

Methyl tetriarybutyl ether

Tetriarybutyl alcohol

7-4

..

1. The fuel economy in miles per gallon decreaied mainly

because of the lower volumetric energy content of the

blends.

2. The fuel economy in miles per BTU decreased because the

cars used were not calibrated for the blends. A major{j

adjustment which would have improved the fuel economy is

the spark timing (which could have been slightlyadvanced) .

3. The NO x and evaporative emissions increased with the

blends.

It is clear from Table 7-2 that both the volatility and octanenumber of a fuel increased after blending with alc~hols. The

results shown are for baseline cars and do not reflect the full

potential of the blends since the cars were tailored to run on the

baseline gasoline. For example, the baseline cars have C.R. less

or equal to 8.5:1, which is limited by the octane number ofIndolene ().N.=9l). The C.R. could be increased to 9.5 or 10

with these blends without producing knock. Increasing the C.R. of

the engine improves the fuel economy of the vehicle.

The major problems associated with the use of alcohol - gaso­line blends are:

1. Phase separation with methanol - gasoline blends

2. Cold starting problems caused by the higher latent heatof the blends

3. Increase of the NOx exhaust emissions and the hydrocarbon

evaporative emissions

4. Incompatibility of some materials which are used success­

fully with gasoline and deteriorate seriously withalcohol - gasoline blends.

7.1.3 Neat Alcohols

The sensitivity of gasoline engines to the use of neat

alcohols, contrasted with Indolene is given in Table 7-3.

7-5

TABLE 7-3. GASOLINE ENGINE NEAT ALCO~OLS COMPAPED TO INDOLENE

Fuel or Engine Parameter Methanol Ethanol

Volatility 1- 1-

Specific gravity t t

In H/C ratio t tQJ

t"""I •.-I Volumetric Energy Content -t -trtI~

tJ ~ Octane Number..-fQJ t tIn c..>to Latent Heat of evaporation t t.cl-lc.c. Stoichiometric A/F 1- ~

Power t N/ABrake Thermal t N/AEmissions

HC ... ~ *CO - ... ... *NOx ... - -t *Aldehydes t t *PNA ..j.

Evaporative

* CVS - Hot Drivingcycle only.

7-6

•

Most of the work conducted has been on methanol, and showed

the following advantages for methanol:

1. Methanol has a high octane rating (RON = 110,-MON = 92)which allow th~ C.R. of the gasoline engine to reach

13:1 or 14:1 and achieve better thermal efficiency than

the current gasoline engine. VW reported an improvement

of 4 percent during the ECE cold start test, and 12 per­

cent for the hot start test.

2. Tests over the whole speed range indicated that with

methanol, the brake output ot the engines is 10 percenthigher than for gasoline engines, both with MBT spark.

3. Tests over the operating range of the equivalence ratio(0.8 to 1.2) indicated that the methanol-fueled engine

produced less NO , CO and HC than the gasoline fueledx .

engine. However, the aldehydes emissions were higher

with methanol than with gasoline.

Operation on methanol on the ECE cold test system resulted in a

reduction of 22 percent in CO, but an increase of 22 percent inHC. In the hot-start test, the CO emissions were reduced by 68

percent HC by 28 percent, and NO by 20 percent.x

Problems

A cold starting aid is absolutely essential for starting the

engine at temperatures below 8°C. Cold starting aid could be in

the form of volatile starting additives (such as butane, methylether, or gasoline) to be sprayed into the intake air during

starting. A small methanol-fueled flame preheater can also be

used in the intake manifold.

7.2 DIESEL ENGINES

The important fuel properties which affect the automotive

diesel engine are summarized in Table 7-4. Automotive diesel·engines are sensitive primarily to the cetane number which affects

almost every aspect of combustion such as: ignition delay,

7-7

TABLE 7-4.

Fuel Property

IMPORTANT FUEL PROPERTIES FOR DIESEL ENGINES

Dependent.Engine Parameter

1 - Cetane Number

()

2 - Distillation range

Light ends

Heavy ends

3 - Aromatic content

4 - Viscosity

5 - Sulfur content

6 - Nitrogen content

7 - Gravimetric

energy content

8 - Volumetric ener y content

Ignition delay

engine noiseHydrocarbon emissionsNOx em~ssions

exhaust smoke, and particulates

cold starting

cold startingHycrocarbon and aldehyde emissions

Vapor lockCavitation in the injection system

Smoke emissions

particulate emissions

waxing and filter plugging

Smoke and particulate emissions

Polynuclear aromatic hydrocarbons

Spray formation and combustion

Injection system lubricationFlow through the fuel system

Sulfate emissions

corrosion and wear

NO emissionsxcorrosion and wear

B.S.F.C.

Miles per allon

7-8

•

•

engine noise, cold starting problems, and emission of hydro­

carbons, nitrogen oxides, smoke, and particulates. Automotive

diesel engines are also sensitive to the distillation range,

aromatic content, viscosity, sulfur content, nitrogen content,

gravimetric energy content and volumetric energy content of their

fuels.

7.2.1 Alternate Diesel Fuel Options

The diesel engine alternate fuels may be one of the following:

1. Wide cut distillates from petroleum crude

2. Synthetic diesel fuel from syncrude produced from oil

shale or coal

3. Alcohols.

7.2.1.1 Distillates from Petroleum Crude - The increase in demand

for jet fuel and heating oil will put pressure on the diesel fuel.production to include heavier compounds. To this effect, DF-3 isbeing considered for transportation diesel engines. No work has

J~,"

been conducted so far to find the sensitivity of automotive dieselengines to DF-3 fuel. Another approach to reduce energy expendi­ture in the refinery is to produce a wide cut fuel which will con­

tain lighter and heavier compounds than DF-2. Very limited work

has been reported so far on the performance of automotive dieselengines on wide cut fuels. The following applies:

1. D.I. truck engines are more sensitive to variations in

fuel properties than I.D.I. engines used in passenger cars.

2. The increase in the volatility of the distillate by

lowering the .10 percent point results in a drop in C.N., increasein I.D., increase in HC and NO emissions and increase in combus-

xtion noise. Some of these problems can be solved by increasing theC.R. of the D.I. engine, retarding the injection timing, turbo­

charging, or redesigning the combustion chamber. The increase involatility is usually associated with a reduction in viscositywhich might result in poor lubrication and fuel leakage in the

injection pump, particularly at low speeds.

7-9

3. The increase in the heavy components of the distillate,

by increasing the 90 percent point, results in more smoke. Derat­

ing the engine power may be needed to limit the smoke. Heavyfuels, which need to be heated to flow readily, increase the

ignition delay, He, NO , and smoke particulate emissions andxnoise. These effect are more pronounced in D.I. engines than In

I.D.I. engines.

()

7.2.1.2 DF-2 Gasoline Blends - Some work has been conducted on

DF-2 gasoline blends and the results are summarized in Table 7-5.

The main advantage of DF-2 gasoline blends is the drop in smoke

formation resulting from the increased portion of premixed combus­

tion. This results, however, in increasing the combustion­generated noise, and the unburned hydr~arbon emissions. Other

problems associated with the use of diesel-gasoline blends are the

difficulty in cold starting, misfire at light loads and high

speeds, vapor lock in the fuel injection system, crankcase oil

dilution and lack of proper lubrication of the fuel injection

parts.

7.2.1.3 DF-2/Synfuels Blends - The effect of blending DF-2 with

synfuels from shale oil and coal - derived crude have not beenwell studied. The limited studies conducted in this area show

unfavorable results as summerized in Table 7-6. The major prob­

lems with shale-derived synfuels are lacquering, needle sticking

and poor reliability. The major problems with coal-derived syn­

fuels are filter plugging, waxing, nozzle fouiing, lubricating oil

sludging and poor reliability.

7.2.1.4 DF-2/Alcohol Blends - The third option is to use alcohols,

as blends with DF-2 or as neat compounds. Very little work has

been conducted in this area. The limited work completed so fQr

showed some effects which are summarized in Table 7-7.

The major problems associated with the use of alcohols to

extend the diesel fuel are:

7-10

•

TABLE 7-5. DF-2 GASOLINE BLENDS

1 - Cetane Rating

2 - Smoke limited power

" 3 - BSFC

4 - BSEC5 - Emissions

HC

CO

NOxNoise

SmokeAldehydes

Major Problems:

7-11

i-

t)

t-t

-t

t

..j.

N/A

· Cold starting

· Misfire at high speedsand light loads

· Vapor .lock in fuelinjection system

· Crankcase oil dilution· Lack of proper lubrication

of the fuel injection parts

· increase in combustiongenerated noise

TABLE 7-6. DIESEL ENGINE ALTERNATE FUELS(DF-2/SYNFUELS BLENDS)

Shale Derived Coal DerivedSynfuel Synfuel

1 - Cetane Ratl.ng .j. .j.

2 - Gum Content t 0 N/A

3 - Smoke-limited Power .j. ..j..

4 - BSFC - t

5 - Aromaticity .j. t

6 - Emissions

HC - t t

CO t t

NO t tx

Noise t t

Smoke t t

7 - Pour Point N/A t

8 - Major Problems Lacquering Filter plug-

Needle stick- ing

ing Waxing

Poor reliability Nozzle foul-ingLub. oil sludg-ing

IPoor reliability

7-12

TABLE 7-7. DF-2/ALCOHOL BLENDS

Methanol Ethanol

•

1 - Cetane Rati~g ~') '" '".2 - Smoke-limited Power - oj; - i-

3 BSFC t t

4 - BSEC - -5 - Emissions

HC t t

CO i- i-

NO i- i-x

Noise t t

Smoke .j. .j.

Aldehydes t t

7-13

a. Blends of Alcohols - DF-2

i. cold starting

ii. lubricating oil contamination and engine wear

iii. injection system wear

b. Alcohols - DF-2 Emulsions

Some of the above problems can be reduced by using p~e

DF-2 at cold starting and increasing the emulsion con­

centration with load. This requires difficult controltechniques particularly under transient modes.

c. Alcohol Carburetion or Manifold Injection and DieselInjection

This results in a large drop in the intake air tempera­

ture which causes misfire at low loads. On the other

hand, self-ignition may occur at high loads. Also,

elaborate control techniques are needed to optimize the

timing and metering of the two fuels

d. Two Separate Injection Systems

. This allows varying the relative amounts of the two

fuels. The main problem associated with two high pres­

sure injection systems is the initial cost, and the

elaborate and expensive control systems needed tooptimize the timing and metering of the two systems.

The major problems associated with the use of neat alcohols

in diesel engines are:

a. Autoignited Alcohols

~.

1. Alcohols have a very low C.N. (about 3).

require to be mixed with cetane improving

such as 8 percent ethyl nitrate.

They

additives,

2. Alcohols have very poor lubricity. They must bemixed with about 2 percent lubricating oil.

3. Lubricating oil contamination with alcohols may cause

7-14

"

~,.,'

increased engine wear.

4. A starting aid such as intake air heating or using

diesel fuel is required under cold starting condi­tions.

b. Spark Ignited Alcohols in Diesel Engines

The major problems are:

1. Alcohols have high l\tent heats of~evaporation which

result in severe cold starting problems.

2. High emission of hydrQcarbons at idling and low loads.

3. Low reliability due to wetting of spark plugs andmisfiring.

4. Requires a much higher voltage for ignition because

of the high compression ratios used.

5. Wear due to cavitation in the injection system.

6. High hydrocarbon and aldehyde emissions.

7.3 EMERGENCY FUELS

7.3.1 Gasoline Engine Emergency Fuels

One research program conducted on the use of emergency fuels

in a limited number of automotive gasoline engines indicated that

only alcohols can be used as gasoline extenders without the need

to reduce the compression ratio of the engine. The emergency

fuels, studied are DF-2, marine diesel fuel, ethanol, methanol,

MTBE (Methyl Tert Butyl Ether), naphtha - ethanol, DF-2 ethanol,

kerosene - ethanol, ethanol extended with water, naphtha, and

kerosene.

7.3.2 Diesel Engines Emergency Fuels

Tests on a limited number of diesel engines showed the

following results:

1. The following fuels were found to be suitable emergency

7-15

fuels for diesel engines and had minor effects on smoke

emissions: Jet A, Jet A-I, medium naphtha, and kerosene.

2. Blending with gasoline and alcohols decreased the C.N.sharply, however, it decreased smoke. The problems with

these fuels are mainly related to their poor lubricity,

particularly in the fuel injection system, and theincrease in combustion noise and cold starting diffi­

culties.

3. Blending with heavier distillates such as No.4,' and No.

S fuel oil, resulted "in an increase ln smoke.

7-16

".

o

8. RECOMMENDATIONS

Research is needed in the following areas to determine the

sensitivity of automotive engines to variations in fuel proper­

ties.

8.1 FUTURE FUEL CHARACTERISTICS.,1. Develop scenarios for future automotive fuels based on

the most energy- and cost-efficient refining techniques, and the

availability of the energy sources.

2. Develop a data base for the variation in fuel properties

·as a function of blending the base fuels with different types of

extenders.

3 .. Develop a data base for the effect of variations in fuel

properties on their autoignition properties (cetnne number and

octane number). The fuels should cover a wide range of the

following:,:'

i. CarJ10n to hydrogen ratio,

i i . aromatic content,

iii . distillation range,

iv. density,

v. sulfur content

vi. ni trogen content.

4. Study the impact of the use of alternate fuels on the

lubrication process in automotive engines and find techniques to

reduce lubricating oil contamination.

8.2 GASOLINE ENGINES

1. Investigate the effect of variations in the base fuel

properties on gasoline engine performance, fuel economy andemissions. Develop engine maps to cover the expected variations

in future fuel properties.

8-1

Emphasis should be on the properties which cost more to controlin the refinery.

3. Study the economy of producing ethanol from U.S. grown

grain, the energy expenditure, and the efficiency of converting

the source energy into useful mechanical work. A system approachI..;

should be taken in this study.

4. Study the use of neat alcohols and blends with gasoline

in gasoline engines. The following should be optimized: com­

pression ratio, spark timing, and fuel metering ... Most of thestudies conducted so far are on mass produced engines calibrated

for gasoline (Indolene).

s. Investigate techniques ~o solve the cold starting prob­

lems of gasoline engines when run on neat alcohols or alcohol­gasoline blends.

8.3 DIESEL ENGINES

1. Investigate the effect of variations in the base fuel

properties on the automotive diesel engine (D.I. and I.D.I) per­

formance, economy and emissions. Develop engine maps to cover

the expected variations in future fuel properties. The engine

systems should be optimized for each fuel.

2. Make an assessment of the tradeoffs in economy, per­formance, emissions and variations in fuel properties which cost

more to control in the refinery;

3. Develop a modified cetane scale to rate the autoignitionquality of alternate fuels. The current scale is unsuitable for

alternate fuels.

4. Study the problem of cycle-to-cycle variation in the

autoignition of alternate fuels in diesel engines, and methods ofreducing their effect on engine reliabjlity.

s. Determine the effect of cetane improvers on increasing

the C.N. of alcohols. These improvers include commercjally

8-2

'"

J

available additives, diesel fuel, and lubricating oil. This study

needs to be done on a CFR-Cetane engine with the Modified Cetane

Scale which is capable of measuring the C.N. of fuels in the range0-20.

6. Study the use of neat alcohols, and alcohol-diesel blends

in optimized diesel engines. The main design parameters which

should be optbnized are: compression ratio, injection pressure,

injection nozzle, intake system, and combustion chamber design.

8-3/8-4

....

APPENDIX AREFERENCES

2.1 "Alternate Portable Fuels for Internal Combustion Engines."

An Assessment by Alternate Fuels Committee of The Engine

Manufacturers Association, SAE Paper No. 790426, ~979

o3.1 "Liquefaction and Chemical Refining of Coal," A Battelle

Energy Program Report, Battelle Columbus Laboratories,

July 1974.

3.2 J. H. Gary, "Liquid Fuels and Chemicals from Coal,"

Mineral Industries Bulletin No.5, Colorado School of

Mines Research Institute, September 1969.

3.3 G. K. Goldman, "Liquid Fuels from Coal," Noyes Data Corp.,.

1972.

3.4 D. P. Montgomery, uRefining of Pyrolytic Shale Oil,"

l55th National Meeting, American Chemical Society,

San Francisco, California, April 2-5, 1968.

3.5 H. B. Jenson, J. R. Morandi and G. L. Cook, "Characteri-

zation of the Saturates and Olefins in Shale-Oil Gas Oil,"

l55th National Meeting, American Chemical Society,

San Francisco, California, April 1968.

3.6 J. R. Morandi and R. E. Poulson, "Nitrogen Types in Light

Distillates from Aboveground and In Situ Combustion

Produced Shale Oils," l69th National Meeting, American

.'\ 3.8

Chemical Society, Philadelphia, Pennsylvania, April 1975 .

"Liquefaction and Chemical Refining of Coal," A Battelle

Energy Program Report, Battelle Columbus Laboratories,

July 1974.

A-I

3.9 H. W. Sternberg, R. Raymond and S. Akhtar, "SYNTHOIL

Process and Product Analysis," 169th National Meeting,

American Chemical Society, Philadelphia, Pennsylvania,

April 1975.

3.10 R. H. Wo1k, N. C. Stewart and H. F. Silver, "Review of

Desu1furization and Denitrogenation in Coal Liquefaction,"

169th National Meeting, American Chemical Society,

Philadelphia, Pennsylvania, April 1975.

3.11 "O.S. Energy Outlook - Coal Availability," National

Petroleum Council, O.S. Dept. of the Interior, Washington,

D.C., 1973.

1,.

3.12

3.13

3.14

3.15

J. H. Gary, "Motor Fuels from Oil Shale - Production and

Properties," G.M. Symposium on Future Automotive Fuels,

Plenum Press, New York, 1977, pp. 136-148.

E. M. Shelton and o. C.. Blade, "Diesel Fuel Oil, II Annual

Reports of Bartlesville Energy Research Center, Bartlesville,

Oklahoma.

"Aldehyde and Reactive Organic Emissions from Motor

Vehicles," Final Report, Part I Agreement No. EPA-lAG-OlSS

(D) and Part II Agreement No. MS PCP-lAG-OOl, Bureau of

Mines, Bartlesville Energy Research Center, March 1973.

R. J. Steffensen, J. L. Agnew and R. A. Olsen, "Combustion

of Hydrocarbons Property Tables," Engineering Bulletin

of Purdue University, Engineering Extension Series No. 122,

Lafayette, Indiana, May 1966.

A-2

3.16 N.W. Snug and D.J. Patterson, "Theoretical Limits of

Performance and Economy for Methanol, Ethanol and Gaso-

line Blends in Automotive Vehicles", Report to DOE

Contract No. E(29-2)-3682, Jan. 1980.

3.17 C.F. Taylor and E.S. Taylor, "The Internal Combustiono

Engine," 2nd Edition, Scranton, Pennsylvania, International

Textbook Company, 1961

. 3.18 "Effect of Automotive Emissions Requirements on Gasoline

Characteristics," ASTM Special Technical Publication 487,

105, 1971.

3.19 C.F. Taylor,· "The Internal Combustion Engine in Theory

and Practice," The M.I.T. Press, 1968.

3.20

3.21

C.M. Urban and J.T. Gray of Southwest Research Institute,

"An Investigation of Methods for Determining Cetane Numbers

of Low Ignition Quality Fuels." Paper presented at S.A.E.

mid-year meeting, Detroit, Michigan, May 20-24, 1968.

N.A. Henein and N.Y. Elias, "A Modified Cetane Scale

for Low Ignition Quality Fuels, "SAE Paper 78064, 1978.

3.22 P. Birdi, "General Correlation for Ignition Delay Period

in Diesel Engines," Ph.D. Dissertation, Wayne State

University, 1979.

3.23 Gene M. Handel, Henry K. Newhall and Echol M. Reed,

"Alternate Transportation Fuels," SAE West Coast Inter-

national Meeting Aug. 1980, 800890.

3.24 "Identification of Probable Automotive Fuels Composition:

1985-2000," u.S. Dept. of Energy publication HCP/W3684-0 1/2,

May 1978.

A-3

3.25

3.26

..

"The Report of the Alcohol Fuels Policy Review," U.S.

Dept. of Energy, Report No. DOE!PE 0012, June 1979.

Thomas C. Austin and Gary Rubenstein, "Gasohol: Technical

Economic, or Political Panacea," Cal. Air Res. Brd., S~.E

West Coast International Meeting, L.A. Aug. 1980 paper

No. 800891. .~

4.2

4.5

4.1 R.T. Johnson and R.K. Riley, "Feasibility of. Methanol!

Gasoline Blends for Automotive Use," Evaporation and

Combustion of Fuels, J.T. Zung, editor, Advances in

Chemistry Series, No. 166, American Chemical Society,

Washington, D.C., 197~, p. 245.

N.A. Henein, T. Singh, J. Rozanski and P. Husak, "Flame

Speeds, Performance and Emi~sions with Methanol-Indolene

Blends" .

4.3 ·E.E. Wigg and R.S. Lung, "Methanol as a Gasoline

Extender - Fuel Economy, Emissions, and High Temperature

Driveability," SAE Paper 741008, 1974.

4.4 N.D. Brinkman, N.E. Gallopoulos and M.W. Jackson,

"Exhaust Emissions, Fuel Economy and Driveability of

Vehicles Fueled with Alcohol-Gasoline Blends," SAE

Paper 750120, 1975.

A. Lawson, A.J. Last, D. Mackay, M. Tsang and

G.B. Maund, "Oxygen Sensor Equipped Engine Operation

on Phase Separated Methanol-Gasoline Blends," 5th

International Automotive Propulsion Systems Symposium,

April 14-18, 1980.

A-4

,./~~ .

4.6 J.J. Mooney, J.G. Hansel and K.R. Burns, "3-Way

Conversion Catalysts on Vehicles Fueled with Ethanol-

Gasoline Mixtures, II SAE Paper 790428, '1979.

4.7 G.T. Engh and S. Wallman, "Development of the Volvo

Lambda - Sond System," SAE Paper No. 770295, 1977.

4.8 1:'Ford's 2.3 Liter Four Adopts Three-Way Approach,"

Automotive Engineering, October 1977.o

4.9 M.S. Harrenstein, K.T. Rhee, R.R. Adt, Jr., "Determination

of Individual Aldehyde Concentrations in the Exhaust of

a Spark Ignited Engine Fueled by Alcohol/Gasoline Blends,"

SAE Paper 790952, 1979.

4.10 V.W. Eccleston and F.W. Cox, "Physical Properties of

Gasoline Methanol Mixtures," Report BERC/RI-76/l2 of

Bartlesville Energy Research Center, Oklahoma, January 1977,

USERDA.

4.11

4.12

H. Menrad, W. Lee, W. Bern?ardt, "Development of a Pure

Methanol Fuel Car, "SAE Paper 770790, 1977.

"Current Status of Alternative Automotive Power S~stems

and Fuels," Vol. III, Contract Report No. 68-01-0417

by the Aerospace Corporation, 1974.

4.13 WoE. Bernhardt and W. 'Lee, "Engine Performance and

Exhaust Emission Characteristics of a Methanol-Fueled

Automobile," Symposium on Future Automotive Fuels,"

Plenum Press, New York, 1977, pp. 214-234.

-'

4.14 R.W. Hurn, "Characteristics of Conventional Fuels from

Non-Petroleum Sources - An Experimental Study," Symposium

on future Automotive Fuels, Plenum Press, New York, 1977

pp . 16 7-1 76 .

A- 5

4.15

4.16

4.17

4.18

T.M. Naman and J.R. Allsup, DOE, "Exhaust and Evaporative

Emissions from 'Alcohol and Ether Fuel Blends," SAE

Passenger Car Meeting, June 1980i Paper No. 8000858.

Russell, John A., Bailey, Brent K., Wimer, William w.,

"Emergency Fuels Utilization Guidebook", Southwest~'1

Research Institute Report DOE/CS/54269-01, Contract No.

ACO~-78CSS4269, Aug. 1980.

R.R. Pefley, "Alcohol Fuels for Automobiles", Sixteenth

Summary Report, Highway Vehicle Systems Contractor's

Coordination Meeting, Dearborn, Michigan, April 1979

pp. 486-501.

Ulrich Seiffert, "Mid-Term Prospects for the Use of

Alcohols as Motor Vehicle Fuels", Automotive Technology

Development Contractors Co-ordination Meeting Nov. 12-13,

1980, Dearborn, Michigan.

5.1 R. Bertodo, "Extenders and Diluents for Middle Distillates -

A Preliminary Evaluation," SAE Paper 800831, 1980.

5.2 E. Holmer, P.S. Berg and B.I. Bertilsson, "The Utilization

of Alternative Fuels in a Diesel Engine Using Different

Methods," SAE Congress, 1980, Paper No. 800544.

5.3 W.M. Scott and D.R. Cummings, "Dual Fuelling the Truck

Diesel with Methanol," International Symposium on Alcohol

Fuel Technology, Volkswagenwerk AG, Wolfsburg, 1977.

A-6

5.4 N.R. Panchapakesan, K.V. Gopalakrishnan and B.S. Murthy,

"Factors That Improve Performance of an Ethanol Diesel

Oil Dual-Fuel Engine," International Symposium on Alcohol

Fuel Technology Methanol and Ethanol, Volkswagenwerk AG,

Wolfsburg, 1977.

5.5 J. Cruz, W. Chancellor and J. Gross, "Dual Fueling aII

Diesel Engine with Carbureted Alcohol," Alcohol Fuels

Technology, Third International Symposium, Univers~ty

of Santa Clara, Asilomar, 1979.

5.6 G. Finsterwalder, "A New Deutz Multi-Fuel System," SAE

Paper 720103.

5.7 A.G. Urlaub and F.G. Chmeta, "High-Speed, Multi-Fuel

Engine: L 9204 FMV, SAE Paper 740122.

5.8 W.M. Scott, "Looking in on Diesel Combustion,IISAE

Paper No. 690002 (SP345), January 1968.

5.9 Quentin A. Baker, "Alternate Fuels for Medium-Speed

Diesel Engines," SAE Paper 800330, 1980.

5.10 N.A. Henein, "Combustion and Emission Formation in

Fuel Sprays Injected in Swirling Air," SAE Paper No. 710220,

1971.

:)

5.11

5.12

D.W. Tuteja and D.W. Clark, IIComparative Performance

and Emission Characteristics of Petroleum, Oil Shale

and Tar Sands Derived Diesel Fuels," SAE Congress, 1980,

Paper No. 800331.

L.C. Broering and L.W. Holtman, "Effect of Diesel Fuel

Properties on Emissions and Performance," SAE Paper

No. 740692.

A-7

5.13

5.14

G.P. Gross and K.E. Murphy, Jr., ~The Effect of Diesel

Fuel Properties on Performance, Smoke and Emissions,"

ASME Paper 78-DGP-26, 1978.

Harvey A. Burley and Theodore L. Rosebrock, "Automotive

Diesel Engines - Fuel Composition of Particulates," SAE

Fuels~and Lubricants Meeting, Houston, Oct. 1979, Paper

No. 790923.

'.

,,

6.1K.L. Kreuz, "Gasoline Engine Chemistry," Lubrication,

Vol. 55, No.6, Texaco Inc., New York, NY, 1969.

6.2 J. Spiers, Discussion of Paper by J.G. Parsons, J. Inst.

Pet. Vol. 55, p. 269, 1969.

6.3 K.L. Kreuz, "Diesel Engine Chemistry as Applied to

Lubricant Problems," Lubrication, Texaco Inc., Vol. 56,

No.6, 1970.

6.4 H.E. Deen and A.A. Schete1ich, SAE Paper No. 542C,

Atlantic City Meeting, June 1962.

6.5 C.C. Moore and W.L. Kent, "Effect of Nitrogen and

Sulfur Content of Fuels on Diesel-Engine Wear," SAE

Quarterly Transactions, Oct. 1947, Vol. l~ No.4,

pp . 687-693.

'6.6 E.C. Owens, H.W. Marbach, Jr., E.A. Frame and T.W. Ryan,III,

"Effect of Alcohol Fuels on Engine Wear", U.S. Army Fuels

and Lubricants Research Laboratory, S.W.R.I., SAE Passenger

Car Meeting, Dearborn, Michigan, June 1980, Paper No.

800857.

A-8

"

"L'

r,'~.

.. ~.

APPENDIX BREPORT OF INVENTIONS

The work presented in this report is of a review nature.

No invention or application for patent rights evolved from theaperformance of this work.

100 copies

B-l/B-Z

\

c,

fl

,j-

,.,.