cobustion analysis with dual fuel

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Combustion analysis on a DI diesel engine with hydrogen in dual fuel mode

N. Saravanan *, G. Nagarajan, G. Sanjay, C. Dhanasekaran, K.M. Kalaiselvan

Department of Mechanical Engineering, Internal Combustion Engineering Division, College of Engineering, Guindy, Anna University, Chennai 600 025, India

a r t i c l e i n f o

Article history:

Received 25 January 2008

Received in revised form 4 July 2008

Accepted 8 July 2008Available online 3 August 2008

Keywords:

Hydrogen

Port injection

Diethyl ether

Dual fuel

Emission

a b s t r a c t

Hydrogen is expected to be one of the most important fuels in the near future to meet the stringent emis-

sion norms. In this experimental investigation, the combustion analysis was done on a direct injection

(DI) diesel engine using hydrogen with diesel and hydrogen with diethyl ether (DEE) as ignition source.

The hydrogen was injected through intake port and diethyl ether was injected through intake manifold

and diesel was injected directly inside the combustion chamber. Injection timings for hydrogen and DEE

were optimized based on the performance, combustion and emission characteristics of the engine. The

optimized timing for the injection of hydrogen was 5° CA before gas exchange top dead center (BGTDC)

and 40° CA after gas exchange top dead center (AGTDC) for DEE. From the study it was observed that

hydrogen with diesel results in increased brake thermal efficiency by 20% and oxides of nitrogen (NO x)

showed an increase of 13% compared to diesel. Hydrogen-DEE operation showed a higher brake thermal

efficiency of 30%, with a significant reduction in NO x compared to diesel.

Ó 2008 Elsevier Ltd. All rights reserved.

1. Introduction

The internal combustion engines have already become an indis-pensable and integral part of our present day life. In recent days

the importance of environment and energy are emphasized in var-

ious energy schemes [1]. Increase in stringent environment regula-

tions on exhaust emissions and anticipation of the future depletion

of world wide petroleum reserves provide strong encouragement

for research on alternate fuels [2]. Hydrogen is one of the most

promising alternate fuels. It’s clean burning characteristics and

better performance drives more interest in hydrogen fuel [3]. Many

researchers have used hydrogen as a fuel in spark ignition (SI) en-

gine [4]. A significant reduction in power output was observed

while using hydrogen in SI engine In addition pre ignition, backfire

and knocking problems were observed at high load. These prob-

lems have resulted in using hydrogen in SI engine within a limited

operation range [5,6]. However hydrogen cannot be used as a sole

fuel in a compression ignition (CI) engine, since the compression

temperature is not enough to initiate the combustion due to its

higher self-ignition temperature [7]. Hence an ignition source is re-

quired while using it in a CI engine. The simplest method of using

hydrogen in a CI engine is to run in the dual fuel mode with diesel

as the main fuel or Diethyl Ether can be used that can act as an

ignition source for hydrogen. In a dual fuel engine the main fuel

is either inducted/carburated or injected into the intake air stream

with combustion initiated by diesel. The major energy is obtained

from diesel while the rest of the energy is supplied by hydrogen.

The hydrogen operated dual fuel engine has the property to

operate with lean mixtures at part load and no load, which results

in NO x reduction, with an increase in thermal efficiency therebyreducing the fuel consumption. It was also observed that hydrogen

could be substituted for diesel up to 38% on volume basis without

loss in thermal efficiency, however with a nominal power loss.

Hydrogen used in the dual fuel mode with diesel by Masood et

al. [8] showed the highest brake thermal efficiency of 30% at a com-

pression ratio of 24.5. Lee et al. [9] studied the performance of dual

injection hydrogen fueled engine by using solenoid in-cylinder

injection and external fuel injection technique. An increase in ther-

mal efficiency by about 22% was noted for dual injection at low

loads and 5% at high loads compared to direct injection. Lee et al.

[10] suggested that in dual injection, the stability and maximum

power could be obtained by direct injection of hydrogen. However

the maximum efficiency could be obtained by the external mixture

formation in hydrogen engine. Das et al. [11] have carried out

experiments on continuous carburation, continuous manifold

injection, timed manifold injection and low pressure direct cylin-

der injection. The maximum brake thermal efficiency of 31.32%

was obtained at 2200 rpm with 13 Nm torque. Hashimoto et al.

[12] have done extensive experimental investigation with DEE

and diesel used as ignition source for igniting hydrogen fuel. Table

1 shows the properties of hydrogen in comparison with diesel and

DEE. Fig. 1 shows the photograph of hydrogen and DEE flow

arrangements.

Electronic injectors for hydrogen can have a greater control over

the injection timing and injection duration with quicker response

to operate under high-speed conditions [13]. The advantage

of hydrogen injection over carburated system is problems like

0016-2361/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.doi:10.1016/j.fuel.2008.07.011

* Corresponding author. Tel.: +91 9881128166.

E-mail address: [email protected] (N. Saravanan).

Fuel 87 (2008) 3591–3599

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backfire and pre ignition can be eliminated with proper injection

timing [14]. The photographic view of the hydrogen injector posi-

tion on the cylinder head is shown in Fig. 2 and the photographic

view of the hydrogen and DEE injector position on the intake man-

ifold is shown in Fig. 3. Fig. 4 shows the cross sectional view of the

hydrogen injector.The distinguished feature of hydrogen-operated engine is that it

does not produce major pollutants such as hydrocarbon (HC), car-

bonmonoxide (CO), sulphur dioxide (SO2), lead, smoke, particulate

matter, ozone and other carcinogenic compounds. This is due to

the absence of carbon and sulphur in hydrogen. However hydro-

gen-operated engines suffer from the drawback of higher NO x

emissions that has an adverse effect on the environment. The for-

mation of NO x could be due to the presence of nitrogen in the fuel

and air and also the availability of oxygen in the air. In the case of

hydrogen it is obvious that NO x is due to the nitrogen present in air

[15]. When the combustion temperature is high some portion of

nitrogen present in the air reacts with oxygen to form NO x. One

of the ways of reducing NO x is to operate the hydrogen engine with

lean mixtures. Lean mixture results in lower temperature thatwould slower the chemical reaction, which weakens the kinetics

of NO x formation [16,17]. NO x emissions increase with increase

in equivalence ratio and peaks at an equivalence ratio of 0.9.

The objective of the present work is to use hydrogen (by injec-

tion in the intake port) in the following ways and study the perfor-mance, combustion and emission characteristics and compare with

baseline diesel:

1. Hydrogen in the dual fuel mode with diesel.

2. Hydrogen with diethyl ether as an ignition source.

2. Experimental setup and procedure

The test engine used was a single cylinder water-cooled DI die-

sel engine, having a rated power of 3.7 kW that runs at a constant

speed of 1500 rpm which was modified to work with hydrogen in

the dual fuel mode. The specifications of the test engine are given

in Table 2. Fig. 5 shows the schematic view of the experimental set-

up. The flow diagram for hydrogen and DEE is shown in Fig. 6. Thefuel injector was controlled by means of an electronic control unit

(ECU). An Infrared detector was used to give signals to the ECU for

injector opening based on the preset timing and also to control the

duration of injection. The injection timing and injection duration

can be varied with the help of ECU. Hydrogen flow was taking place

based on the preset value. A pressure regulator as well as a digital

mass flow controller controlled the flow. Table 3 shows the techni-

cal specifications of the hydrogen injector.

In the experimental investigation first the injection timing and

injection duration for hydrogen were optimized. For this injection

timing from 5° CA before ignition top dead center (BITDC) to 25°

CA after ignition top dead center (AITDC) in steps of 5° CA was ta-

ken with hydrogen injection duration of 30° CA. 60° CA and 90° CA

at a constant hydrogen flow rate of 5.5 liters per minute. The nextstep in the investigation was optimizing the hydrogen flow. For

this hydrogen was varied from 1.5 liters per minute to 9 liters

per minute insteps of 1.5 liters per minute for the entire load con-

ditions. The optimized conditions for hydrogen based on the per-

formance, emission and combustion characteristics are as follows.

Hydrogen injection timing 5° BGTDC.

Hydrogen injection duration 30° CA.

Hydrogen flow rate 7.5 liters per minute.

3. Instrumentation

An electrical dynamometer with 10 kW capacity with a current

rating of 43.5 A was used as a loading device. A non-dispersive in-fra red (NDIR) type exhaust gas analyzer (Qrotech make) was used

Nomenclature

J/° Joules per degreekg/h kilograms per hourkW kilowattsmm millimetercm3 cubic centimeter

Abbreviations

PPM parts per millionDEE diethyl etherBSN Bosch smoke numberTDC top dead centerBGTDC before gas exchange top dead centerCAD crank angle durationDI direct injection

CI compression ignitionSI spark ignitionECU electronic control unitDFC digital mass flow controllerIR infra red

NRV non-return valveDSO digital storage oscilloscopeLPM liters per minuteUBHC unburned hydro carbonsNO x nitrogen oxidesCO carbon monoxideBTDC before top dead centerCA crank angleHHR heat release rate

Table 1

Properties of hydrogen in comparison with diesel and DEE

Sl. No. Properties Diesel Hydrogen DEE

Formula CnH1.8nC8–C20 H2 C2H5OC2H5

1 Auto ignition temperature (K) 530 858 433

2 Minimum ignition energy (mJ) – 0.02 –

3 Flammability limits (volume %

in air)

0.7–5 4–75 1.9–36.0

4 Stoichiometric air fuel ratio

on mass basis

14.5 34.3 11.1

5 Molecular weight (g mol) 170 2.016 74

6 Limits of flammability

(equivalence ratio)

– 0.1–7.1 –

7 Density at 160 C and 1.01 bar

(kg/m3)

833–881 0.0838 713

8 Net heating valve MJ/kg 42.5 119.93 33.9

9 Flame velocity (cm/s) 30 265–325 –

10 Quenching gap in NTP air (cm) – 0.064 –

11 Diffusivity in air (cm2/s – 0.63 –

1 2 Octane numb er

Research 30 130 –

Motor – – –

13 Cetane number 40–55 – >125

14 Boiling point (K) 436–672 20.27 307.4

1 5 Viscos ity at 1 5.5°C, centipoise 2.6–4.1 – 0.023

16 Vapour pressure at 38°C kPa Negligible – 110.3

17 Specific gravity 0.83 0.091 –

3592 N. Saravanan et al./ Fuel 87 (2008) 3591–3599



for the measurement of HC, CO, NO and CO2 emissions. Technovi-

sion analyzer was used for the measurement of NO2 emission. NO x

emission was determined by adding NO and NO2 emissions. Boschtype smoke meter was used to measure smoke intensity. The ex-

haust gases were filtered and dehumidified by the exhaust gas ana-

lyzer before measurement. The gas analyzer was calibrated by

passing a known amount of span gases and readings were taken

with variation in span gas concentration. If the deviations are out-

side the accuracy limits the analyzer was calibrated by adjusting

the knob for the specific gases. The cylinder pressure was mea-

sured using a piezoelectric pressure transducer which has a pres-

sure range of 250 bar and a charge amplifier and the pressure

data were given as input to the oscilloscope for further analysis.

A Kistler make crank angle encoder with an accuracy of 1° was

used for crank angle measurement. After 30 min of engine running

on stabilized condition the pressure data were collected. The pres-

sure data’s were collected for 1000 cycles by using Yokogawa dataacquisition system. The mass flow of hydrogen was measured

using a digital mass flow controller, which controlled and mea-

sured the flow in liters per minute. The engine was operated at a

constant speed of 1500 rpm at all loads with torques correspond-

ing to full load percentages.

4. Error analysis and estimation of uncertainity

All measurements of physical quantities are subject to uncer-

tainties. Uncertainty analysis is needed to prove the accuracy of

the experiments. In order to have reasonable limits of uncertainty

for a computed value an expression was derived as follows:

DR ¼oR

o x1

D x1

2

þoR

o x2

D x2

2

þ Á Á Á þoR

o xn

D xn

2" #1=2

ð1Þ

Using Eq. (1) the uncertainty in the computed values such as

brake power, brake thermal efficiency and fuel flow measurements

were estimated. The measured values such as speed, fuel time,

voltage and current were estimated from their respective uncer-

tainties based on the Gaussian distribution. The uncertainties in

the measured parameters, voltage (DV) and current (DI), method,were ±10 V and ±0.16 A, respectively. For fuel time (Dtr) and fuel

Fig. 1. Photographic view of the hydrogen and DEE flow arrangement.

Fig. 2. Photographic view of the hydrogen injector position on the cylinder head.

Fig. 3. Photographic view of the hydrogen and DEE injector position on the intake

manifold.

Fig. 4. Cross sectional view of the hydrogen injector.

N. Saravanan et al./ Fuel 87 (2008) 3591–3599 3593



volume (Dt), the uncertainties were taken as ±0.2 s and ±0.1 s,

respectively.

A sample calculation is given below

Speed, N = 1500 rpm.

Voltage, V = 230 V.

Current, I = 12 A.

Fuel volume, fx = 10 cc.

Brake power, BP = 4.4 kW.

BP ¼VI

gg Â 1000kW

BP ¼ f ðV ; I Þ

oBP

oV ¼

I

ð0:85 Â 1000Þ¼ À

16

ð0:85 Â 1000Þ¼ 0:0188

oBP

oI ¼

V

ð0:85 Â 1000Þ¼

230

ð0:85 Â 1000Þ¼ 0:2705

DBP ¼

ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffioBP

oV Â DV

2

þoBP

oI Â DI

2s 2

435 ð2Þ

¼ ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffið0:0188 Â 10Þ2þ ð0:2705 Â 0:16Þ

2

q ¼ 0:1929 kW

Therefore, the uncertainty in the brake power from Eq. (2) is

±0.1929 kW and the uncertainty limits in the calculation of B.P

are 4.4 ± 0.1929 kW. The percentage of uncertainty for the mea-

surement of speed, mass flow rate, NO x, hydrocarbon, smoke and

pressure is given below:

(i) Speed: 1.5.

(ii) Mass flow rate of air: 1.9.(iii) Mass flow rate of diesel: 2.1.

(iv) Mass flow of hydrogen: 1.8.

(v) NO x: 2.7.

(vi) Hydrocarbon: 3.2.

(vii) Smoke: 2.0.

(viii) Pressure: 3.2.

5. Results and discussion

Experiments were carriedout with hydrogen and diesel in dual

fuel operation and with DEE. The engine was not able run beyond

75% load in hydrogen DEE mode due to severe knocking. This is

attributed to the instantaneous combustion of both hydrogen

and DEE. The numerical values of the results are given in Appendix.

6. Performance characteristics

Fig. 7 shows the variation of brake thermal efficiency with re-

spect to load. It is observed that the brake thermal efficiency of

hydrogen with DEE at 75% load is 29.3% compared to diesel of

21.6%. Whereas in the case of dual fuel mode it is 26.23%. The in-

crease in brake thermal efficiency in the case of hydrogen-DEE

operation is due to higher inlet charge cooling that reduced the

temperature by about 12–15 °C due to the presence of DEE as a re-

sult of its higher latent heat of vapourisation. As the inlet charge

cools, the inlet charge (both hydrogen and air) density increases,

which in turn results in better combustion, hence an improvement

in brake thermal efficiency is noticed. The increase in brake ther-mal efficiency for hydrogen operation is due to uniformity in mix-

ing hydrogen with air [18].

Fig. 8 shows the variation of specific energy consumption with

load. The specific energy consumption of hydrogen-diesel dual fuel

is reduced by 24% for hydrogen diesel dual fuel operation at 25%

load compared to diesel. The lower specific energy consumption

for hydrogen-diesel dual fuel is due to better mixing of hydrogen

with air resulting in complete combustion of fuel. With DEE as

ignition source for hydrogen the specific energy consumption is

60% lower compared to that of base diesel. The reduction in SEC

for hydrogen-DEE dual fuel operation compared to that of hydro-

gen-diesel dual fuel is due to increased charge density because of

the presence of DEE, which reduces the intake temperature by

about 15 °C.

7. Combustion characteristics

The cylinder pressure variation is given in Fig. 9. The maximum

firing pressure obtained in hydrogen diesel dual fuel mode is 2%

higher than that obtained with diesel. The peak pressure rise cor-

responds to the large amount of fuel burnt in pre mixed combus-

tion stage and also earlier start of combustion compared to diesel

fuel. The peak pressure in the case of hydrogen with DEE reduced

by 15% than that of the base diesel. The reduction in peak pressure

is due to the use of DEE, which ignites earlier creating a hotter

environment inside the combustion chamber thereby reducing

the delay period.

Fig. 10 shows the pressure crank angle diagram for hydrogen-diesel, hydrogen-DEE dual fuel operation and base diesel at 75%

Table 2

Engine specifications

Make and model Kirloskar, AV1 make

General details Four stroke, compression ignition, constant speed,

vertical, water-cooled, direct injection.

Number of cylinders One

Bore 80 mm

Stroke 110 mm

Rated speed 1500 rpm

Swept volume 553 cc

Clearance volume 36.87 cc

Compression ratio 16.5:1

Rated output 3.7 kW at 1500 rpm

Injection pressure 205 bar

Fuel injection timing 23° BTDC

Type of combustion Hemispherical open combustion chamber

Lubricating oil SAE 20 W40

Connecting rod length 2 35 mm

1. Hydrogen cylinder 10. IR sensor for hydrogen2. Pressure regulator Electronic control unit for H2

3. Hydrogen tank 12. Engine4. Filter Dynamometer

5. Digital mass flow controller 14. Diesel tank 6. PC to control DFC 15. DEE fuel pump7. Flame trap DEE Electronic control unit

8. Flame arrester DEE Injector9. Hydrogen injector 18. IR sensor for DEE

11.

13.

16.

17.

Fig. 5. Schematic view of the experimental setup.




load. It is observed that hydrogen diesel dual fuel mode gives a

higher peak pressure compared to base diesel fuel. The peak pres-

sure occurs 5° CA earlier than that of diesel. This might be due to

the fact that hydrogen combustion is instantaneous compared to

diesel combustion. Hydrogen with DEE as ignition source results

in a lower cylinder pressure than the base diesel fueling with peak

pressure advance of 7° CA than diesel. This may be attributed tocharge cooling due to DEE.

Hydrogen (4-5 bar)

Hydrogen tank

(150 bar)

Mass flow controller

(l/min or kg/h)

Pressure regulator

Filter

Flame trap (Visible indicator

for hydrogen flow)

Flame arrestor (Suppress fire

hazard)

Two way valve Atmosphere

Hydrogen injectorECU (Controlling

injection timings)

for hydrogen

IR detector 1

Battery Intake manifold

DEE injectorECU (Controlling

injection timings)

for DEE

Engine

IR detector 2

DEE pressure regulator

DEE fuel pump DEE tank

Fig. 6. Work flow diagram for hydrogen and DEE.

Table 3

Hydrogen injector specifications

Make Quantum technologies

Supply voltage 8–16 V

Peak current 4 A

Holding current 1 A

Flow capacity 0.8 g/s @ 483–552 kPa

Working pressure 103–552 kPa




Fig. 11 shows the variation of heat release rate (HRR) at 75%

load. The HRR was measured with one-degree crank angle accu-

racy. It is noted that the heat release rate (HRR) is 21% higher for

hydrogen operation than the diesel fuel mode. This may be due

to the higher flame velocity of hydrogen and also due to instanta-

neous combustion. The heat released in the premixed combustion

zone is higher; this indicates the increased pressure rise in com-

bustion chamber [19]. The hydrogen with DEE mode results in

50% lesser peak heat release rate than the base diesel fuel. This

might be due to instantaneous combustion of DEE well before by20° CA than that of normal combustion of diesel.

Fig. 12 shows the rate of pressure rise at 75% load. The rate of

pressure rise is higher by about 80% in the case of hydrogen with

diesel compared to diesel fuel. The hydrogen with DEE mode re-

sults in 11% decrease in the rate of pressure rise than the base die-

sel fuel. The reduction in the rate of pressure is due to DEE that

cools the intake charge, which results in a reduction in combustion

chamber pressure.

Fig. 13 shows the cumulative heat release at 75% load condition

for hydrogen with diesel and DEE mode. The hydrogen diesel dual

fuel mode gives similar cumulative heat release pattern as that of

diesel. This might be in dual fuel mode while using hydrogen and

DEE which undergo instantaneous combustion resulting in rapid

combustion of primary fuel followed by lower diffusion period

compared to progressive combustion of diesel [20]. Hydrogen with

DEE as ignition source results in a lower cumulative heat release

than the base diesel fuel. This might be due to DEE that cools the

intake charge lowering the temperature inside the engine cylinder.

8. Emission characteristics

Fig. 14 shows the variation of NO x emission. With hydrogen-

diesel dual fuel operation NO x is 21.9 g/kW h compared to

20.65 g/kW h for diesel at 75% load. The higher concentration of

NO x is due to the peak combustion temperature [21]. With hydro-

gen-DEE the NO x emission is 0.55 g/kW h. The reduction in NO x

emission in the case of DEE operation is due to the lower peak

combustion temperature, which is due to inlet charge cooling by

around 15 °C [22].

0

5

10

15

20

25

30

35

Load,%

B r a k e t h e r

m a l e f f i c i e n c y , %

Diesel

H2 (7.5 lpm)+ DieselH2 + DEE

0 25 50 75 100

Fig. 7. Variation of brake thermal efficiency with load.

0

5

10

15

20

25

30

35

Load,%

s p e c i f i c e n e r g y c o n s u m

p t i o n ,

M J / k W h

Diesel


250 50 75 100

Fig. 8. Variation of specific energy consumption with load.

50

55

60

65

70

75

80

85

Load,%

P e a k p r e s s u r e , b a r

Diesel


0 25 75 10050

Fig. 9. Variation of peak pressure with load.

0

20

40

60

80

100

120

330 350 370 390 410 430 450

Crank angle, deg.

H e a t r e l e a s e r a t e ,

J / d e g . C

A Diesel


Fig. 11. Variation of heat release rate with crank angle at 75% load condition.

0

10

20

30

40

50

60

70

80

90

250 280 310 340 370 400 430

Crank angle, deg.

P r e s s u r e , b a r

Diesel

H2 (7.5 lpm)+ Diesel

H2 + DEE

Fig. 10. Variation of cylinder pressure with crank angle at 75% load condition.




The variation of smoke with load is shown in Fig. 15. The smoke

of 0.7 BSN is observed in hydrogen-DEE operation compared to

base diesel fuel of 2.2 BSN and 0.8 BSN for hydrogen-diesel dual

fuel at 75% load. The hydrogen on combustion produces mainly

water vapor and does not form any particulate matter due to the

absence of carbon atom, hence lower smoke level [22].

Fig. 16 shows the variation of hydrocarbon with load. The

hydrocarbon increases for hydrogen-DEE operation compared tothat of hydrogen-diesel dual fuel operation and base diesel fuel

mode. At 25% load hydrocarbon emissions are maximum, it is

2.01 g/kW h in hydrogen-DEE operation compared to both diesel

hydrogen-diesel dual fuel of 0.3 g/kW h. While using DEE the cyl-

inder charge temperature is less, which leads to a lower combus-

tion temperature, hence an increase in HC emission. At 75% load

the HC emission is found to be 0.322 g/kW h in hydrogen DEE

mode compared to diesel of 0.12 g/kW h, whereas in hydrogen-die-

sel mode it is 0.14 g/kW h. The increase in HC emission is due to

the non-availability of oxygen during diffusion combustion period,

since hydrogen and DEE undergoes instantaneous combustion as

soon as the ignition starts [23].

The variation of carbon monoxide emissions with load is shown

in Fig. 17. At 25% load condition CO emission is 1.07 g/kW h inhydrogen with DEE operation, whereas in the hydrogen diesel dual

fuel mode it is 0.43 g/kW h compared to diesel of 0.64 g/kW h. The

higher CO emission during hydrogen-DEE operation is due to the

lower combustion temperature. At 75% load the carbon monoxide

emission is 0.15 g/kW h in hydrogen-DEE operation and hydrogen

diesel dual fuel mode while that of diesel is 0.316 g/kW h.

The variation of carbon dioxide emissions with load is shown in

Fig. 18. At 25% load the CO2 emissions are 0.47 g/kW h in hydrogen

DEE operation. The hydrogen diesel dual fuel mode gives 0.84 g/

kW h compared to diesel of 1.29 g/kW h. At 75% load the carbon

dioxide emission is 0.33 g/kW h with hydrogen DEE, whereas inthe hydrogen diesel dual fuel mode it is 0.64 g/kW h compared

-3

-1

1

3

5

7

300 330 360 390 420 450

Crank angle, deg.

R a t e o f P r e s s u r e R i s e , b a r / d e g . C A

Diesel

H2 (7.5 lpm) +Diesel

H2 + DEE

Fig. 12. Variation of rate of pressure rise with crank angle at 75% load condition.

0

50

100

150

200

250

300

300 330 360 390 420 450

Crank angle, deg.

C u m u l a t i v e h e a t r e l e a s e r a t e , J

Diesel

H2 (7.5 lpm)+Diesel

H2 + DEE

Fig. 13. Variation of cumulative heat release rate with crank angle at 75% load

condition.

0

5

10

15

20

25

30

Load,%

O x i d e s o f

N i t r o g e n , g m / k W h

Diesel

H2 (7.5 lpm)+ DieselHydrogen +DEE

0 25 50 75 100

Fig. 14. Variation of oxides of nitrogen with load.

0

0.5

1

1.5

2

2.5

3

3.5

4

Load,%

S m o k e , B S N

Diesel

H2 (7.5 lpm)

+ Diesel

0 25 50 75 100

H2 + DEE

Fig. 15. Variation of smoke with load.

0

0.5

1

1.5

2

2.5

Load, %

H y d r o c a r b o n , g m / k W h Diesel

H2 (7.5 lpm)

+ Dieseldrogen a

DEE

0 25 50 75 100

H

Fig. 16. Variation of hydrocarbon with load.




to diesel of 0.775 g/kW h. The CO2 emissions are lower compared

with the base diesel fuel, because of the absence of carbon in

hydrogen [24].

9. Conclusions

Experiments were done on a diesel engine using hydrogen in

the dual fuel mode and hydrogen with DEE as ignition source.

The optimized conditions were found to be 5° CA before gas

exchange top dead center (BGTDC) for injection of hydrogen,

30° CA for hydrogen injection duration in the dual fuel modeand 40° CA after gas exchange top dead center (AGTDC) for

DEE. The following conclusions are drawn from the present

investigation:

1. Hydrogen in both dual fuel and with DEE operation showed an

increase in brake thermal efficiency by about 22% and 35%,

respectively compared to diesel.

2. A significant reduction in NO x emissions was obtained with DEE

operation hydrogen diesel dual fuel mode as well as baseline

diesel.

3. Hydrogen diesel and DEE operation exhibited a significant

reduction in smoke emissions compared to base diesel fuel.

4. A severe knocking was noticed during the operation of the

engine with hydrogen-DEE operation beyond 75% load due tothe instantaneous combustion of hydrogen at high loads.

Appendix

S. No. Load Diesel Hydrogen-diesel Hydrogen-DEE

Brake thermal efficiency

1 28.600 11.90 15.29 17.90

2 50.000 16.85 21.48 24.30

3 78.600 21.59 25.66 29.304 100.000 23.38 25.45 –

Specific energy consumption

1 28.600 28.8 23.540 17.13

2 50.000 20.89 16.760 11.19

3 78.600 16.25 14.020 8.03

4 100.000 16.42 14.140 –

Oxides of nitrogen

1 28.600 25.34956 20.36357 0.024683

2 50.000 20.65469 21.90777 0.549102

3 78.600 17.9191 20.28236 1.267648

4 100.000 15.95163 15.8727 –

Smoke

1 No load 0.3 0 02 28.600 1.1 0 0.2

3 50.000 2 0.2 0.3

4 78.600 2.2 0.8 0.7

5 100.000 3.6 2 –

Hydrocarbon

1 28.600 0.309616 0.290265 2.012502

2 50.000 0.203984 0.192958 0.755291

3 78.600 0.124092 0.156001 0.322639

4 100.000 0.135343 0.135343 –

Carbon monoxide

1 28.600 0.647513 0.431676 1.079189

2 50.000 0.368952 0.245968 0.491936

3 78.600 0.316366 0.316366 0.1581834 100.000 0.8806 0.5661 –

Carbon dioxide

1 28.600 1.293633 0.840862 0.474332

2 50.000 0.934678 0.68871 0.38125

3 78.600 0.775098 0.640642 0.332185

4 100.000 0.752154 0.683207 –

Peak pressure

1 No load 57 52.7 51

2 28.600 65 65.5 57.75

3 50.000 71 71.3 64.8

4 78.600 78.5 78.5 68

5 100.000 82.2 82.7 –

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0

0.2

0.4

0.6

0.8

1

1.2

100

Load,%

C a r b o n M o n o x i d e , g m / k W h Diesel

H2 (7.5 lpm)+ DieselHydrogen +DEE

0 25 50 75

Fig. 17. Variation of carbon monoxide with load.

0

0.2

0.4

0.6

0.8

1

1.2

1.4

Load, %

C a r b o n d i o x i d e , g m / k W

hDiesel

H2 (7.5 lpm) +DieselHydrogen + DEE

0 25 50 75 100

Fig. 18. Variation of carbon dioxide with load.




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