2010 diesel emission reduction consortium experimental studies of exhaust chemistry and...

2010 Diesel Emission Reduction Consortium

Experimental Studies of Exhaust Chemistry and Aftertreatment

Professor Thatcher RootDepartment of Chemical and Biochemical Engineering

September 21, 2004


DPF, LNT, DPNF Agenda

Investigate the link between surface chemistry and macroscopic trap behavior. – Chemical reactions to reaction engineering– Reaction parameters and model validation

Effects of engine operation via soot chemistry– Elemental vs. organic carbon with engine load– Trapping efficiency, reactivity during regeneration

Trap diagnostics – T, P, sensors for O2, NOx, …

Track soot and NOx accumulation

– Link to surface chemistry– Eventual goal: control of cyclical operation


Diesel Particulate Matter

Semi-Volatile Condensed Aerosol

(VOC+sulfate+H2O+ trace metal

compounds)

Elemental Carbon Agglomerate

Adsorbed Semi-Volatile

Compounds(VOC+sulfate+

H2O + trace metal compounds)

0.1 m


EC, OM, Sulfates (SO4) in PM2.5

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.00

50

100

150

200

250

300

350

400

450

EC

/PM

2.5,

OM

/PM

2.5

Equivalence Ratio,

Mode 5 [100%]Mode 6 [75%]

Mode 7 [50%]Mode 4 [25%]

Spe

cific

Par

ticul

ate

Che

mic

al C

ompo

sitio

n [m

g/ih

p-hr

]

Equivalence Ratio,

Engine Speed:1200 rpm Elemental Carbon Organic Mass Sulfates

0.0 0.2 0.4 0.6 0.8 1.00.0

0.2

0.4

0.6

0.8

1.0

OM/PM2.5

EC/PM2.5

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.00

50

100

150

200

250

300

350

400

450

Equivalence Ratio,

EC

/PM

2.5,

OM

/PM

2.5

Mode 1 [100%]

Mode 2 [75%]

Mode 3 [50%]

Spe

cific

Par

ticul

ate

Che

mic

al C

ompo

sitio

n [m

g/ih

p-hr

]Equivalence Ratio,

Engine Speed:1800 rpm Elemental Carbon Organic Mass Sulfates

0.0 0.2 0.4 0.6 0.8 1.00.0

0.2

0.4

0.6

0.8

1.0

OM/PM2.5

EC/PM2.5

1200 rpm 1800 rpm

Specific EC, OM, and sulfates shift significantly with the change in the engine load.


Chemical Characterization of Diesel Exhaust

EXHAUST

SECONDARY DILUTION TUNNEL

RESIDENCETIMECHAMBER

PRIMARY DILUTION TUNNEL

PRIMARY DILUENTS

FLOW ORIFICE

REGULATOR

FILTER

BUILDING AIR

TO

RE

AC

TO REAC

TO REAC

TO REAC

T

T

142 MM FILTER HOLDER

FLOW ORIFICES

EXHAUST

VACUUMPUMP

47 MMFILTER HOLDER

EXHAUST FLOW ORIFICE

VACUUM PUMP

T, P

T, P_VAC

T, P_ABS

P_VAC

P_VAC

INCLINED MANOMETER

AIHH CYCLONE

Augmented sampling system Sulfate ions Trace metals EC/OC PM Con.

Organics Semi-volatile organics

Size dist. - number - mass - volume

Real-time PM - concentration - total mass - mass rate

Trace metals Sulfate ionsMass

Mass EC/OC

Organic compounds

Semi-volatileorganiccompounds


Engine Layout

Pre

ssur

e T

rans

duce

rF

eed

Gas

Air Compressor

Fro

m F

uel

T

ank

pum

p


Fuel Burning System for Filter Regeneration

MV 1

MV 2

MV 3

MV 4

EV

LV ZFG

Control Unit

MixingChamber

Pressurereducer

Diesel Fuel Tank

Compressed Air Tank

Burner / Filter Unit

TB

PG

TvF TnF

PLD+

V1530Diagnosis

M

4

6

8

10

12

14

16

18

20

800 1000 1200 1400 1600 1800

30 35

4045

50 60

70

11 l DI/TCI Diesel Engine with cooled EGR (EURO 4)

BM

EP

(b

ar)

Engine speed (rpm)

2

25

Power in kWComplete burner system for retrofit applications. OEM applications might use an air pump instead of compressed air.

Power draw of the burner to heat exhaust to 650 C depends on the load point. 2% instantaneous fuel penalty is typical

Zeuna Staerker, AVL International Commercial Powertrain Conference, Budapest, 10/01

Alternative: regeneration in external furnace for comparison with complete regeneration


DPF, LNT, DPNF Agenda

Investigate the link between surface chemistry and macroscopic trap behavior. – Chemical reactions to reaction engineering– Reaction parameters and model validation

Effects of engine operation via soot chemistry– Elemental vs. organic carbon with engine load– Trapping efficiency, reactivity during regeneration

Trap diagnostics – T, P, sensors for O2, NOx, …

Track soot and NOx accumulation

– Link to surface chemistry– Eventual goal: control of cyclical operation


Chemistry in a Four-Way Catalyst

The principle of combination diesel particulate/NOx reduction system.

PM is oxidized in both lean and rich conditions.

Periodic rich pulse causes PM to oxidize

Toyota SAE 2002-01-0957


Trapped soot on inlet wall surface Cell Plugs

Exhaust(Soot, CO, HC)Enter

Exhaust (CO2, H2O)Out

Ceramic HoneycombWall with SupportedCatalyst

Plugged-monolith Wall-flow Filter

Place a catalyst in front of or within filter to oxidize NO to NO2


Mechanism for NOx Storage, Part I

Adsorption, desorption, and reaction over Pt sites

Rate parameters from Olsson et al.

PtNOPtOPtNOPt

NOPtPt NO

NOPtPt NO

O2PtPt 2O

2r

r

2r

r

2(g)

r

r

(g)

r

r

2(g)

8

7

6

5

4

3

2

1

RRhh

AlAl22OO33

NONO + + ½OO22

Ba(NOBa(NO33))22

BaCOBaCO33

NONO22

COCO22

Pt

Rh


Mechanism for NOx Storage, Part II

NOx storage on Barium sites


RRhh

AlAl22OO33

NONO + + ½OO22

Ba(NOBa(NO33))22

BaCOBaCO33

NONO22

COCO22

Pt

Rh

PtNOBaNOSNOPt

O2SO2S

NOBaNOSNO

NOSOSNO

NOOSNOS

NOSSNO

23r

r

312

2(g)1r

r

1

23r

r

312(g)

31r

r

12(g)

1r

r

21

21r

r

12

20

19

18

17

16

15

14

13

12

11

10

9


Regeneration With Hydrocarbon

Reduction of NOx with propene


AlAl22OO33

CO + HC + HCO + HC + H22

PPtt

BaCOBaCO33

RRhhBa(NOBa(NO33))22

NN22 + + COO22

NOxNOx COCOO2

2(g)22(g)2r

22

(g)22(g)2(g)r

222

22r

r

22

21r

r

12(g)

(g)22(g)31(g)r

223

(g)22(g)1(g)r

221

(g)22(g)r

63

63r

6(g)3

2(g)(g)22(g)r

2

(g)22(g)r

2

2r

63

63r

r

6(g)3

1.5NOHCOS3PtNO3PtCHS

OHCOS3Pt3NONO3PtCHS

CHSPtSCHPt

COSSCO

OHCONO3SPt3NOCHPtNO3Ba

OHCO3SPt3NOCHPtNO3S

O3H3CO9PtO8PtHCOPt

HCOPtOPtHC

1.5NOHCO4PtNO3PtCHPt

OHCO4PtO3PtCHPt

CH3Pt2PtHCPt

HCPtPtHC

35

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2010 diesel emission reduction consortium experimental studies of exhaust chemistry and...

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