Bifurcaon features of CO and HCs in DOC · 2017. 4. 18. · and HCs is done using short-monolith...

Bifurca(onfeaturesofCOandHCsinDOC

RamaKrishnaDadi

Advisers

Dr.VemuriBalakotaiahandDr.DanLuss

UniversityofHouston

CLEERS2016

Introduc(on

DOCCO,HCs,NO

CO2,H20,NO2

Oxida;onreac;onsR1:CO+ 0.5O2 →CO2R2 :C3H6 + 4.5O2 → 3CO2 +3H2 0R3 :C2H6 +3.5O2 → 2CO2 +3H2 0

ΔH (R1) = −283kJΔH (R2) = −1925kJΔH (R3) = −1560kJ

Introduc(onandobjec(ves

•  DieselengineexhaustconsistsofCO,H2andseveralhydrocarbonswhichigniteatdifferenttemperatures.

•  Theheatgeneratedbytheoxida(onofeasilyigni(ngspeciescanbeusedtoignitelateigni(ngspecies.

Objec(ves•  Tostudythebifurca(onfeaturesofindividualoxida(onreac(onsandco-oxida(onreac(ons.

•  Toillustrateseparateandsimultaneousigni(onsduringco-oxida(on

Mathema(calmodel

Xjm,in − Xjm −

kc ( j)L< u > RΩ

(Xjm − Xjs ) = 0

§  Speciesbalanceinfluidphase

§  Speciesbalanceinsolidphase

§  Energybalanceinfluidphase

Tm,in −Tm −hf L

< u > ρ fCpf RΩ(Tm −Ts ) = 0

§  Energybalanceinsolidphase

hf (Tm −Ts )− ΔHl Rv,l (Ts,X)0δc∫

l=1

rgl

∑ = 0

Kine;cmodel

RCO =k1XCOXO2

(1+KCOXCO )2

RC3H6 =k2XC3H6XO2

(1+KC3H6XC3H6 )2

RC2H6 = k3XC2H6XO2

COandHCs

RC3H6 =k2XC3H6XO2

(1+KC3H6XC3H6 +KICOXCO )2

RC2H6 =k1XC2H6XO2(1+KCOXCO )

2

cTmDje∂2Xj∂y2

+ υljRv,l (Ts,Xs )l=1

rgl

∑ = 0

COoxida(on

•  Steady-statehysteresisregionexpandswithincreaseininletmolefrac(onofthereac(ngspecies.Nega(veordereffectismorepronouncedthanexothermeffect

Tf,in(K)100 200 300 400 500

Conversion

0

0.2

0.4

0.6

0.8

1

500ppm

1%3%

Tf,in(K)100 200 300 400 500

Solid

tem

pera

ture

(K)

300

350

400

450

500

550

600

650

700

500ppm

1%3%

COoxida(on

=(sec)10-4 10-3 10-2 10-1

y in(

%)

0.2

0.25

0.3

0.35

0.4

0.45

0.5

No steady state multiplicity

Steady state multiplicity exists

•  Steady-statemul(plicityexpandswithincreaseinresidence(me

Igni(on-ex(nc(onlocus Hysteresislocus

CO(%)0 0.5 1 1.5 2 2.5 3

T f,in(K)

150

200

250

300

350

400

450

==0.1s

COExtinction

==0.01s Ignition

Propyleneoxida(on

•  Propyleneoxida(onfollowsLangmuir-Hinshelwoodkine(cs

Tf,in(K)300 350 400 450 500

Conversion

0

0.2

0.4

0.6

0.8

1

200ppm

2000ppm

(a)

Tf,in(K)300 350 400 450 500

Solid

tem

pera

ture

(K)

300

350

400

450

500

550

600

200ppm

2000ppm

(b)

Propyleneoxida(on

Igni(on-ex(nc(onlocus Hysteresislocus

=(sec)10-4 10-3 10-2 10-1

C3H

6(%

)

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

No steady-statemultiplicity

Steady-state multiplicityexists

(b)

C3H6(%)0 0.1 0.2 0.3 0.4 0.5

T f,in(K)

150

200

250

300

350

400

450

==0.1s

==0.01s

Extinction

Ignition

Modelcalibra(on•  Kine(cmodelforCO-

C3H6istakenfromtheworkRajetal.[1]

•  Kine(cmodelforethaneiscalibratedusingexperimentaldata.[2]

1.Rajetal.,ChemicalEngineeringJournal281(2015)322-33312.Gare]oetal,AppliedCatalysisB:Environmental73.1(2007)65-72

ECOR

=14422;

EC3H6R

=11306;

EC2H6R

= 9262

Ethaneoxida(on

Tf,in(K)200 400 600 800 1000

Co

nve

rsio

n

0

0.2

0.4

0.6

0.8

1

500ppm C2H61.5% C2H6

Tf,in(K)200 400 600 800 1000

Sol

id te

mpe

ratu

re(K

)

200

400

600

800

1000

12001.5%500ppm

Ethaneoxida(on

Bifurca(onset Hysteresislocus

=(sec)10-3 10-2 10-1

C2H

6(%

)0.5

1

1.5

2

2.5

3

3.5

4

No steady-statemultiplicity

Steady-state multiplicityexists

C2H6(%)0.5 1 1.5 2

T f,in(K)

350

400

450

500

550

600

650

700

==0.1s

==0.01s

Ignition

Extinction

Co-oxida(onofCOandC3H6

Tf,in(K)200 300 400 500 600 700

Con

vers

ion

0

0.2

0.4

0.6

0.8

1

CO 500ppmC3H6 500ppm

Tf,in(K)200 300 400 500 600 700

Sol

id te

mpe

ratu

re(K

)250

300

350

400

450

500

550

600

650

Simultaneousigni(onofCOandC3H6


Tf,in(K)200 300 400 500 600 700

Con

vers

ion

0

0.2

0.4

0.6

0.8

1CO 1%C3H6 2000ppm

•  COinhibitspropyleneoxida(ononPt/Al2O3.Igni(ontemperatureincreaseswithincreaseininletmolefrac(onofCOandC3H6

C3H6(%)0 0.1 0.2 0.3 0.4 0.5

T f,in

(K)

100

150

200

250

300

350

400

450

IgnitionNo CO

Extinction

CO 1%


Tf,in(K)200 400 600 800 1000

Con

vers

ion

0

0.2

0.4

0.6

0.8

1

CO 500ppm

C2H6 500ppm


C2H6(%)0.5 1 1.5 2

T(K

)

300

350

400

450

500

550

600

1% CO

Pure ethane

•  Theexothermgeneratedbytheoxida(onofCOincreasessolidtemperatureandthisriseinsolidtemperaturereducestheigni(ontemperatureofC2H6duringco-oxida(onofCOandC2H6

Separateandsimultaneousigni(ons

Tf,in(K)200 400 600 800 1000

Con

vers

ion

0

0.2

0.4

0.6

0.8

1

1% CO1.5% C2H6

Tf,in(K)200 400 600 800 1000

Solid

tem

pera

ture

(K)

200

400

600

800

1000

1200

1400MixtureCO 1%C2H6 1.5%

Tf,in(K)200 400 600 800 1000

Con

vers

ion

0

0.2

0.4

0.6

0.8

12.2% CO1.5% C2H6

Tf,in(K)200 400 600 800 1000

Solid

tem

pera

ture

(K)

200

400

600

800

1000

1200

1400

Mixture2.2% CO1.5% C2H6


CO(%)0 0.5 1 1.5 2 2.5 3

T(K)

150

200

250

300

350

400

450

500

550

600

Ethane

CO

1.5%C2H6

CO(%)0 0.5 1 1.5 2 2.5 3

T(K

)

150

200

250

300

350

400

450

500

550

600

C2H6

CO

Ethane 1%

1.0%C2H6


Tf,in(K)200 400 600 800 1000

Solid

tem

pera

ture

(K)

200

300

400

500

600

700

800

900

1000

1

Tf,in(K)200 400 600 800 1000

Solid

tem

pera

ture

(K)

200

300

400

500

600

700

800

900

1000

1100

2

Tf,in(K)200 400 600 800 1000

Solid

tem

pera

ture

(K)

200

400

600

800

1000

1200

3

Tf,in(K)200 400 600 800 1000

Solid

tem

pera

ture

(K)

200

400

600

800

1000

1200

1400

4

Tf,in(K)0 200 400 600 800 1000

Solid

tem

pera

ture

(K)

200

400

600

800

1000

1200

5

CO(%)0 0.5 1 1.5 2 2.5 3

C2H

6(%

)

0

0.5

1

1.5

2

2.5

3

3

21

4

double limit locus

5

Co-oxida(onofCO,C3H6andC2H6

Tf,in(K)200 400 600 800 1000 1200

Con

vers

ion

0

0.2

0.4

0.6

0.8

1

C2H6 500ppm

C3H6 500ppm

CO 500ppm


Tf,in(K)0 200 400 600 800 1000 1200

Con

vers

ion

0

0.2

0.4

0.6

0.8

1

CO 3%

C3H6 500ppm

C2H6 500ppm

Tf,in(K)0 200 400 600 800 1000 1200

Con

vers

ion

0

0.2

0.4

0.6

0.8

1

CO 500ppmC3H6 6000ppmC2H6 500ppm

•  Theheatgeneratedbytheoxida(onofCOorC3H6isusedtoignitelateigni(ngspecieswhichischaracterizedbyethaneinourstudy.


C2H6(%)0 0.5 1 1.5 2

"T a

d(°C

)

180

200

220

240

260

280

300

Simultaneous ignition

Separate ignition

ΔTad = 9433YCO + 64200YC3H6

•  Theexothermicityofalllowtemperatureigni(ngspeciesisusedtosimultaneouslyignitehightemperatureigni(ngspecies

•  Lowtemperatureigni(ngspeciescanbeCO,C3H6andH2

•  Hightemperatureigni(ngspeciescanbeC2H6orC6H14

Summary

•  Bifurca(onanalysisofmixturescontainingCOandHCsisdoneusingshort-monolithmodel.

•  Simultaneousigni(onisobservedduringco-oxida(onofCOandC3H6.

•  Twoseparateigni(onsareobtainedduringco-oxida(onofCOandC2H6.

•  COinhibitsC3H6oxida(onbutimprovesthelight-offperformanceofC2H6

Thankyou

Bifurcaon features of CO and HCs in DOC · 2017. 4. 18. · and HCs is done using short-monolith...

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