Lecue 5 Emiion and Low-NOx Combuo Emiion: CO, Nox, UHC, Soo Modeling equiemen vay due o diffeence in ime and lengh cale, a well a pocee In geneal, finie-ae ineic i needed o pedic emiion Flamele appoach ill ue ineic! Reduced ineic ucceful fo hea eleae and global dynamic many no wo fo emiion Accuacy in PPM i needed fo eliable pedicion Compuaional co fo finie-ae! Soo phyic i elaively unnown
Emiion nea LBO in DOE-HAT Combuo 40 NOx a 5% exce O2, ppmv 30 20 0 NO 200 pi 280 pi 00 pi Emiion Pobe 0 0.4 0.45 0.5 0.55 0.6 0.65 Equivalence aio NO T inle 700K P inle 3.8 am S 0.6 0.4 < φ < 0.53
DOE-HAT Seup and Condiion Tinle 700K,Pinle 3.8 am S 0.6, 0.4 < φ < 0.53 * 85 x 75 x 8 cylindical gid * 85 x 24 x 24 inne Caeian gid * O(2-4) inepolaion LES-LEM only in he flame zone eolve he flame * Load balancing o achieve peedup
Simplified appoach o pedic emiion Polluan (CO, NO, UHC) aced a he LES level ~ Y x ~ Y ~ Y m ( D D ) w! m ~ u ~ m j m T j x j Slow chemiy, eacion ae obained fom CHEMKIN G-equaion appoach ued o ac flame in LES Hea eleae in enegy equaion a a hin zone Tubulen flame peed model in he LES G-equaion S S ( uʹ, S ), uʹ obainedfom LDKM T T L LES-LEM appoach Global finie-ae ineic ued in he ubgid o obain lamina flame peed and flame ucue Tubulen flame peed acually pediced
CO Pedicion Thee mechanim modeled CO poducion a he flame fon Teaed a a jump diconinuiy Rae obained uing CHEMKIN Equilibium beween CO oxidaion and CO2 diociaion CO O CO 2 2 Fowad/bacwad ae obained fom CHEMKIN CO poducion via UHC oxidaion UHC fomed due o local flame quenching UHC oxidaion o CO modeled a an Aheniu ae O
UHC Pedicion Local quenching of flame due o ech effec (Meneveau and Poino, 9) Unbun fuel eleaed on he poduc ide Efficiency coefficien deemine poion of quenched flame Efficiency Eddy Size Size oo lage o peneae ino he eacion zone Size oo mall o uvive long enough o quench he flame
NO Pedicion Two mechanim included Fomaion a he flame fon Obained fom CHEMKIN Fomaion via he Zeldovich mechanim N N 2 O O 2 N O2 2 NO NO O and N aumed o be in equilibium N O 2NO
LES-G veu LES-LEM Reoluion Iue Eddie lage han flame hicne eolved in LES-G and LES-LEM LES-G baely eolve flame hicne while LES-LEM ha aound 2 cell wihin flame hea eleae implemened in enegy equaion a a hin-zone Eddie of ize of flame pehea zone ae eolved in LES-LEM Flame boadening effec included in LES-G via a model Eddie of ize of flame eacion zone ae paially eolved in LEM No eolved in LES-G δ RR L Δ LES Δ LEM η δ F
Emiion pedicion: UHC (φ 0.4 ) Flame uface UHC io-uface Conou line ae CO ma facion UHC poducion localized in egion of high hea Oue bounday laye Flame lif-off Combuion in he diibued egime.
Emiion pedicion: CO φ 0.4 φ 0.53 CO ma facion (ppm) 8000 0 Flame locaion (oange) and CO ma facion (conou line) Low equivalence aio: long flame and low CO oxidaion High equivalence aio: ho flame and fa CO oxidaion
CO Pedicion fo φ 0.4 NO UHC UHC wih fa oxidaion in CO UHC wih low oxidaion in CO Dump plane Poducion of CO a he flame fon CO oxidaion Emiion pobe Poducion of CO via UHC oxidaion CO a equilibium UHC oxidaion ae i eenial o pedic CO emiion accuaely
CO emiion in he DOEHAT Combuo Indicae level Of inabiliy GLES LEMLES A GLES: Model can be uned o mach daa bu wih no phyic LEMLES: No paamee o adju o conol Noe: Boh imulaion employed he ame CO emiion model
How Soo i Fomed? Sep in Soo Fomaion Fomaion of pecuo Paicle Incepion Suface gowh paicle agglomeaion Paicle oxidaion Range of cale 0. 0 nm Spaially and empoally vaying in he domain
Modeled Soo Relaed Pocee Inenal pocee Nucleaion: Soo nuclei incepion by aceylene Coagulaion: Paicle coalece Suface gowh: Ma depoiion on paicle Agglomeaion: Fomaion of lage chain-lie ucue Oxidaion: Deucion by O2 and OH Exenal pocee Radiaion (opically hin model fo abopion by oo, CO 2 H 2 O gae (Kaplan 996) Themophoei Tanpo by Bownian diffuion Ohe unnown pocee
Radiaion Model Cuen Implemenaion Opically Thin model fo abopion by oo and CO 2, H 2 O gae (Kaplan 996) Moe deailed, bu elaively efficien FAST Coelaed appoach unde udy (Dembele and Wen, 2003) Ue 43 pecal band of vaiable widh fo H2O, CO2 and CO inead of many naow band 5 poin G-L quadaue (inead of 7 o 0 poin) Need moe wo o chec i applicabiliy wihin LEMMOM
Soo Kineic - Linded (994) Soo nucleaion Soo uface gowh Soo Oxidaion CH 2C H n 2 2 2 CH C H 2 2 2 2 C OH CO H C O2 CO 2 Baed on aceylene a a oo pecuo Suiable fo ubulen flame, wih low cabon conen fuel (CH 4 - C 2 H 4 )
Mehod of Momen Appoach The paicle ize diibuion (PSD) i unnown in advance Fo polydipee paicle i i vey had o pecify one ype of PSD (Fiedlande, 2000) Howeve, nowing he momen i equivalen o nowing he PSD (Hudon, 963) MOM wih Inepolaive Cloue (MOMIC) developed by Fenlach and Wang ued in LEMLES El-Aag e al. (Comb. Flame 2006, 2007) Ohe mehod being developed (Pich)
LEM-MOM Subgid Model LEM (Diffuion Reacion Hea Tanfe Soo anpo) T Ga pecie C 2 H 2, OH, O 2 Y -- f v Aea oo Soo Opical Pop. (Ligh caeing- Exincion- Radiaion) MOM
Subgid Combuion Model fo Sooing Flame Ti N p p N p p F q W h C x T x C x T Y V C C T.., ω κ ( ) Si c T Ki K F W x V V Y Y N F W x V Y Y ω ω.., i i i N m M M i S G R d dm Whee M i he h Momen of Paicle Size Diibuion (PSD) Funcion R Nucleaion ae G Coagulaion ae S Suface Gowh ae
LEM-MOM Subgid Model Rad F W h C x T x C x T Y V C C T Ti N p p N p p., ω κ Ki c Ki K F W Y N F W x V Y Y ω ω.., i i i N m M Mi F Ox S G R M Whee M i he h Momen of Paicle Size Diibuion Funcion R Nucleaion ae G Coagulaion ae S Suface Gowh ae Ox Oxidaion ae
Soo Popeie Fom MOM Δ M M d M A M M d Y f M Y M N p o o p v o 2 /3 6 ω π π N Soo Numbe Deniy Y Soo Ma Facion f v Soo Volume Facion d p Soo Paicle Diamee A Soo Suface Aea ω Souce Tem fo LEM M 0 Zeo Momen of PSD M Fi Momen of PSD