Analysis of a Mesoscale Fuel Reformer with Heat Recirculation and Porous Surface Stabilized Flame

Transcription

1 Pape #070MI-085 Topic: Micocombustion & New Combustion Deices 8 th U. S. National Combustion Meeting Oganied by the Westen States Section of the Combustion Institute and hosted by the Uniesity of Utah May 19-, 013 Analysis of a Mesoscale Fuel Refome with Heat Reciculation and Poous Suface Stabilied Flame William C. Thompson and Ajay K. Agawal Depatment of Mechanical Engineeing, Uniesity of Alabama, Tuscaloosa, Alabama 35401, USA Abstact Syngas, o synthetic gas, is composed pimaily of hydogen (H ) and cabon monoxide (CO). Cabon monoxide and hydogen stoe chemical enegy, thus syngas can be used as a fuel souce. Fuel efomation is the pocess used to conet an existing fuel souce, such as methane o diesel, into synthetic gas. In this study, themal patial oxidation is used fo fuel efomation to eliminate the need fo the catalyst. Themal patial oxidation employs themal enegy to patially oxidie the fuel to poduce syngas. The majo dawback to this method of fuel efoming is the significant heat loss associated with the pocedue. Futhe, fuel efoming at the mesoscale is difficult because of the shot esidence time aailable. In this study, a fuel efome with a counteflow annula heat exchange fo heat eciculation and poous inet media to stabilie the flame is pesented. These design featues addess the issue of majo heat loss and make the pocess much moe efficient. A detailed computational analysis is pesented to ealuate design featues and show themal and combustion chaacteistics of the system. The analysis is based on conseation equations of mass, momentum, and species mass conseation in an axisymmetic domain. The computational analysis includes simulations unde ich conditions at ambient pessue. Chemkin and Fluent softwae wee integated to simulate ich methane-ai combustion at diffeent equialence atios using a detailed chemical kinetic mechanism. Analysis eeals the effects of eactant inlet tempeatue and fuel efome opeating conditions on fuel to syngas conesion. Ultimately this study shows that themal oxidation fo fuel efoming can be a iable and efficient pocess. I. Intoduction As enegy demands incease aound the wold, moe iable fuel souces must be found and utilied. Fuel flexible combustion deices must also be deeloped to satisfy enegy demands in the commecial and industial sectos. Hydogen is a clean fuel that contains moe enegy pe unit mass than any hydocabon fuel. Hydogen also geneates minimum emissions when buned and no emissions when electo-chemically coneted to electicity in a fuel cell [1]. Fuel efoming is used to poduce hydogen, which is the main eactie component in synthetic gas, o syngas. Moe boadly, syngas is pimaily composed of hydogen (H ) and cabon monoxide (CO), along with cabon dioxide (CO), unbuned hydocabons (UHC), and seeal othe mino species. Syngas is combustible and can be used as a fuel souce in intenal combustion engines and gas tubines. Syngas is poduced by thee majo methods: cabon dioxide efoming, wate steam efoming, and patial oxidation (POX). Typically, methane is used in these fuel efoming pocesses but

2 Pape #070MI-085 Topic: Micocombustion & New Combustion Deices othe hydocabon fuels such as diesel, glyceol, bio-diesel, and egetable oil can also be used to poduce syngas []. Steam efoming is an endothemic pocess that occus at a tempeatue ange of 700 C to 850 C, and because of its low tempeatue ange, coking can be an issue. Patial oxidation efoming is an exothemic eaction that can be achieed though the use of a catalyst o themally with the use of heat. Catalytic patial oxidation (COPX) efoming occus in a tempeatue ange of 800 C to 1000 C. CPOX can also be combined with steam efoming in a pocess called autothemal efoming (ATR). Themal patial oxidation (TPOX) efoming occus aboe a tempeatue of 1100 C. Because of the high tempeatue associated with TPOX, heat loss can be a poblem that can decease the efficiency of the efoming pocess significantly [3]. This study inestigates patial oxidation efoming to poduce syngas, specifically TPOX efoming. Numeical simulations using detailed chemical kinetics analysis and computational fluid dynamics analysis integated with detailed chemical kinetics ae pesented to show the effect of equialence atio, eactant inlet tempeatue, and pessue on syngas poduction, specifically the poduction of hydogen and cabon monoxide. Methane was the fuel studied fo TPOX efoming, but othe hydocabon fuels could be employed in the futue. Figue 1 shows a schematic of the combusto used fo the simulations. It utilies an annula design to eciculate heat to the incoming eactants and a poous inet media (PIM) to homogenie the mixtue, as well as to stabilie the flame and peheat the incoming eactants. Lid Inlet Axis of Symmety 63 mm Combustion Zone Flame Stabiliing PIM 10.0 mm 13.5 mm 17.0 mm 0.0 mm 5 mm 15 mm Figue 1. Combusto Schematic The PIM stabilies the flame and anchos the flame to the suface at the matix inteface of the PIM, which allows fo highe buning speeds. PIM also ceates a supe adiabatic effect, i.e. highe adiabatic flame tempeatue locally esus the adiabatic flame tempeatue of a fee flame at the same equialence atio. The sensible enthalpy fom the poducts is eciculated though conection fom the hot gas to the inet media, which then tansfes heat though conduction and adiation to the media upsteam of the eaction one to peheat the incoming eactants. The high

3 Pape #070MI-085 Topic: Micocombustion & New Combustion Deices themal conductiity of the solid matix compaed to the conductiity of the gas enhances heat tansfe fom the poducts to the eactants. Thus, the oeall effect is a substantial peheating of the incoming eactants. The peheating as well as the heat eciculated though the annulus allow fo faste kinetics, highe flame speed, and extended flammability limits of the fuel/oxidie mixtue. The highe tempeatue compaed to the fee flame conditions allows initiation and chain-banching mechanisms to occu at ulta-ich equialence atios. The extended ich flammability limit allows patial oxidation conditions to be established, thus allowing the stipping of the hydogen fom the oiginal fuel molecule to poduce syngas [4]. These adantages allow TPOX to be a iable appoach fo syngas poduction. Seeal simulations ae pesented to show how these adantages affect syngas poduction. II. Methods Chemkin-Po and Ansys Fluent wee used to simulate methane-ai combustion. Chemkin was used to un a pefectly-stied eacto (PSR) model at aious inlet tempeatues, equialence atios, and opeating pessues. Chemkin was also used to un a pemixed bune-stabilied flame model. A commecial computational fluid dynamics (CFD) softwae (Fluent) was integated with detailed a chemical eaction mechanism to simulate the coupling among fluid dynamics, chemical kinetics, and heat tansfe. PSR and bune-stabilied models wee used to calculate the optimum opeating conditions fo the system. The CFD model was used to inestigate the oeall tend of syngas poduction. All thee model esults ae pesented in sequence, each model with inceasing complexity to account fo flow and chemical kinetics of the poblem. Pefectly Stied Reacto (PSR) Model. The simplest model, used to obtain baseline data, is the PSR model. PSR model is a homogenous eacto model in which the contents ae assumed to be nealy spatially unifom due to high diffusion ates, and the eacto is assumed to be pefectly mixed to descibe the spatially aeaged popeties, o bulk popeties. Because of the homogeneous natue of the mixtue, the conesion of eactants to poducts is contolled by eaction ates and not by the mixing pocesses. This model consists of a chambe, which may allow fo heat loss, with inlets and outlets. The geneal conseation equations in this model as implemented in the Chemkin softwae include the conseation equations of mass, enegy, and species. Figue depicts a schematic epesentation of a geneic pefectly stied eacto. [5] Figue. Schematic Repesentation of a Pefectly Stied Reacto

4 Pape #070MI-085 Topic: Micocombustion & New Combustion Deices This study uses a single PSR eacto with one inlet and an outlet at steady state. This model can ealuate steady state systems and tansient systems, but steady state was chosen to obtain poduct gas popeties fo a fixed esidence time. The inlet and outlet see as a means fo mass to ente and leae the system. A majo paamete fo this simulation that must be specified is a nominal esidence time (τ), which is calculated using the nominal density of the mixtue, mass flow ate, and eacto olume. A sufficiently lage esidence time of 0.5 s was used in this study to achiee nea equilibium conditions at the eacto exit. The eacto olume and mass flow ate ae abitay alues while the density emains constant. Othe paametes that must be specified ae inlet tempeatue, pessue, equialence atio, heat loss, suface tempeatue, the species of fuel and oxidie. In this study heat loss was assumed eo, the suface tempeatue was consideed to be equal to the gas tempeatue, and methane-ai combustion was used fo eactant and poduct species. A paametic study was conducted by aying equialence atio, opeating pessue, and eactant inlet tempeatue. The equialence atio was aied fom 1 to 3 in incements of 0.5. The pessue was aied fom 1 atm to 5 atm in incements of 1 atm. The inlet tempeatue was aied fom 300 K to 600 K in incements of 50 K. This simulation was used to calculate the optimum opeating conditions when most syngas is effectiely poduced. Pemixed Bune Stabilied Flame Model. The pemixed bune-stabilied flame model is a 1-D pemixed lamina flame model. This model is often used to study the chemical kinetics of a poblem in a combustion enionment. This simulation has the ability to model the chemical kinetics and tanspot pocesses that occu inside the flame to undestand the combustion pocess itself. Like the PSR model, the geneal conseation equations of mass, enegy, and species ae used. In addition, the conseation of momentum in 1D is also used [5]. This model can be un by soling the enegy equation o by specifying the gas tempeatue pofile to account fo the heat loss. Regadless, the model has to hae a tempeatue pofile, geneated o specified, to complete the simulation. In this study, the enegy equation was soled by neglecting the heat loss [6]. A sufficiently lage unbunt gas tempeatue of 600 K was specified because optimum esults occu when the eactants ente the combusto at a high tempeatue (highe than ambient). An equialence atio of.5 was used to maximie syngas poduction. This analysis was conducted only at 1 atm since pessue effects obseed fom PSR models would also be iable fo this model. Methane-ai combustion simulation was pefomed to detemine how the poduct species of hydogen and cabon monoxide deelop axially. Futhe, the tempeatue pofile will be geneated fo the analyed length (10 cm), and along with pofiles of the poduct species, the eaction one can be detemined. Computational Fluid Dynamics-Chemical Kinetics Model: This detailed model, though peliminay at this stage, combined CFD analysis with chemical kinetics analysis. The computational domain was assumed to be axisymmetic to appoximate the actual hadwae. Fo steady, lamina flow, the goening equations of mass, momentum, and enegy ae pesented in Equations though 5. Mass conseation equation: Sm ()

5 Pape #070MI-085 Topic: Micocombustion & New Combustion Deices Momentum conseation equation in the axial () diection: S P (3) Momentum conseation equation in the adial () diection: S P (4) Enegy conseation equation: E p p S T k T k T c T c 1 1 (5) Hee is the total elocity and and ae the adial and axial components of elocity, espectiely [7]. The goening equations ae soled in Fluent softwae. The chemical eactions wee epesented by a 60-step eaction mechanism fo methane-ai combustion typically used to calculate lamina flame speed in Chemkin softwae. The elements associated with this kinetics input file ae hydogen (H), oxygen (O), cabon (C), and nitogen (N). The associated 19 species ae CH 4, CH 3, CH, CH, CH O, HCO, CO, CO, H, H,O, O, OH,HO,H O, H O, and N. Table 1 shows the eactions inoled in the 60-step eaction mechanism. The computational domain was diided into aious ones including the inlet, poous media one, and combustion one. Bounday conditions wee specified fo each of these ones, such as mass flow ate into the combusto, the poosity of the poous media, and total eactant inlet enthalpy. These ae just a few examples of the many bounday conditions specified fo this poblem. Reactions wee tuned off eeywhee except in the poous media one and combustion one fo this simulation, which was compised of domain including PIM and the combusto downsteam of it. Souce tems to specify the mass flow ate into the system. Thee olumetic mass souce tems wee used in this simulation, the total mass souce tem, the methane mass souce tem, and the oxygen mass souce tem. The mass souce tems wee based on a ṁtotal = 7.911e-4 kg/s, a ṁch 4 = 1.041e-4 kg/s, and a ṁo = 1.60e-4 kg/s. It is possible to use a adiation model with this simulation, but it was not used fo simplicity. The enegy model and species tanspot models wee the main models utilied fo this simulation. The mixtue popeties ae specified o calculated in the species tanspot model. These popeties must be coect to ensue coect simulation.

6 Pape #070MI-085 Table 1. Reactions fo 60-Step Methane Reaction Mechanism CH3+H+M=CH4+M CH4+O=CH3+HO CH4+H=CH3+H CH4+O=CH3+OH CH4+OH=CH3+HO CH3+O=CHO+H CH3+OH=CHO+H CH3+OH=CH+HO CH3+H=CH+H CH+H=CH+H CH+OH=CHO+H CH+OH=CH+HO CH+O=HCO+O CH+O=CO+H CH+OH=HCO+H CH+CO=HCO+CO CH+CO=CHO+CO CH+O=CO+H+H CH+O=CO+H CH+O=CO+H+H CH+O=CHO+O CH+O=CO+H CH+O=CO+HO CH+O=CO+OH+H CH+O=HCO+OH CHO+OH=HCO+HO CHO+H=HCO+H CHO+M=HCO+H+M CHO+O=HCO+OH HCO+OH=CO+HO HCO+M=H+CO+M HCO+H=CO+H HCO+O=CO+H HCO+O=HO+CO CO+O+M=CO+M CO+OH=CO+H CO+O=CO+O HO+CO=CO+OH H+O=OH OH+H=HO+H H+O=OH+O O+H=OH+H H+O+M=HO+M OH+HO=HO+O H+HO=OH O+HO=O+OH OH=O+HO H+H+M=H+M H+H+H=H+H H+H+HO=H+HO H+H+CO=H+CO H+OH+M=HO+M H+O+M=OH+M H+HO=H+O HO+HO=HO+O HO+M=OH+OH+M HO+H=HO+H HO+OH=HO+HO Topic: Micocombustion & New Combustion Deices

7 Pape #070MI-085 Topic: Micocombustion & New Combustion Deices The solution methods used fo this poblem consisted of the SIMPLEC pessue-elocity coupling scheme, and QUICK and powe-law diffeencing schemes. Diffeent schemes wee used fo enegy, momentum, species, etc. The powe law scheme was exclusiely used fo species equations, while the enegy and momentum utilied the QUICK scheme. All species and the enegy equations wee unde-elaxed by a facto of 0.5, and the momentum equation was unde-elaxed by a facto of 0.7. Conegence citeion (mostly 0.001) wee specified and the solution was initialied with initial guesses fo the species and tempeatue. Tempeatue was guessed to be 500 K eeywhee, and the mole factions of H and O wee specified to be and , espectiely. Methane-ai combustion was analyed with this simulation at an equialence atio of 1.0 and 1.5. Because of the simplifications made fo this poblem, such as tuning off the adiation model and not efining the gid at high elocities inside the combusto, the simulation at an equialence atio of 1.5 eached blow-off. Blow-off would not hae occued if fewe assumptions wee made. Fom expeimental wok, it is known that stable methane-ai combustion easily occus at an equialence atio of 1.5. Thus, these assumptions that simplify poblem also intoduce eos because some of the ealism is emoed. Howee, the model used shows the tend of how hydogen and cabon monoxide ae poduced as the eactants become ich with inceasing equialence atio. The assumptions made wee necessay to educe the complexity bought to the simulation with detailed chemical kinetics, and although these assumptions intoduced eo, they still poduce iable initial esults that can be used to intepet the behaio of the system. III. Results and Discussion PSR Model. PSR model poided data showing the optimum opeating conditions fo this system. Figue 3 depicts the adiabatic flame tempeatue esus pessue fo diffeent eactant inlet tempeatues. Reactant inlet tempeatue was aied fom 300 K to 600, the pessue was aied fom 1 atm to 5 atm, and the equialence atio was aied fom 1 to 3. Fom Figue 3, it can be seen that the adiabatic flame tempeatue deceases as equialence atio inceases, and adiabatic flame tempeatue inceases as pessue inceases. Some of the tempeatue pofiles appea constant, because of the scale of the plot. As inlet tempeatue inceases, the adiabatic flame tempeatue also inceases, as expected. These esults just eified what was expected of the system. Figue 4 shows how the adiabatic flame tempeatue deceases with inceasing equialence atio fo eactant inlet tempeatue of 300 K. The mole faction of hydogen and cabon monoxide ae of the geatest inteest because they ae the pimay eactants in syngas. Figue 5 shows how hydogen and cabon monoxide poduction ae affected by equialence atio and eactant inlet tempeatue fo opeating pessue of 5 atm. Syngas poduction inceases with inceasing eactant inlet tempeatue. As seen in Figue 5, hydogen poduction stats to decease afte an equialence atio of.5, and cabon monoxide poduction stats to decease afte an equialence atio of.0. Syngas poduction efficiency is sometimes defined as seen in equation 6:

8 Pape #070MI-085 Topic: Micocombustion & New Combustion Deices, (6) Accoding to this definition, the most efficient opeating conditions ae at an equialence atio of.3. Thus, fom this simulation it is shown that the optimum opeating conditions fo optimum syngas poduction ae at a high inlet tempeatue and an equialence atio of.3. Since the optimum syngas poduction occus at an equialence atio of.3, the effect of pessue was inestigated fo equialence atios between and 3 and aying the pessue fom 1 atm to 5 atm. Figue 6 shows how poduction of hydogen and cabon monoxide ae affected by pessue at an inlet tempeatue of 600 K. Figue 3. Adiabatic Flame Tempeatue as a Function of Pessue and Inlet Tempeatue Figue 4. Equialence Ratio esus Adiabatic Flame Tempeatue at Inlet Tempeatue of 300 K

9 Pape #070MI-085 Topic: Micocombustion & New Combustion Deices Figue 5. Species Mole Faction as a Function of Equialence Ratio and Inlet Tempeatue Figue 6. Hydogen and Cabon Monoxide Poduction between Equialence Ratios of and 3 Ranging Fom a Pessue of 1 atm to a Pessue of 5 atm Figue 6 futhe states that the optimum opeating conditions occu at an equialence atio of.3. This is whee the maximum hydogen poduction to cabon monoxide poduction atio occus. This figue also shows that hydogen poduction and cabon monoxide poduction both incease with inceasing pessue. Thus, the optimum conditions fo syngas poduction occu at a high inlet tempeatue, an equialence atio of.3, and high pessue.

10 Pape #070MI-085 Topic: Micocombustion & New Combustion Deices Pemixed Bune Stabilied Model. The pemixed bune-stabilied model was used to detemine how hydogen and cabon monoxide ae poduced axially as the eactions pogess though the combusto. The tempeatue pofile was also geneated fo the length examined (10 cm). Figue 7 shows hydogen and cabon monoxide pofiles along the 10 cm length of the bune-stabilied adiabatic flame. Figue 7 shows that the eactants ente the combustion one, eact in the fist 0.5 cm of the combusto, and incease the tempeatue to 1655 K. Cabon monoxide mole faction emains faily constant afte the eaction one, and while hydogen mole faction inceases along the length examined. This esult shows that the eactions that poduce the hydogen extend past the eaction one, while eactions poducing cabon monoxide occu mainly within the eaction one. This simulation was only caied out at 1 atm only because as the pessue inceases, a simila tend of pessue on species mole factions as the PSR model is expected fo the bunestabilied model.. Figue 7. Bune-Stabilied Model Results Computational Fluid Dynamics-Chemical Kinetics Model: Figue 8 compaes the tempeatue contous fom detailed CFD simulations at equialence atio of 1.0 and 1.5. As Figue 8 depicts, the poous media plays a ital ole in peheating the eactants. Heat fom the eaction is conducted into the poous media, which is in contact with the combusto wall, and in tun is conducted though the wall into the incoming eactants. In the eaction one, bounday layes ae fomed, which tend to insulate the eactants in the annulus fom the high tempeatue eaction one of the combusto. Thus, most of the peheating of the eactants takes place aound the poous media. Less heat is conducted in the case wee the equialence atio equals 1.5 because the adiabatic flame tempeatue is less than in the case whee the equialence atio equals 1.0. The eactant inlet tempeatue fo both cases is aound 400 K and the combusto pessue was specified as atmospheic. Moe efficient syngas poduction will occu at the optimum conditions specified ealie, but this simulation was caied out at a lowe inlet tempeatue, pessue, and equialence atio to gain basic undestanding of the coupling effects between fluid flow, heat tansfe, poous media, and chemical kinetics. The heat tansfe pathways would also be influenced by adiation which could be significant in some egions of the system, but ignoed in this peliminay study.

11 Pape #070MI-085 Topic: Micocombustion & New Combustion Deices Figue 8. Tempeatue Contous fo CFD-Detailed Kinetics Simulation Figue 9. Methane Mole Faction Contous fo CFD-Detailed Kinetics Simulation Figue 9 depicts the methane (CH 4 ) mole faction. The simulation specified whee eactions could take place, which is only in the poous media, flame and exhaust ones. Figue 9 shows no methane pesent in these ones, signifying complete oxidation of the oiginal fuel. The same can be said fo Figue 10, which shows the oxygen (O ) mole faction. Both cases fo Figues 9 and 10 ae the same because the total mass flow ate was held constant. Next, the adical poduction was examined to undestand how it affected the eaction one. Oxygen adical (O) and hydogen adical (H) ae geneated at the plane just downsteam of the poous media, and ae confined to a naow but intense flame one. These adicals help sustain eactions that would eentually poduce poduct species including H and CO in case of fuel-ich combustion. Figue 11 shows contous of the mole factions of oxygen adicals (O) poduced in this system. Similaly, Figue 1 and 13 show contous of the mole faction of hydogen adicals (H) and hydoxyl adical (OH) poduced in the system.

12 Pape #070MI-085 Topic: Micocombustion & New Combustion Deices Figue 10. Oxygen (O ) Mole Faction Contous fo CFD-Detailed Kinetics Simulation Figue 11. Oxygen Radical (O) Mole Faction Contous fo CFD-Detailed Kinetics Simulation

13 Pape #070MI-085 Topic: Micocombustion & New Combustion Deices Figue 1. Hydogen Radical (H) Mole Factions fo Fluent Simulation Figue 13. OH Mole Factions fo Fluent Simulation Figues 11, 1, and 13 show that at stoichiometic conditions (=1.0) moe adicals ae poduced compaed to the fuel-ich combustion at =1.5. Radical concentation elated to the eaction one tempeatue, which is highe fo =1.0. These esults also identify the axial and adial extend of adical poduction ones, although complete eliance on these esults will equie a fully gid-independent solution which has not been attained in the pesent study because of the lage computational equiements. Still, these esults offe unpaallel insight into the eaction one and its coupling with aious fluid flow and heat tansfe phenomena eident in the pesent system.

14 Pape #070MI-085 Topic: Micocombustion & New Combustion Deices Next, CFD esults ae examined to ealuate poduction of H and CO. Figue 13 depicts the contous of hydogen (H ) mole factions fo this system. As the equialence atio inceases past stoichiometic condition and the mixtue becomes fuel-ich, H poduction can be expected to incease as infeed fom PSR and bune-stabilied models. Pesent simulations eplicate this tend, and also show inceased H in the bounday laye egion whee the tempeatue is lowe fo the = 1.5 case. Figue 14 shows the contou plots of CO mole faction fo this system. A simila tend as obseed fo the H mole factions is also obseed fo the CO mole faction. Moe CO is poduced fo fuel-ich conditions as expected. Unde ich conditions excess fuel is pesent, and since methane s molecula make up is of cabon and hydogen, moe hydogen and cabon become aailable in the fom of uneacted poducts. Figue 14. H Mole Factions fo Fluent Simulation Figue 15. CO Mole Factions fo Fluent Simulation

15 Pape #070MI-085 Topic: Micocombustion & New Combustion Deices Finally, Figue 16 shows the contou plot of CO mole faction in the system. Results show that moe CO is poduced outside of the flame in the bounday laye, and moe CO is poduced within the flame one. This effect can be explained by inceased dissociation in the hightempeatue eaction one. Figue 15. CO Mole Factions fo Fluent Simulation IV. Conclusions Thee models with inceasing complexity wee used to inestigate fuel-ich combustion of methane to poduce syngas containing hydogen (H ) and cabon monoxide (CO). Simple PSR model poided esults that allowed the optimum opeating conditions fo syngas poduction to be detemined. These optimum conditions wee at high opeating pessue, high inlet tempeatue, and an equialence atio of aound.3. The bune-stabilied model showed how the poduct species, specifically H and CO, wee poduced in the eaction one, as well as the pe-eaction one and post-eaction one. Most H was poduced in the eaction one, but these eactions continued downsteam to futhe incease H poduction. The CO was poduced mainly in the eaction one, and downsteam of this one, CO was consumed by futhe oxidation eactions. CFD analysis with detailed chemical kinetics eealed the complex coupling among fluid flow, heat tansfe, poous media, and chemical eactions. Fom this simulation it was found that most of the peheating of the eactants occus in the poous media egion. Because of the simplification intoduced (e.g., no adiation), the heat tansfe model is not completely accuate, but the tend obseed with the poous media is consistent with peious expeimental obseations. Simulations eealed that fewe adicals ae poduced in the eaction one as the mixtue becomes fuel-ich. Simulations also identified how H and CO poduction is affected by the local tempeatue. H poduction inceases in the bounday laye fo the fuel-ich eactant mixtue. CO poduction also inceased in the bounday laye because of low tempeatue and less dissociation. These tends offe unpaallel insight into combustion pocesses inside this system. Howee, futue studies will focus on fully alidated, gid independent solution incopoating detailed chemical kinetics with themal adiation fo a ange of opeating conditions to optimie the system pefomance.

16 Pape #070MI-085 Topic: Micocombustion & New Combustion Deices V. Acknowledgments This eseach was suppoted by US Depatment of Enegy Awad EE Refeences [1] Toledo, M., Bubnoich, V., Saelie, A., Kennedy, L., Intenational Jounal of Hydogen Enegy, 34(009), [] Dobego, K.V., Gnesdilo, N.N., Lee, S.H., Choi, H.K., Chemical Engineeing Jounal, 144(008), [3] Ayabe S., Omotoa H., Utaka T., Kikuchi R., Sasaki K., Teaoka Y., & Eguchi K., Applied Catalysis A: Geneal, 41(003), [4] Pastoe, A., Mastoakos, E., Fuel 90 (010) [5] Chemkin Theoy Manual [6]Chemkin Tutoial Manual [7] Mabach, T.L., Mesoscale, Poous Media Heat Reciculating Combusto, Ph.D. Dissetation, Depatment of Mechanical Engineeing, Uniesity of Oklahoma, 005.