S. Authayanun 1 and A. Arpornwichanop 2 1

S. Authayanun 1 and A. Arpornwichanop 2 1 Department of Chemical Engineering, Faculty of Engineering, Srinakharinwirot University, Thailand 2 Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University,, Thailand

Outline INTRODUCTION METHODLOGY RESULTS CONCLUSION 2

Fuel cell and its applica.on

Proton Exchange Membrane Fuel cell PEMFC - - H 2 H 2 Flow field plate - - H 2 O + + + + H 2 O O 2 Heat H 2 O Flow field plate Gas diffusion layer (Anode) Gas diffusion layer (Cathode) Catalyst Catalyst Proton Exchange Membrane Limitation : CO poisoning and water flooding

Fuel processing for fuel cell As hydrogen is not readily available, it is necessary to investigate fuel processing for hydrogen production from other sources Fuel - Methane - Ethanol - Glycerol - Biomass Reforming process Reformate gas - Hydrogen - CO - CO 2 - CH 4 - Remaining water The complex CO purification process is needed for conventional PEMFC systems. 5

HT-PEMFC Improve cathode kinetics Improve CO tolerance Simplify water management Enhance heat management

Reduction in System complexity of HT-PEMFC Higher CO tolerance reforming Addi8onal hydrogen produc8on and hydrogen purifica8on Water gas shi5 CO removal unit q Preferential oxidation q membrane separation q methanation PEMFC Humidifier Proton conductivity does not depend on water 7

The design of HT-PEMFC system Fuel processor Fuel Water Air T in = T r Preheater Heat recovery Flue gas ATR HT-PEMFC Electricity Adiabatic operation Air Fuel Water Air T in = T r Fuel processor Preheater Heat recovery Flue gas ATR WGS HT-PEMFC Electricity Adiabatic operation Air 8

Model Reformer " Gibb reactor model " Reactant : Methane, air and water PEMFC " Electrochemical model " CO poisoning model " Studied parameter : T, T in and S/C C C ( t )! fi min G = = T, P nigi ni Gi + RT ln n! i i= 1 i= 1 fi C i= 1 a ji n i = b j, for 1 " Reactant : reformate gas and a i r Use Lagrange multiplier method to solve the optimization problem j M 9

Model Reformer " Gibb reactor model " Reactant : Glycerol and water " Studied parameter : T and S/C PEMFC " Electrochemical model " CO poisoning model " Reactant : reformate gas and air Fit model with experimental data from literature Get parameter and model to represent process Use model to explore optimal condition

The effect of inlet temperature on fuel processor efficiency 80 Fuel processor without WGS 90 Fuel processor with WGS Fuel processor efficiency ( η FP ) 70 60 50 40 30 20 Tin = TR Tin = 298 K Fuel processor efficiency ( η FP ) 80 70 60 50 40 30 20 Tin = TR Tin = 298 K 10 673 773 873 973 1073 1173 Reformer temperature (K) 10 673 773 873 973 1073 1173 Reformer temperature (K) The inlet temperature has significant effect on system efficiency because the required oxygen flow rate to sustain the autothermal reforming operation decreases with increasing the inlet reformer temperature.

Performance of HT-PEMFC system without WGS reactor Stack voltage (V) 2000 1500 1000 500 673 K 773 K 873 K 973 K 1073 K Power = 50 kw T in = 298 K S/C = 2 140 120 100 80 60 40 Power (kw) Stack voltage (V) 2000 1500 1000 500 673 K 773 K 873 K 973 K 1073 K Power = 50 kw T in = 298 K S/C = 3 140 120 100 80 60 40 Power (kw) 20 20 0 0 0 100 200 300 400 0 0 0 100 200 300 400 Current (A) Current (A) The autothermal reformer should be operated at temperature lower than 873 K and 973 K for S/C ratio of 2 and 3 to meet the target power output (50 kw)

Performance of HT-PEMFC system with WGS reactor Stack voltage (V) 2000 1500 1000 500 673 K 773 K 873 K 973 K 1073 K T in = 298 K S/C = 2 140 120 100 80 60 40 Power (kw) Stack voltage (V) 2000 1500 1000 500 673 K 773 K 873 K 973 K 1073 K T in = 298K S/C = 3 140 120 100 80 60 40 Power (kw) 20 20 0 0 0 100 200 300 400 500 0 0 0 100 200 300 400 500 Current (A) Current (A) All studied case can meet target power output (50kW).

Efficiency at the optimal operating conditions ηfp ηfc Case ηsys HT-PEMFC system without WGS reactor Case 1 : T in = 25 C 67.8 31.4 21.3 Case 2 : T in =T R 69.5 32.1 22.3 HT-PEMFC system with WGS reactor Case 1 : T in = 25 C 74.9 32.5 24.3 Case 2 : T in =T R 87.8 32.9 28.9

" The inlet reformer temperature has a crucial effect on efficiency because it is a key factor for controlling energy usages of autothermal reformer. " HT-PEMFC system without WGS reactor should be operated at higher S/C ratio and lower reformer temperature compared to HT-PEMFC system with WGS reactor. " WGS reactor is necessary for fuel processor of HT-PEMFC system when efficiency is first priority for system design.

Acknowledgements Faculty of Engineering, Srinakharinwirot University Chulalongkorn University 16

Thank you 17