Thesis (M.Eng.)--Chulalongkorn University, 2007

This research concentrates on the performance analysis of a polymer electrolyte membrane fuel cell (PEMFC). A two-phase model taken into account the formation of liquid water is used to simulate the steady state behavior of the PEMFC under isothermal condition. The mass transfer resistance of reactants due to a water flooding effect is taken into account to analyze cell performance. The effect of key operating conditions such as temperature, pressure and humidification of reactant gases on the PEMFC in terms of the distribution of gas composition and current density, and cell voltage and power density is studied. Simulation studies show that the performance of PEMFC increases when operating temperatures, the humidity of the fuel gas and air gas, and operating pressure are increased. In contrast, the cell performance decreases while the anode and cathode inlet temperatures increase due to the dehydration of membrane. The water flooding at the cathode side increases with increasing operating current density. The occurrence of water flooding results in lower void fraction in the cathode and thus, less oxygen can diffuse to the catalyst layer. Therefore, higher concentration loss is observed.