Experimental Analysis of Large Active Area Polymer Electrolyte Membrane Fuel Cell Stack for Determining Optimal Operating Conditions

Various parameters affect the performance of the PEM fuel cell. Determining the optimal point for the performance of a fuel cell stack has attracted the attention of many researchers. In this paper, the effect of various operating parameters such as relative humidity, temperature, pressure and stoichiometry for the performance of a three-cell fuel cell stack with a large active area (500 cm(2)) has been investigated. Local voltage measurement of each cell under different conditions was performed during the experiment. Appropriate operating conditions have been extracted by analyzing the polarization curve, the standard deviation of voltage and stack efficiency using the least-squares optimization method. The results showed that the performance of the stack is improved by about 1-2%, by increasing the relative humidity of the cathode (from 50 to 100%) at low current densities due to the hydration of the membrane. By increasing the temperature of the stack from 50 to 80 degrees C, it is observed that the reaction rate is increased resulting in a performance improvement of 4%. It is found that by increasing the reactant's outlet pressure from 0.5 to 2.0 barg, the gas diffusion rate in the diffusion layer and the catalyst surface increased, the voltage deviation between the cells decreased by half, and therefore stack performance improved by 4-6%. By increasing the stoichiometry of the cathode from 1.02 to 1.6, water and fuel management is enhanced, the voltage deviation between the cells is reduced by 2%, and fuel cell stack performance is improved by 1%.