Analysis of Excessive Heating on The Thermal and Electrical Resistance of a Polymer Electrolyte Membrane Fuel Cell

Abstract

The performance on a polymer electrolyte membrane (PEM) fuel cell is evaluated based on the relationship of thermal and electrical resistances to its electrical and thermal power output. An analytical method by which the electrical resistance is evaluated based on the polarisation curve and the thermal resistance from the mass balance, was applied to a 72-cell PEM fuel cell assembly. In order to evaluate the effect of resistances at elevated stack temperatures, the cooling system was operated at half of its maximum cooling effectiveness. The increase in current and resistance due to a unit change in temperature at a particular density was evaluated and it was found that the stack has a ratio of thermal resistance rise to current rise of 1.7, or equal to 0.00584 A/W of current increase per stack heat increase. These values suggest that the internal resistance of the stack components, most probably the electrode assemblies, are very high, which should be addressed in order to obtain lower resistances to current flow.