Heat transfer analysis of air cooling in forced air and forced convection PEM fuel cells

The optimum operating temperature of a Polymer Electrolyte Membrane (PEM) fuel cell is approximately 80°C. The electrochemical reaction inside a PEM fuel cell stack produces approximately 50% of electrical and 50% of heat energy. The power output of the fuel cell stack is significantly influenced by the humidity and temperature inside the power stack. Therefore, an effective cooling system is necessary for a fuel cell stack to maintain its temperature within an acceptable level to produce optimum power output. In this study, a Finite Element Analysis (FEA) computer simulation model of the bipolar plate was developed to conduct a steady-state heat transfer analysis and eliminate the expensive and laborious laboratory testing. Two different air supply systems for PEM fuel cells, namely "forced air" and "forced convection" systems, and two different bipolar plate materials, namely "aluminum" and "graphic composite", were investigated in the heat transfer analysis. In addition, an air cooling fin was designed and integrated into a bipolar plate as a part of a power stack in order to dissipate the excessive heat and maintain the operating temperature at 80°C or less. The results show that cooling fin design can produce effective cooling mechanism for 4.8 mm thick bipolar plates.