Performance Evaluation of a Cylindrical PEM Fuel Cell and the Stack

Air-breathing fuel cells, due to their ability of using oxygen directly from air, have the potential to emerge as a primary power source for various applications. Cylindrical fuel cells offer the advantage of higher gravimetric and volumetric power densities compared to conventional planar fuel cells. In the present study, the durability of single cylindrical cell is tested based on a new European driving cycle and the cell is shown to be stable for more than 200 h of operation at different current densities. The decrease in the performance is observed to be the result of increase in membrane resistance rather than catalyst degradation or hydrogen crossover. Furthermore, the performance of a stack of 16 cylindrical fuel cells is evaluated at different relative humidities and temperatures of air on the cathode side. The effect of cell positioning on the stack performance in terms of deficiency of oxygen is also studied. Both relative humidity and temperature are observed to have an effect on the durability of the stack. Increment in the temperature of air is also seen to upset the performance of the stack. Higher relative humidity (similar to 80%) and lower temperature (similar to 35 degrees C) are observed to stabilize the stack in terms of performance and durability on a time scale of more than 2 h.