The effect of pressure on an air-reformate proton exchange membrane (PEM) fuel cell system

The choice of operating pressure in a proton exchange membrane fuel cell power system is one of the most critical decisions in the design of a balanced, cost effective power system. Ultimately, the overall system performance is a complex composite of the performance of each interdependent subsystem as constrained by the efficiency of individual system components and the application at hand. To understand better the interactive relationships between components and subsystems and to evaluate the systematic effect of operational variables such as temperature and pressure, AlliedSignal has developed a computer model of a 50 kW fuel cell power system. Using this model, the effect of pressure has been evaluated and shown to have a significant impact on both the size of the fuel cell stack (for a given target power level) and the stack and overall system efficiency. At this stage, it appears that the decision of whether to operate a stack at increased pressure depends heavily on the target application and its electrical demand profile