Limit Operating Temperature in Polymer Electrolyte Membrane Fuel Cells

In this research, a control technique for polymer electrolyte membrane (PEM) fuel cells based on the limit operating temperature is introduced. The limit operating temperature is the highest temperature in which the PEM fuel cell can operate, preserving a recommended relative humidity and air stoichiometry. The operating temperature influences the fuel cell voltage; the higher the temperature, the better the voltage. A PEM fuel cell model is applied to analyze the evolution and dependence among the variables. The tests were performed considering two situations: PEM fuel cells without extra humidification and PEM fuel cells with an external humidifier. Also, the influence of humidity and temperature of the input air can be analyzed separately. The results show that the limit temperature strategy is stable and consistent under different operational conditions such as different load requirements and presence/absence of extra humidification.