Thermal modeling and analysis of polymer electrolyte membrane open cathode fuel cells

In the past decade renewable energies have increasingly become a commodity in everyday life. Because of their high power densities and their application versatility, fuel cells have stood out among other sources of renewable energy. In order to improve this technology as the needs for it increases, thermal modeling is an essential step. Researchers in the past have investigated the effect that temperature has on fuel cells. However, not much work has been done on the thermal dynamics of these devices and no one, to the authors knowledge, has studied the speed of response in thermal changes as a function of stack size, current demand or mass flow rate of air. This research presents a one-dimensional lumped model for an open cathode polymer electrolyte fuel cell. This study analyzes the contribution of all the heat sources traditionally involved in the thermal study of fuel cells, and determines simplifications that have not been identified previously in the literature. Moreover, this work presents an analysis of open cathode fuel cells by comparing the fuel cell stack to a heat exchanger. This analogy provides researchers with a tool to evaluate heat dissipation in air breathing fuel cells without having to develop a complicated electrochemical model that would have to account for mass transport phenomena. Finally, this analysis studies both the steady state and transient thermal distribution in the fuel cell stack and how this distribution is affected by stack size, operation current and mass flow rate of air flowing though the cathode/cooling channels --Abstract, page iv