Interaction of cell flow directions and performance in PEM fuel cell systems following an anode based water management approach

Abstract

A good water management is very important for the operation of PEM fuel cell systems as the proton conductivity is dependent on the membrane water content. In contrast to state of the art approaches, this study focuses on an anode based water management approach of fuel cell systems with an anode recirculation loop. The aim of the anode based water management is to reach a high and homogeneously distributed anode humidity without condensation in all relevant operating conditions. A criterion is defined to evaluate the anode humidity distribution.A macroscopic discrete 2D+1D model was developed that can simulate humidity distributions and the cell voltage for various flow directions of the fluids and operating conditions. The model considers the system behavior including the anode recirculation loop.This study shows that flow directions that support an internal water circulation are beneficial for fuel cell systems without external humidification. Furthermore, the study shows a correlation between the anode humidity distribution at the membrane and the cell voltage. The higher the temperature is, the more important is a flow field that supports a high and homogeneously distributed anode humidity.