Uncoupling Characteristics of Temperature and Relative Humidity Distribution in a Commercial-Size Polymer Electrolyte Membrane Fuel Cell

Abstract

The microenvironment of the electrodes in a polymer electrolyte membrane fuel cell (PEMFC) is critical to its performance and is significantly affected by the distribution of water and heat along the cell. In this work, the temperature and relative humidity (RH) distributions at both anode and cathode were for the first time investigated simultaneously via in situ measurement. Through this method, we successfully evaluate the effects of coflow and counterflow arrangements on cell performance and the uncoupling characteristics of temperature and RH. The experimental results show that coflow has better coupling characteristics than counterflow between the anode and cathode, especially at high current density. At low and medium current densities, the temperature and RH distributions are more uniform in counterflow mode at the same degree of humidification, producing better performance. At high current density, a bigger temperature difference and severe water flooding were observed in the cell in counterflow mode, with adverse effects on performance and durability. We evaluate a number of other conditions that give us greater insight into the influence of fuel cell design and operating conditions. This work paves the way for the optimization of bipolar plates and water–heat management in PEMFCs.