Gas/Water and Heat Management of PEM-Based Fuel Cell and Electrolyzer Systems for Space Applications

Hydrogen/oxygen fuel cells were successfully utilized in the field of space applications to provide electric energy and potable water in human-rated space mission since the 1960s. Proton exchange membrane (PEM) based fuel cells, which provide high power/energy densities, were reconsidered as a promising space power equipment for future space exploration. PEM-based water electrolyzers were employed to provide life support for crews or as major components of regenerative fuel cells for energy storage. Gas/water and heat are some of the key challenges in PEM-based fuel cells and electrolytic cells, especially when applied to space scenarios. In the past decades, efforts related to gas/water and thermal control have been reported to effectively improve cell performance, stability lifespan, and reduce mass, volume and costs of those space cell systems. This study aimed to present a primary review of research on gas/water and waste thermal management for PEM-based electrochemical cell systems applied to future space explorations. In the fuel cell system, technologies related to reactant supplement, gas humidification, water removal and active/passive water separation were summarized in detail. Experimental studies were discussed to provide a direct understanding of the effect of the gas-liquid two-phase flow on product removal and mass transfer for PEM-based fuel cell operating in a short-term microgravity environment. In the electrolyzer system, several active and static passive phaseseparation methods based on diverse water supplement approaches were discussed. A summary of two advanced passive thermal management approaches, which are available for various sizes of space cell stacks, was specifically provided