Thermal management for optimal performance of polymer electrolyte membrane unitized regenerative fuel cells

Hydrogen is an excellent carrier for energy storage and can be produced from various green and renewable sources. However, the cost of producing hydrogen and converting it to useful energy is much higher than fossil fuel and traditional energy generation and storage systems. Unitized regenerative fuel cells (URFC) maximize utilization of high-cost cells and their components, thus, lowering system capital cost. Improving the URFC efficiency is an effective way to lower its operating cost. This study evaluates utilization of waste heat during operation and recovery strategy to improve system efficiency of Proton Exchange Membrane (PEM) URFC. A COMSOL Multiphysics 3-D model of 25 cm2 5-cell PEM URFC stack is used to simulate the URFC operation. The results show that the employed cooling strategy can recover 76% and 78% of waste heat when the URFC operates in fuel cell mode and in reverse water electrolyzer mode, respectively, and the PEM URFC round-trip efficiency can thereby be improved from 32% to 81%.