Using electrochemical cycles to efficiently exploit the waste heat from a proton exchange membrane fuel cell

With the help of the current models of a proton exchange membrane fuel cell (PEMFC) and a thermally regenerative electrochemical cycle (TREC), a novel model of the hybrid system composed of a PEMFC and N TRECs is established. The TRECs in the system can effectively exploit the waste heat released form the PEMFC. The expressions for the power output and efficiency of the hybrid system are analytically derived. The effects of some key parameters including the electric current density and electrode area of the PEMFC and the electric current and regenerative efficiency of TRECs on the performance of the system are discussed in detail. It is found that when the regenerative efficiency of TRECs is in the range of 0.2-0.8, the maximum power output density of the hybrid system is about 1.11-1.20 times of that of the PEMFC. The maximum power output densities and corresponding efficiencies of the hybrid system at the differently operating temperatures of the PEMFC are calculated and compared with those of other PEMFC-based hybrid systems, and consequently, it is revealed that the proposed model can more efficiently utilize the waste heat produced in a PEMFC than other PEMFC-based hybrid systems.