Equivalent power output and parametric optimum design of a PEM fuel cell-based hybrid system

A new hybrid system composed of a proton exchange membrane (PEM) fuel cell, an irreversible three-heat-source heat pump, and a regenerator is originally established, so that the waste heat produced in the PEM fuel cell may be efficiently utilized. With the help of the current models of PEM fuel cells and three-heat-source cycles, expressions for the equivalent power output and efficiency of the hybrid system are analytically derived. The curves of the equivalent power output and efficiency of the hybrid system varying with the electric current density and the equivalent power output versus equivalent efficiency curves are represented through numerical calculation. The maximum equivalent power output of the hybrid system is determined. Some of the key parameters such as the equivalent efficiency of the hybrid system, the electric current density of the fuel cell, and the heat transfer areas of the three-heat-source heat pump are optimally designed. The performance between the hybrid system and the single PEM fuel cell is compared, and consequently, the advantages of the hybrid system are expounded.