Thermal analysis of high-temperature proton exchange membrane fuel cell integrated compression-assisted absorption heat pump system

Abstract

A combined distributed energy system with integrated high-temperature proton exchange membrane fuel cell (HT-PEMFC) and compression-assisted absorption heat pump (CAHP) is proposed. The HT-PEMFC has the advantage of high efficiency in clean power generation, but also produces abundant waste heat. To achieve waste heat recovery, CAHP with dimethyl ether triethylene glycol (DMETEG)/R134a as working fluid is applied to convert waste heat into cooling/heating capacity. The mathematical model of the combined distributed energy system is established, and the energy conservation of the system in the basic design condition is verified. The effects of five system parameters on the energy output and efficiency of the system are analyzed, and the optimization strategy for the system design is proposed. In the basic design condition, combined distributed energy system yields a heating capacity of 7.8898 kW in heating mode and a cooling capacity of 2.3773 kW in cooling mode, while consuming 9.96% and 7.51% of HT-PEMFC output power respectively. By contrast, sole HT-PEMFC has an only electrical power output of 2.333 kW. An appropriate increase of the compression ratio can improve the exergy efficiency and the performance coefficient of the CAHP, and enlarge the operating temperature range. The outlet working fluid temperatures of each component in the heat pump have different effects on the system performance in heating/cooling mode. The results can provide a reference for further development of such distributed energy system.