Performance improvement of high-power PEMFC using wet compression and exhaust energy multiple utilizations

Abstract

To improve the efficiency of the high-power proton exchange membrane fuel cell (PEMFC) system, a novel system integrated with wet compression and cathode exhaust energy recovery is proposed. A 1D steady-state model is established for the proposed system to obtain the thermodynamic operating modes. The NSGA Ⅱ algorithm is used to identify the suitable humidification strategy for each operating point. The results show that the utilization of wet compression for the PEMFC system has multiple combined benefits. Considering the available gains in the practical wet compression process, the trade-off in compression efficiency at the rated point results in an increment of 3.6 %. The parasitic power of the compressor decreases from 15.3 kW to 12.1 kW. The electrical efficiency and the net output power of the proposed system increase by 1.7 % and 8.0 kW, respectively. Furthermore, parametric analysis of wet compression reveals additional advantages in precooling and external humidification processes. At the rated point with the wet compression, the heat load of the liquid cooling heat exchanger decreases from 6.6 kW to 4.1 kW, and the water recovery ratio of the membrane humidifier reaches 30 %. The findings of the novel PEMFC system provide substantial guidelines for treating cathode exhaust gas and for the development and utilization of wet compression in fuel cell systems.