Thermal economic analysis of hybrid open-cathode hydrogen fuel cell and heat pump cogeneration

Abstract Proton exchange membrane fuel cell (PEMFC) receives increasing attention as an alternative in small-scale residential distributed generation (DG) application, especially for remote cold region where the utility electricity is not accessible. The open-cathode PEMFC is featured with the integrated fabrication of air supply and coolant flow cathode. Although simple, the waste heat of the exhaust air is difficult to reuse by heat exchangers, because of the low exhaust temperature. To this end, this paper investigates a hybrid structure consisting of open-cathode PEMFC and heat pump. It is revealed in this paper that the oxygen excess ratio of open-cathode PEMFC is usually as big as 100, which makes it doable and safe to directly exporting the exhaust air into the indoor environment. The temperature of the mixed air is thereby lifted. The thermal load of the heat pump is consequently alleviated and the power consumption is reduced. A comprehensive quantitative model is developed by considering the fuel cell electrochemical characteristic, cathode thermodynamics and heat pump coefficient. A case study is carried out by comparing the coefficient of performance (COP) of the system with and without the cogeneration design, showing a 7.6% improvement of the proposed hybrid structure. The results of the paper depict a promising prospect in accelerating the commercialization of open-cathode PEMFC in the field of domestic cogeneration filed.