Performance evaluation of an integrated high-temperature proton exchange membrane fuel cell and absorption cycle system for power and heating/cooling cogeneration

In addition to electricity generation, high-temperature proton exchange membrane fuel cells also produce numerous high-quality waste heat, which may be further used in combined cooling, heating and power systems. In this study, a new general model of an integrated system consisting of a high-temperature proton exchange membrane fuel cell, a regenerator and an absorption cycle is proposed for waste heat recovery, where the absorption cycle can be functioned as either an absorption heat pump for heating or an absorption refrigerator for cooling. Considering various irreversible losses within the system, mathematical expressions for the equivalent power output and efficiency of the proposed system are derived, from which the general performance characteristics are revealed and the optimum criteria are given. When the absorption cycle is operated in the heat pump mode or refrigerator mode, the maximum attainable power densities for the proposed system allow 33.41% and 19.34% greater than that of the sole high-temperature proton exchange membrane fuel cell system, respectively. Furthermore, the effects of the operating current density, operating temperature, doping level, relative humidity, heat leak and heat-transfer irreversibilities on the performance characteristics of the proposed system are discussed in detail. The results obtained in this paper may offer some theoretical help for the integration and design of such an actual system.