Design and multi-objective optimization of low-temperature proton exchange membrane fuel cells with efficient water recovery and high electrochemical performance

Water generated by electrochemical reaction in the proton exchange membrane fuel cell (PEMFC) could be used as an important resource. Several studies have been carried out to recycle the water from PEMFC emissions, which verifies the feasibility of water recovery. However, the quantitative description of the water recovery mechanism inside PEMFC is not clear and the water recovery performance could be further improved from the perspective of internal mass transfer. In this paper, a two-dimensional model is developed to present the fluid flow and mass transfer inside a PEMFC. Also, a detailed investigation into the effects of operating parameters, including pressure, temperature, and relative humidity, on both the electrochemical performance and the water recovery performance is conducted. Besides, a multi-objective optimization is carried out for the performance optimization of PEMFC. The results show that the expanded water recovery efficiency (EWRE) of PEMFC is more sensitive to pressure and relative humidity than temperature. The optimum solution at 1 atm shows that EWRE reaches 141 % with the current density of 0.7163 A·cm⁻². The operation strategy of decreasing the humidification temperature and increasing the relative humidity at the cathode inlet, and maintaining PEMFC working at a moderate temperature is proposed to keep the balance between the electrochemical and water recovery performance. This work contributes to the operation optimization of water recovery and to the application extension of PEMFC.