Optimization of PEMFC operating parameters considering water management by an integrated method of sensitivity analysis, multi-objective optimization and evaluation

Proper water management is necessary for an efficient operation of proton exchange membrane fuel cell (PEMFC) by avoiding dehydration and flooding. Operating parameters have significant impact on the water management of PEMFC. Therefore, operating parameters considering three water management indexes including highest value of liquid water saturation (s_l,high), lowest value of water content (λ_low), and current density (i) are quantitatively optimized by a systematical integrated method of sensitivity analysis, multi-objective optimization and evaluation. First of all, a multi-physics model is established to analyze the water characteristics, obtaining s_l,high and λ_low in PEMFC. Then, one-at-a-time (OAT) analysis identified sensitive operating parameters including back pressure (p_out), stack temperature (T_st), anode relative humidity (RH_an,in), cathode relative humidity (RH_ca,in), and oxygen excess ratio (ξ_c). Finally, three water management indexes are optimized at various voltages via combining with elliptical basis function neural network model, non-dominated sorting genetic algorithm, and fuzzy membership degree. The results show that optimal model demonstrates varying degrees of water management improvement compared to the base model, with maximum reductions of 5.4 % in s_l,high, maximum increases of 8.1 % in λ_low, and maximum increases of 2.4 % in i. Furthermore, the maximum PEMFC efficiency improvement of optimal model is 4.0 %. The ranking of variation of optimal operating parameters with voltage is as follows: T_st, RH_ca,in, p_out, ξ_c, and RH_an,in. As the voltage decreases from 0.65 V to 0.50 V, the optimal operating parameters of T_st = 335.82 K, RH_ca,in = 92.8, p_out = 1.581 bar, ξ_c = 3.46, and RH_an,in = 98.8 changes to T_st = 351.15 K, RH_ca,in = 73.7, p_out = 1.968 bar, ξ_c = 3.41, and RH_an,in = 99.6. The optimal operating parameters applied in performance experiment proves the accuracy of optimization direction. This study obtains optimal operating parameters considering water management at various voltage by proposed integrated method, which increases PEMFC performance.