気液二相流を考慮した数値シミュレーションによる固体高分子形燃料電池の過渡応答時の解析(熱工学,内燃機関,動力など)

概要

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It is important to elucidate the transient characteristics of polymer electrolyte membrane fuel cell (PEMFC), because it may be operated at a wide range of loads, and may have frequent starts and stops. In these unsteady conditions, the water management problem such as the flooding in cell and the drying of proton exchange membrane (PEM) tends to occur and degrades the performance of PEMFC. Based on these issues, a two dimensional, two-phase and transient numerical simulator for unit-PEMFC has been developed to study the transient characteristics of PEMFC. As for the gas/ liquid two-phase flow formulation in GDL. multiphase mixture model have been employed. In this study, we derived four time constants, which characterize the transient response of PEMFC. In addition, we numerically simulated the transient response of PEMFC to step-wise change of load current from 0.5 to 1.0 A/cm^2 and succeeded to explain the transient response of cell voltage (V_<cell>) by the four time constants. The results show that, just after the change of current, Vce_<cell> decreases by IR resistance in a moment, and then decreases in 10^<-1> s time-scale by the re-distribution of oxygen gas and by the charge of electric double layer capacitor. Then Ken increases slightly in 10^1 s time-scale by wetting of PEM. Finally, V_<cell> decreases again in 10^2 s time-scale by the development of liquid saturation in GDL.
一般社団法人日本機械学会の論文
2007-03-25