质子交换膜燃料电池流场设计最佳化的反问题求解方法

Inverse problem method applied to flow field optimization of proton exchange membrane fuel cells

为寻求最佳的流道高度参数,利用由简化共轭梯度法(反向求解器)和完整的三维、两相、非等温燃料电池数学模型(正向求解器)构成的质子交换膜燃料电池多参数最佳化反问题求解方法,将流道各弯头处高度作为搜寻变量(最佳化对象),以电池输出功率密度的倒数作为目标函数,通过搜寻目标函数最小值,得到了流道各弯头处最佳高度(最优化设计参数值).结果表明,最佳的蛇型流场除出口流道为高度渐扩型外,其余流道均为高度渐缩型,其性能比传统蛇型流场提高了约11.9%.渐缩型的流道强化了肋下对流,可有效移除肋条下方多孔扩散层中的液态水,提高反应气向多孔电极的传递速率,因而改善了电池性能.渐扩型的出口流道可防止过强的肋下对流导致燃料"短路",直接跨过多孔扩散层从电池出口流出造成燃料浪费.

An optimization approach,combining a simplified conjugate-gradient method（inverse problem solver） and a three-dimensional,two-phase and non-isothermal fuel cell model（direct problem solver）,was developed to determine the key geometric parameters of a proton exchange membrane fuel cell.In this approach,with channel height as the searching variable（optimized object） and the reciprocal of cell output power density as the objective function,the optimum channel height（optimized design variable） was derived from searching the minimum of the objective function.The results show that for the optimized serpentine design,except the outlet channel being diverging,the other channels should be tapered.The cell performance is,meanwhile,improved by 11.9% compared to the convectional serpentine flow field under the same operating conditions.A detailed investigation of local transport characteristics reveals that the tapered channel design enhances sub-rib convection,leading to more oxygen transport over the cell and more effective liquid water removal out of the cell;however,the diverging outlet channel can provide relatively proper sub-rib convection to prevent reactants from ＂short-circuit＂,which means that reactants directly flow out of the cell and thus results in reactant waste.