質子交換膜燃料電池之端板改良設計以及相關性能探討

Abstract

質子交換膜燃料電池內部的電阻會影響電池組的性能，電阻包含元件自身的片電阻以及元件接觸面上之接觸電阻，而後者的影響遠大於前者。接觸電阻的大小主要由夾持壓力決定，本文首先探討夾持壓力和接觸電阻之間的關係，並使用函數式表示；而後利用有限元素分析軟體進行接觸電阻值的預測，並探討壓力分佈情形對接觸電阻的影響；結果顯示夾持壓力大小才是影響接觸電阻值的主因，當夾持壓力增加時，可以明顯降低接觸電阻，而壓力分佈均勻雖然可以降低接觸電阻，但是改善的效果非常有限。 壓力分佈均勻除了稍微改善接觸電阻外，對於電池組內之熱管理、水管理以及燃料傳輸亦有正面效益，本文後半段以壓力分佈之均勻性為目標，進行燃料電池組夾持端板的改良設計，並以壓力分佈的標準差來判斷壓力分佈是否均勻，然後和傳統端板比較；結果顯示本文設計之新型端板，在提供均勻壓力之性能上，遠高於傳統端板，而且經過簡單的輕量化後，重量還能低於傳統端板。

The electrical resistance in PEMFC will reduce the performance of the fuel cell stack. The electrical resistance includes the bulk resistance of the components and the contact resistance between the components, the latter has larger influence on the performance of the fuel cell than the former. The contact resistance is mainly determined by the clamping pressure. In this paper, we first investigate the relation between the clamping pressure and the contact resistance, then we use some kind of functions to represent the relation. According to the relation, we can predict the contact resistance with FEM software, and investigate the effects of the contact pressure distribution on the contact resistance. We find that the contact resistance is affected by clamping pressure significantly, but lightly affected by the pressure distribution, though the uniform distribution could decrease the contact resistance. In addition, the uniform distribution can improve the managements of heat, water and the transportation of the fuel. So we design the clamp endplate of the stack to provide the uniform pressure distribution. We use the standard deviation of the pressure to judge the uniformity of the pressure distribution using newly designed endplate and compare with the traditional one. The results show that the new endplate give more uniform pressure distribution than traditional endplate, and could be lighter after simple weight reduction.