質子交換膜燃料電池陰極氣體擴散層內的兩相流傳輸分析

質子交換膜燃料電池是目前最被看好的新型替代能源之ㄧ，尤其是在汽車應用方面。然而目前尚未廣泛商業化，主要原因是因為當電池在高電流密度時，反應產生的水會阻礙燃氣傳輸，其中又以陰極最為嚴重，因此如何提升電池的性能是非常重要的。本研究主要探討質子交換膜燃料電池陰極氣體擴散層內的兩相流傳輸現象，利用數值方法求解出燃料電池陰極氣體擴散層內液態水飽和度分佈、氧氣濃度分佈以及性能曲線。研究中發現當考慮兩相流模式時，反應產生的液態水會降低氣體擴散層內的有效孔隙度並阻礙燃氣傳輸。當氣體擴散層的疏水性越好時，反應產生的水較易藉由毛細力排除，對於電池性能的影響就越小。孔隙度較小以及氣體擴散層厚度較厚時，質傳損失會較早發生，此外由於氣體擴散層內的液態水較多，對於電池的影響也較明顯。當流道過長或是入口流速較低時，質傳損失也較早發生，而當電流密度就越高，由於反應產生的液態水越多，對於電池的影響就會越大。

關鍵字

質子交換膜燃料電池；氣體擴散層；兩相流

並列摘要

The proton exchange membrane (PEM) fuel cell is most anticipated among several kinds of substitute energy, particularly in the area of automotive technology. However, at high current density liquid water will hinder oxygen transport to reaction site especially in the cathode side and make them unrealistic for widely commercialization up to the present. How to improve the cell performance is very crucial. The study focuses on transport phenomena of cathode gas diffusion layer of PEM fuel cell by using two-phase flow model. Liquid water saturation and oxygen concentration profile in gas diffusion layer and polarization curve are investigated by numerical simulations. Results show that liquid water due to chemical reaction reduces effective porosity of gas diffusion layer and hinders oxygen transport to reaction site. When the gas diffusion media is more hydrophobic, the liquid water removal rate by the capillary force is faster. With the decreasing GDL porosity or the thicker GDL thickness, the mass transport limitation takes place at lower current density. Besides, since liquid water saturation in gas diffusion layer is higher, liquid water effect on the cell performance becomes more significant. With the longer channel length or the slower inlet velocity, the mass transport limitation also takes place at lower current density. And with the increasing current density, liquid water effect on the cell performance becomes more significant.

並列關鍵字

PEM fuel cell ； gas diffusion layer ； two-phase flow

參考文獻

1. J. Larminie, A. Dicks, “Fuel Cell Systems Explained,” Wiley, UK, 2000.

2. P. Costamagna, and S. Srinivasan, “Quantum Jumps in the PEMFC Science and Technology from the 1960s to the Year 2000 Part I. Fundamental Scientific Aspects,” J. Power Sources, 102(1-2) 2001, pp. 242-252.

3. P. Costamagna , and S. Srinivasan, “Quantum Jumps in the PEMFC Science and Technology from the 1960s to the Year 2000 Part II. Engineering, Technology Development and Application Aspects,” J. Power Sources, 102(1-2) 2001, pp. 253-269.

4. D.M. Bernardi, “Water-Balance Calculations for Solid-Polymer- Electrolyte fuel cells,” J. Electrochem. Soc., 137(11)1990, pp.3344-3 350.

5. D.M. Bernardi, and M.W. Verbrugge, “Mathematical Model of a Gas Diffusion Electrode Bonded to a Polymer Electrolyte,” AIChE Journal, 37(8) 1991, pp. 1151-1163.

國際替代計量

質子交換膜燃料電池陰極氣體擴散層內的兩相流傳輸分析

全文下載

主題瀏覽