質子交換膜燃料電池(Proton Exchange Membrane Fuel cell‚ PEMFC)的水熱管理一直是個相當困擾的問題，如何保持薄膜內含水量以及均勻溫度分佈是電池正常運轉的重要關鍵因素。電池陰極側所生成的液態水量、生成位置及分佈，會直接影響電池的效能；產生過量的水，可能導致陰極氣體擴散層水氾濫，阻礙氣體的輸送；若薄膜水分不足，則氫離子就難以通過薄膜抵達陰極觸媒層來產生反應。溫度的分佈，也是一項相當重要的因素，當溫度過高，可能就會導致電池某區域發生損壞。所以可經由數值模擬的方式，來改善質子交換膜燃料電池的水熱管理，以提高其效能。
本研究是利用CFDRC數值流力分析轉換來探討質子交換膜燃料電池，分析在不同氣體濃度、增濕程度、操作溫度、陰陽極壓力差等條件對於薄膜內水含量、電流密度分佈的影響，進而評估燃料電池的性能。依照燃料電池之物理及化學現象，建立數學模式，進而模擬PEMFC的流場分佈。本研究的主要目的是要驗證CFDRC流力分析軟體，用於PEMFC水熱管理模擬的能力，其次，對各參數做靈敏度分析，使燃料電池的性能達到最佳化。
本文模擬結果顯示:使用乾空氣及純氧時，陽極入口處附近會有乾化現象發生，所以必須作增濕處理；使用純氧為氧化劑時，反應氣體濃度提高，能產生很高的極限電流密度約1.81 A/cm2，若為反向流可提高至1.85 A/cm2。增濕氣體方面，陽極相對溼度越高，性能曲線越佳；但陰極相對溼度降低，會減少低電流密度區的電流密度，但會增加高電流密度區的電流密度，前者與薄膜水含量降低有關，後者與氣體濃度的提升有關。操作溫度方面，提高溫度有利於增加電化學反應速率，但高分子薄膜的耐溫程度有限，且要考慮水含量問題，結果顯示以操作溫度在353K性能最佳，溫度提高到373K性能反而會降低。操作壓力方面，提高壓力可明顯提升電池的性能，且以陰極端加壓的效果會比陽極加壓的效果好，因為加壓氣體會使得觸媒層界面濃度提高，且可提高兩電極端的濃度梯度，使得薄膜水含量更為均勻，也不易出現氧氣過早被反應消耗完。因此，提高氣體壓力能夠減少活性與濃度極化損失。

Water and heat management are important issues in the design and analysis of proton exchange membrane fuel cell (PEMFC). In the present study, a computational fluid dynamic (CFD) code, CFDRC-ACE+, is used to simulate the hydrodynamic behavior of PEMFC. A single cell three dimensional model of PEMFC is built. The input values of physical and chemical parameters are determined based on the results of literature survey. The polarization curve as predicted in the present study is very closed to the experimental results and the simulated results in the related literatures . Sensitivity studies are preformed to identify the impact of major operating parameters on the polarization curve.
The results of sensitivity studies show that the water content of membrane near the channel entrance will be significant lower when dry air or pure oxygen is used in the cathode flow channel. To humidify the cathode gas flow can improve the performance of fuel cell in low current density (high voltage) portion of polarization curve. However, If has adverse effect in the high current density (low voltage) portion of polarization curve. The performance in the high current density portion is better when the gas flow in anode channel and cathode channel is in reversed direction. The performance of PEMFC can also significantly improved by increasing the pressure of cathode flow channel and by incorporating forced convection.
The condensation of water vapor in the flow channel and porous media is not considered in the present study. The CFDRC-ACE+ code has the capability to consider the phenomenon. However, the numerical scheme of the code is extremely unstable when the phenomenon is considered.

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