本研究是建立出不同孔隙率的實體發泡材流道與不同肋條比例的平行流道，綜合探討氣體傳輸與電流傳遞對質子交換膜燃料電池性能的影響，且觀察電池內部的氣體分布、流場變化及電流傳輸的細部現象。建立三維局部燃料電池模型及格點是使用D E S IGN MOD E LE R 與M E S HING 軟體， 且使用計算流體力學軟體FLU E N T 的燃料電池模組進行分析。研究結果顯示，發泡材流道較平行流道有較佳的氣體利用率，若將發泡材壓縮使其孔隙率縮小，會幫助流體加速往氣體擴散層移動，使得性能再往上提升。發泡材流道因肋條較均勻分布於流道中，將電流向外往集電板傳出的效果也較平行流道突出，為了看出導電的差異，本研究計算出流道的有效導電率進行量化比較。最後綜合了流道中，氣體利用率與電流傳遞的兩大因素，找出發泡材流道的最佳孔隙率與平行流道的最佳肋條比例，且經由參數分析討論肋條材料的電傳導係數與當量比對燃料電池最佳肋條比例與孔隙率的影響，結果顯示，若流道材料為金屬時，對肋條的最佳比例影響不大，而當量比對最佳比例則有較明顯的影響。This study investigates the effects of solid volume fraction of the flow fieldon the gas transport, electron transfer and fuel cell performance through microscale modeling. Three dimensional model and grid system are built by usingDesign Modeler and Meshing, while solutions to the governing equations areobtained by employing commercial CFD software package ANSYS-Fluent.The results show that using highly porous metal foam to replace traditionalchannel flow field results in better gas utilization rate (GUR). Reducing thepermeability of metal foam increases gas flux to the gas diffusion layer, andthus enhances cell performance. This study also compares the effectiveelectrical conductivity (EEC) of the flow field. Metal foam flow field has higherEEC because electric current can be collected more uniformly distributedthroughout the whole electrode. By simultaneously considering EEC and GUR,one can find the optimal porosity for metal foam or the optimal rib-to-channelratio for the channel flow field. Results show that stoichiometry affects theseoptimal values. When the solid material used is metal, the electric conductivityof the material does not affect these optimal values.
