本研究使用理論模式探討重組器熱質傳現象以及燃料電池性能之最佳流道設計。為了提升燃料電池性能，分別探討指插型流道內的最佳擋塊位置、蛇行流道最佳寬度與高度配置以及梯度孔隙率對不同流道設計之電流密度分佈。而在氫氣產生部分，為了提升重組器的甲醇轉換率，在此針對重組器之平行流道長度、寬度、高度與進出口分歧管寬度，使用參數分析與最佳化方法觀察重組器之氣體濃度、溫度分佈對甲醇轉換率、氫氣與一氧化碳的生成所造成的影響。另外也使用簡易共軛梯度法(Simplified Conjugate-Gradient Method，SCGM)，搜尋中間進/中間出之最佳流道寬度。其數值分析則是使用那維爾-史都克斯(Navier-Stokes equation)作為流場的統御方程式，配合能量及成份守恆方程式與電化學相關方程式，求解燃料電池之電化學反應與重組器之化學反應。此外亦使用簡易共軛梯度法進行重組器與燃料電池幾何最佳化搜尋。
於燃料電池部分，經由簡易共軛梯度最佳化搜尋指插型擋塊位置以及蛇行流道寬度與高度，能有效的提升電流密度分別為14％以及22.5％；另外，藉由參數分析得知除了指插型流道之外，梯度孔隙率能增加Z蛇流道以及平行流道的氣體擴散能力與觸媒層的電子傳遞能力，進而提升電流密度。相較於均勻孔隙率（ε1=0.5/ε2=0.5），當梯度孔隙率為ε1=0.7/ε2=0.3的條件下，Z蛇流道以及平行流道的電流密度最高可提升22.8％以及18.2％。另一方面，也能有效的增加氣體擴散能力，其平行流道以及Z蛇流道的氧氣使用率分別提升28%以及22%。
於重組器部分，為了觀察其幾何構型對氣體濃度分佈的影響，以參數分析的方式找出不同流道尺寸以及進出口位置對重組器性能的影響，其結果發現中間進/左右兩邊出的進出口設計，在入口條件為1 cc/min的流量下，不僅可以有效的增加甲醇轉換率31.3％也能降低31.7％的一氧化碳生成；最後，並以中間進/中間出為基本構型結合簡易共軛梯度之最佳化方法，搜尋最佳寬度分佈。模擬結果可明顯的看出，經由流道寬度的最佳化，不僅能有效的提升甲醇轉換率，還可降低一氧化碳的生成。而且藉由流道寬度的演化過程，明確的詮釋一氧化碳生成的主要原因為高濃度的氫氣與二氧化碳在局部高溫的條件下所產生的逆水氣反應。

The theortic models were performed to analyze the heat and mass transfer of reformer and optimal channel pattern design for proton exchange membrane fuel cell (PEMFC). In order to increase the performance of PEMFC, the location of baffles in channels with interdigitated channels pattern, channel widths and channel heights with serpentine channels pattern and porosity gradient in cathode gas diffusion layer were adjusted toward the maximization of the average current density of the flow field. In terms of reformer, this study was aim at parameter study for channel lengths, channel widths, channel heights, inlet manifold widths, outlet manifold widths and inlet/outlet positions to discuss the influence of methanol conversion ratio, hydrogen production rate and concentration of carbon monoxide. Moreover, the Simplified Conjugate-Gradient Method, SCGM, was used to search the optimal channel widths in case of central inlet/central outlet. The approach is developed by using the commercial CFD code as the direct problem solver, which is able to provide the numerical solutions for the three-dimensional mass, momentum and species transport equations as well as to predict the electric chemical reaction in a PEMFC and chemical reaction in reformer. In addition, the optimal algorithm SCGM was also integrated to search the geometric parameter.
Results show that the optimal design of the locations of the baffles with interdigitated channel pattern and channel heights and widths of serpentine channel pattern can be determined by using the SCGM in just a finite number of iterations. Compared with the initial design, the optimal design increases the fuel cell power output with interdigitated and serpentine channel patterns by 14% and 22.5%, respectively. Moreover, according to the parameter study the gas diffusion and ability for electron transfer of z-serpentine and parallel channel patterns can be enhanced by porosity gradient expect for interdigitated channel patterns. Compared with the uniform porosity design (ε1=0.5/ε2=0.5), the porosity gradient ε1=0.7/ε2=0.3 in z-serpentine and parallel channel patterns increases the current density by 22.8% and 18.2%, respectively. Furthermore, the gas usage was also increased 22% and 28% with z-serpentine and parallel channel patterns, respectively.
In terms of reformer, the parameter study of geometric parameter was performed to realize the performance of reformer. Results show that the design of central inlet/two outlets can not only increase the methanol conversion ratio to 31.3%, but also decrease the concentration of carbon monoxide to 31.7% at inlet condition of liquid flow rate 1 cc/min. At the final case, the SCGM algorithm was integrated with reformer model for central inlet/central outlet to search the optimal channel width distributions. According to the optimum channel width distributions, the methanol conversion ratio and concentration of carbon monoxide can be increased and decreased by optimal algorithm, respectively. Through the evolution of channel width, the reaction rate of reverse water gas shift reaction can be increased by high concentration of hydrogen and carbon dioxide in local high temperature.

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