臺灣博碩士論文加值系統

本研究可分為三個部份，第一部份以一維的數學模型只考慮氣相來模擬質子交換模燃料電池在陰極中的質傳以及電化學現象。固定Pt loading 為1mg/cm2,研究不同觸媒層結構,對於電池的性能影響，由模擬結果可以看出，觸媒層的厚度越薄，性能越好。第二部份以一維的數學模型只考慮單一相並且假設觸媒層氾濫來模擬質子交換模燃料電池在陰極中的質傳以及電化學現象。在此模擬中，實驗的條件包含有不同Pt loading的影響，不同Nafion loading的影響，進料端壓力的影響，以及不同進料溼度的影響。從結果可以知道，進料端壓力越大，觸媒層越薄，電池的性能越好。觸媒層的Nafion含量越高，導電度高，電池性能也越好，但是過多的Nafion會造成質傳阻抗，降低電池性能。第三部份使用一個二維、多成分的模型討論質子交換模燃料電池陰極。此研究使用不同的操作條件下去模擬陰極電池性能的影響。可以發現在較薄觸媒層厚度，較大的孔隙度，較高的電池操作溫度下，較大的流道與肋條寬度比例以及較低的進料溼度會使得電池性能提升。

This study is divided into three parts. First part is a one-dimensional considering only gaseous phase to study the mass transfer and electrochemical kinetics of a cathode of the Polymer Electrolyte Fuel Cells. We fixed Pt loading at 1mg/cm2. We studied the effect of different catalyst layer structures cell performance. It was found thinner catalyst layer can enhance the cell performance. The second part is a one-dimensional model of single phase, assuming catalyst layer is fully flooded to simulate the mass transfer and kinetics of a cathode of the Polymer Electrolyte Fuel Cells. The parameters studied are Pt loading, Nafion loading, inlet gas pressure and inlet relative humidity. It was found that increase of inlet gas pressure at cathode and decrease of catalyst layer thickness can increase performance. Higher Nafion content in catalyst layer, can increase conductivity, but too much Nafion causes the mass transfer resistance and decrease cell performance. The third part is a two-dimensional, multicomponent model to study the cathode of the proton exchange membrane fuel cells. The model is to study the effects of various operating conditions on cell performance. It was found that thinner diffusion layer thickness, larger channel to rib ratio, larger diffuser porosity, higher cell temperature, and drier inlet gas stream all improve cell performance.

摘要 i
Abstract ii
Contents iii
List of figure v
List of table vii
Chapter 1 Introduction 1
1-1 Introduction 1
1-2 Motivations and objectives 3
Chapter 2 Simulation of cathode catalyst multilayer of Proton Exchange Membrane Fuel Cells 4
2-1 Introduction 4
2-2 Mathematical model 5
2-2-1 Governing equations for mass balance 6
2-2-2 Governing equations for momentum balance 8
2-2-3 Governing equations for current conservation 9
2-2-4 Boundary conditions 10
2-3 Results and discussions 12
2-4 Conclusions 16
Chapter 3 Simulation of flooding cathode catalyst layer of Proton Exchange Membrane Fuel Cells 17
3-1 Introduction 17
3-2 Mathematical model 18
3-2-1 Total mass conservation 18
3-2-2 Oxygen and vapor water conservation 20
3-2-3 Current conservation 22
3-2-4 Boundary conditions 23
3-3 Results and discussions 26
3-3-1 Effect of different Pt loading 26
3-3-2 Effect of different Nafion loading 28
3-3-3 Effect of different inlet stream relative humidity 28
3-3-4 Effect of different pressure 28
3-4 Conclusions 32
Chapter 4 Parametric study of two-phase, 2-D in the cathode of PEM fuel cells. 33
4-1 Introduction 33
4-2 Mathematical Formulations 34
4-2-1 Governing equations 35
4-2-2 Boundary conditions 38
4-3 Results and discussions 40
4-3-1 Effect of different inlet stream relative humidity with 1D and 2D 40
4-3-2 Effect of different cell temperature 44
4-3-3 Effect of different porosity 48
4-3-4 Effect of different gas diffuser thickness 48
4-3-5 Effect of the ratio of channel to rib 51
4-3-6 Transient profiles for the base conditions 51
4-4 Conclusions 56
Reference 57
Nomenclature 58

[1]C. Marr and X. Li, J. Power Sources, 77 (17) (1999) 17-27.
[2]J.J Hwang, S.D. Wu, R.G. Pen, P. Y. Chen, C.H. Chao, J. Power Sources, 160 (2006) 18-26.
[3]J.J. Hwang, J. Electrochem. Soc., 153(8) (2006) A1584-A1590.
[4]R. Krishna, R.Taylor, Multicomponent Mass Transfer, Wiley, New York (1993).
[5]K.M. Yin, J. Electrochem. Soc., 152 (2005) A583-A593.
[6]R. Chen, T.S. Zhao, W.W. Yang, C. Xu, J. Power Sources, 175 (2008) 276-287.
[7]T.S. Zhao, W.W. Yang, C. Xu, Electrochimica Acta, 53 (2007) 853-862.
[8]T.E. Springer, T.A. Zawodzinski, S. Gottesfeld, J. Electrochem. Soc., 138 (8) (1991) 2334-2342.
[9]D.M. Bernardi, M.W. Verbrugge, J. Electrochem. Soc., 139 (9) (1992) 2477-2491.
[10]D.M. Bernardi, M.W. Verbrugge, AIChE, 37 (9) (1991) 1151-1162.
[11]T.V. Nguyen, R.E. White, J. Electrochem. Soc., 140 (8) (1993) 2178-2186.
[12]D. Natarajan and T. V. Nguyen, J. Electrochem. Soc., 148(12) (2001) A1324-A1335.
[13]M. Vynnycky, Applied Mathematics and Computation, 189 (2007)1560-1575.
[14]X. Wang and T. V. Nguyen, J. Electrochem. Soc., 155(11) (2008) B1085-B1095.
[15]COMSOL Multiphysics 3.5 http://www.comsol.com