臺灣博碩士論文加值系統

本文主要研究在不同的陰極氣體當量比、氣體外部加濕與否、氧氣濃度及陰極流道積水對PEMFC性能之影響，本研究製作透明燃料電池模型以CCD攝影機拍攝並觀察陰極流道內之積水模式。
結果發現柵狀流道及指叉流道較易發生積水，若要減少積水現象，流道路徑的設計要盡量符合流線模式。在高電壓(0.7V以上)、低陰極氣體當量比或低電池操作溫度條件下，陰極流道均易發生積水；電池達到最佳輸出性能之條件為電壓介於0.45~0.55V、電池溫度50℃、氣體加濕溫度70℃、陰極氣體當量比達到6；在低電壓(0.4~0.6V)，電池溫度固定在50℃，在陰極氣體有外部加濕時，性能與陰極氣體當量比成正比關係，直到當量比達到臨界值6止。當陰極氣體改為氧氣不加濕時，電池性能與陰極氣體當量比則呈現相反之趨勢。
樹枝狀流道對於液態水有較佳的保存能力，在加濕溫度大於電池溫度條件下流道卻反而容易出現積水現象。實驗也發現當流道內壓力較小時，上游區開始積水並導致壓力上升，當流道內之壓力達到排水的臨界點時，積水隨即被推至下游區並由流道出口排出，流道內的壓力亦隨即下降，液態水再次重複開始累積。
由暫態電流負載實驗發現，當電池切換為大電流負載時，GDL內的氫氣及薄膜內的氫離子濃度不足以及時供應反應所需，造成電壓下降。

The study investigates the effect of cathode water flooding, gas stoichiometries and humidified temperature on PEMFC performance. In order to observe the flooding pattern, the transparent experiment model is used in this study.
It is found that the parallels and interdigitated flow channels are easily flooding. In order to remove the flooding, the path of flow channel should be fitted the streamline. The results indicated that the cathode channel is easily flooding at high cell voltage (above 0.7V), low cathode stoichiometry or low fuel cell temperature. The performance will reach the best when the output voltage is between 0.45~0.55V, cell temperature 50℃, gases humidified temperature 70℃ and cathode stoichiometry is at 6. The performance and the cathode stoichiometry have positive relation till the stoichiometry is at 6 under the cell temperature is fixed at 50℃, low output voltage between (0.4~0.6V) and gases have external humidity; The relation has an inverse trend when the cathode gas is replaced by dry oxygen.
It is found that the ramification flow field has a better ability of keeping water in the flow channel. The water flooding is appeared more easily in this flow field due to this feature under high gas inlet RH. It is also found that the upstream began has flooding when the pressure is small. But it will result in the pressure increasing. The flooding will be removed when the pressure is large enough and the pressure will decrease. The flooding will began again.
The output voltage appears undershoot in current density step increase. The reason is that the gases are insufficient to supply the reaction in the fuel cell.

Name of Thesis i
Abstract in Chinese iv
Abstract in English v
Content vii
List of Figures ix
Nomenclature xiv


Chapter 1. Introduction 1


Chapter 2. Experimental 16
2.1. Fabricating a simulating experimental model of PEMFC 16

2.2. Fabricating a transparent PEMFC 19

2.3. Ramification field 21

2.4. Fabricating 5cm2 fuel cell for transient study 22


Chapter 3. Results and discussion 24
3.1. Flooding pattern in various flow field 24

3.2. The study of performance at different oxygen stoichiometries in fuel cell 29
3.2.1. Cell voltage performance 29
3.2.2. A constant electronic load of 0.3A/cm2, cell 50℃, electrochemical reaction region 30
3.2.3. A constant electronic load of 0.5A/cm2, cell 50℃, ohmic reaction region 32
3.2.4. A constant electronic load of 0.7A/cm2, cell 50℃, mass transport region 34
3.2.5. Voltage vs. oxygen stoichiometry chart 36
3.2.6. Different temperatures study 38

3.3. The study of the effect on concentration and humidification 40
3.3.1. A constant electronic load of 0.7A/cm2 at different humidified oxygen stoichiometries 40
3.3.2. A constant electronic load of 0.3A/cm2 was applied to the cell and at different humidified air stoichiometries 43
3.3.3. A constant electronic load of 0.3A/cm2 was applied to the cell and at different non-humidified oxygen stoichiometries 46
3.3.4. Fluctuation of voltage on the effect of concentration and humidification at different cathode gas stoichiometries 48

3.4. The study of the effect on concentration and humidification 49
3.4.1. A constant electronic load of 0.7A/cm2 at different humidified oxygen stoichiometries 49
3.4.2. A constant electronic load of 0.3A/cm2 was applied to the cell and at different humidified air stoichiometries 51
3.4.3. A constant electronic load of 0.3A/cm2 was applied to the cell and at different non-humidified oxygen stoichiometries 52
3.4.4. Fluctuation of voltage on the effect of concentration and humidification at different cathode gas stoichiometries 54

3.5. Study of transient in PEMFC with current density step increase 56


Chapter 4. Conclusions 63


References 65

[1]J.J. Baschuk and X. Li, “Modelling of polymer electrolyte membrane fuel cells with variable degrees of water flooding”, J. Power Sources, Vol. 86, 181-196, 2000.

[2]D. Natarajan and T.V. Nguyen, “Three-dimensional effects of liquid water flooding in the cathode of a PEM fuel cell,” J. Power Sources, Vol. 115, 66-80, 2003.

[3]L.B. Wang, N.I. Wakayama, and T. Okada, “Numerical simulation of a new water management for PEM fuel cell using magnet particles deposited in the cathode side catalyst layer”, Electrochemistry communications, Vol. 4, 584-588, 2002.

[4]T. Okada, G. Xie and M. Meeg, “Simulation for water management in membranes for polymer electrolyte fuel cells,” Electrochimica Acta Vol. 43, Nos. 14-15, 2141-2155, 1998.

[5]T.V. Nguyen and R.E. Whitte, “A water and heat management model for proton-exchange-membrane fuel cells”, J. electrochem. Soc., Vol. 140, No. 8, 1993.

[6]Y. Shan and S.Y. Choe, “Modeling and simulation of a PEM fuel cell stack considering temperature effects”, J. Power Sources, Vol. 158, 274-286, 2006.

[7]B. Zhou, W. Huang, Y. Zong, and A. Sobiesiank, “Water and pressure effects on a PEM fuel cell”, J. Power Sources, Vol. 155, 190-202, 2006.

[8]L. Matamros and D. Brüggemann, “Simulation of the water and heat management in proton exchange membrane fuel cells”, J. Power Sources, vol. 161, 203-213, 2006.

[9]B. Cheng, O. Minggao, and Y. Baolian, “Analysis of water management in proton exchange membrane fuel cell”, Tsinghua Science and Technology, Vol. 11, 54-64, 2006.

[10]A. Kraytsberg and Y. Ein-Eli, “PEM FC with improved water management”, J. Power Sources, Vol. 160, 194-201, 2006.

[11]T. Okada, G. Xie, and Y. Tanabe, “Theory of water management at the anode side of polymer electrolyte fuel cell membranes”, Journal of Electroanalytical Chemistry, Vol. 413, 49-65, 1996.

[12]T. Okada, “Theory for water management in membranes for polymer electrolyte fuel cells-Part 1. The effect of impurity ions at the anode side on the membrane performances”, Journal of Electroanalytical Chemistry, Vol. 465, 1-17, 1999.

[13]T. Okada, “Theory for water management in membranes for polymer electrolyte fuel cells-Part 2. The effect of impurity ions at the cathode side on the membrane performances”, Journal of Electroanalytical Chemistry, Vol. 465, 18-29, 1999.

[14]J. Larminie and A. Dicks, “Fuel cell system explained”, John Wiley&Sons Ltd, 2000.

[15]P.B. Whalley, “Two-phase flow and heat transfer”, Oxford Science Publications 1996.

[16]M.M. Mench, Q.L. Dong, and C.Y. Wang, “In situ water distribution measurements in a polymer electrolyte fuel cell”, J. Power Sources, vol. 124, 90-98, 2003.

[17]T.V. Nguyen and M.W. Knobbe, “A liquid water management strategy for PEM fuel cell stacks”, J. Power Sources, Vol. 114, 70-79, 2003.

[18]R. Satija, D.L. Jacobson, M. Arif, and S.A. Werner, “In situ neutron imaging technique for evaluation of water management systems in operating PEM fuel cells”, Journal of Power Sources, Vol. 129, 238-245, 2004.

[19]K. Tüber, D. Pócza, and C. Hebling, “Visualization of water buildup in the cathode of a transparent PEM fuel cell”, Journal of Power Sources, Vol. 124, 403-414, 2003.

[20]A. Hakenjos, H. Muenter, U. Wittstadt, and C. Hebling, “A PEM fuel cell for combined measurement of current and temperature distribution, and field flooding”, Journal of Power Sources, vol. 131, 213-216, 2004.

[21]W.H.J. Hogarth and J.B. Benziger, “Operation of polymer electrolyte membrane fuel cells with dry feeds: Design and operating strategies”, J. Power Sources, Vol. 159, 968-978, 2006.

[22]Y. Yoshikawa, T. Matsuura, M. Kato, and M. Hori, “Design of low-humidified PEMFC by using cell simulator and its power generation verification test”, J. Power Sources, Vol. 158, 143-147, 2006.

[23]C.R. Buie, J.D. Posner, T. Fabian, S.W. Cha, D. Kim, F.B. Prinz, J.K. Eaton, and J.G. Santiago, “Water management in proton exchange membrane fuel cells using integrated electroosmotic pumping”, J. Power Sources, Vol. 161, 191-302, 2006.

[24]T.A. Trabold, J.P. Oweian, D.L. Jacobson, M. Arif, and P.R. Huffman, “In situ investigation of water transport in an operating PEM fuel cell using neutron radiography: Part 1- Experimental method and serpentine flow field results”, Int. J. Heat and Mass Transfer, Vol. 49, 4712-4720, 2006.

[25]J.P. Oweian, T.A. Trabold, D.L. Jacobson, D.R. Baker, D.S. Hussey, and M. Arif, “In situ investigation of water transport in an operating PEM fuel cell using neutron radiography: Part 2- Transient water accumulation in an interdigitated cathode flow field”, Int. J. Heat and Mass Transfer, Vol. 49, 4721-4731, 2006.

[26]Q. Yan, H. Toghiani, and H. Causey, “Steady state and dynamic performance of proton exchange membrane fuel cells (PEMFCs) under various operating conditions and load changes”, J. Power Sources, Vol. 161, 492-502, 2006.

[27]S. Kim, S. Shimpalee, and J.W. Van Zee, “Effect of flow field design and voltage change range on the dynamic behavior of PEMFCs”, J. The Electrochemical Society, Vol. 152 (6), A1265-A1271, 2005.

[28]S. Kim, S. Shimpalee, and J.W. Van Zee, “The effect of reservoirs and fuel dilution on the dynamic behavior of a PEMFC”, J. Power Sources, Vol. 137, 43-52, 2004.

[29]S. Kim, S. Shimpalee, and J.W. Van Zee, “The effect of stoichiometry on dynamic behavior of a proton exchange membrane fuel cell (PEMFC) during load change”, J. Power Sources, Vol. 135, 110-121, 2004.

[30]Y. Wang and C.Y. Wang, “Transient analysis of polymer electrolyte fuel cells”, Electrochimica Acta, Vol. 50, 1307-1315, 2005.

[31]Y. Wang and C.Y. Wang, “Dynamics of polymer electrolyte fuel cells undergoing load changes”, Electrochimica Acta, Vol. 51, 3924-3933, 2006.

[32]Y. Shan and S.Y. Choe, “A high dynamic PEM fuel cell model with temperature effects”, J. Power sources, Vol. 145, 30-39, 2005.

[33]F.N. Büchi and S. Srinivasan, “Operating proton exchange membrane fuel cells without external humidification of the reactant gases”, J. Electrochem. Soc., Vol. 144 (8), 2767-2772, 1997.

[34]H. Yang, T.S. Zhao, and Q. Ye, “A study of CO2 gas bubble behavior in a direct methanol fuel cell”, Fuel Cell Science, Engineering and Technology June 14-16, 2004.

[35]F.B. Weng, A. Su, C.Y. Hsu, and C.Y. Lee, “Study of water-flooding behavior in cathode channel of a transparent proton-exchange membrane fuel cell”, J. Power Sources, Vol. 157, 674-680, 2006.

[36]P. Argyropoulos, K. Scott, and W.M. Taama, “Carbon dioxide evolution patterns in the direct methanol fuel cells”, Electrochim. Acta, Vol. 44, 3575-3584, 1999.