平板式固態氧化物燃料電池穩態熱應力分析

Steady-state thermal stress analysis of a planar solid oxide fuel cell

周欣鋒(Hsin-Feng Chou)

指導教授 ： 李雄

國立中央大學/工學院/機械工程學系/碩士(2007年)

摘要

平板式固態氧化物燃料電池(SOFC)是由連接板、正電極-電解質-負電極(PEN)、Frame(框架)、玻璃陶瓷、多孔性鎳網所組成。在穩態操作下，由於溫度很高，SOFC會因為溫度梯度及組件間熱膨脹係數的差異而產生熱應力。當SOFC的熱應力很高時，可能會導致SOFC組件發生氣體洩漏或者破裂的情況，降低SOFC的效能。所以在設計SOFC時，對SOFC穩態操作情況進行熱應力分析是必要的。
本文使用ANSYS作為分析軟體，套用以發展中平板式SOFC設計為基礎建構出的3D模型來作熱應力分析，並且探討不同拘束條件、不同通入氣體方式及熱膨脹係數差異對熱應力的影響。模擬結果顯示，在穩態操作下，連接板及Frame可能已經發生塑性變形，PEN及玻璃陶瓷則還在強度安全範圍內。底面三種不同的拘束條件對於SOFC熱應力的影響並不大。兩種不同的氣體通入方式中，Co-flow產生之熱應力比Counter-flow小，對SOFC結構上較為安全。當忽略熱膨脹係數時，熱應力分佈完全被溫度分佈所影響著。

關鍵字

熱應力分析 ； 固態氧化物燃料電池

並列摘要

Planar solid oxide fuel cell is composed of the interconnect, positive electrode-electrolyte-negative electrode (PEN), frame, glass-ceramic, and porous nickel. At steady-state operation, the temperature is high and the thermal stresses in planar SOFC are caused by the temperature gradients and mismatch of coefficient of thermal expansion (CTE) between all cell components. When the thermal stresses in a fuel cell are sufficiently high, gas leakage or failure may occur in the SOFC components. This will reduce the SOFC efficiency. A steady-state thermal stress analysis of SOFC is necessary for the design of SOFC.
Commercial FEA code ANSYS is utilized to analyze the thermal stress distribution in planar SOFC under steady-state condition in this study. A 3-D model based on a developing planar SOFC design would be constructed in the current study to perform a thermal stress analysis for planar SOFC. We discuss the influence on thermal stress due to different constraint, different flow-path configurations, and the mismatch of CTE. Modeling results indicated that interconnect and frame might have plastic deformations under steady-state operation, but PEN and glass-ceramic were still in the range of strength security. Three different constraint at bottom interconnect of SOFC would not cause significant changes in the thermal stress distribution. The thermal stresses owing to co-flow are smaller than counter-flow, and co-flow is more safe for SOFC structure. Thermal stress distribution is fully influnced by temperature distribution when we ignore the mismatch of CTE.

並列關鍵字

thermal stress analysis ； solid oxide fuel cell

參考文獻

[11] 陳宗廷，「平板式固態氧化物燃料電池堆熱應力分析」，國立中央大學，碩士論文，民國95年。

[1] K. P. Recknagle, R. E. Williford, L. A. Chick, D. R. Rector, and M. A. Khaleel, “Three-dimensional thermo-fluid electrochemical modeling of planar SOFC stacks” , Journal of Power Sources, Vol. 113, pp. 109-114, 2003.

[2] C. S. Montross, H. Yokokawa, and M. Dokiya, “Thermal stresses in planar solid oxide fuel cells due to thermal expansion differences” , British Ceramic Transactions, Vol. 101, pp.85-93 , 2002.

[3] A. Selimovic, M. Kemm, T. Torisson, and M. Assadi, “Steady state and transient theraml stress analysis in planar solid oxide fuel cells” , Journal of Power Sources, Vol. 145, pp. 463-469, 2005.

[5] H. Yokokawa, N. Sakai, T. Horita, and K. Yamaji, “Recent developments in solid oxide fuel cell materials” , Fuel Cells, Vol. 1, pp. 117-131, 2001.