固態氧化物燃料電池（SOFC）發電系統在運轉使用時，隨著工作溫度的改變，由於不同組件材質間具有不同的熱膨脹係數值及溫度梯度，會產生不可忽視的熱應力，使得熱應力成為設計開發一套高可靠度及高效能平板式SOFC系統必須考慮的重要因素之一。在穩態運轉階段，高溫與應力的長久同時作用，會造成SOFC電池堆結構受到潛變機制的影響，產生過大變形甚至損壞的可能，若結構拘束條件限制變形的發展，潛變機制亦會造成應力重新分配。本研究計畫，將以核研所開發的平板式SOFC系統電池堆為研究對象，利用有限元素分析法，進行熱應力與結構變形的數值模擬分析。為了符合SOFC電池堆的實際運作狀況，本研究將潛變機制在高溫穩態運轉階段對組件結構應力及應變分佈的影響納入考量，特別是將前幾期委託研究計畫已經獲致之金屬連接板、玻璃陶瓷接合劑、二者接合件之各項高溫機械性質與潛變性質，融入所建構之有限元素模型中，以求得在高溫穩態運轉階段，SOFC電池堆各組件熱應力與應變分佈隨時間變化的趨勢，藉此評估SOFC電池堆結構強度的穩定性及耐久壽命，進而建立一套平板式SOFC電池堆電腦輔助結構耐久壽命評估技術，作為核研所設計開發平板式SOFC系統之用。 ;The high-temperature operating conditions could generate significant thermal stresses in a planar solid oxide fuel cell (pSOFC) stack due to thermal mismatch between components. Such thermal stresses can cause significant deformation and damage in the components and degrade the structural integrity and electrochemical performance of pSOFC stacks under long-term operation. In particular, creep could take place in the components during steady operation at high temperature, leading to unpredictable, considerable deformation and rupture. The purpose of this study is to characterize thermal stress distribution in a pSOFC stack which is being developed at the Institute of Nuclear Energy Research (INER). A 3-D finite element model for a multiple-cell pSOFC stack is constructed to solve the thermal stress distribution at different stages including start-up and steady operation. The effect of creep mechanism on the variation of stress/strain distribution is taken into account by applying to the finite element model the previously obtained creep properties of the interconnect steel and glass ceramic sealant. Combing the numerical results with mechanical strength of relevant materials, a life assessment model for structural integrity of pSOFC stack will be developed and applied to the pSOFC system being developed at INER.
