平板式SOFC钎焊自适应密封热应力与变形分析

Thermal stress and deformation in bonded compliant seal design for planar SOFC

提出了一种平板式固体氧化物燃料电池钎焊自适应密封方法,利用有限元法分析热应力,与常规玻璃陶瓷作为密封材料进行比较,从热应力角度验证了钎焊自适应密封的优越性.结果表明,与玻璃陶瓷密封相比,自适应密封产生的热应力小167 MPa.钎焊自适应密封通过金属箔片连接电池和金属框架,由于密封结构具有一定的弹性,降温过程中发生侧向偏移变形.利用金属箔片的弹性变形和塑性变形,吸收电池堆系统内部产生的热应力,降低热应力对电池内部结构的损伤.钎焊自适应密封的最高热应力位于钎角部位,成为最薄弱环节.

In this paper,a bonded compliant seal(BCS) is designed for planar solid oxide fuel cell(SOFC).Its thermal stress and deformation are analyzed by finite element method.In addition,the thermal stress generated in the conventional glass-ceramic sealing method is also calculated to compare with BCS method,through which the advantages of BCS design are verified based on the consideration of thermal stresses.It is shown that the thermal stress in BCS design is reduced by 167 MPa compared with the glass-ceramic sealing.In BCS design,a thin foil metal is used to bond the cell and the window frame.During the cooling process,a bowing deformation is generated,which makes SOFC deform flexibly.The thermal stress in SOFC stack can be mitigated by trapping much of it as elastic or plastic strain within the sealing foil,which leads to a decrease of thermal stress in the SOFC stack.The maximum thermal stress in BCS design locates at the fillet of filler metal which becomes the weakest area.