固体氧化物燃料电池(SolidOxideFuelCell,SOFC)是一种高效的发电装置,其通过高温电化学反应直接将燃料中的化学能通过电化学反应转化为电能,具有极高的理论转换效率,但其内部运行温度高(超过700℃)、温差大,各结构组件在运行过程中易产生较大热应力,从而致使其内部微宏观结构发生形变,导致电化学催化反应性能衰退,严重情况下甚至会造成电堆结构损坏。改善电堆内的热应力分布可以提升电堆可靠性,降低结构损坏风险,延长电堆使用寿命。建立了5层平板式电堆的三维多物理场耦合数值模型,在保持阴极有效反应面积相同的情况下,分析了一系列应用不同长宽比单电池时其电堆的热应力变化。结果表明:调整单电池的长宽比对电堆内温度分布及各组件的热应力分布有显著影响,增加单电池长宽比能够改善电堆温度分布,有效降低电堆内热应力,改善堆内应力分布。当长宽比增加到2.8∶1时,与最常见的1∶1正方形单电池相比,电堆的最高温度从1128K降低至1106K,最大温差由107K减小至81K,除温度分布改善显著,应力分布的幅度可以减小40%以上,电解质内最大主应力由81.5MPa降至46.8MPa,阳极、阴极及密封胶内的最大主应力由46.3、31.3、21.1MPa降低至21.1、11.3、9.7MPa。因此,合理增大单电池长宽比是降低电堆热应力的有效途径。

The Solid Oxide Fuel Cell (SOFC) is a highly efficient power generation device that directly converts the chemical energy infuel into electrical energy through high-temperature electrochemical reactions,boasting exceptionally high theoretical conversionefficiency. However,its internal operating temperature is high (exceeding 700 °C) and has a large temperature gradient,which results insignificant thermal stress on various structural components during operation. This,in turn,causes deformation of the internal micro andmacro structures,leading to a decline in electrochemical catalytic performance and,in severe cases,can result in damage to the fuel cellstack structure. Improving the thermal stress distribution within the stack can increase stack reliability,reduce the risk of structuraldamage,and extend the lifespan of the stack. A three-dimensional multi-physics coupled numerical model for a 5-layer planar fuel cellstack was established. While maintaining the same effective reaction area of the cathode,a series of thermal stress changes in the stack wereanalyzed when applying single cells with different length to width ratios. The results show that adjusting the length to width ratio of thesingle cells significantly affects the temperature distribution within the stack and the thermal stress distribution of each component.Increasing the length to width ratio of the single cells can improve the temperature distribution of the stack,effectively reduce thermal stress within the stack,and improve the stress distribution. When the length to width ratio is increased to 2.8∶1,compared to the mostcommon 1∶1 square single cell,the highest temperature of the stack decreases from 1128 K to 1106 K,and the maximum temperaturedifference decreases from 107 K to 81 K. Besides the significant improvement in temperature distribution,the magnitude of stressdistribution can be reduced by more than 40%. The maximum principal stress in the electrolyte decreases from 81.5 MPa to 46.8 MPa,andthe maximum principal stress values in the anode,cathode,and sealant decrease from 46.3 MPa,31.3 MPa,and 21.1 MPa to 21.1 MPa,11.3 MPa,and 9.7 MPa,respectively. Therefore,reasonably increasing the length to width ratio of the single cells is an effective way toreduce thermal stress in the stack.