Study On Residual Stress Distribution And Its Effect On Failure Probability Of Solid Oxide Fuel Cells

With the continuous development of modern industrial technology,energy problems are increasingly aggravated.SOFC(solid oxide fuel cell)cells as the fourth generation of power generation technology has been widely used by civil and military.The technology uses hydrogen and oxygen,respectively to pass through the battery’s airways,causing an electrochemical reaction between the two gases inside the battery to deliver electricity to the outside world.Its reactants and products are friendly to the environment and have a high energy conversion rate.In this paper,the influence of different process parameters on the internal residual stress of SOFC battery was studied,and a new sealing process was proposed based on this.The difference of thermal stress distribution and numerical value of single SOFC battery and 1×3 battery pack in ideal and real conditions is studied.Meanwhile,the influence of the new sealing process on the thermal stress of single SOFC battery and 1×3battery pack at work is discussed,and the failure probability under different parameters is analyzed.Through the simulation analysis of the residual stress distribution and numerical value of SOFC battery under different sealing process parameters,it is found that the residual stress in the sealing process is mainly concentrated in the contact between the SOFC battery connector and the electrode,the analysis of the reason is that the thermal expansion coefficient of the two does not match,and it is found that in order to reduce the residual stress inside the SOFC,the need for slower cooling and heating speed.And longer holding time.By introducing Nichchromium alloy as an intermediate layer between the connector and the electrode as a new sealing,it is found that the addition of the intermediate layer can effectively reduce the residual stress in the sealing process and increase the range of process parameters in the sealing process.Through the analysis of the working thermal stress of SOFC battery and 1×3 battery pack under low stress state,it is found that the new sealing process still has a positive effect on reducing the thermal stress of SOFC battery during operation.After the working cycle of single cell reaches 9 T,the internal thermal stress reaches equilibrium.The thermal stress of SOFC battery pack is greater than that of single cell.The failure probability of SOFC is positively correlated with the thermal stress value inside the cell.By analyzing the working thermal stress of SOFC cell and 1×3 battery pack under high stress state,it is found that the excessive residual stress left in the component during the sealing process will aggravate the expansion of thermal stress inside SOFC cell.The new sealing process can still reduce the value and change rate of thermal stress inside the cell when it reaches equilibrium.The failure probability under high residual stress state is greater than that under low residual stress state.The order of failure probability is :1×3 battery pack>1×3 battery pack with nickel-chromium alloy as intermediate layer > single battery >single battery with nickel-chromium alloy as intermediate layer.