Study On The Gas Tightness Of Seals In Planar Solid Oxide Fuel Cells With Numerical Simulation

One of the key obstacles precluding the development and large-scale application of planar solid oxide fuel cells(pSOFCs)has been the absence of a robust sealant.Some previous studies focus on the experimental and material mechanics analysis about the sealant,but lacked quantitative analysis of leakage mechanism of sealing materials.In this paper,the leakage mechanism of compressive seals in pSOFCs is studied,and a theoretical method for predicting leakage rate is proposed.Firstly,the Lattice-Boltzmann method was introduced to simulate the nonlinear flow in the interface clearance of a sealed rough wall due to its flexibility when dealing with flow problems related to complex boundaries.The basic theory of LBM is introduced,and the application of LBM to isothermal incompressible flow problem in SOFCs seals is studied with relevant boundary conditions defined.The dimensionless and parameter selection in numerical simulation are also discussed.Then,a numerical three-dimensional(3D)rough-surface generation technique was applied for the geometry configuration of sealing interface gaps.Combined with LBM,the 3D flow characteristics of the gas in interface gaps were numerically studied.The flow state was analyzed and two important dimensionless flow factors,the flow factor?_?of roughness and the flow factor?_h of height,were proposed to characterize the effect of rough surface morphology and effective height of interface clearance on leakage rate of seals,respectively.Finally,the finite element analysis was adopted for micro-contact mechanics of single asperities to determine the effective gap height of rough interface under stress.Based on this method,all numerical results were fitted as dimensionless criteria for calculating the interface leakage rate.These criteria can be directly used to predict the leakage rate of a given compressive seal under specific working conditions without relying on any experimental empirical formula.Furthermore,the leak rate prediction model proposed in this paper is also compared to existing experimental data and good agreement was obtained,corroborating the accuracy of the method.In this paper,the leakage mechanism model of SOFCs compressive seals is established.Based on LBM micro-gap hydrodynamic analysis and rough surface numerical reconstruction technology,combined with micro-contact mechanical analysis of sealing materials,the model can conveniently predict the gas leakage characteristics under various working conditions.The research results can be used to optimize the sealing design of SOFCs and predict the performance of sealing structure under actual working conditions.