Impact of Random Geometric Distortions on the Performance and Reliability of an SOFC

It is now common knowledge that flow uniformity within repeat-elements - as well as among them in stack configuration - is of major importance for the performance and reliability of solid oxide fuel cells (SOFCs). At first, a design optimization of the configuration of the gas diffusion layer (GDL) may appear sufficient to ensure that the fuel is converted uniformly. However, in practice, the precision of assembly and manufacturing tolerances are known to have a large impact on the quality of the fuel distribution. Hence, the purpose of this study is to evaluate the impact of random geometric distortions on the performance and reliability of an SOFC. The methodology is based on Monte Carlo simulations (MCS) by using CFD tools. The idea is to compute quality indicators for a set of randomly deformed GDLs. From that point, several sensitivity analyses are performed to forecast the GDL quality and highlight the best GDL geometries: comparison of different GDL configurations, sensitivity to variations of mean and standard deviations of tolerances, impact on maximum fuel utilization, and resulting production yield, etc. The scope of the current work is limited to standardised distortions and a simple model of the GDL. Both planar and vertical deformations can be applied to a reference geometry. Amplitudes of the deformations follow a normal distribution whereas the position and extent of the affected area are uniformly distributed over a specified interval. Those random geometric distortions are generated with a MATLAB routine which is used to post-process the original mesh free from distortions. The CFD simulations are then carried out with FLUENT and finally post-processed using MATLAB. The methodology and routines developed for this study can be used as a decisional tool to conduce the design optimization phase of the GDL and manifolds.