Numerical Simulation Of The Influence Of Anode Degradation On SOFC Performance Degradation

Solid oxide fuel cell(SOFC)is a new type of energy conversion device,which has the advantages of high efficiency and cleanness,and is one of the clean energy technologies vigorously developed in the 21 st century.At present,the short service life is one of the problems hindering the commercialization of SOFC,and the performance degradation of cell components is the main factor affecting its service life.As an important part of SOFC,the performance degradation of anode has a great influence on the performance degradation of SOFC.As an important means to study SOFC,the numerical simulation method is used to study the influence of anode degradation on the performance degradation of SOFC.It can deeply understand the physical field change law of the cell performance degradation process caused by the anode degradation mechanism.Also,the law of SOFC performance degradation under different operating parameters is studied,which provides a reference for SOFC attenuation experiment.(1)Firstly,the durability model of SOFC based on anode degradation mechanism is established.The model starts from the particle agglomeration coarsening model of the anode of the SOFC,and connects the particle growth model with the TPB length model through the percolation theory.Combined with the empirical equation,the electrochemical equation based on the anode particle agglomeration coarsening model is constructed.The growth of particle size with time will directly lead to the degradation of cell performance.The model was verified on the basis of the model,and the results were in good agreement with the experiments,which verified the accuracy and rationality of the model.Then,the physical field distribution of SOFC performance degradation under constant voltage mode is analyzed,and the following conclusions are drawn: The degradation of SOFC physical field mainly occurs in the first 1000 h of operation.The degradation of current density field mainly occurs in the high current density area at the collector side,and the degradation of temperature field occurs at the outlet.The degradation of hydrogen concentration is small and the change trend is not obvious.(2)Based on the established model of anode particle agglomeration degradation,the effects of different operating modes,operating parameters(temperature,flow rate and flow mode),different thermal boundary conditions and different anode microstructure on the performance degradation of SOFC were studied.The degradation rate of output performance under constant voltage mode is greater than that under constant current density mode;The higher the operating temperature,the lower the degradation rate of cell output performance;The degradation rate of cell output performance under counter-flow mode is smaller than that under co-flow mode;The greater the cathode side flow rate,the greater the degradation rate of SOFC output performance;The output performance degradation rate of SOFC with adiabatic thermal boundary condition is smaller than that with normal thermal boundary condition;The change of anode microstructure has little effect on SOFC output performance.(3)Finally,based on the model of anode particle agglomeration degradation,the contact resistance growth model between anode and collector plate and the degradation model of electrolyte are coupled,and the fully coupled SOFC degradation model is obtained.The numerical simulation results are compared with the experimental results,and the simulation results are in good agreement with the experimental results,which proves the correctness of the model in this paper.On this basis,the degradation law of SOFC performance and the variation law of internal physical field under constant current density mode and constant voltage mode are studied.Through the research and analysis,the following conclusions are drawn: In the constant current density mode,the degradation of physical field mainly occurs in the first 3000 h of operation,and basically does not decay after 3000 h.The current density field inside the anode catalyst layer degenerates at the inlet section of the cell near the ridge of the current collector.The degradation of temperature field in the outlet section is greater than that in the inlet section.The hydrogen concentration only degenerates at the inlet.Under the constant voltage mode,the performance degradation rate of the cell is greater than that under the constant current density mode.The degradation of the current density of the anode catalyst layer mainly occurs in 3000 h before operation,and occurs in the entrance to the middle of the cell.The main degradation time periods of different parts of the temperature field are different.The entrance section occurs in 3000 h-6000 h,and the exit section occurs in the first 3000 h of operation.The degradation of the concentration field occurred in the first 3000 h of operation,and occurred at the entrance to the middle of the cell.In this paper,the influence of anode degradation on the performance degradation of SOFC is studied by numerical simulation method.The research contents and results help us to have a deeper understanding of the physical field variation in the process of SOFC degradation based on anode degradation mechanism.The study of the degradation law of SOFC performance by changing the operating parameters has certain reference significance for the study of SOFC durability experiment.