Simulation Of Multi-physics Fields In Solid Oxide Fuel Cell

Solid Oxide Fuel Cell(SOFC)is a kind of clean energy conversion device that converts the chemical energy in fuel directly into electric energy through electrochemical reaction.This energy device can make efficient use of renewable energy.It can be used in electric vehicles and distributed generation systems.It has a good application prospect in solving the problems of fossil energy shortage and environmental pollution.Experiment method applied in the study of SOFC requires much time and manufacturing cost.The flow field,electrochemical and temperature distributions in batteries are complex,which makes it difficult to get internal specific parameters through measurement.In addition,flow,component transmission,charge transport,electrochemical reaction and heat transfer processes are all coupling.Using traditional experiment method is hard to grasp the influence of coupling rules.Then computer simulation becomes an effective means,which can speed up the acquisition of data to optimize the structure of the battery.In this project,COMSOL software is applied to simulate the coupling multiple physical fields in the SOFC,including flow field,temperature field,component transfer,and current density,etc.In addition,a series of improvement designs are proposed for a single cell structure of SOFC to explore the influence of its structure design on the uniformity of internal flow field.The structure design mainly includes the shape and size of the external manifold of single cell and the selection of the location of fuel gas inlet and outlet.First,when using rectangular outside manifold design in single cell,in order to achieve a more uniform velocity distribution,the width scale a of inlet manifold and flow channel shoud not be less than 3.6.In this model,when width scale a is 4.8,distribution of flow field in the single battery is most uniform.Second,in order to achieve more uniform flow field,the fuel entrance should be placed in the middle of the whole structure.Compared with entrance in the left,the flow uniformity index increases 0.53.Third,when adopting the trapezoidal outside manifold design,compared with the rectangular outside manifold with the same area,the flow uniformity index increases 1.3%,and the standard deviation of flow velocity decreases 13.6%,indicating that the new structure makes the flow field distribution in the battery more uniform.What's more,a new attempt is made to control the temperature in the SOFC stack.In this paper,a thermal cloak structure is introduced to control the heat flow in the specified area of a fuel cell stack.The model of the two-layer equivalent thermal cloak is parameterized.In conclusion,the relationship between its geometric structure,thermal conductivity and shielding effect is found.The result shows that the larger ratio of ri/ro and k-inner,the better manipulation effect is,which provides a reference for the design of this kind of thermal cloak to control the heat flux in the SOFC stack.