Modeling and analysis of two phase flow in gas diffusion layer of fuel cell

Abstract

Nowadays proton exchange membrane fuel cells (PEMFCs) are more and more important Many countries are working hard to promote hydrogen and PEMFC related products Including build thousands of hydrogen refueling stations sold hundreds of thousands of fuel cell electric vehicles (FCEVs) invest tens of billions of funds For PEMFC’s efficiency enhancement water management is an unavoidable problem PEM need moderate water to transport proton However the cathode is where water is produced and will be blocked when water is excessively producing For dealing with this problem we refer to existing literature to develop a numerical model The existing literature cover a model with two phase flow in porous media However the fluid in cathode is pure oxygen not air which is commonly used in commerce And the model does not explain how to apply itself into a low aspect ratio domain For using air in cathode we introduce multicomponent reacting system which is commonly used in combustion into our model For dealing with low aspect ratio issue we also introduce separate perturbation algorithm into our model We discover the pressure of nitrogen in GDL will greater then channel but oxygen in GDL lower than channel And shrink baffle is better than triangular baffle While the height of baffle is 0 8 times of inlet height shrink baffle makes the efficiency greater then no baffle 80% and triangular baffle make the efficiency greater 57% We also discover standard water saturation dominate all water saturation in GDL So we need to critical the assumption of standard water saturation more severely This assumption connects average current density and standard water saturation directly But one of them is physical property at connect boundary the other is physical property at reaction boundary We think this assumption need to be local physical model So we are suspicious of the connection between model and real PEMFC

Date of Award	2020
Original language	English
Supervisor	Tian-Shiang Yang (Supervisor)