Simulation Study On Transmission Characteristics Of Liquid Water Based On VOF In Proton Exchange Membrane Fuel Cell

Fuel cells are considered to be the preferred clean and efficient power generation unit in the 21 st century.The transport characteristics of liquid water in fuel cells have a great impact on the performance of PEMFC and its water management.This paper simulates the distribution and transport of liquid water in the flow channel and the diffusion layer.In this paper,the structure and working principle of proton exchange membrane fuel cells are analyzed.The mass conservation,energy conservation and momentum conservation of liquid water transport in PEMFC and the governing equations such as volume fraction equation in VOF model are discussed.the three-dimensional,transient and two-phase flow models of proton exchange membrane fuel cells are established.Based on the Volume of fluid(VOF)model in Fluent,the transmission process of liquid water in flow channels with different cross-section shapes is simulated.The distribution of liquid water in the flow channel at different times,the distribution of liquid water and pressure at different cross sections perpendicular to the direction of the flow channel,the relationship between the average volume fraction of liquid water in the flow channel of different cross-section shapes and time are studied.The results show that compared with the other three working conditions,liquid water has a higher transmission speed in the rectangular flow channel,which is more conducive to the discharge of liquid water from the fuel cell.The liquid water transfer process in rectangular flow channel of proton exchange membrane fuel cell is simulation analysis.The distribution of liquid water in rectangular flow channels at different times,The distribution of liquid water and pressure at different sections perpendicular to the direction of the flow channel,the influence of pressure difference and contact angle on liquid water transport process in flow channel are studied.The results show that the transport speed of liquid water in the flow channel will increase with the increase of pressure difference,and the average volume fraction of liquid water in the flow channel will decrease as the contact angle becomes larger under the same pressure difference.The transport process of liquid water in the diffusion layer is simulation.The distribution of liquid water and pressure distribution in the diffusion layer at different times,Influence of pressure difference and contact angle on liquid water transport in diffusion layer are discussed.The results show that the transport speed of liquid water in the diffusion layer will increase faster with the increase of pressure difference.However,when the pressure difference reaches a certain value,the influence of the pressure difference on the liquid water transport process in the diffusion layer will be reduced.In this paper,the transport process of liquid water in the flow path and the diffusion layer of proton exchange membrane fuel cell are simulated.The distribution of liquid water in the flow channel and the diffusion layer is analyzed in detail,which will promote the research of gas-liquid two-phase flow in fuel cell water management in the future.