Research Of Two-Phase Flow Transmission Characteristics And Numerical Simulation Of Proton Exchange Membrane Fuel Cell

Due to some advantages,such as low operating temperature,high battery-running speed,low noise,compact construction and high power density,proton exchange membrane fuel cell(PEMFC)has gained world-wide attention.Therefore,it can not only be used on special areas like spaceflight and military,but also possesses great marketing potential on electric automobiles,hybrid electric vehicles,fuel cells power stations,portable electrical equipment,etc..PEMFC has high requirement on the water content inside the cells.On one hand,enough water is needed to guarantee the moisture of the proton exchange membrane to improve the proton's conductivity;On the other hand,excess water will drown the fuel cells,it will prevent the delivering of interior substance inside the cells and influent the long-term and stable running of cells,which causes to sharply reducing the performance of cells.Therefore,appropriate water management should be achieved on PEMFC by analyzing and researching the internal distribution of water and condition of two-phase flow.Based on numerical simulation,by analyzing the water distribution and two-phase flow condition of cells,along with the deep analysis on internal dynamical process,can explain the internal operation theoretically and lower the experimental cost.Obviously,it has significant meaning for guaranteeing the stable running of cells and improving its performance.At present,in the two-phase flow management module the simulation analysis software about fuel cells,there is an obvious difference between the flowing type and speed of liquid water transportation equation designed by program and the actual flowing state and speed of the liquid water in PEMFC.The simulation result does not correspond with the actual operating condition of cells.Based on the deficiency of the simulation analysis software of fluid kinematics calculation and the consideration of actual flows of liquid water of fuel cells,this paper establishes governing equation of liquid water transportation which complies with cells' actual working condition.This paper also adds this liquid water transportation equation into the fluid simulation analysis software to re-develop controlling program of two-phase flow management module of fuel cells.Setting PEMFC which uses single flow channel of regular conventional flow field as an example,using new liquid water transportation equation and simulation module developed,it is established for the mathematical module of gas-liquid two-phase flow in PEMFC.Based on the established module to analyze cell performance,it analyzes mainly the influence of substance distribution and transmission characteristics on cell performance in the article,and discusses the effect on water transportation phenomena and cell performance caused by different parameters,such as different outlet pressure in the anode,different operating temperature of cells,different humidity of reactant gas in the anode and operating pressure etc..Especially,it analyzes the influence on cell's operating condition and performance causing by the two-phase flow inside fuel cells and the distribution of liquid water in the diffusion layer.