Numerical Simulation And Optimization Of Flow Field Of Proton Exchange Membrane Fuel Cell For Vehicles

Clean and efficient energy use is becoming the direction of future energy development and utilization with the primary energy (oil, coal, etc.) becoming increasingly depleted and the increasingly serious environmental pollution. Proton exchange membrane fuel cell (PEMFC) is becoming the ideal energy for vehicle because of its easy to start at low temperature, smaller size, greater power density, high-efficiency energy conversion, pollution-free, changing electricity output according to requirement, etc. At present, the proton exchange membrane fuel cell is at a research stage, and the study of bipolar plates flow field is a critical issue. Well development flow fields are core factors to improve the proton exchange membrane fuel cell (PEMFC) performance. In this paper, we mainly research the effect of flow fields structure and size to the battery performance using CFX.First of all, we described the three-dimensional mathematical models of proton exchange membrane fuel cell, including the electrochemical dynamics, electrochemical reaction, the electrochemical rate, electrode polarization, and the mass equation, the momentum equation, and other mathematical equations;Then, it analyzed the gas flow inside the battery cathode, the gas mass transfer and distribution, the concentration of components and so on based on establishing cathode simplified calculation model of the proton exchange membrane fuel cell and determining the boundary conditions. And then, it researched the pressure effect on cell performance through observing battery work conditions under different air pressure and pressure difference. It analyzed the cell performance when the flow field size was different. The results show that 1:1:1 is the best ratio of the channel width, ridge width and the channel depth.Then, we changed the upper wall of channel from flat face to wavy face and took several different wave length and wave height (the distance between peaks and troughs) value calculated based on the previous model calculation. By comparing and analyzing the results, we can see that the mass flow of gas through the channel / diffusion layer interface into the diffusion layer increased by 1.23倍under the wave height of 0.03mm, the wave length of 0.833mm, and the improvement of the mass transfer is very clear Finally, it established the overall computing model of single-passage flow field , multi-passage flow field and interdigitated flow field of cathode whose upper wall of channel were flat and wavy surface and calculated. The results showed that, when the upper wall of channel is wavy shape, there is a higher concentration and more uniform distribution of oxygen, a lower concentration of water, a good drainage performance in diffusion layer comparing to the flat upper wall flow field regardless of the single-channel flow or multi-channel flow of fuel cells, and the performance of fuel cell has been enhanced.