Simulation Of Two-phase Transport By Lattice Boltzmann Method And Application In PEMFC

When proton exchange membrane fuel cell Works, the oxygen transport in porous media in cathode is an important control step that limit the whole process. At the existence of liquid water, two-phase flow could reflect the flow and transport at large current density. Liquid water form two-phase flow, the diffusion layer may result in partial obstruction, thus lead to the reduction or interruption of flow and diffusion of hydrogen and oxygen, and then affect the performance of cell.The mesoscopic size and characteristic of lattice Boltzmann model make the method more suitable to simulate the two-phase flow in porous media in the diffusion layer of proton exchange membrane fuel cell. This paper consider the diffusion layer composing of different size and different shape at the foundation of the scanning electric microscope figure of micro hole layer, research the effect of structural properties to effective diffusion coefficient of oxygen, such as porosity, size, thickness, grads and shape, obtain the quantitative relationship of effective diffusion coefficient and the saturation. Study the transport of oxygen and obtain the quantitative relationship effective diffusion coefficient of oxygen and saturation at the presence of liquid water transfer, the results show that the larger the porosity, the better the transport performance, at the same porosity smaller and scattered porous is benefit to transport, but not as scattered as possible, the thinner diffusion layer the better gas transmission, and the lager the porosity gradient, the more favorable to the catalyst layer of gas diffusion.Use lattice Boltzmann simulation results to build polarization curve model of the proton exchange membrane fuel cell, investigate the effects of different operating conditions to the liquid saturation distribution and battery behavior. Obtain liquid saturation distribution of diffusion layer under different operating conditions of the first; further investigate the effect of operating temperature, humidification temperature, and excessive coefficient and pressure of the battery.This study contributes to a better understanding of two-phase transfer of the proton exchange membrane fuel cell and provides guidance for cathode diffusion layer in the design and selection of operating conditions.