Research And Design Of Liquid-cooled Proton Exchange Membrane Fuel Cell With Metallic Bipolar Plates

A proton exchange membrane fuel cell has developed rapidly in the fields of portable power supplies,electric vehicles and aerospace due to its high energy density,fast response speed,and low emission.How to reduce the production cost and weight of PEMFC is the main problem faced in the industrialization of the PEMFC.The bipolar plate is the largest component in weight and volume of the PEMFC.Traditional graphite bipolar plates have a high cost in the flow field production,while metallic bipolar plates are of great significance for reducing size,weight and cost.The liquid-cooled PEMFC assembled with metallic bipolar plates has small size and high mechanical strength.It is suitable for working in enclosed spaces.It is an ideal choice for the PEMFC development of size reduction and power increasing.However,the liquid-cooled PEMFC with metallic bipolar plates also puts forward new optimization requirements for the flow field design,the arrangement of the reactant gas and the coolant,as well as the design and assembly of the stack.In order to improve the performance and stability of the liquid-cooled PEMFC with metallic bipolar plates and promote its large-scale commercialization process,the main research content and results are as follows:(1)A three-dimensional simulation model of the PEMFC is established.Based on model assumptions and mathematical control equations,a multiphysics coupling three-dimensional multi-phase simulation model of PEMFC is established in the computitional fluid dynamics software ANSYS Fluent,and its grid independence and validity are verified.(2)The influence of the contact resistance between the bipolar plate and the gas diffusion layer on the flow field design of the bipolar plate is studied,and the influence of the flow direction of the reactant gas in a single cell is analyzed.The results show that the distribution of various physical quantities in the cell is related to the flow field design,and the contact resistance can affect the internal resistance of PEMFC,thereby affecting the selection of the optimal flow field size.Comprehensive considerations show that the channel and rib widths of1.0 mm and 0.8 mm are the optimal flow field size.The simulation results of the polarization curves,the temperature distribution and the liquid water accumulation show that the asymmetric flow direction is the best gas flow direction in a single cell.(3)The influence of the reactant gas flow direction and liquid cooling strategy in the PEMFC stack with metallic bipolar plates is analyzed.According to the uniformity of the cell voltage and the reactant gas distribution,it is found that the gas distribution uniformity under the Z-shaped reverse flow direction in the stack is the best.The use of the coolant whose temperature slightly lower than the cell inlet temperature has lower requirements of flow rate control accuracy,and the current density of the stack is higher,the temperature distribution is more uniform.(4)The design of the single cell and stack of liquid-cooled PEMFC with metallic bipolar plates is completed.Accooding to the simulation results,it is determined that the flow field of the metallic bipolar plate is a four-channel serpentine flow field.The structure of the single cell is designed and the experiment test of the single cell is carried out.The experimental results are used to modify the simulation model.A liquid-cooled PEMFC stack with metallic bipolar plates is designed.A simple stack simulation model composed of 3 single cells is estabilished.The tightness of the reactant and coolant flow channel is verified.The performance of the stack is simulated to provide experience for the subsequent assembly of the high-power liquid-cooled PEMFC stack with metallic bipolar plates.