Study On Optimization Of Flow Field Structure And Gas-liquid Transfer Of Core Components In Hydrogen Fuel Cells

With the goal of carbon neutrality and carbon peaking,hydrogen energy enters a stage of fast development,and proton exchange membrane fuel cells(PEMFC)becomes a promising technology.One of the most critical challenges for fuel cell technology to achieve large-scale commercialization is to increase the power density of PEMFCs.Uneven distribution of reactants and poor water management will cause energy loss and affect the improvement of fuel cell power density.In this context,optimizing the flow field structure of the bipolar plate and the operating conditions of the cell are of key importance to improve the fuel cell performance.The gas-liquid distribution of the core components of the fuel cell is optimized through the Computational Fluid Dynamics(CFD)analysis of the flow field structure and operating conditions,and the performance of the fuel cell is improved.The main research content of this thesis:(1)The finite element analysis software ANSYS is used to build the PEMFC model,and the three-serpentine flow field is selected as the model for this topic,and the rationality of the model is verified by experiments.Starting from the dimension of enhancing the convection under the ridge of the flow field and reducing the flooding,on the basis of the three serpentine flow channels,a flow field with a gradual number of flow channels and a sinusoidal flow field are set up.Through the established CFD model,the fuel cell performance based on three flow fields and the gas-liquid distribution of the core components are studied,including the parameters of hydrogen and oxygen transport as reactants,current density distribution,etc.and the parameters of water management as membrane water content and water saturation degree,etc.The results show that the performance of the 3-2-1wave flow field enhances the land convection compared to the conventional triple serpentine flow field,which increases the net power density of the fuel cell by 10.03%.(2)This study focuses on the problems of uneven gas distribution and easy flooding,and adds distributors and baffles on the basis of the parallel flow field.Through the established model CFD,the performance of the fuel cell based on the new flow field and the gas-liquid of the core components are studied.Distribution,and explain the role of baffles in optimizing water management through the VOF model.The results show that the performance of the improved parallel flow field is improved by 29.5%,which solves the problems of uneven gas distribution and flooding.(3)The orthogonal experiment method was used to study the effect of the coupling of fuel cell operating temperature,operating pressure and relative humidity of cathode and anode gases on cell performance,and the power density and net power density were analyzed based on range analysis.The optimal working conditions in the density area are: the temperature is 333 K,the operating pressure is 1 atmosphere,and the relative humidity of the cathode and anode is 80% and 100%,respectively.The optimal working conditions in the high current density area are as follows: the temperature is353 K,the operating pressure is 1 atmosphere,and the relative humidity of the cathode and anode is 20% and 40%,respectively.