Design Of Ramp-stepped Flow Field And Development Of Test System For Proton Exchange Membrane Fuel Cell

With the global energy consumption gradually changing to clean and low-carbon energy,hydrogen,an advanced sustainable energy carrier,has gained a huge development opportunity and is regarded as a best choice of next-generation clean energy and the "ultimate energy" for human beings in the future.As a key hydrogen energy utilization device,proton exchange membrane fuel cell(PEMFC)has the advantages of low noise,high energy conversion efficiency and zero emission,and is one of the most commonly used cells worldwide.Bipolar plate is one of the major components of PEMFC,which can significantly affect the performance,weight and efficiency of the whole fuel cell,and the flow channel of bipolar plate is the main factor affecting the performance of bipolar plate.Hence,the optimization of flow channel is one of the hot topics for bipolar plate research.In this thesis,a novel ramp-stepped flow field(RSFF)has been designed,which is inspired by the variable diameter of plant leaf veins as well as lung trachea.The control equations in the numerical simulation were established for the PEMFC,and the simulation parameters and boundary conditions were set.The model was calculated by using the COMSOL Multiphysics platform and the finite element analysis solver.First,the ramp-stepped flow channel was investigated and the simulation results showed that the best output performance at a ramp inclination angle of 7°,which increased the power density by 13.5% compared with that of PEMFC without any structures.Afterwards,the ramp-stepped structure was further simulated in the flow field,which showed the largest increase of net power density of 17.55% at the ramp inclination angle of 5° compared to the conventional parallel flow field(CPFF).These results suggest different effects of the same structure applied in the flow channel and the flow field.Finally,a high-power fuel cell test platform was designed and developed for the application of the flow field designed in this work,based on the in-depth investigation of the main problems of the current PEMFC test platform.The performance test of a120-k W fuel cell was completed through the design,selection,construction,and debugging of the system.The test platform integrates hydrogen flow,air flow and thermal management control systems into an optimal layout of the various subsystems,which makes post-maintenance more convenient.At the same time,the test platform uses LABVIEW software to design the control interface of the upper computer and Simulink software to design the control program of the lower computer controller.The determined parameters of the components are written into the controller to realize the communication through the CAN box between the upper computer and the controller.The online real-time control of the system by the host computer control interface can automatically optimize the operating parameters of each component according to the load change.This test system provides testing conditions for the large-scale application of our designed flow field as well as for the development of novel bipolar plate flow channels.