Study On Simulation And Startup Strategy Of Cold Start Performance Of Proton Exchange Membrane Fuel Cell

Proton exchange membrane fuel cells are recognized as clean power sources in the 21 st century by virtue of their clean,efficient,and noise-free characteristics,and can be widely used in automobiles in the future.The problem of cold start has been affecting the large-scale commercialization of proton exchange membrane fuel cell vehicles.During the cold start process,icing inside the battery affects the output performance of the battery,and also damages the internal structure of the battery to a certain extent,which affects the battery life.Therefore,it is important to improve the cold start performance.In this paper,a three-dimensional multi-phase multi-physics coupled transient single cell single straight channel cold start model is established.The effect of cathode catalytic layer design parameters and battery operating parameters on cold start performance is studied by simulation analysis.The formation of ice,the acceleration of ice melting,and the shortening of start-up time have formulated an auxiliary cold start strategy,which provides a reference and method for improving the possibility of cold start success.The main research contents of the paper are as follows:(1)The physical processes such as phase change,transmission,ice formation and melting,water evaporation and condensation of water inside the battery are considered.The physical processes such as the phase change and transmission of water during the cold start are described.The cold start model is reasonably assumed to establish the conservation equations of mass,momentum,composition,energy,electron and ion potential during the cold start Form an equation to provide a numerical basis for the subsequent establishment of a cold start model.(2)Using simulation software,a three-dimensional multi-phase multi-physics coupled transient single cell single straight channel cold start model was built,and grid independence verification and model verification were carried out.Cathode catalytic layer is the place of electrochemical reaction,so it is very important to study the design of cathode catalytic layer.Through the cold start model,the effects of cathode catalyst layer thickness,cathode catalyst layer porosity,cathode catalyst layer platinum-carbon ratio and other cathode catalyst layer design parameters on the battery current density,ice volume fraction,and temperature changes during cold start were studied.Through the distribution cloud map of water,ice and temperature inside the battery,the cold start process is described in detail and intuitively.The study found that a thicker cathode catalyst layer,a larger cathode catalyst layer porosity,and a lower cathode catalyst layer platinum-carbon ratio help delay the start-up duration and improve cold start performance.(3)According to the established cold start model,the influence of battery operating parameters such as heat transfer coefficient and starting current density on the outer surface of the battery on cold start performance is analyzed.The changes of battery current density and battery temperature under different battery external surface heat transfer coefficients were studied respectively;the changes of ice volume fraction and battery temperature under different starting current densities.The study found that batteries with better insulation and a smaller outer surface heat transfer coefficient can reduce heat loss;higher starting current density can also increase battery temperature.(4)A hydrogen-oxygen-catalyst assisted cold start strategy based on different starting power and different intake air components of the anode is proposed,which aims to increase the internal temperature of the battery and accelerate the melting of ice.The changes of current density,battery temperature,cathode catalyst layer ice volume fraction,cathode catalyst layer porosity,and temperature distribution at different locations,and ice volume fraction distribution in the middle cathode cross section were analyzed under different operating conditions.The study found that a successful start at-20°C was achieved with a large starting power and anode air intake component.