Research On Cold Start Strategy Of Proton Exchange Membrane Fuel Cell

In recent years,the intensification of environmental pollution has caused a lot of inconvenience to people and caused a series of problems.With the implementation of the "double points" policy and the "National Six" standard,the demand for energy replacement in the transportation industry has become stronger.Proton exchange membrane fuel cell(Proton Exchange Membrane Fuel Cell,PEMFC)is considered to be one of the ideal choices for next-generation automotive power plants because of its high energy density,low operating temperature,no noise,and no pollutant emissions.However,when the ambient temperature is lower than 0 ?,the freezing of water in the PEMFC can easily lead to failure of starting and damage to the proton exchange membrane,which seriously restricts its commercialization process.In view of the fact that there is no lumped parameter model including the freezing and thawing process in PEMFC and the incomplete start-up study at-30 ?,based on the theoretical research of PEMFC,this paper mainly carried out the following work:(1)Based on the theories of electrochemistry,heat transfer,fluid mechanics,etc.,combined with the water and heat transfer and phase transition phenomena of the PEMFC startup process at 0 ?,a PEMFC cold start lumped model including water icing-melting and temperature changes was established And verified its correctness.(2)According to the established PEMFC lumped parameter model,the start-up characteristics of PEMFC at different cold start temperatures are analyzed,and the effects of initial water content of the membrane and start current density on the cold start process are studied at an ambient temperature of-30 ?.It was found that it was difficult to realize the self-starting of PEMFC at-30 ?.(3)The PEMFC distributed parameter model is established,and the model is verified by the polarization curve method.Based on this model,the effect of purge water removal on the membrane water content after shutdown is studied.It is found that purge can effectively reduce the residual water content in the film,and the purge gas temperature has a greater influence on the water removal effect than the purge gas flow rate.(4)The cold start process of PEMFC at an ambient temperature of-30 ? is divided into preheating and start-up phases.In the preheating stage,a variety of intake air preheating methods were proposed,and the influence of preheating gas flow rate,temperature,etc.on the preheating effect was studied.It was found that the preheating intake air temperature was the main factor affecting the preheating effect;In addition to the influence of battery start temperature and start intake temperature on the PEMFC start process,it is found that the battery start temperature has little effect and the start intake temperature has a greater effect.(5)Through the above research,PEMFC was jointly started to simulate,and finally the PEMFC start strategy at-30 ? was determined.