Research On Startup And Shutdown Control Strategy Of Air-cooled PEMFC

Proton exchange membrane fuel cell(PEMFC)as a new type of electrochemical power generation device,breaks the traditional power generation mode.It uses solid electrolyte,using hydrogen as fuel,using air as oxidant,directly convert chemical energy into high quality electrical energy through the combination of hydrogen and oxygen.Due to PEMFC's advantages of good stability,quick response speed,high power density,low operating temperature,it has a very broad application prospects in the field of new energy vehicles,portable mobile power and distributed power station.In this paper,based on the experimental platform of air-cooled proton exchange membrane fuel cell(PEMFC)built by ourselves,the effects of startup and shutdown control strategy on the performance of PEMFC are studied.The main results of research are as follows:(1)In order to reduce high voltage in start-up process and shorten the time of high voltage maintenance,we study the effects of PEMFC on the three different start-up methods of the PEMFC on the regular start-up,associate minimum monolithic voltage and lower hydrogen inlet pressure through experiment,putting forward a new start-up control strategy about reducing the hydrogen inlet pressure in start-up process and putting a 10? load in when the minimum monolithic voltage value of the stack is greater than 0.3V.The results show that the new system shut-down control strategy of PEMFC can reduce high voltage in start-up process and shorten the time of high voltage maintenance.So it is a very effective start-up strategy which improving the long-term performance and durability of the stack.(2)The primary reason for proten exchange membrane fuel cell performance degradation during the shut down process is that there is residual hydrogen in the anode side.In order to consume the residual hydrogen as soon as possible,two shut-down control strategies,which discharge every single fuel cell by making use of the fan of air-cooling stack and auxiliary load respectively,are proposed in this paper.Through experimental research,this paper compares the effects of three shut-down strategies,namely direct shut-down strategy,overall discharging shut-down strategy using,and individually discharging shut-down strategy using auxiliary load,on the performance of PEMFC.The results demonstrate that the proposed strategy in this paper shortens the time of individual cell's remaining high voltage and at the same time prevents the occurrence of single cell reverse polarity when shutting down.Thus,the effectiveness of the proposed strategy is proved.(3)In order to consume residual hydrogen of the stack rapidly,we study the effects of PEMFC on the three different shut-down methods of the PEMFC on the direct shutdown,the use of the auxiliary load and nitrogen purging through experiment,putting forward a new shut-down control strategy about combining auxiliary load and nitrogen purging to discharge the stack.The results show that the new system shut-down control strategy of PEMFC can not only shorten the time of single battery maintenance high potential,but also can avoid the formation of hydrogen-air interface in the process of starting and stopping for PEMFC.So it is a very effective shutdown strategy which improving the long-term performance and durability of the stack.