Research On Dynamic Response Of Air-Cooled PEMC Considering Voltage Uniformity

Today,in the face of the energy crisis.proton exchange membrane fuel cell(PEMFC),as a new energy source,has broad application prospects.It uses solid electrolyte,using hydrogen as fuel, to directly convert the chemical energy into electrical energy through the combination of hydrogen and oxygen.It is environmentally friendly energy because of zero emissions.Among PEMFCs,air-cooled PEMFC can often be seen in many small power condition because of its simple structure and convenient use.But because of the simple structure,it is easily affected by the external conditions, which decreases the stack performance and individual cell voltage uniformity and shortens its life.So it is important to study the factors that affect the performance of the stack and the individual cell voltage uniformity and give the suggestions to improve the working life of the fuel cell.Existing kW class air-cooled PEMFC is usually controlled by controlling purge valve and fan,which are based on the purge interval and optimum temperature recommended by the manufacturer.But even if the temperature control meets the requirements, single cell voltage uniformity,which is an important factor reflecting and affecting the performance and life of the stack,may be poor.Therefore it is necessary to study on the single cell voltage uniformity under existing kW class air-cooled PEMFC control mode.There were some experiment studies carried out on the homemade 2kW air-cooled PEMFC test platform.The voltage response and uniformity of PEMFC stack during dynamic load change were investigated. Finally,based on the experimental results,load change suggestion considering voltage uniformity was proposed.The structure of air-cooled PEMFC is simple,so there are only three main control means:optimal temperature control, purge valve control and inlet hydrogen pressure control.In this paper, the effects of hydrogen pressure on the stack performance and the individual cell voltage uniformity are studied in the steady state operation and dynamic operation.The frequent dynamic process of fuel cell is an important factor to cause the degradation of the stack performance. Regular purge,as a dynamic process,is often ignored.In view of this process, the changes of pressure fluctuation and pressure drop of inlet and outlet are studied in this paper.This study provides experimental data basis for actual working conditions of the air-cooled stack dynamic load change management and hydrogen pressure control,with certain guidance and reference value.