Study On Performance And Accelerated Aging Service Life Of Air-cooled Polymer Electrolyte Fuel Cell Stack

In recent years,fuel cells have attracted the many countries'attention because they are efficient and non-polluted.They have been widely used in many fields.Among them,proton exchange membrane fuel cell(PEMFC)is the most popular fuel cell in the market because of its simple structure,low operating temperature and fast start-up speed.Air-cooled proton exchange membrane fuel cell(PEMFC)stack uses air instead of water as the coolant of the stack,which reduces the BOP(auxiliary equipment)of the stack system.It is widely used in portable power supply,UAV and other fields.However,The performance and life of air-cooled stacks are important factors that restrict their large-scale development.In this paper,a 50W miniature air-cooled reactor is fabricated,and the conical air intake pipeline is used instead of the original fan device to regulate the specific air intake flow.In order to ensure the performance of the stack,we tested the selected membrane electrodes on a single cell.The test results show that the power of the cell can reach 1W/cm2 at 0.6V.Then we study the performance optimization of the stack under different conditions.The specific research is as follows:Firstly,the effect of ambient temperature(5?400?)on the performance of the stack was studied in a high and low temperature alternating environment test box.The experimental results show that the stack has the best performance at ambient temperature of 20?30?.If the ambient temperature is too low,the overall temperature of the stack will be low and its performance will deteriorate;If the ambient temperature is too high,the internal water shortage of the stack will affect the performance of the membrane electrode.Secondly,the effect of air intake(30 L/min,60 L/min,90 L/min)on the performance of the stack was studied by using a conical intake pipe.The results show that the stack has the best performance under 60 L/min air intake flow.Because the air is both the gas and the coolant of the air-cooled stack,the larger the air intake is,the better the cooling effect of the stack.Then the temperature of the stack become lower and the performance become lower.Finally,the influence of exhaust gas emission cycle on the performance of the stack is studied under the rated current condition of the stack.The results show that the performance of the stack is the best when the exhaust emission cycle is 0.3s/20.0s.The life of the stack is also an important factor affecting its commercial development.However,there are few researches on the life of the air-cooled fuel cell stack.In this paper,under the optimized experimental conditions,the life test and evaluation method of automotive stack is used to test the life of the stack under different working conditions.The operation of the stack is divided into idle mode,rated mode,variable load mode and start-stop mode.Under these four conditions,a total of 15 experiments were tested and each group required 4 hours,the attenuation change of the reference voltage of the stack is studied.The results show that the stack operates stably under idle and rated conditions.In this condition,the voltage drops slowly.And the attenuation rate is the fastest under start-up and shutdown conditions.The service life of the stack can reach 2000 hours by calculation,which is the general level of the market.