Study And Application Of High-resolution Segmented Measurement Device Of Fuel Cell

Proton Exchange Membrane Fuel Cell(PEMFC)has broad prospects for the transportation applications due to its advantages such as high efficiency,zero emission and noise free.During operation of a PEMFC stack for vehicle with active area of generally 150-500 cm~2,the nonuniformity of distributions for reactants,water and thermal behaviors has a great impact on the internal reaction distributions of fuel cell stack.The uneven distributions of internal reactions of fuel cell not only lower the stack performance but also accelerate the performance degradation.At present,most researches on fuel cell performance focus on the tested cell and stack voltages.The lack of local information inside the fuel cell stack prevents quick diagnosis of performance limits and degradations.In this thesis,a high-resolution segmented measurement device for large-active area fuel cell stack is developed.With the help of segmented measurement methods,the current distribution inside the fuel cell stack is detected.The influence of operating parameters on the steady-state performance of the stack and the dynamic response of fuel cell under variable load conditions is studied.The research contents of this thesis are as follows:The requirements of an on-line segmented measurement device for fuel cell stack are specified.The lab developed water-cooled stack with reaction area of 406cm~2 are fitted for the development of the high-resolution on-line detection device.According to the dimensions of the fuel cell stack reaction area,an online detection device with a resolution of 396 segments is designed.The software and hardware of the system are designed at the module level,and corresponding detection principles and measurement schemes are given to provide a powerful research platform for subsequent fuel cell performance research.Secondly,based on various design parameters,the effectiveness of the device is verified.The effect of different stack assembly pressures on the precision of the device is analyzed.The performance verification experiment under typical working conditions proves that the device can detect the true dynamic distribution of the current during the operation of the fuel cell.Then,the effects of gas flow rate,operating temperature,and reaction gas humidity on the steady-state performance of the fuel cell stack are studied from the perspectives of the cell voltage and the internal current distributions.Finally,the influence of various load conditions on the dynamic performance of the fuel cell is studied.The mechanism of the dynamic response of the stack performance is analyzed,and load changing strategy of the stack is optimized to improve the fuel cell performance and lifetime.