A Research Of Water Management Of PEMFC Based On In-site Detection

As fossil-energy dependent industrialisation is increasingly constrained by energy reserves and the environment,governments are increasingly focusing on hydrogen research.As an energy conversion device utilizing hydrogen energy,air-cooled fuel cell(PEMFC)is widely used in UAV,backup power and other fields.However,the internal environment of air-cooled fuel cells is complex,especially the detection of water distribution is very difficult.The water distribution is closely related to the stack output performance,and the detection of water distribution is a necessary condition for studying the water management strategy.In this paper,the water distribution was detected by the in-situ detection technology based on the segment fuel cell,and the temperature,assembly pressure and anode gas discharge were analyzed as the key factors affecting the water distribution inside the stack.Based on the above factors,a set of water management strategy applicable to the entire operation process of air-cooled fuel cell is proposed,and the maximum current output capacity of the air-cooled fuel cell used in this paper is increased by 40%.The main work of this paper is as follows:Firstly,the in-situ detection system of fuel cell is designed and built,which is mainly divided into hardware design and software design.The off-line test of the system shows that the impedance variance of each segment is lower than 0.011.Then,through the online test,the test error of the whole system is lower than 4.5%.In particular,when the current is greater than 20 A,the test error is lower than 1%.The in-situ detection system has high impedance consistency and good linearity in different current.Secondly,the steady-state experiment of the fuel cell reactor is carried out by using the designed detection system.Based on the experimental results,the steady-state performance of the fuel cell used in this paper is analyzed.Then the operation process of the stack is divided into low current,medium current and high current,and the water distribution is studied respectively.Combined with the structure and design of the stack,the phenomena of the water distribution of the stack are explained,and the temperature and assembly pressure are analyzed as the main factors affecting the water distribution of the fuel cell stack.Finally,combined with the practical conditions of the stack,the effect of the strategy on the distribution and output performance of the stack for the temperature and anode gas discharge is studied,and then the effect of the strategy of combining temperature and anode gas discharge on the output performance of the stack is studied,and finally,combined with the experimental results,a water management strategy for the whole operating range of the air-cooled fuel cell is proposed,and the effectiveness of the water management strategy is compared to verify.