Analysis Of Factors Influencing The Power Efficiency Of Fuel Cell System And Its Hydrothermal Management

Fuel cell system has the characteristics of environmental protection,pollution-free and so on,and it is generally regarded as "the most promising vehicle energy conversion device".In recent years,more and more scientific researchers and companies around the world have paid attention to and developed it,which made it a research hotspot.The fuel cell power system relies on the reaction of hydrogen and oxygen in the reactor body to produce energy,and helped by auxiliary devices to provide power.Among them,the fuel cell battery is the core component of the system.Its electrical efficiency affects the vehicle’s average cost,driving distance,performance,etc.It is greatly affected by temperature and humidity,and its output performance is also determined by these issues.Therefore,the study on temperature and humidity and reasonable control can make the fuel cell work in an efficient operating range,ensure stable operation and give full play to its performance.This paper relies on the provincial and university co-construction project "research and platform development of key technologies of high specific power fuel cell engine".Firstly,the definition of electric efficiency is put forward,and the study of electric efficiency is transformed into the study of voltage loss.Starting from the voltage loss,the causes of internal resistance of fuel cells in activated section,ohm section and concentration section are studied.A fuel cell test bench was set up,and the reactor output performance experiment was designed under the load of current variation.The polarization curve of the reactor under different temperature and humidity conditions was obtained,and the variation trend of the electrical efficiency was further studied.The specific performance of the influence of temperature and humidity on the reactor output characteristics and electrical efficiency was verified.According to the composition of fuel cell system,the design includes cathode gas supply system,anode gas supply system,water management system and thermal management subsystem.According to the limit operating condition,the heat dissipation demand of fuel cell is established and the relevant parameters are matched,including the heat dissipation demand of fan and water pump.Further on the basis of the experimental method,according to the reaction mechanism and empirical formula,the mathematical model is established by the way of theoretical research,including the air supply system model of anode and cathode,the model of water pump,fan and humidifier.Based on Matlab/Simulink software platform to build the simulation model of fuel cell system and made the evaluation points of water thermal management process analysis,application of PID and fuzzy PID control algorithm,thermal management system for fuel cell water,through the associated coupling each module,realized with electricity in the reasonable control of the fixed target value of temperature and humidity.On the basis of temperature and humidity control of fuel cell,a numerical example analysis is carried out,and the basic characteristics,variation characteristics and optimization results of the fuel cell under interference,specific conditions and cycle conditions are briefly analyzed.In order to control the stability of temperature and humidity and improve the electrical efficiency,different control methods were used for simulation analysis to verify the rationality.