| Social and economic development is plagued by energy crisis and environmental problems,proton exchange membrane fuel cell(PEMFC),as a new type of electrochemical power generation device has a broad application prospect,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 has the advantages of high energy density,low operating temperature,fast start-up speed and long working life.Operating temperature is a key parameter affecting the output performance of water-cooled PEMFC system,a reasonable thermal management can maintain the stability of temperature under steady and dynamic load state,improve the performance and extend the working life of fuel cells.Therefore,it is very meaningful to study the thermal management system of the water-cooled PEMFC.Firstly,based on the temperature characteristics of fuel cell,the dynamic simulation model of stack,thermal management system structure optimization and control strategy improvement,this paper introduces the research status of water-cooled PEMFC,and then a dynamic model of stack is proposed based on the working principle and experimental data of fuel cell,the simulation and experimental comparison show that the model can respond well to the dynamic response characteristics of the output voltage and power of the fuel cell under dynamic load change,based on the dynamic model of the stack,the temperature characteristics of the fuel cell are studied,and the effect of temperature change of the stack on its output performance is analyzed.Secondly,the functions,objectives and control requirements of the thermal management system are clarified,the process of heat production and dissipation is analyzed,improvement and optimization of structure and temperature control strategy for heat management system based on the the strong coupling within the thermal management system and the shortage of traditional heat management system,a thermostat is added,a flow following control strategy is proposed,and the feasibility is illustrated by theoretical analysis.Finally,an experimental platform for water-cooled PEMFC thermal management system based on PLC controller is built,the parameters calculation and equipment selection are carried out according to the theoretical analysis and the actual requirements,the PLC control and man-machine interface program are designed which can set system parameters based on operational requirements.Based on the experimental platform,the temperature characteristics of the thermostat and the influence of its installation method on the thermal management system was first studied,and then the strong coupling relationship between the cooling fan and the circulating pump in the thermal management system was determined.Finally,the temperature control effects of the traditional temperature control strategy and flow following control strategy under the dynamic load change of the fuel cell are analyzed,the comparison and analysis of the experimental results shows that the flow following current control strategy enables the thermal management system to quickly respond to load changes.and meet the system temperature control requirements,through the relevant experiments also demonstrate the practicality of the thermal management system experimental platform.The work done in this paper has certain guiding significance and reference value for optimizing the thermal management system and improving the working performance of the water-cooled PEMFC system. |
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