Optimal Design And Characterization Of Liquid Cooling Battery Thermal Management System With Multi-Geometry Structure

With the advantages of high energy density,long cycle life,low self-discharge and high capacity,lithium-ion batteries are widely used in power,consumption and energy storage and other fields.Current electric vehicles often use lithium-ion batteries to complete the power storage and supply.However,lithium-ion batteries are very sensitive to storage and operating temperatures,and either too high or too low temperatures result in loss of capacity and power,which seriously affects the health and performance of the battery.Therefore,it is of theoretical importance and engineering application to regulate the battery temperature in the optimal range using an efficient battery thermal management system(BTMS)in order to obtain the maximum battery life and power delivery.The thermal management system of liquid-cooled battery is used as the object of study,and the heat production of the battery at each discharge rate is obtained based on Bernardi heat production model.Then,24 different flow channel forms of liquid cooled plates based on the common geometric structure and are designed by adding the diverting channel,and the temperature rise experiments of liquid cooled plates are set up to verify the reliability of the numerical simulation model,combine thermodynamics and fluid dynamics to study the comprehensive performance of the optimal channel characteristics.Further,aiming at the internal channel structure of the optimal cold plate type,the multiobjective collaborative optimization,grey correlation analysis and arc optimization are carried out,and the effect of the cooling medium type on the performance of the optimized liquid-cooled plate is discussed.Finally,the characteristics of the liquid-cooled battery pack composed of the optimal cold plate model and the battery are investigated.The main research contents of the thesis are as follows:The first,combining with the working principle,heat production principle and heat transfer principle of lithium-ion battery,and building an experimental platform of single battery temperature rise based on Bernardi heat production model to obtain the heat production of batteries at each discharge rate,which established the foundation for subsequent research;The second,based on the common geometric structure,the diverting channel is added,and 24 different flow channel forms of liquid cooled plate are designed,and the flow performance,heat transfer performance and comprehensive performance of liquidcooled plates in each channel form are analyzed by combining thermodynamics and fluid dynamics,and the cooling plate experiment platform of liquid cooled plate is built to verify the reliability of the numerical simulation model;The third,the multi-objective optimization analysis of the internal channel structure of the liquid-cooled plate is carried out with the optimal cold plate type sensitivity higher structural parameters as the design variables and the power consumption and heat dissipation performance of the liquid-cooled plate as the objective function;based on Taguchi’s experimental design,the optimization of the internal diagonal channel parameters of the liquid-cooled plate is carried out by combining gray correlation analysis and ANOVA,and the arcing and Reynolds number analysis of the optimized liquid-cooled channel are carried out;The fourth,based on the thermophysical parameters of nano-fluids,the effects of the types and volume fractions of pure water and nano-fluids on the heat dissipation and power consumption of liquid-cooled plates are discussed,and the different battery structure layouts are designed and the factors affecting the battery performance are analyzed.