Numerical Investigation On Battery Thermal Management System Based On Solid-liquid Phase Transition Principle And Peltier Effect

As one of the main power batteries of new energy vehicles,the charge discharge performance and cycle life of lithium-ion battery change greatly due to the influence of temperature in the working process,and even lead to accidents in some extreme cases.Therefore,the research on thermal management system of power lithium-ion battery has important academic significance and engineering application value for the economy and safety of battery operation.This paper takes the new 21700 cylindrical lithium-ion battery as the research object,analyzes the heat generation mechanism and the heat production law of lithium-ion battery under different working conditions.The model of the coupling system of lithium-ion battery heat management of solid-liquid phase change materials and thermoelectric component is established,and the mechanism of the influence of different physical parameters on the temperature of the battery is explored.The optimization scheme of the thermal management system of lithium-ion battery is proposed The thesis work of body is as follows :(1)The heat generation mechanism of lithium-ion battery is analyzed,the heat generation power under different working conditions and the temperature distribution of single cell are predicted,and the temperature rise during the discharge process of the battery in the sealed battery module under the natural convection condition is simulated and predicted.By analyzing the distribution of air flow field in the module,several factors affecting the uneven temperature distribution of single cell were analyzed;(2)Considering the extreme hot conditions in East China,a numerical model of passive thermal management system based on solid-liquid phase change material and heat conduction frame is established,and the influence of phase change material thickness on the temperature rise characteristics of battery is analyzed systematically.The mathematical model of thermal management coupling system of lithium-ion battery based on solid-liquid phase change materials and thermoelectric refrigeration was established.The influence of thermoelectric element layout and heat conduction frame materials on the discharge temperature rise characteristics of lithium-ion battery was explored,and the optimization scheme was proposed;(3)Considering the extreme cold conditions in East China,the mathematical model of thermal management coupling system of solid-liquid phase change materials and thermoelectric heating for lithium-ion batteries was established.The effects of thermal insulation materials,numbers of thermoelectric element and types of phase change materials on the preheating performance of lithium-ion batteries were studied,and the mechanism of different schemes on the thermal insulation performance of lithium-ion batteries was elucidated.