Research On The Optimization Of Liquid-Cooled Heat Dissipation Performance Of Lithium-Ion Battery Based On Bionic Structure

The popularization and application of electric vehicles are very important for alleviating environmental pollution,solving the oil crisis,guaranteeing national energy security,and achieving sustainable socio-economic development.An essential component of electric vehicles is the power battery,and lithium-ion batteries stand out among the many power batteries by virtue of their various advantages.The operating temperature of lithium-ion batteries has an essential role to play in performance,life,and safety.A high-temperature environment negatively impacts the performance of the battery,not only in terms of capacity but also in power degradation,and the battery is highly susceptible to thermal runaway or even fire and explosion.Thus,establishing an efficient battery thermal management system is vital for lithium-ion batteries.In this thesis,the geometry of the flow channel structure is optimized to obtain an efficient and reasonable liquid cooling battery thermal management system to solve the thermal safety problem of a particular specification of Li Fe PO₄ power battery.Reference to the blade shape in nature,a blade-like mini-channel liquid cooling plate is designed based on the bionic structure in the thesis.Based on the validation experiments,the design of the liquid cooling plate structure is optimized,the influence of various factors on the performance of the cooling system is evaluated,and a series of studies on the battery module is conducted.Firstly,the simulation model is established for the initial liquid cooling plate structure.Four groups of heat dissipation experiments of the liquid cooling plate are performed,and the obtained experimental data is basically matched with the simulation data.It confirms the accuracy and effectiveness of the simulation method.Then,the number of channels and blade branches are optimized to obtain a better model.In addition,single-factor analyses are conducted mainly for the inner angleα,circular angle1,circular angle2,and channel height d to evaluate their effects on the performance of the mini-channel liquid cooling plate.Secondly,using a combination of orthogonal tests and fuzzy grey correlation analysis as the evaluation method.The effects of four structural parameters,which are inner angleα,circular angle1,circular angle2,and channel height d,on the performance of the mini-channel liquid cooling plate,are investigated.Then the degree of influence of various factors on the average temperature,heat transfer coefficient,and friction coefficient of the cooling system are analyzed,and their priority is distinguished.The results indicate that the greatest influence on average temperature is the channel height d,the greatest influence on heat transfer coefficient is the internal angleα,and the greatest influence on friction coefficient is the channel height d.Then,the thermal performance,hydraulic performance,and field synergy coefficient of different liquid-cooled plate structures are compared,the overall performance is measured by the comprehensive evaluation index,and the optimal liquid-cooled plate model is obtained by comprehensive analysis.Moreover,the influence of cooling medium on the performance of liquid-cooled plate is investigated.Finally,according to the optimal liquid-cooled plate obtained in the previous chapters,the simulation research on the liquid cooling heat dissipation of the battery module is launched.Among them,the arrangement forms of the battery group,the inlet and outlet positions of the coolant are optimized,from which a more reasonable battery pack arrangement form was obtained.Besides,the influences of the discharge rate of the battery,the mass flow rate of coolant,and inlet temperature on the heat dissipation efficiency of the battery module are investigated.