| In electric vehicles,the temperature of the power battery has a significant impact on its performance.The high performance power battery thermal management system can not only ensure the stability of the battery,but also improve the safety performance of the battery working process.Therefore,it is very important to delve into the thermal management technology of power battery,so that the power battery can play a greater role under the premise of ensuring the safe temperature.In this paper,the vehicle type 21700 ternary lithium battery as the research object,through theoretical analysis,experimental investigation and numerical simulation,the thermal characteristics of the battery module were studied,and a micro-channel liquid cooling structure was designed.The research contents mainly include:1.The heat generation mechanism and heat transfer characteristics of the power battery were analyzed,and the heat physical property parameters of the battery were calculated based on the internal material parameters.2.The mixed pulse power characteristic（HPPC）test method is used to test the internal resistance of single battery.The test data is fitted by Matlab,and the UDF files of heat source under different discharge rates are written.The internal resistance test of single battery provides data support for the temperature field simulation in the following paper.Then,a single cell model was created and its temperature field distribution under different discharge rates was obtained by using ANSYS/Fluent,and the accuracy of the simulation model is verified by the temperature rise experiment of the single cell.3.Four micro-channel liquid cooling structures with different coolant inlet and outlet locations were designed,and the temperature field characteristics,flow field characteristics and pressure field characteristics of the battery module under each structure were compared and analyzed.The heat dissipation structure of the micro-channel liquid cooling system with relatively good temperature control effect is determined by comprehensive comparison.4.The heat dissipation structure of micro channel liquid cooling system was optimized with rounded corners.On this basis,the influences of the number of micro-channels,the diameter of micro-channels,the wall thickness of micro-channels and the mass flow rate of coolant inlet on the thermal characteristics of the cell modules were analyzed.Then,orthogonal analysis of three structural factors of micro-channel heat dissipation structure was carried out.The results show that when the number of micro channels is 8,the diameter of micro-channels is 1.2mm,and the wall thickness of micro-channels is 1.6mm,the heat dissipation and temperature uniformity of the battery module are the best.The heat dissipation structure of the micro-channel liquid cooling system designed and studied in this paper has a battery module with TmaxandΔTmax,both of which can meet the operating requirements of the BTMS with good heat dissipation. |
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