Thermal Analysis And Cooling Optimization Of Lithium-Ion Power Battery

the traditional one-way flow air easily lead to uneven battery cooling problems. In order to maintain the thermal stability of the power battery, an effective cooling measures was designed to control the temperature of the battery pack and keep the temperature uniformity of the battery pack in this paper, which is of great significance to prolong the service life of the electric vehicle and to improve the safety of the electric vehicle.The main contents of this thesis are listed as follows:(1)The structure and working principle of lithium-ion battery are introduced. The mechanism of heat generation and heat transfer mechanism of lithium-ion battery was analyzed.(2)Experiment on the thermal characteristics of a single lithium-ion battery was done,and the thermal effect model of battery was established.The thermal characteristics of the battery were simulated by using Ansys software. And the temperature field of the single lithium-ion battery is simulated. The simulation results showed that the temperature rise characteristic obtained from the numerical simulation and the experimental temperature rise characteristic were basically consistent, which proved that the battery thermal effect model and the numerical calculation related parameters were reasonable.(3)The structure of the original power battery pack was simplified and the computational fluid dynamics(CFD) method was adopted to analyze the traditional unidirectional flow air cooling mode on the basis of the battery thermal effect model. The surface temperature difference of the battery pack was still 8.76℃ when the single cell in the battery pack was under 5A discharge condition and the battery pack was cooled by air conditioning wind with the wind speed of 4m/s.The simulation result illustrated that the desired effect of the controling battery pack temperature difference could not be achieved by increasing the air flow rate or lowering the cooling air temperature.(4)As the temperature nonuniformity of the battery pack caused by the air cooling was obvious, a liquid cooling pipe device of battery pack was designed to solve the problem. At the same time the unidirectional flow cooling pattern was improved and the defect on the original design structure of the liquid cooling device was optimized. The simulation result of optimized model showed that the surface temperature difference of the battery pack was only2.12℃ under the same discharge conditions, and the optimized liquid cooling device had greatly improved the temperature nonuniformity.