| At present,the importance of energy conservation and environmental protection has aroused the resonance of industry.Electric vehicles have been attracted more attention at home and abroad because of their advantages in energy saving and emission reduction compared with traditional fuel vehicles.The power battery is an important factor for the development of electric vehicles.There are many kinds of power batteries.However,considering the energy density,cycle life,cost and energy efficiency,lithium-ion power battery is the best choice.As the core component of the vehicle,its chemical performance and cycle life are significantly affected by temperature.Abnormal temperature will lead to thermal runaway of the battery.Therefore,it is of great significance for the development of electric vehicle industry to study the thermal behavior of single cell,battery module and battery pack system,as well as the performance of batteries at different ambient temperatures,so as to design a reasonable battery thermal management system.Firstly,the working principle,heat generation and heat transfer principle of lithium iron phosphate monomer battery are analyzed in the paper.At the same time,the effect of temperature on battery charging and discharging performance was explored experimentally,and the theoretical formula of heat generation of single cell battery was obtained,and the finite element thermal simulation model of single cell battery was constructed.Then the temperature rise characteristics of the cell at different discharge rates are obtained by STAR-CCM+ simulation analysis.The validity of the finite element thermal model of the cell is verified by comparing with the experimental results.The temperature field distribution of single battery under different environmental conditions is simulated and compared,which provides a basis for the selection of cooling conditions of the following cold plate model.Secondly,the influence of the structure parameters of the cold plate on the heat dissipation performance of lithium-ion batteries was studied.Based on the theory of liquid cooling and hydrodynamics,the effects of the shape of the flow channel(rectangular angle,circular angle)and the number of flow channels on the temperature field of the cold plate system are analyzed.Orthogonal experiments were designed for four parameters: width,thickness of the convection channel,and distance between the central axis of the channel and the top or side of the cold plate.The parametric modeling and CFD simulation are carried out to analyze the heat dissipation,and the cold plate design model with better comprehensive heat dissipation performance is obtained by variance analysis.Then,the heat dissipation performance of battery pack module composed of battery and cold plate is studied.The temperature field differences of different combinations of battery modules are compared from the cooling conditions and cold plate structure aspects.Finally,different types of battery packs,such as T-shaped,earthen-shaped,I-shaped and rectangular,were designed to compare the difference of temperature field between different combinations of battery packs.The rectangular battery pack with good heat dissipation performance was analyzed as the research object.By analyzing the effect of coolant temperature on the temperature distribution of battery pack,the influence law of cooling temperature on the heat dissipation performance of liquid-cooled battery pack was obtained.Based on the research of liquid-cooled battery module,the influence of the number of cooling channels in battery pack and the direction of coolant inlet and outlet on the overall heat dissipation performance was compared and analyzed. |
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