Study On Thermal Management Of Battery Based On Thermal Conductive Silica Gel/Phase Change Material Composite

Today,with more and more emphasis on sustainable development,new energy vehicles with its characteristics of no exhaust emissions,energy saving,power recycling and utilization become the inevitable trend of the future development of the automotive industry.Lithium ion battery,as the core component of new energy vehicles,directly determines the performance of the vehicle's endurance and safety,while the performance of the lithium ion battery itself is closely related to its own temperature.Therefore,effective and reasonable thermal management of power battery is of great significance.In recent years,phase change materials(PCM)have been widely used in battery thermal management systems due to their advantages of low cost,compact structure,heat recycling and good homogeneity.This paper around the liquid precipitation,high phase transition temperature,phase change materials to add shapes material bring latent heat attenuation and other problems,put forward a kind of based on thermal conductive silicone/phase change materials(SCPCM-BN)composite component of battery thermal management system solutions,and through numerical simulation and the method of experimental contrast new battery thermal management system with the traditional thermal management system based on air cooling effect.The influence of different factors on the heat dissipation performance of the system is analyzed,and the structure and performance of the whole system are further optimized.The main research contents include the following parts:(1)the polyethylene glycol(PEG),expanded graphite(EG)and boron nitride(BN)to carry on the quality of different proportion of compound,preparation of best quality percentage of polyethylene glycol(PEG),expanded graphite and boron nitride composite phase change material(CPCM-BN),and study the quality of different proportion of polyethylene glycol(PEG),expanded graphite and boron nitride composite phase change materials thermal properties.The results show that when the mass ratio of polyethylene glycol,expanded graphite and boron nitride is 91:5:4,the thermal conductivity of the composite phase change material is 3.127 W /(m·K).(2)the thermal conductive silica gel/phase change material(SCPCM-BN)composite component was designed,in which the addition of the thermal conductive silica gel shell greatly limited the liquefaction and precipitation of the phase change material and effectively reduced the contact thermal resistance of the system.(3)the optimal thermal management system based on SCPCM-BN/HP composite components is adopted,and applied to the 16 v/50 ah square Li Fe PO4 battery module,battery module test platform is established and the study of the thermal management system of battery module thermal field distribution and the influence of heat transfer performance,especially in the big discharge under the thermal characteristics and cycle performance of battery module.The experimental results show that the maximum temperatures of SCPCM-BN/HP composite component,SCPCM-BN composite component and blank battery module are 50.41?,54? and 72.67?,respectively,at 4C discharge rate.When SCPCM-BN/HP composite components are coupled with fins,only the wind speed of 3m/s can achieve the optimal heat dissipation efficiency,which can effectively reduce the maximum temperature of the battery to 45.8?.(4)the three-dimensional thermal model of the battery module based on the coupled heat pipe(SCPCM-BN/HP)of thermally conductive silica gel/phase change material composite component was used to calculate the temperature changes in each battery under different discharge rates.The temperature changes in the battery under phase change cooling and natural cooling were studied by Fluent simulation.The experimental results show that the difference between the experimental value and the simulated value of the model is within 2?.It can be seen from the experimental analysis that the temperature drop effect of the battery module of SCPCM-BN/HP composite component is very obvious.At 4C discharge rate,the maximum temperature of the battery module of SCPCM-BN/HP composite component is 52.32?,the maximum temperature of the SCPCM-BN composite component is 54.44?,and the temperature of the battery module without heat dissipation component has reached 73.03?.It can also be seen from the temperature cloud diagram that the maximum temperature difference of the battery module based on SCPCM-BN/HP composite component can be kept within 5? even under the condition of 4m/s.