| New energy vehicles have made great progress in recent years,and the sales of electric vehicles are increasing year by year.However,with the operation of electric vehicles,various safety problems have become increasingly prominent,especially the safety accidents caused by overheating of batteries.As the power source of new energy vehicles,the performance of battery charging and discharging directly affects the operation of vehicles.The working environment of batteries requires strict temperature.The internal chemical reaction of the battery will be affected when the temperature exceeds 50 and the charge and discharge of the battery will be affected when the temperature is lower than 15,so it is necessary to conduct thermal management of the battery to ensure that the battery works in a reasonable temperature range and to give full play to the performance of the battery.In this paper,a new type of liquid cooling and heat management system is designed.The specific work is as follows:(1)In this paper,A123 lithium-ion battery is taken as the research object.The temperature rise characteristics of the battery monomer are studied experimentally,and the heat generation model of the battery is established.The thermal conductivity,specific heat capacity and density of the battery are calculated,and the thermal simulation model of the battery monomer is built based on the calculated data.Compared with the experimental data of temperature rise of monomer and the thermal simulation model data,it is found that the thermal simulation model data are close to the experimental data,and the error is small,which meets the requirements of the thermal simulation model of monomer.(2)A new type of liquid-cooled heat dissipation system is proposed.Taking a battery group in the battery module as the research object,the temperature rise characteristics of the battery group and the temperature consistency of the battery group are studied when the cooling fluid flow rate is different,the coolant temperature is different,the discharge rate is different,and the height of the cooling plate is different.Combining with the characteristics of liquid cooling heat dissipation system,a low temperature preheating system for battery packs is designed,which shows good heating performance and temperature consistency.(3)After optimizing the original heat management system,a "ladder" cooling plate structure is proposed,which shows good temperature consistency.When the "ladder" cooling plate is used,the weight of the cooling plate decreases by 22.26%compared with the integral one with the best temperature characteristics,while the temperature difference between batteries decreases by 9.46%.It also reduces the weight of the battery pack while showing better temperature consistency.(4)For the "ladder" cooling structure,the flow rate can be reduced to achieve the same goal of temperature consistency as the original one.The minimum temperature difference of the battery pack can be achieved at 12 g/s flow rate for the integral structure,and only 7.8 g/s flow rate is needed for the stepped cooling structure to achieve the same temperature difference.Thus,the energy consumption of the system can be reduced by reducing the flow rate.(5)Temperature consistency of the cell can be improved by changing ladder cooling structure to intermediate symmetrical structure. |
PDF Full Text Request