Design Of Composite Refrigeration System Based On Thermal Management Of Power Battery

With the intensification of energy crisis and environmental pollution problems,electric vehicles as low emission or near zero emissions have attracted more and more attention.As the power source of electric vehicles,the performance and life of power batteries are the key to the development of electric vehicles.The performance and life of the power battery are greatly influenced by the temperature and temperature consistency of their work.In order to control the working temperature of the power battery in different environment,the battery heat management system can provide the refrigeration or heating service for the battery according to the needs.When the power battery continues to charge and discharge at the large rate,if the large amount of heat generated by the chemical reaction can not be quickly and effectively dispersed inside the battery,the heat loss of the battery,the oxidation of the electrolyte,and even the explosion may occur.In addition,the excessive battery temperature will lead to the increase of irreversible reactants in the battery.A series of problems such as reducing the capacity of the battery and reducing the life span of the battery,and so on.When the temperature of the battery is too low,it will lead to the degradation of the battery activity,the decrease of the charge current of the battery,the prolongation of the charging time and the significant decrease of the charging rate.Under the restriction of the working principle and the temperature of the cooling medium,the traditional heat management system can not effectively and efficiently ensure the consistency of the working temperature of the power battery.Aiming at the above problems existing in the current power battery thermal management system,this paper studies the feasibility of the application of the dynamic separation type heat pipe / steam compression composite refrigeration system in the thermal management of the power battery with the aim of energy saving,reliability,high adaptability and good adjustment.In this system,the dynamic separation heat pipe is coupled with the automobile air conditioning system,and different working modes are selected according to the air temperature of the external environment and the temperature of the power battery.The main contents of this paper are as follows:(1)looking up the relevant documents related to the thermal management of power battery at home and abroad with the dynamic separation type heat pipe / steam compression composite refrigeration system,the research status of the current heat dissipation and the research status of the compound refrigeration system are thoroughly and systematically understood,and the feasibility of applying the compound refrigeration system to the power battery package heat management is explored.Sex;(2)according to the thermal management scheme of power cell for the dynamic separation type heat pipe / steam compression composite refrigeration,the working principle and different working modes are discussed and analyzed in detail,and the system is compared with the conventional air cooling or water cooled battery heat management system.(3)on the basis of the selection of the dynamic separation type heat pipe / steam compression composite refrigeration system,according to the ambient air temperature and the working temperature level of the battery,the different working modes of the thermal management scheme of the system are discussed in detail,and how to switch between the different working modes and improve the battery thermal management system.The control strategy provides reference data for engineering practice.(4)on the basis of the previous work,the design and selection of the components in the power cell heat management scheme of the dynamic separation type heat pipe / steam compression composite refrigeration are carried out,and the reference scheme is provided for the engineering practice.