Thermal Effect Analysis And Heat Dissipation Optimization Of Lithium Ion Power Battery

With the development of The Times,the destruction of the natural environment is gradually intensified.Many countries have begun to look for clean energy with sustainable development in order to cope with the obvious environmental problems.Lithium-ion batteries have excellent performance and can be used as a power source.The number of electric ships began to increase.In the process of shipping,ships occasionally encounter emergency emergencies.In case of emergency,the lithium ion batteries need to break away from normal operation and release a high multiplier current.This sudden increase in the discharge current will greatly increase the rate of heat generation of the battery pack.If proper temperature control measures are not taken,the safety and service life of lithium ion batteries will be affected.In order to control the temperature of lithium ion batteries and improve the safety and service life of the batteries,this paper conducts an in-depth study on the problem of heat dissipation when the batteries suddenly turn into a high-rate discharge state.The main research contents are as follows:(1)Introduce a type of lithium ion battery used by the ship.Based on its composition,heat generation mechanism and heat exchange principle,briefly analyze the heat transfer process of the battery pack.Use CFD software to simulate the temperature field of the battery to verify the validity of the mathematical model of thermal effect of lithium ion battery.(2)Determine the factors affecting the temperature field change of lithium ion battery,and establish the heat dissipation models of battery pack(including single-medium and double-medium coupled heat dissipation models).The temperature field of battery pack under normal discharge and abrupt high rate discharge is obtained by simulation.The simulation results show tha t all models can reach the temperature control target under normal discharge,but only the liquid-solid coupling heat dissipation model does not exceed the temperature upper limit under abrupt and high-rate discharge.(3)On the basis of the above work,the heat dissipation mode of the models are optimized on the premise of no additional energy consumption.The temperature field of the optimized models are calculated to verify the temperature control enhancement effect of changing the flow direction of the cooling medium under the condition of high rate discharge.The best time to change the air flow direction of the gas heat dissipation model is 2355 s by enumeration method.