Thermal Management Simulation Of Power Battery Based On Phase Transition

New energy vehicles have become an effective solution to environmental pollution and energy threats,and lithium-ion batteries are the main source of power for electric vehicles.Their performance and longevity are directly related to temperature.Excessive temperature and inconsistency of battery can lead to a decline in performance and even cause a risk of thermal runaway in severe cases.By studying the heat generation characteristics and heat transfer mechanism of the battery,the battery cooling system based on phase transition is researched.In this research,a novel low-cost and lightweight lithium ion batteries thermal design based on EG-based composite phase change material to store heat under normal EV operating conditions is developed and verified theoretically.The three dimensional thermal simulation model is proposed to compute the transient temperature of the battery at some actual driving conditions during discharge.The performance of battery thermal management system based on composite PCM under four kinds of actual electric vehicles thermal safety evaluation condition is investigated,and some factors influencing the system are discussed in detail.Simulation results show that the temperature of the lithium ion battery of 38.4k Wh can be maintained within a reasonable range by adopting the cooling system.The highest temperature of battery discharging at 1C rate can be kept no more than 45.0? in the cost of 0.5mm in thickness and 1.02 kg in weight increment of PCM and the temperature consistency evaluation methods based on integral values were proposed.The conclusions got in this paper can be valuable reference for battery thermal management design and analysis of dissipating heat against daily driving discharge condition.The development of unmanned aerial vehicle brings another important application scenario for lithium-ion batteries.Since the discharge rate is extremely high when the drone takes off,hovers,and lands,the heat generated by battery is very serious,while the space of drone is narrow and the weight gain is sensitive,the battery thermal management system design becomes a difficult point.In this research,a novel lithium ion batteries thermal design to manage ultrahigh thermal shock of a commercial small four-rotor electric unmanned aerial vehicle is developed and optimized.The cooling relies on internal heat pipe and convective cooling of UAV body,so that the heat generated by the battery can reach exterior cooling through a dedicated thermal path.The thermal management system is passive and requires no additional energy consumption.Finite element simulation is established to model the system and advanced thermal materials,and the system is optimized by response surface method in a dual objectives approach: minimizing maximum battery temperature and weight of the UAV.Simulation results show that the new passive cooling system can keep the temperature of the lithium ion battery within a reasonable range.The effects of convective heat transfer coefficient,discharge rate and fuselage thermal conductivity were studied.After optimizing the system,the highest temperature of battery discharging at 3C rate can be kept no more than 36? in the cost of 32.18 g weight increment.