Design And Optimization Of Vehicle Power Battery Thermal Management System Based On I-shaped Channel Liquid Cooling Plate

The development of electric vehicles offers a variety of benefits,including improved vehicle performance,compatibility with advanced control systems,reduced energy consumption and reduced environmental pollution.The International Energy Agency（AIE）,in its report"Global Electric Vehicle Outlook 2021,"predicts that global sales of electric vehicles will reach 145 million by 2030.The power and control systems of electric vehicles are more complex than those of conventional fuel vehicles because they require additional electronics,including electric motors,battery packs and control units.However,these additional components create new challenges for the design of powertrain thermal management systems,notably the design of battery pack heat dissipation systems.Vehicle power packs accumulate heat during operation,and excessive temperatures will permanently damage the battery.Therefore,the design of the battery thermal management system is particularly important for the development of electric vehicles.First,the mechanism of heat generation inside common vehicle power batteries and the main ways of heat energy transfer are introduced.Based on the results of previous researchers,a model of the heat generation rate of lithium-ion batteries is obtained by means of theoretical calculations.A single battery discharge experiment platform is built,and the linear relationship between discharge current and temperature rise is established by the temperature rise data of the battery at different discharge multipliers,and then the equivalent specific heat capacity of the single battery is calculated.Then,a liquid-cooled battery thermal management system design based on a double-layer I-shaped channel liquid cooling plate is proposed to address the problem of high temperature during the operation of lithium-ion batteries.The I-shaped channel liquid cooling plate designed in this paper is borrowed from the fractal geometry of the mammalian circulation and respiration system with efficient transport capability and heat transfer performance,and at the same time,the design of the double-layer channel liquid cooling plate is proposed in order to realize the coolant to circulate back in the channel.Three design parameters（length ratio,width ratio and channel spacing）are constructed for the layout of the I-form channel,and 60 sets of simulation experiments are designed by full factorial experiments.The effects of the three design parameters on the temperature characteristics and pressure drop of the liquid-cooled plate are discussed based on the experimental results.In addition,a one-way discussion of the three design parameters was carried out by combining the orthogonal experimental design and ANOVA methods,and the results showed that each design parameter responded well to the relationship between the response.To obtain the optimal design parameters for the I-shaped channel liquid-cooled plate,response optimization plots were calculated using the composite expectation function to obtain confidence intervals for the predictions（Tmax=303.87 K,Tσ=0.37 K,Pmax=288.966 Pa）,at which time the design parameters were combined as A=0.70,B=0.85,and C=2.0 mm.The effect of inlet flow rate on the heat transfer performance and pressure drop is discussed for the optimized liquid-cooled plate.The numerical results show that the maximum temperature of the liquid-cooled plate decreases from 305.99 K to 302.87 K and the standard deviation of surface temperature decreases from 0.53 K to 0.30 K when the inlet flow rate increases from 6 g·s^-1 to 15 g·s^-1,but the pressure drop increases by 330%.The inlet flow rate is selected to satisfy the balance between heat transfer performance and energy consumption.Finally,the comprehensive performance of the I-shaped channel liquid-cooled plate and the serpentine channel liquid-cooled plate was evaluated under the same heat transfer area and boundary conditions.The results show that the heat transfer performance of the I-shaped channel liquid-cooled plate is significantly better than that of the serpentine channel liquid-cooled plate,and its pressure drop is only 26.64%of that of the serpentine channel.It is proved that the local pressure drop in each branch of the fractal channel is smaller than that in the serpentine channel.The proposed double-layer I-channel liquid cooling plate can be widely used in liquid-cooled battery thermal management system.Figure[30]table[12]reference[85]...