Analysis Of Structure And Heat Transfer Performance On Liquid-Cooled Of Electric Construction Machinery

Under the call of the country to promote environmental protection and energy conservation,the company must respond the summons positively.Solving the increasingly serious air pollution and the depletion of petroleum fuels and developing new energy construction machinery has become an inevitable trend of mechanical development.As an important part of electric construction,the performance of power battery plays an important role in the normal operation of construction machinery.The battery pack of electric of construction machinery will generate much heat while working.If the heat cannot dissipate in time,the battery temperature will rise rapidly and the temperature distribution will be uneven,which in turn severely deteriorate the working efficiency,service life and safety performance of the battery pack.Seriously,it will even cause explosion.Similarly,power battery cannot work normally in cold environment,so it is very important to study the heat exchange of power battery.This paper takes the liquid-cooling structure of power battery in construction machinery as the research object,calculates the thermal parameters of battery based on theory,establishes the physical model of power battery pack,uses CFD method to analyze the temperature rise characteristics of power battery under different working conditions.Through optimizing the liquid-cooling structure of power battery,putting forward the optimization measures of heat dissipation structure and compare the heat dissipation under different parameters based on the optimized structure.The main contents of this paper are as follows:1.According to the different types and working characteristics of power batteries,this paper analyze the advantages and disadvantages of lead-acid batteries,nickel-hydrogen batteries and lithium iron phosphate batteries are analyzed,and choose the suitable power batteries.Then analyze and calculate its structure,heat generation mechanism and heat transfer characteristics.Which lays a foundation for the simulation calculation and parameter selection of the battery pack simulation.2.A preliminary design of the liquid-cooled structure of the power battery pack of the excavator power system is carried out,including the battery arrangement and series-parallel connection mode,the structure design of the liquid-cooled plate,the layout and distribution of the runner.The typical working conditions of the electric excavator are analyzed and the preliminary simulation of the power battery under two different working conditions is carried out.Combining with the simulation results,expounding the importance of structure and inlet parameters for battery cooling,which provides a direction for subsequent optimization of battery cooling system.3.Taking the runner layout structure as the main entry point,comparing the temperature distribution of the battery pack under the single and two-way runner structure.It is pointed out that the heat dissipation of parallel two-way runner is better when the number of runners is the same.For parallel two-way runner,the effects of cooling fluid inlet flow rate and temperature on temperature rise and temperature uniformity of batteries are discussed respectively.Ensure that the whole battery pack works in the range of 293.15K(20 ℃)to 313.15K(40 ℃),and keep the temperature difference of the battery pack within 5K.4.In order to simplify the system,the whole battery system is heated by adjusting the parameters along with the structure of high temperature coolant cooling plate when the battery is working in low temperature environment.According to the second optimization scheme,the simulation calculation was carried out to compare the change of heating rate of the battery under different inlet flow rate and different inlet temperature.The inlet flow rate has little effect on the temperature rise of the battery,which mainly affects the temperature difference of the battery after preheating.The higher the inlet temperature is,the higher the temperature rise rate of the battery is.Finally,the temperature of the battery was increased to 283.15 K within 10 minutes,meeting the requirements of low temperature environment.The simulation results show that the two-way runner structure flow channel liquid heat exchange system which designed in this paper can effectively adjust the temperature of the battery to the normal working range under hot and cold extreme conditions,and ensure the normal operation of the battery.