Research On Battery Thermal Management Of Staggered Parallel Flow Type Based On Liquid-cooling

As the the main source of power,battery performance is crucial to the development of electric vehicle industry.Battery operating temperature will directly affect their performance,life and reliability.Power battery at work will generate a lot of heat,and is easier to gather more heat when packed in the compact vehicle space;therefore the research of cooling methods is important to ensure that the operating temperature of the battery pack can be maintained within a reasonable range,as well as the temperature consistency.In this paper,the liquid cooling system of battery thermal management is designed,and What’s more,the research of high temperature cooling has been done with the application of CFD simulation method combined with the experimental verification.This study concluded the development of electric vehicles and power batteries,summarized the progress of research work about battery cell heat generateing model and power battery thermal management technology at home and abroad.Analyzes the basic structure of lithium-ion batteries,compared the characteristics of the different types of lithium-ion batteries,and introduces the working principle of lithium-ion batteries,analyses the heating generating principle and calculates the heating genarating rate of battery cell.Then in the perspective of heat transfer principle,do the the heat transfer analysis,including the internal heat transfer mode and the heat transfer mode between it with the external.Next take the equivalent substitution method to calculate the thermal physical parameters of the equivalent value,including the equivalent specific heat,density,three directions of the equivalent coefficient of thermal conductivity,etc.For classified batteries,designed symmetric cross rowed battery fluid flow heat exchanger structure,Researches established modal around fluid flow system of classified batteries,which includes model establish,numerical simulation,calculation method,analysis and evaluation method and etc.Among them,study the modal simplification,boundary condition and work condition in details,develop the experimental verification of model and calculation method to ensure the calculation accuracy.Analyze its flow characteristics and cell surface temperature uniformity of the fluid flow heat exchange system.Results show that flow rate of the heat exchange system in regional port on both ends are greater than the middle one.The surface temperature for different battery monomers is almost of no difference.By studying the influence of differentcooling fluid inlet temperature,different coolant flow rate and discharge rate on the cell surface temperature field,Result shows that normal flow and initial temperature make little influence on feature point temperature and temperature uniformity of the surface on the battery but the discharge ratio influence is bigger,the more the discharge rate is,the greater the temperature uniformity on the surface of the battery is.When the discharge ratio is 3C or4 C,the cooling heat exchange system has been unable to meet the requirements.Finally optimize the cooling system,the results of the optimized cooling system is improved obviously,even if the 4C discharge rate,it can also ensure the highest temperature maintained at appropriate temperature range,the maximum temperature difference is 2.3℃,when discharge rate is 1C,2C the maximum temperature difference is within 1℃,which proved that improved design can fully meet the requirements of design.