Structural optimization design of liquid cooling plate adding water-like droplet fins
With the increasing demand for comfort and dynamic performance of electric vehicles,the demand for power of batteries is also constantly increasing.Placing more batteries in a smaller space and improving the power density of the batteries have become important questions.Suitable temperature range can maximize the performance of the batteries.Due to the advantages of low self-discharge,high power increasing,no memory effect and long cycle life,batteries are widely used as the power source of electric vehicles.Safety performance and service life of lithium-ion battery pack are easily affected by temperatures.As the power source of electric vehicles,the battery temperature directly affects the driving safety of electric vehicles.Especially in a high-temperature environment,the battery continues to discharge,which can easily cause excessive temperature,and even lead to battery combustion,explosion.Therefore,various cooling methods are proposed.At present,the cooling methods for lithium-ion batteries at high temperatures,mainly include air cooling,liquid cooling,phase change materials,heat pipes,and coupling.Liquid cooling is an effective cooling style and has been widely used on electric vehicles.In order to ensure the reliability of liquid cooling,indirect liquid cooling mode is often used on vehicles made by Tesla,BYD and Geely.The main ways to improve liquid cooling effectiveness including using cooling medium materials with high thermal conductivity,improving flow channel pipeline design,optimizing of liquid cooling plate structures,adding cooling plate splitters into the straight channel et al.They all can improve the heat dissipation performance to a certain extent.To improve the thermal equilibrium performance of lithium-ion battery packs,water-droplet split fins are arranged into liquid cooling plate structure based on flow around bluff body theory.Our results show cooling plate structure with water-droplet split fins reduces the maximum temperature and the maximum average temperature difference of lithium-ion battery module.But it increases the flow resistance.A water-droplet fin has four structural parameters,which include head radius,head angle,tail length and space between two fins.Numerical simulation method is employed to investigate the impact of the 4 splitter structure parameters mentioned above on the maximum temperature,the maximum average temperature difference and the flow resistance.Then,orthogonal experimental design method is adopted to perform the same tasks.The primary and secondary order of their effects are obtained.And local optimal results are generated.The best combination of structural parameters is α3r3b2h1.In this case,the maximum average temperature difference of lithium-ion battery module reaches the minimum of 1.78 ℃.The thermal equilibrium performance improves by 25.27％,and the effect is the best.Our research supports the optimized design of lithium-ion battery thermal management system for electric vehicles.
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