Investigation On Performance Of A Heat Pipe-based Thermal Management System For Lithium-ion Battery Pack With Cylindrical Cells

With the development of new energy vehicles,it is important to investigate the cooling performance for the battery thermal management system?BTMS?.Cylindrical lithium-ion battery has the advantages of high energy density,no memory effect,long life-time,which has been the most popular choice.Heat pipe has high thermal performance,and is a heat transfer element with wide application prospects in the field of battery thermal management.Therefore,the reasonable design for the cylindrical lithium-ion battery with heat pipe-based cooling is a key to improve the cooling performance of battery.A BTMS based on the combination of heat pipe and conduction element is proposed for a battery pack with cylindrical lithium-ion batteries.A computational fluid dynamics?CFD?model is built for the BTMS and validated with experimental results.With and without conduction element between battery and conduction element,the circumference angle between battery and conduction element,and the height of conduction element on the thermal performance is investigated.An orthogonal experiment is conducted to obtain the sensitivity of various parameters,including the battery spacing,the thickness of conduction element,the circumference angle between battery and conduction element,and the height of conduction element on the thermal performance for the proposed BTMS.The optimal value of the height of conduction element is also determined under the various masses of conduction element.In order to save the computational time,a thermal equivalent circuit model?TECM?is developed for the proposed BTMS.The TECM is experimentally validated and compared with the CFD model.The effects of coolant flow rate and battery row number on the cooling performance of battery are investigated by using the TECM.The results show that the conduction element significantly improves the thermal performance of the unit module due to the increase of the contact area between conduction elements and batteries.The thermal performance can be improved by increasing the circumference angle between conduction elements and batteries to enlarge the contact area.But this improvement effect is slight when the circumference angle is greater than 95°.Its temperature can be slightly decreased by increasing the thickness of conduction element,and it is suggested that the thickness should be within 4 mm.The height of conduction element has the most sensitive effect on the temperature of battery;the circumference angle between battery and conduction element is the second;the battery spacing and the thickness of conduction element has the minimal effect.The best thermal performance is obtained under the condition of 19 mm battery spacing,4 mm conduction element thickness,120ocircumference angle and 60 mm conduction element height.Based on the optimal parameters,the maximum temperature and the temperature difference of battery module are 27.62oC and1.08oC,respectively.The circumference angle and the height of conduction element are related to the mass of conduction element.The optimal value of the height is 55 mm under various masses of conduction element.The computational time of the TECM is about 99.3%lower than that of the CFD model under the same conditions.The thermal performance of the battery pack is slightly improved when the coolant flow rate exceeds 6 L·min^-1.The maximum battery row numbers of the battery pack can reach 65 under 5C discharge rate using the TECM.