Numerical Study And Lightweight Design Of Liquid-cooled Thermal Management Module For Cylindrical Power Batteries

With the prosperity of new energy vehicles,the demand for battery thermal management（BTM）is also growing.Among many BTM technologies,liquid-cooled BTM technology has the characteristics of high heat transfer coefficient,excellent temperature control capacity and low system energy consumption.In addition to the basic performance requirements,the BTM system should be lightweight.In this paper,for a 18650-type cylindrical battery,based on one thermal conductive structure（TCS）,a liquid-cooled thermal management module is proposed.The numerical simulation research and lightweight design of the performance of the liquid-cooled thermal management module were carried out.In addition,the distribution characteristics of the flow channel structure of the liquid-cooled module were studied.The main research contents are as follows:（1）Through the internal resistance characteristic experiment and the open circuit voltage temperature coefficient test,the heat generation rate of the 18650 cylindrical battery at 5C discharge rate was determined.Based on this,a three-dimensional thermal model of the battery cell was established,and its rationality was verified by the temperature rise characteristics experiment of battery.The experimental results show that at the end of 5C discharge,the surface temperature of the battery has reached 360 K（87°C）,and it is urgent to design an effective battery thermal management scheme.（2）In this paper,numerical simulation method was used to investigate the effects of different cooling water mass flow rate（m_f）and TCS structural parameters on TCS performance and TCS weight(m_TCS)when 5C discharge rate is performed.It is found that when m_f is 6×10^-4 kg/s,the thermal management requirements of the battery can be satisfied.Increasing the inner diameter（d）of the TCS can effectively reduce theΔP of the cooling water.And m_TCS is reduced.Appropriately reducing the contact surface height（h）of the TCS with the battery can effectively reduceΔT and m_TCS.The increase of the contact surface angle（α）between the TCS and the battery can effectively reduce T_max andΔT,but m_TCS also increases.Subsequently,the lightweight structure was obtained by structure design.Compared with the initial structure,the correspondingΔT is reduced by 14%.ΔP was reduced by 80%and m_TCS was reduced by 46%.（3）Taking the flow channel structure of the liquid-cooled module as the object,the influence of the position and direction of fluid inlets and outlets on the uniformity of flow distribution was explored.The results show that,based on U-shaped design of the inlet and outlet,AA₁-10 structure,with the fluid inlet perpendicular to the reservoir plate,shows excellent distribution uniformity.Compared with the original structure,the dimensionless range and unevenness coefficient are reduced by 74%and 84%,respectively,withΔP increases by only 3%.Subsequently,by using the established battery module temperature prediction fitting curve,it was found that the maximum temperature and maximum temperature difference of AA₁-10 are 312.93 K and 4.57 K,respectively,indicating that the performance of the liquid-cooled module meets the requirements of battery thermal management.