To determine the influence of refrigerant phase change on the temperature control performance of a power battery cooling system

an electric-thermal coupling analysis method was proposed by combining a battery equivalent circuit model and a thermal resistance network model. Subsequently

a discrete system model was built based on AMESim. Numerical research on the temperature performance of the power battery was conducted

and the results were verified using experimental data. Subsequently

parametric studies were conducted to obtain the temperature control performance of the power battery cooling system

including the temperature control performance under 2 C high-rate charging and cyclic charging-discharging conditions. The results show that the liquid-vapor heat transfer and overheated heat transfer regions of the refrigerant in the cooling plate have a significant impact on the temperature control performance. Compared with the traditional liquid cooling system

the liquid-vapor region of the direct cooling system reduces the maximum temperature of the battery by 28.3%

whereas the overheated region leads to significant heat transfer deterioration and increases the maximum temperature and temperature difference. When the refrigerant changes from liquid-vapor heat transfer to overheated vapor heat transfer at the 2 C condition

the surface coefficient of heat transfer is reduced by 73.6%

which increases the temperature of the battery units by 12–14 ℃. In addition

a sufficiently low refrigerant temperature increases the maximum temperature difference

which restricts the practical application of the direct cooling system. Increasing the evaporating pressure and configuring the plates on both sides can decrease the temperature difference in the vertical direction. However

these two methods cannot eliminate overheating

and thus it is necessary to design a new system to solve the problem of heat deterioration caused by refrigerant overheating.