Investigation of Heat Transfer and Flow Characteristics of Nanofluids In Battery Thermal Management Systems.

The aim of this study is to investigate the thermal behaviour of lithium-ion battery packs with a liquid cooling system using numerical methods. The numerical analyses cover various battery configurations, coolant velocities, and fluid types. Water and a water-propylene glycol mixture are used as coolants, and system performance is evaluated at three different inlet velocities. The main criteria used to evaluate thermal performance are maximum battery temperature and inter-cell temperature difference. The results show that, in general, as the refrigerant velocity increases, the battery temperatures decrease and the temperature distribution becomes more homogeneous. However, it was found that, at high flow rates, the temperature drop is limited and thermal gains gradually decrease. In some cases, water was found to provide lower maximum temperatures, whereas the water-propylene glycol mixture provided a more balanced temperature distribution under certain operating conditions. Additionally, it was found that as the number of cells connected in series increases, the temperature differences along the flow direction become more pronounced. In addition, the preliminary evaluation of a nanoparticle-doped coolant for a selected battery configuration was investigated. It was found that the addition of Al₂O₃ nanoparticles had a limited effect on thermal performance; therefore, the nanoparticle-doped fluid was not applied to all configurations. Overall, the study revealed that coolant type, flow rate and battery configuration should be evaluated together to ensure effective battery thermal management.