Effect of Different Heat Pipe Lengths on Heat Transfer in Battery Cooling Systems

Nowadays, electric vehicles have become widespread all over the world. Although lithium-ion batteries, which are one of the most commonly used battery types in electric vehicles, have many advantages, they release high amounts of heat during operation, which causes the battery temperature to increase, which in turn causes performance and safety problems. In order to eliminate these problems and keep the batteries in the optimum temperature range, heat pipe systems have been used in recent years and the effect of heat pipe systems on battery cooling performance has been examined in many studies. In this study, battery modules formed with heat pipes of different lengths, 15 cm and 17 cm, were examined at different discharge rates as 1C, 3C and 5C in order to examine the effect of heat pipe length on battery cooling performance. It was observed that the short heat pipe system reduced the maximum battery surface temperature from 23.19°C to 22.93°C at 1C discharge rate, from 29.26°C to 28.94°C at 3C discharge rate, and from 34.12°C to 33.89°C at 5C discharge rate. It was calculated that the temperature difference between the evaporator and condenser sections of the heat pipe decreased from 1.04 °C to 0.83 °C at 1C discharge rate, from 5.36 °C to 4.29 °C at 3C discharge rate, and from 14.91 °C to 11.93 °C at 5C discharge rate in the short heat pipe system compared to the long heat pipe system, and it was determined that the temperature difference between the evaporator and condenser sections was 20% less in the short pipe system, thus faster cooling.