Performance of beeswax phase change material (PCM) and heat pipe as passive battery cooling system for electric vehicles

Increasing greenhouse gas (GHG) emissions in the atmosphere and the scarcity of fossil fuel sources have encouraged car manufacturers to develop more environmentally friendly electric vehicles (EVs). The technology advancements of EVs—those with battery systems in particular—have increased their travel distances. Therefore, increasing and maintaining the battery capacity is a key concern in the development of sustainable EVs. In this study, passive cooling systems were constructed with a heat pipe and phase change material (PCM), and their performances were investigated with battery simulators. The aim was to determine the effectiveness of the cooling system and to identify the optimal PCM (beeswax or Rubitherm RT 44 HC) for a temperature range of 25–55 °C. The use of a heat pipe could decrease the battery temperature by 26.62 °C under a 60 W heat load compared to the case without passive cooling system. Furthermore, the addition of RT 44 to a heat pipe resulted in a maximal temperature decrease of 33.42 °C. Thus, an RT 44 HC is more effective than beeswax because its melting temperature lies within the recommended range of the battery working temperature, and its latent heat allows the absorption of more heat compared to beeswax.