Effect of working fluid on heat transfer characteristics of meander-shaped low-fill heat pipe

抄録

With the increasing power density of modern electronic devices, efficient thermal management has become a critical challenge. This study investigates the highly efficient heat transfer phenomenon observed when the working fluid filling ratio in a pulsating heat pipe (PHP) is extremely low. The authors previously introduced this phenomenon as a novel heat pipe concept, termed the meander-shaped low-fill heat pipe (MLFHP). The device comprises a flat aluminum tube, 400 mm in length, with 28 straight channels, each having a square cross-section of 1.26 mm per side. In this study, the heat transfer characteristics of the heating and cooling sections were evaluated to understand this unique phenomenon. The working principle of the MLFHP differs from that of the conventional PHP, in that the MLFHP relies predominantly on latent heat transfer through stable phase change, with minimal oscillatory motion, especially in the cooling section. This distinction is essential in interpreting the observed thermal performance. Additionally, experiments were conducted using working fluids other than water, including alcohol-based fluids and refrigerants, to investigate the effect of different working fluids on the device performance. The results confirmed that the MLFHP operated effectively with these alternative fluids, achieving a minimum thermal resistance of 0.041 K/W in the 400-mm device. These findings suggest that MLFHPs offer a promising solution for next-generation thermal management systems for compact and high-performance electronic applications.