Heat transfer characteristics of a novel loop heat pipe using eco-friendly refrigerant HP-1 as the working fluid

With the rapid advancement of 5G technology, electronic devices are evolving toward higher integration and miniaturization, leading to a significant increase in heat flux. However, traditional loop heat pipes (LHPs) face limitations in heat flux density due to inherent heat leakage issues, failing to meet emerging thermal demands. In previous studies, an innovative injector-integrated loop heat pipe (LHPI) was developed and demonstrated superior thermal management performance. However, early experiments utilized water as the working fluid, which suffers from low freezing points and ice formation in low-temperature environments, restricting its broader application. To address this, this study introduces a novel low-freezing-point refrigerant, HP-1, and systematically investigates the effects of heat loads (50—300 W) and heat sink temperatures (5—15℃) on LHPI performance. Experimental resultsreveal that the injector’s operational modes—classified as low-efficiency, normal injection, restricted expansion, and superheated modes—significantly influence LHPI’s heat transfer characteristics. At elevated heat sink temperatures, the transition to restricted expansion and superheated modes occurs earlier. Compared with waterbased working fluids, HP-1 increases the heat flux of LHPI to 41.7 W/cm² at a base plate temperature of 85℃, and its low temperature adaptability is significantly enhanced, providing a new idea for passive heat dissipation of highpower electronic devices.