Experimental investigation of a lightweight aluminum-ethanol loop heat pipe coupled with vapor-driven injector for long-distance heat transport

Loop heat pipe (LHP), as an efficient passive two-phase heat transfer device, has been recognized as a pivotal technology for resolving the thermal management bottlenecks of high-power electronic devices, owing to the superior long-distance heat transport capability, flexible piping layouts and high reliability associated with the absence of moving parts. To address the urgent demands for system lightweighting and wide temperature range adaptability in electronic thermal management, a flat-plate LHP coupled with an injector (LHPI) was proposed and developed, utilizing the 3-series aluminum alloy structure and the working fluid of ethanol with a low freezing point of −114℃. Experimental investigations were conducted to evaluate the system's start-up characteristics and heat transport capabilities over a long distance of 1200 mm. It is indicated by the results that the interfacial thermal resistance was significantly reduced from 0.15 K/W to 0.05 K/W by the integrated sintering process. It was observed that at an optimal filling ratio of 80%, a high stable entrainment ratio ( ϕ ≈ 50) and liquid-side pressure ratio ( β ₂ > 1.03) were maintained by the injector, by which the flow resistance induced by the long transport line was effectively overcome. Consequently, a maximum heat dissipation capacity of 375 W and a remarkable heat flux of 62.5 W/cm² were achieved by the proposed LHPI, with a minimum system thermal resistance of 0.32 K/W. The superior potential of the aluminum-ethanol LHPI for next-generation long-distance and high-heat-flux cooling applications is demonstrated by these findings.