Experimental study on a rectangular evaporator loop heat pipe with a phase-change material heat sink

To satisfy the heat dissipation requirements of high heat flux electronic devices in extreme conditions where no suitable heat sink exists, such as in the flight process of hypersonic aircraft and the re-entry process of spacecraft, a rectangular evaporator loop heat pipe (LHP) with a phase-change material heat sink was designed and developed. Extensive experimental studies on the thermal control performance of the LHP have been performed, mainly including the startup performance, maximum temperature control time, dynamic response to varying heat load, and the heat transfer limit. Experimental results showed that the LHP could successfully realize the startup at a small heat load as low as 5 W. Under 100 W heat load, the LHP can keep operating for 4 h and 16 min at most with the operating temperature lower than 50 °C, including 2 h and 40 min of quasi-stable operation. The heat transfer limit of the LHP could reach up to 200 W, corresponding to a heat flux of 13.3 W/cm² at the evaporator. In addition, the LHP exhibited excellent dynamic response characteristics to varying heat loads, holding great application potential in future thermal control tasks in extreme conditions.