Heat-Transfer Characteristics of a Cryogenic Loop Heat Pipe for Space Applications

Abstract

Infrared detectors on satellites and spacecraft require cooling to increase their measurement sensitivity. To efficiently cool infrared detectors in a zero gravity environment and in limited spaces, a cryogenic loop heat pipe (CLHP) can be used to transfer heat over a certain distance by the capillary forces generated from porous wicks without a mechanical power source. The CLHP presented in this study transfers the heat load to a condenser 0.5 m away from an evaporator at temperatures below −150 °C. The CLHP with two evaporators includes a subloop for initial start-up, and uses a pressure reduction reservoir (PRR) for the supercritical start-up from room to cryogenic temperature. Nitrogen is used as the working fluid to verify the thermal behavior of the CLHP, and the heat-transfer capacity according to the nitrogen charging pressure of the PRR is investigated. To simulate a cryogenic environment, the CLHP is installed inside a space environment simulator, including a single-stage GM (Gifford McMahon) cryocooler to cool the condenser. The CLHP is horizontally installed to simulate zero gravity. The heat-transfer characteristics are experimentally evaluated through the loop circulation of the CLHP.

Performance investigation of a loop heat pipe integrated with thermoelectric cooler under acceleration field

“…Compared with traditional heat pipe, LHP possess the advantages of long-distance heat transfer capability, flexible installation, precise temperature control and anti-overload acceleration [4][5][6]. Over the past three decades, LHPs have been widely applied in various aircraft, spacecraft and electronic cooling equipment [7][8][9][10][11]. Different from conventional LHP, the dual compensation chamber loop heat pipe (DCCLHP) has two compensation chambers (CCs) distributed at both ends of the evaporator, which enables the capillary core to be more effectively infiltrated under gravity field or acceleration field [12][13].…”