Operating characteristics of a miniature cryogenic loop heat pipe

Aiming at future space applications, a miniature cryogenic loop heat pipe (CLHP) with nitrogen as the working fluid was designed, whose condenser could provide the interface with the cold finger of cryocooler, and its operating characteristics were experimentally investigated in this work. Based on the experimental results, important conclusions below have been drawn: (1) with only 2.5 W applied to the secondary evaporator, the CLHP can realize the supercritical startup, and the larger the heat load applied to the secondary evaporator, the sooner the temperature drop process of the primary evaporator; (2) when the heat load applied to the primary evaporator is no less than 3 W, the primary evaporator can operate independently; whereas when it is smaller than 3 W, the secondary evaporator must be kept in operation to assist the normal operation of the primary evaporator; (3) the CLHP has a heat transport capacity of 12 W × 0.56 m, and its thermal resistance decreases with the increase of the heat load applied to the primary evaporator; (4) the CLHP has the ability to operate with a small heat load applied to the primary evaporator for a long time, and manifests good thermal control performance.