LAUSR

It is becoming increasingly difficult to meet the challenging thermal control requirements of modern spacecraft missions with only existing thermal control devices such as conventional heat pipes. A loop heat pipe (LHP) is an effective method to overcome some of these thermal control constraints. The LHP is a passive two-phase heat transfer device that utilizes the evaporation and condensation of a working fluid to transfer heat and capillary force to circulate the fluid. The LHP can transport much heat for a long distance against gravity and has many other excellent characteristics, such as high controllability of operating temperature and a shutdown function. In this study, LHPs for space application have been developing. As a part of the study, a bread board model (BBM) of LHP was designed and fabricated. As a result of an on-ground test of the BBM, it was confirmed that the BBM fulfilled all requirement (e.g. maximum heat transport rate, minimum required heat load for start-up, operating temperature control and shutdown function). To adopt the LHP as a heat transfer device in practical spacecraft mission, the thermal characteristics under micro-gravity conditions should be examined in advance. An on-orbit experiment of a LHP radiator system is planned. This paper describes the test plan of on-orbit experiment of a LHP radiator system on the International Space Station (ISS) and the results of thermal vacuum test of flight model for on-orbit experiment on ground.