Operation Concept of the GAPS Thermal Control System

Abstract

This study presents the overall operation concept of a multi-loop capillary heat pipe (MCHP) system. This system is developed to cool the central detectors of the balloon-borne General AntiParticle Spectrometer (GAPS). MCHP, as a gasliquid two-phase closed heat transport device, transfers heat from detectors to a radiator. The MCHP is equipped with a reservoir. By regulating the temperature of this reservoir, which dictates the system’s saturation pressure, the MCHP operation is managed. A full-scale MCHP model was developed to investigate MCHP’s time response. Analysis of MCHP operation tests revealed that one-shot heat-up of auxiliary heaters attached to the MCHP induced the boiling of fluids in the MCHP and contributed to uniformity in detector temperatures. In addition, when the radiator was colder than the detectors, the MCHP quickly adapted to changes in ambient temperature—a scenario that is expected to occur during balloon flights. Conversely, the investigation of off-nominal cases where the radiator was warmer than the detectors demonstrated that the MCHP effectively prevented the detectors from experiencing rapid warming. These experimental results support the design and operation concept of the GAPS MCHP.