小川 博之

A capillary pumped loop (CPL) is a capillary force-driven heat transport device that uses the phase change of a working fluid. A CPL has excellent properties in terms of heat transport capability, heat transport distance, and flexibility in heat transport path arrangement. However, its startup reliability is low, and its startup characteristics have yet to be determined. This study aims to investigate the startup characteristics of a CPL and improve its startup reliability. The startup procedures are newly proposed and experimentally verified in this paper. In the proposed method, the evaporator was preheated in addition to the reservoir preheating before startup. Verification was done by switching the order of the reservoir preheating and evaporator preheating. The experimental results showed that the proposed methods enable the CPL to start up even in conditions where the CPL was unable to start up by a conventional method (reservoir temperatures ranging from 40 °C to 80 °C). It was also confirmed that the order of the evaporator preheating and reservoir preheating affects the degree of overshoot of the evaporator temperature. The maximum temperature of the evaporator at the startup was reduced by up to 91.5 °C in case the evaporator was preheated before the reservoir preheating.

Typically, spacecraft development is costly and time-consuming because of the many iterations usually needed to reach optimal design solutions. This paper presents an innovative approach that eliminates the need to iterate the thermal design process using a network of variable conductance oscillating heat pipes (VC-OHPs) on every structural panel. The temperatures of the panels where components are mounted would thus be maintained at constant levels by VC-OHPs, even if the instruments' locations or heat dissipation changes. A structural thermal model was built to verify the proposed thermal and structural design in a simulated deep space environment and in a launch environment. It consisted of two VC-OHPs and six aluminum honeycomb panels. A thermal vacuum test was conducted to demonstrate the temperature control by the VC-OHPs. The test results showed that temperature control by VC-OHPs could maintain the panels operating as evaporators at stable temperatures and follow the reservoir temperature. A vibration test was conducted under the launch environment of a Japanese H2A rocket. The results confirmed that the structural thermal model met requirements for resistance to mechanical launch environment. The VC-OHPs functioned after the vibration test. The structural thermal model showed that the proposed thermal control architecture is feasible in an actual spacecraft in terms of thermal and structure design.