Development of Two-Phase Mechanically Pumped Fluid Loop with Large Isothermal Evaporator using Porous Wick Structure

"In recent years, space exploration is improving. Therefore, requirements for the thermal control system of the electric devices on spacecraft are getting higher. The requirements are accommodating high heat generation, keeping science instruments isothermal, and so on. For the easy installing and the cost reduction of the spacecraft, the free arrangement of on-board devices is also necessary. Therefore, the large isothermal evaporator has been proposed. The present state of the technology of thermal control systems is mainly Single-Phase Mechanically Pumped Fluid Loop (SPMPFL) and Loop Heat Pipe (LHP). The merit of SPMPFL is the long heat transport distance. The demerit of SPMPFL is the large temperature difference on the evaporator because heat transport is carried out by sensible heat of working fluid. For this reason, the heat transport capability is small. The merit of LHP is capillary force-driven without the electrical power, whereas the heat transport distance and capability are limited by the wick capillary force. Then, Two-Phase Mechanically Pumped Fluid Loop (2PMPFL) which has pumped driving force and two-phase flow is remarkable. The 2PMPFL enables the long heat transport distance, the high heat transport capability and the large isothermal area. We developed the Two-Phase Mechanically Pumped Fluid Loop with large isothermal evaporator using porous wick structure. This evaporator consists of a liquid channel, a vapor channel and a wick.　The vapor channel has a lot of pillars which conduct heat for the wick. The wick holds the working fluid on the whole area of the evaporator. Then, the working fluid evaporates and two-phase state is held. Therefore, the temperature on the evaporator surface can be kept isothermal. In the present study, we investigated the thermal performance of the 2PMPFL and verified the temperature uniformity on the evaporator surface."