Experimental study of a solar receiver for JEM experiment program

A fundamental study was performed to develop a high efficiency solar heat receiver system for a solar energy experiment mission on the Japanese Experiment Module (JEM) - Exposed Facility (EF) of the International Space Station (ISS). This system is aimed to transport solar thermal energy to a bottoming system with a high efficiency. It is composed of a solar heat absorber, thermal energy storage (TES) and heat pipes (HPs). Solar light of approximately 1.8 kW is concentrated on a focal plane of the absorber aperture, and then net thermal heat of 1.3 kW is transported to the HP and supplied to a bottoming element such as a Stirling engine alternator, an AMTEC and a furnace for material processing. Uniform heating of HPs were confirmed using secondary mirror and C/C composite receiver. One ground testing model of the solar receiver was designed and fabricated in 1998, and then experimentally evaluated at a test vacuum chamber of National Aerospace Laboratory. The receiver was heated uniformly and the good heat conduction at the interfaces (receiver-HP, and HP-TES) was confirmed. The periodic sunshine/sunshade mode occurs on the orbit JEM-EF of ISS. The thermal cycle test was performed to demonstrate sunshine/shade modes using the ground testing model. The temperatures of components changed periodically and the heat transfer rates of 100 W at sunshine mode and 75 W at sunshade mode were derived.