High-temperature, deployable, membrane heat-pipe radiator element; demonstration and status

Performance tests of a high-temperature, deployable, membrane heat pipe have been conducted. This system is intended for use in thermal rejection systems for space nuclear power plants. Because current developmental programs for space nuclear power require heat rejection systems in the 2 to 100-megawatt range, development of lightweight, large-area, heat rejection radiators with operating temperatures of greater than 600 K is being investigated. Heat-pipe radiators are potentially the lightest-weight closed-loop systems available in this power and temperature range. Current state-of-the-art radiator designs provide a specific mass in the range of 5 to 20 kg/m{sup 2}. Membrane heat-pipe designs using alkali metals as the working fluids and metal foil for containment, offer the potential for a specific mass of about 1.8 kg/m{sup 2} and a mass-to-power ratio of approximately 0.04 kg/kW at 1000 K. Because the membrane heat pipes are flexible, the radiator may be rolled up for compact storage and shielding between operating periods. Passive deployment is achieved by the internal pressure developed as the working fluid is brought to operating temperature and thus requires no linkages, actuators, or special-purpose elements. Upon deployment, the high-temperature radiator unrolls, like a party favor, to a fully extended position. 5 refs