Development of Lightweight Radiators for Lunar Based Power Systems

Abstract

This report discusses application of a new lightweight carbon-carbon (C-C) space radiator. technology developed under the NASA Civil Space Technology Initiative (CSTI) High Capacity Power Program to a 20 kWe lunar based power system. This system comprises a nuclear (SP-IOO derivative) heat source, a Closed Brayton Cycle (CBC) power conversion unit with heat rejection by means of a plane radiator. The new radiator concept is based on a C-C composite heat pipe with integrally woven fins and a thin walled metallic liner for containment of the working fluid. Using measured areal specific mass values (1.5 kglm 2 ) for flat plate radiators, comparative CBC power system mass and performance calculations show significant advantages if conventional heat pipes for space radiators are replaced by the new C-C heat pipe technology.

A Liquid Sheet Radiator for a Lunar Stirling Power System

“…The maximum temperature at the lunar equator at noon has been calculated to be 387 K. 2 For power system heat rejection calculations a mean effective daytime lunar sink temperature of 360 K was determined by radiatively coupling the lunar sky temperature with the lunar surface temperature profile. 11 For lunar applications waste heat elimination is limited due to the small difference between the rejection temperature and heat sink temperature. The sink temperature can be lowered to approximately 340 K if the radiator is in a horizontal configuration.…”

“…The sink temperature can be lowered to approximately 340 K if the radiator is in a horizontal configuration. 11 In order to reduce the heat sink even further; the area around the radiator could be covered with a highly reflective aluminized blanket. This would decrease the sink temperature to 230 K and would only increase the mass of the radiator system by less than 0.1 kg/m 2 .…”

“…This would decrease the sink temperature to 230 K and would only increase the mass of the radiator system by less than 0.1 kg/m 2 . 11 Another option would be to place the radiator in a crater where it is not illuminated by sunlight. In previous liquid sheet radiator designs as seen in figure 6, multiple sheets were needed to create large radiating surface areas to dissipate the heat flux.…”