Thermal control system for lunar base cooling

Abstract

The design of a thermal control system (TCS) for cooling a lunar base is considered. Conventional techniques cannot be used for this purpose because of the lack of a readily available heat sink during most of the lunar day. The temperature of the lunar surface near the equator reaches a maximum of about 390 K during the lunar day. The projected range of temperatures for operation of sensors and thermally conditioned habitat spaces is 270-293 K. A heat-pump-augmented TCS can be used to increase the operating temperature of the radiator, thereby enabling heat rejection. The masses of TCSs utilizing Rankine cycle and closed Brayton cycle heat pumps are examined in detail. The TCSs are optimized for minimum total mass. Quantitative comparisons show that the Rankine cycle systems are less massive than the Brayton cycle systems. The optimal total TCS mass for a Rankine cycle heat pump with Rll as the heat pump working fluid and R717 in the rejection loop is 5940 kg at a rejection temperature of 362 K. Sensitivity analyses are performed for radiator-specific mass and power penalties.