Lunar base thermal control systems using heat pumps

Abstract There is considerable interest at the present time to design a thermal control system (TCS) for a lunar base. Conventional techniques cannot be used for the purpose due to the lack of a readily available temperature sink during most of the lunar day. The lunar surface near the equatorial regions reaches a maximum of about 390 K during the 336-h lunar day. The projected range of temperatures for operation of sensors and 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. Rankine, absorption, and reverse Brayton cycle heat pumps with various working fluids are examined to identify the optimal cycle and working fluid combination. A base-line cooling load of 100 kW to be rejected at 270 K is used in the analysis. A Rankine cycle heat pump operating with R11 as the working fluid and R717 as a rejection loop coolant provides an optimal total TCS mass of 5940 kg at a radiator temperature of 362 K.