External Thermal Control System Research Articles

Comparison of Heat Pumps for Permanent Lunar Base

A permanent lunar habitat will require a heat pump to elevate waste heat from ∼298 K to ∼340-360 K to reject it from a reasonably sized radiator array because the effective sink temperature is 265 K for horizontal radiators at noon of the 336 h lunar daylight period. Because launch cost is proportional to mass, the figure of merit is overall mass of the external thermal control system: compressor, power source, radiators, heat exchangers, pumps, and piping. Previous investigations involved very detailed optimizations for electromechanical compressors. This investigation expands upon those by conducting a comprehensive assessment of thermally driven sorption heat pumps: absorption (liquid-vapor), adsorption (solid-vapor), and chemisorption (thermally reversible reaction between binder and refrigerant). The lowest mass alternative is a new design for an adsorption (carbon-methanol) heat pump with an overall system mass of 652 kg, as compared with 726 kg for an electromechanical compressor.