Design of Adsorption Heat Pump for Permanent Lunar Base

The design of an adsorption heat pump for a permanent lunar habitat is described herein. The adsorbent refrigerant pair is chopped carbon fiber and methanol. The adsorption vessels are shell-and-tube with innovations to enhance conductance. The tubes have both radial internal and annular external fins, with metal wool loosely packed between the annular fins. Shell, tubes, fins, and wool are aluminum alloy. Carbon particles are vibratory compacted to 50% porosity between the annular fins and around the wool. An analytical model is presented for predicting efficiency and validated against a state-of-the-art prototype reported in the literature. The new design is compared with three of the highest efficiency prior designs on the basis of a figure of merit, which roughly correlates to efficiency, and is defined as the number of transfer units for the adsorption vessel's internal heat exchanger multiplied by the ratio of adsorbent to inert thermal mass. The new design has a predicted coefficient of performance for cooling of 1.5, 25% greater than previously reported. Specific cooling power is 355 W (.) kg(-1) of adsorbent or 141 W (.) k g(-1) of total mass (carbon, methanol, aluminum, and ethylene glycol heat transfer fluid), requiring 106 kg of adsorbent vessels to provide 15 kW of cooling.