Thermodynamic analysis of adsorption refrigeration cycles using parent and surface treated Maxsorb III/Ethanol pairs.

Adsorption equilibrium uptake of environment friendly refrigerant ethanol onto highly porous activated carbon based adsorbents has been experimentally investigated by using a magnetic suspension balance adsorption measurement unit (MSB-VG-S2). Adsorbents used in the present study are parent Maxsorb III, H2 and KOH-H2 surface treated Maxsorb III. Experiments have been conducted over adsorption temperatures range from 30 to 70°C and evaporation temperatures between -6 and 65°C. The Dubinin-Radushkevich and Dubinin-Astakhov adsorption isotherm models have been used to correlate adsorption isotherm data and to plot the pressure-temperature-concentration (P-T-W) diagrams of the assorted pairs. Isosteric heat of adsorption is estimated using the Clausius–Clapeyron equation. In the present study, the performance of adsorption refrigeration cycles using activated carbons/ethanol pairs has also been investigated employing a time-independent mathematical model. Results are compared with other adsorbent/refrigerant pairs found in the open literatures. Theoretical analysis show that the H2-treated Maxsorb III/ethanol adsorption refrigeration cycle can achieve coefficient of performance (COP) of 0.51 and specific cooling effect of about 374 kJ/kg at the evaporator temperature of -5°C in combination with heat source and heat sink temperatures of 100 and 30°C, respectively.