Abstract
Adsorption equilibria of ethanol and methanol vapors on activated carbon fibers (ACF) and granular one (GAC) were measured at 30 and 50°C, and adsorption isotherms over a wide temperature range were predicted from the experimental equilibrium curves. The cooling effect in an ideal cycle of adsorption refrigerators was estimated under the typical operating temperature conditions from the predicted isotherms. The results obtained showed that the ACF with large surface area has high adsorptive capacity for both ethanol and methanol vapors. The cooling effect estimated for the ACF/methanol pair exceeded 300 kJ/kg, and these values were greater than those for the GAC/methanol pair. Furthermore, we could successfully prepare ACF with high bulk density (HD-ACF) from phenol resin fibers without adding any binders. The prepared HD-ACF has a dense structure with smooth fibers, and has micropores mainly in the range of the radius below 2 nm. The HD-FAC adsorbed rapidly ethanol and methanol vapors comparable to the felt-type ACF. The cooling effect on the apparent volume basis showed an extremely high value of 177 MJ/m3 for the HD-ACF/methanol pair. Therefore, we concluded that it is feasible to apply this working pair to adsorption refrigerators.
