Performance analysis of activated carbon + HFC-134a adsorption coolers

The purpose of this paper is to present the results of performance analysis of a heat driven continuous vapor adsorption refrigerator with activated carbon as the adsorbent and 1,1,1,2-tetrafluoroethane (HFC-134a) as the refrigerant. A set of four adsorption cells takes on the role of the mechanical compressor in the conventional vapor compression refrigeration (VCR) system. Three specimens of activated charcoal under various packing densities were investigated. A parametric analysis was carried out with several evaporating, condensing/adsorbing and desorbing temperatures which are typical operating conditions catered to by HFC-134a. A new integrated relative performance evaluation scheme is proposed. It uses the maximum cycle uptake difference as a factor against which the coefficient of performance (COP) and exergetic efficiency are evaluated. It is shown that there is an optimal set of operating conditions wherein the exergetic efficiency is the maximum. A major part of the thermal energy input is for sensible heating of the compressor body.