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The objective of this study is to investigate the adsorption characteristics of granular activated carbon GAC/R-134a pair in the temperature range of 20–60°C and pressure up to 10 bars. The Dubinin–Astakhov adsorption equilibrium model is fit to experimental data with acceptable error limit. The pressure–temperature–concentration (P–T–X) diagram of the pair is also presented. The isosteric heat of adsorption of R-134a on AC has been calculated using the Clausius–Clapeyron equation as a function of adsorption capacity. The maximum adsorption capacity was found to be 1.92 kg_R134a/kg_carbon at 20°C after 1200 s. The experimental results also shows that the increase of heat transfer area improves the adsorption capacity per kg of adsorber, which lead to the design of a finned tubes heat exchanger adsorption unit.

Enhanced tubes are widely used in shell and tube condensers of refrigeration, air-conditioning and process industries because of their high heat transfer performance. In this study, condensation heat transfer tests were conducted for four three-dimensional enhanced tubes having different fin density and fin height using R-134a. The satuartion temperature was 40${}^{\circ }$C. The heat transfer was significantly enhanced by the present enhanced geometry. At 5K wall subcooling, the enhancement ratio is 6.3 for 1654fpm, 4.6 for 1575fpm, 4.0 for 1496fpm and 3.3 for 1102fpm tubes. Within the geometric variation of the present study, the condensation heat transfer coefficient increased with the increase of fin density and of fin height. The heat transfer coefficients of the 1654fpm tube were approximately the same as those of the commercial three-dimensional enhanced tube Turbo-C.