In this paper, adsorption isotherms and kinetics of ethanol onto highly porous activated carbon powders have been investigated. Adsorbents used in the present study are (i) parent Maxsorb III, (ii) KOH-H2 treated Maxsorb III, and (iii) H2 treated Maxsorb III. Adsorption isotherms and kinetics of the assorted pairs have been measured using magnetic suspension adsorption measurement unit (MSB-VG-S2). Experiments have been conducted across assorted adsorption temperatures that are useful for the operation of adsorption chillers. The Dubinin-Astakhov equation is used to fit adsorption isotherms of parent Maxsorb III/ethanol and KOH-H2 treated Maxsorb III pairs whilst the Dubinin-Raduskevich isotherm model is found to be more suitable for fitting of adsorption uptake of H2-treated Maxsorb III/ethanol pair. Adsorption kinetics of assorted pairs are presented by the Fickian diffusion model. Experimental results show that, among the assorted pairs, H2 treated Maxsorb III/ethanol pair possesses the highest adsorption equilibrium uptake. However, the diffusion time constant of KOH-H2 treated Maxsorb III isfound to be higher than that of other two studied pairs. NomenclatureA adsorption potential (kJ Kg -1 ) W equilibrium adsorption uptake (kg kg -1 ) w instantaneous adsorption uptake (kg kg -1 ) win initial uptake (kg kg -1 ) Wo maximum adsorption capacity (kg kg -1 )

Heat pump systems are often considered as one of the major contributors to environmental problems due to the usage of chlorofluoro, hydrochlorofluoro, and hydrofluoro carbon-based refrigerants. Earlier versions of refrigerants used to have high ODP as well as GWP. However, next generation refrigerants that are environmentally benign with excellent thermophysical properties are still under development stage. This study reviews the historical development of refrigerants, their environmental impacts and observes the viewpoint for present options in terms of Montreal Protocol, Kyoto Protocol, and EU F-gas regulation. The discussion extends to the actions of international agreements on the phase-out of hydrochlorofluorocarbons for developed and developing countries. This study also highlights the approach of large heat pump industries in Asia region regarding the use of various refrigerants. The direct CO2 emission per year from air-conditioning and refrigeration sectors due to the system leakage is assessed. It also examines the major contributors of CO2 emission in every year among the various sectors for providing per kilowatt cooling effect. Finally, the ideal cycle performance is compared to various refrigerants and stated the current best option.

a b s t r a c tAdsorption characteristics of ethanol onto two promising adsorbents have been investigated for developing high performance adsorption chillers. These new adsorbents are based on spherical phenol resin treated with different mass ratios of KOH named as KOH4-PR and KOH6-PR. Experimental adsorption isotherm measurements show that the adsorption capacity of KOH4-PR/ethanol is as high as 1.43 kg kg À1 whilst one kg of KOH6-PR able to adsorb nearly about 2 kg of ethanol. To the best of our knowledge, the studied adsorbents possess the highest ethanol uptake. Moreover, it is found that the KOH4-PR/ethanol pair has notably high adsorption kinetics at the lower range of adsorption temperatures. Experimental measurements of adsorption uptake and adsorption uptake rate of the studied pairs have been analyzed and isosteric heats of adsorption have also been extracted.

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