Adsorption working pairs for adsorption cooling chillers: A review based on adsorption capacity and environmental impact

Adsorption working pairs are the vital main components in the adsorption refrigeration machines. Therefore, the key for the further development is focusing on the adsorption pairs, which lead to the improvement of the adsorption refrigeration machines. In this study, an overview of both classical and modern adsorption pairs of the adsorption refrigeration systems is presented, compared and summarized. It was found that the maximum adsorption capacity for the classical working pairs was 0.259 kg/kg for activated carbon/methanol pair and that for the modern working pairs was 2 kg/kg for maxsorbIII/R-134a pair. This study concluded that, further investigations are still necessary to improve the performance of the adsorption working pairs of adsorption cooling systems as well as to develop the adsorption pairs with higher sorption capacity while with low or no impact on environment, in order to build compact, efficient, reliable, and long-life adsorption chillers. It was additionally found that activated carbon powder adsorbent has not been paid much attention so far, and hence, the study and application of it are to be of great interest. Further researches need to be focused on designing the adsorption system that provides efficient heating and cooling for the adsorbent materials by distributing the adsorbent material over heat exchanger surface, to allow good heat and mass transfer between the adsorbent and the refrigerant.