Adsorption working pairs for adsorption cooling chillers: A review based on adsorption capacity and environmental impact Ahmed N. Shmroukh a,b,n , Ahmed Hamza H. Ali a , Shinichi Ookawara c a Energy Resources Engineering Department, Egypt–Japan University of Science and Technology E–JUST, New Borg Elarab, Alexandria 21934, Egypt b Mechanical Engineering Department, South Valley University, Qena, Egypt c Department of Chemical Engineering, Graduate School of Science & Engineering, Tokyo Institute of Technology, Tokyo 152-8552, Japan article info Article history: Received 11 September 2013 Received in revised form 27 August 2014 Accepted 9 May 2015 Keywords: Adsorption Adsorbent/adsorbate pairs Refrigeration abstract 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 summar- ized. 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. & 2015 Elsevier Ltd. All rights reserved. Contents 1. Introduction ........................................................................................................ 445 2. Adsorption pairs overview ............................................................................................ 446 2.1. Classical working pairs ......................................................................................... 446 2.2. Modern working pairs .......................................................................................... 447 2.2.1. Review studies ......................................................................................... 447 2.2.2. Theoretical studies ...................................................................................... 447 2.2.3. Experimental work ..................................................................................... 449 3. Conclusion ......................................................................................................... 455 Acknowledgment ....................................................................................................... 455 References ............................................................................................................. 455 1. Introduction The improvement of living standards makes people demand more comfortable and more suitable homes and working environ- ment, which resultantly and inevitably increases the need for Heating, Ventilation and Air-Conditioning (HVAC) systems. In the research field of air conditioning, therefore, for maintaining our environment green as well as for efficient use of energy, much effort should be devoted to developing air conditioning and refrigeration systems that are driven by renewable energy resources such as solar energy. Surely, the operation of HVAC systems with renewable energy is expected to decrease the peak power demand effectively. On the other hand, the conventional air Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/rser Renewable and Sustainable Energy Reviews http://dx.doi.org/10.1016/j.rser.2015.05.035 1364-0321/& 2015 Elsevier Ltd. All rights reserved. n Corresponding author. Tel.: +20 1113038100. E-mail address: eng_Ahmednagah@yahoo.com (A.N. Shmroukh). Renewable and Sustainable Energy Reviews 50 (2015) 445–456