Numerical and experimental development of an efficient adsorption desalination and cooling system

Abstract

In this Ph.D. thesis, different methods for enhancing the performace of heat powered adsorption system for water desalination and cooling are investigated through numerical and experimental works. These enhancement methods include: (i) optimizing the geometric design of the adsorber bed heat exchangers for both packing or coating with the adsorbent material , (ii) determining the best method of connecting the heat exchanger modules of the adsorber bed and the best vapor gap between them to reduce the mass transfer resistance, (iii) using metal-organic framework (MOF) adsorbent materials namely aluminium fumarate and a newly developed composite zirconium fumarate (MOF-801) / graphene to replace the conventional adsorbent materials, (iv) reducing the dead volume in the condenser and evaporator chambers to enhance the compactness of the adsorption system and (v) integrating the adsorption system with different desalination technology to increase the water recovery, and reduce the specific energy consumption. After optimizing the geometrical design of the heat exchanger in the adsorber bed, a comparative study between a packed rectangular-finned tube and a coated wire-finned tube is conducted. Results showed that the coated wire-finned tube enhanced the adsorption system specific daily water production (SDWP) and specific cooling power (SCP) by 82% compared to the packed rectangular finned tube, while it lowered the system coefficient of performance (COP) by 52%. In terms of the specific volumetric daily water production (SVDWP), the adsorption system with coated wire-finned adsorber beds has SVDWP lower than the system with packed one by 21%. Integrating the adsorption system with a Batch Reverse Osmosis (BRO) desalination system using packed rectangular-finned tube adsorption system and a wide range of water salinity, it is found that the water recovery can be increased to 96.9% and 65.3% when brackish water and seawater are fed to the hybrid system respectively. Finally, using a newly developed composite zirconium MOF (MOF-801) material with graphene nanoplatelets enhanced the SDWP and SCP by 40% due to its higher thermal conductivity and faster kinetics compared to the neat MOF