Reducing Electricity Consumption in Saudi Arabia using Novel Vapour Compression Cooling System with Evaporator and Condenser Coated with Advanced Metal Organic Framework Desiccant Material


The electricity sector in the Kingdom of Saudi Arabia (KSA) is facing great challenges of meeting the annual increase in electricity demand at approximately 7%. Over 50% of the Kingdom’s total electricity production is consumed by the residential sector. With ambient air temperatures reaching up to 50◦C in the summer, 60% to 70% of the energy consumed by residential buildings is due to the air-conditioning systems causing extra strain on the electricity generation sector which is mainly generated using fossil fuels. With this increased electricity consumption, KSA emitted 588 million metric tons of carbon dioxide (MtCO2) in 2020 making it one of the largest producers of CO2 emissions per capita worldwide, at roughly 18 metric tons per person per year.

In air conditioning applications, the vapor compression system (VCS) generally operates through refrigeration-based dehumidification process. In this process, the humidity load is removed by condensation through cooling the air below its dew point leading to a large temperature difference across the vapour compression cycle. This results in decreasing the VCS’ Coefficient of Performance (COP) and increasing the air conditioning system electricity consumption. Furthermore, in hot and humid climates (coastal cities) with low sensible heat ratios, an additional reheating process may be required after the refrigeration-based dehumidification process leading to further increasing the electricity consumption of the air conditioning system. Coating the evaporator and condenser in air conditioning systems with desiccant material brings great advantages since it enables utilizing the isothermal adsorption and desorption of water vapour to control the humidity and temperature of the air thus reducing the temperature difference across the vapour compression system and enhancing its COP. 

Metal Organic Frameworks (MOFs) are new class of meso-porous desiccant materials with exceptionally high porosity, large surface area (up to 5500m2/g) and superior water vapour uptake (up to 1.5kgw/kgads). They significantly outperform conventional desiccant materials like silica gel and zeolites with water uptake of <0.3kgw/kgads. This project aims to develop a new generation of highly efficient vapour compression air conditioning systems integrated with MOF desiccant coated evaporator and condenser. The MOF coated evaporator can simultaneously remove both the sensible and latent loads of the incoming air without reducing the temperature below its dew point. While the regeneration of wet MOFs is completely driven by the rejected heat from the coated condenser. Thus, the operation of the evaporator and condenser will alternate to enable the regeneration of the MOF desiccant material and continuous operation of the vapour compression system to produce the required cooling. It is expected that this vapour compression cooling system with MOF coated evaporator and condenser to have COP of 7-8 leading to electricity saving of around 40%.

Project Objectives

  1. Review the various vapour compression systems used in KSA and identify the most commonly used ones for domestic air conditioning. Acquire the identified domestic air conditioning system, carry out performance testing and develop a validated thermodynamic model which predicts its performance at various operating conditions. 
  2. Detailed review of recent advances in Metal Organic Framework Materials and their composites (MOFs and cMOFs) for water adsorption in terms of their water uptake, kinetics and thermophysical properties to identify the best MOF/cMOF materials that suit the weather conditions in KSA. Synthesize the identified MOF/cMOF material, characterize its performance and produce the required quantities (5kg).
  3. Update the thermodynamic model of the air conditioning system to include the effect of MOF/cMOF coating on its evaporator and condenser. Use this model to predict the optimum amount of MOF/cMOF needed for coating and the performance of the new system.
  4. Coat the evaporator and the condenser of the acquired air conditioning system with the identified MOF/cMOF and carry out performance testing and compare to the performance of the system without coating.
  5. Carry out an extensive program of knowledge transfer of the project outcomes through holding one workshop, two seminars and publication of two papers. Also, preparation of educational material that can be used for undergraduate and postgraduate studies.