Enhancing HVAC Efficiency Through Seasonal Separate Sensible and Latent Cooling in Hot and Humid Climates

This paper investigates the application of Separate Sensible and Latent Cooling (SSLC) using a desiccant-coated heat exchanger (DCHE) across four distinct seasonal variations in hot and humid climates, such as those in the Gulf region. The objective is to reduce the cooling load and thereby achieve higher cooling efficiency. Adapting SSLC in the United Arab Emirates (UAE) in summer (∼45°C, 90% RH), fall (∼37°C, 80% RH), winter (∼25°C, 35% RH), and spring (∼32°C, 65% RH) demonstrates significant seasonal energy savings. A high-fidelity numerical simulation was developed based on the Navier-Stokes equations of non-isothermal humid air flow coupled with conjugate heat transfer and adsorption processes on desiccant-coated silica gel fins. At a desiccated cooling temperature of 10°C below the ambient, the DCHE exhibited varying degrees of sensible and latent cooling performance. The system achieved the highest total energy reduction during summer, reaching 0.08015 kW/m, owing to a large outlet temperature drop of 31.14°C and a moderate humidity ratio reduction of 0.00117 kg/kg. In fall and spring, the system achieved energy savings of 0.06019 kW/m and 0.04815 kW/m, respectively, corresponding to modest thermal and moisture gradients. Winter recorded the lowest total energy reduction of 0.03194 kW/m, due to limited thermal and moisture gradients at the inlet. These results demonstrate a clear seasonal dependency, where higher energy saving occurs under hot and humid conditions. For instance, using 100 fins, the estimated monetary savings are 1,435 USD in summer, 1,078 USD in fall, 862 USD in spring, and 572 USD in winter, further highlighting the DCHE’s economic viability when scaled appropriately. The results emphasize the operational advantage of DCHEs over conventional systems. By effectively removing moisture from the air through adsorption, the compressor no longer needs to cool the air to the dew point, thereby minimizing its energy consumption. This highlights a substantial improvement in cooling efficiency, particularly in high temperature and humidity environments observed during summer in the Gulf regions. Scaling up the system to multiple fins (∼100 practically) will clearly underscore the DCHE’s potential as a sustainable solution for energy-efficient HVAC systems in extreme climates.