Sustainable Indoor Thermal Regulation with Hybrid Desiccant and Post-Cooling Technologies

This study investigated the performance of a hybrid desiccant dehumidification system integrated with a post-cooling mechanism, focusing on its application to energy-efficient indoor climate control. A liquid desiccant system using magnesium chloride (MgCl2) was tested in its pure form and in combination with silica gel at 10% and 20% concentrations to enhance its moisture removal capabilities. The key parameters, including the air velocity (3–6 m/s), desiccant flow rate (1–3 LPM), and desiccant composition, were varied to analyze their effects on the dehumidification efficiency, moisture removal rate (MRR), temperature reduction after post-cooling, and coefficient of performance (COP). The results show that post-cooling using a crossflow heat exchanger effectively lowered the exit air temperature, ensuring thermal comfort. Addition of silica gel significantly improved system performance. The MgCl2 + 20% silica gel mixture achieved the highest dehumidification efficiency of 0.86, the greatest temperature drop of 1.95 °C, and the maximum COP of 2.36 at optimal flow conditions. While the dehumidification efficiency declined with increasing air velocity due to reduced contact time, the COP increased owing to the higher thermal processing of the air stream. This study highlights the potential of optimized hybrid desiccant systems as sustainable solutions for building air conditioning, aligning with the key Sustainable Development Goals (SDGs) related to clean energy, climate action, and sustainable infrastructure.