MgCl2-silica gel mixture as a sustainable liquid desiccant for humidity control

Despite the growing demand for efficient dehumidification systems, limited research has explored the potential of magnesium chloride (MgCl 2 ) combined with silica gel as a composite liquid desiccant. The primary objective of this study is to systematically investigate and quantify the dehumidification performance enhancement achieved by incorporating silica gel (10 % and 20 % by weight) into MgCl 2 solution under varying operational conditions. Specifically, this work aims to: (1) evaluate the hygroscopic properties and moisture absorption capacity of MgCl 2 -silica gel composits compared to pure MgCl 2 , (2) determine the optimal operating parameters including air velocity (5–7 m/s) and desiccant flow rates (1–3 LPM), and (3) establish relationship between silica gel concentarion and dehumidification efficinency. The key contribution of this research is the development and performance characterization of a novel MgCl 2 -silica gel composite liquid desiccant that demonstrates significantly enhanced moisture removal capabilities. Experimental results reveal that MgCl 2 + 20 % silica gel achieves the highest moisture removal (ΔW=0.00196 kg/kg) at 2 LPM flow rate, representing a substantial improvement over pure MgCl 2. At optimal air velocity (7 m/s), the composite desiccant achieves a moisture removal rate of 0.00110 kg/s, a 22 % enhancement over pure MgCl 2 . The dehumidification efficiency ranges from 35 % at 5 m/s to 41.5 % at 7 m/s, with the 20 % silica gel composite showing 22 % higher efficiency than pure MgCl 2 at maximum air velocity. For desiccant flow rates, peak efficiency of 67 % is achieved at 2 LPM. This study makes a significant contribution to the field by demonstrating that silica gel incorporation creates a synergistic effect, where the high surface area and porosity of silica gel complement the hygroscopic properties of MgCl 2 , resulting in enhanced moisture absorption across broader humidity ranges. The findings provide a foundation for developing more sustainable and energy-efficient liquid desiccant systems for air conditioning applications, addressing both environmental and economic sustainability goals. A schematic representation of the composite liquid desiccant’s dehumidification process, its mass transfer mechanisms, and energy-saving potential • Mixed desiccant made of MgCl2, 30 % concentration, and varied volume fraction of silica gel was tested for dehumidification applications. • Operating parameters such as desiccant flow rate, air velocity and desiccant types are varied and results obtained were analysed. • MgCl₂ + 20 % Si showed the highest specific humidity reduction at 0.00198, compared to 0.00192 for MgCl₂ + 10 % Si and 0.00188 for bare MgCl₂. • Increasing desiccant flow rate enhances moisture removal up to an optimal flow rate of 2 LPM, beyond which efficiency decreases. • MgCl₂ + 20 % Si consistently shows the highest efficiency, with peak performance at 0.00105 kg/s moisture removal rate.