Study on activated carbon/silica gel/lithium chloride composite desiccant for solid dehumidification

Abstract

An activated carbon/silica gel/lithium chloride composite desiccant (AC-SL) for air dehumidification is proposed. Lithium chloride and silica gel are impregnated into activated carbon pores to improve the density, thermal conductivity and water vapor adsorption capacity of AC-SL. Nitrogen isothermal adsorption lines, SEM images and Fourier Transform Infrared showed that impregnation significantly reduced AC-SL is specific surface area and pore parameters and increased the content and types of oxygen-containing functional groups on its surface. The sorption kinetics study shows that the equilibrium adsorption capacity of AC-SL is 6.8 times that of activated carbon. The Dubinine-Astakhov equation based on Polanyi potential theory is used for nonlinear fitting of the water vapor isotherms adsorption, and the correlation coefficients of the fitting equations are all above 0.98. When the relative humidity is 60%, the water vapor adsorption capacity of AC-SL reached 0.81 kg kg−1, 4.5 times that of pure activated carbon. The simulation results show that the AC-SL coated heat exchanger's dehumidification capacity is 3.13 kg h−1, which has a higher cost performance than other materials.