Performance evaluation of a vertical-axis rotary silica gel dehumidifier for energy-efficient and sustainable HVAC applications

Abstract This study focuses on the design and construction of a vertical-axis rotary dehumidifier test rig, which utilizes silica gel as the desiccant to remove moisture from the air. Regeneration of the desiccant is facilitated by a heater and a dedicated blower that generates suction to remove moisture adsorbed onto the solid desiccant. The tests were conducted by varying the motor speed from 40 to 100 rpm and adjusting the air Reynolds number between 13,682.43 and 45,608.1. The results demonstrated a maximum change in temperature of 4.2 °C, a specific humidity change of 3 gkg −1 , a moisture removal rate (MRR) of 0.090 gs −1 , dehumidification efficiency of 0.91, and a mass transfer coefficient (MTC) of 74.54 kgm −2 s −1 . Experimental findings indicated that the dynamic humidifier outperformed the static humidifier in terms of performance. Air quality tests revealed that pollution levels increased with motor speed and air velocity; however, pollutants such as carbon dioxide, total volatile organic compounds, and formaldehyde remained within acceptable limits. It was observed that the velocity of air entering the dehumidifier decreases with increased motor speed. Additionally, the change in air velocity and the change in specific humidity were found to be inversely proportional to each other.