Influence of desiccant concentration and temperature on moisture absorption using a multistage dehumidifier

Moisture control is essential for appropriate indoor air quality, mainly in humid regions. Liquid desiccant dehumidification system is among the latest techniques used to minimize the humidity indoors and maintain thermal comfort, requiring less energy than dehumidification through conventional refrigeration. In the current work, a four-stage dehumidifier is constructed, which consists of a dynamic packing soaked in the solution containing the desiccant. The linear motion of packing is induced by a cam spring follower mechanism powered by a motor. Celdek 7090 is used as packing along with Calcium Chloride of different concentrations as desiccant. Experiments are conducted for varying air velocity, desiccant concentration, and inlet dry bulb temperature. Input parameters are noted and performance parameters such as coefficient of performance, moisture removal rate, dehumidification efficiency, and humidity and temperature drops are evaluated. Results indicate that an increase in the desiccant concentration yields larger dehumidification, though 40% desiccant concentration led to adverse effects on the system components and hindered the flow. Rise in the inlet temperature slightly raised the dehumidification. System gave maximum moisture removal rate, dehumidification efficiency, and coefficient of performance equal to 4.83 g/s, 72.74%, and 4.35 respectively. Results also showed that increasing air velocity reduced the dehumidification efficiency. Air quality check conducted on the exit air, it is found that air quality is good and meets ASHRAE standards.