Dynamic dehumidifier characterisation under varied climatic conditions & pad thickness

Abstract

A Dehumidifier's performance mainly depends upon the climatic conditions of the area it is placed in. Also, the geographical location of the area influences its design. The current paper focuses on constructing a multistage dynamic dehumidifier where the packing has a reciprocating motion inside the duct. It is built for areas that has weather conditions similar to that of the United Arab Emirates. Packing is allowed to dip in the calcium chloride desiccant tank and the air interacts with soaked pads in the duct in the counter flow direction. Experiments and predictions are carried out by changing the climatic conditions and packing thickness. A mathematical model is constructed by adopting the heat and mass governing equations and validated by comparing with the experimental results. Performance parameters such as temperature changes, specific humidity changes, moisture effectiveness, moisture removal rate, and mass transfer coefficient are predicted. Results indicates that with an increase in the inlet dry bulb temperature and relative humidity, there is an increase in the dehumidification performance. Experimental and theoretical results agree with each other and are found to be within 9% deviation range. Performance parameters improved until the packing thickness was increased to 20 cm. However, with further increase in the pad thickness, the performance deteriorated. The system gave maximum moisture effectiveness, and the moisture removal rate is equal to 0.75 and 4.89 g/s. Experimental results revealed that climatic variations of change in relative humidity influences dehumidification performance more than the climatic changes involved with only temperature values. Air quality check revealed that air released to the working space is of high quality with zero carryover.