Experimental investigations of humidification parameters and transient analysis in a rotating centrifugal humidifier

Abstract

Evaporative cooling is one of the easiest methods of achieving thermal comfort inside defined space, especially in arid regions. The current work adopts a novel approach in the design and fabrication of a humidifier unit that works on the centrifugal effect. The system consists of a cylindrical mesh that is filled with packing material driven by a motor. The rotating packing cylinder is soaked by the water dripping by gravity. The vortex effect caused by the centrifugal action on the packing allows dispersing the fine water particles in the air. Airblown inside the chamber gets humidified due to the evaporation of water. Output parameters such as evaporation rate (ER), cooling efficiency (HE), coefficient of performance (COP), cooling effect, and specific cooling effect (SCC) are determined for various combinations of air velocities and cylinder speed of rotation. Experiments are carried for both static and dynamic packing conditions. It is found that dynamic packing with 150 rpm and air velocity of 8 m/s gave a superior performance in terms of change in DBT, change in RH, humidification efficiency, and evaporation rate. The system gave a maximum COP of 5.85, an evaporation rate of 0.51 g/s, and a humidification efficiency of 79.23%. Transient analysis indicated that required thermal conditions could be attained in the dynamic case earlier than the static conditions saving both energy and valuable time. Overall, the performance of dynamic packing is superior compared to the stationary packing in terms of higher ΔRH, ΔDBT, humidification efficiency, and evaporation rate.