Studies on evaporative cooling pads employed for fin and tube condenser

Abstract

Evaporative cooling is one of the earliest techniques used for space and process cooing. Though vapour compression refrigeration systems (VCRS) are dominantly used nowadays, evaporative cooling is getting renewed attention due to environmental awareness. Abundant studies have been carried out by researchers to understand the cooling effect due to direct interaction of water and air. Improving this cooling effect is key area of research since evaporative cooling is being widely used in building cooling and process cooling systems. In the present work, a test facility consisting of Fan-Cooling pad-Water spray (FCW) unit has been developed to observe direct water-air interaction with and without a cellulose cooling pad. Experiments are conducted during two different climatic conditions namely cool and humid (25and#61616;C and 75% RH), hot and less humid (33and#61616;C and 45% RH) DBT and humidity of exit air, spray water outlet temperature are continuously monitored and performance parameters namely cooling rate and evaporation rate of spray water, volumetric heat and mass transfer coefficients have been determined. Volumetric heat and mass transfer coefficients have been introduced to understand air-water interaction so that contact volume between air and water with and without pad can be used as an effective parameter in the analysis. Experimental values of these parameters have been determined and correlations for Nusselt and Sherwood number have been obtained using multi-linear regression analysis with a maximum of and#61617;20% error band. Also, a two dimensional, numerical model for water and air interaction in cross flow has been developed based on mass and energy balance as well as convective heat and mass transfer relations, with transfer coefficients obtained from experimental correlations. newline