MODELING OF A SPRAY ASSISTED NATURAL DRAFT COOLING TOWER

Abstract

Cooling towers are one of the largest heat and mass transfer devices that are in common use. A novel type of coolingtower has been proposed in which air flow rate into the tower is drawn by ejector action of sprays instead of fans as isdone in conventional mechanical forced or induced draft cooling towers. This novel design offers the potential of savingthe energy cost for driving the fan. The paper presents mathematical models for momentum transfer which is the drivingforce causing the entrainment of air. Also the heat transfer model for co-current flow of liquid and gas in the tower hasbeen presented. The liquid to gas ratio tend to decrease as liquid rate increases. The ratio attained in the experimentallaboratory tower was 3.3, correspondingly the Momentum transfer efficiency for the tower was 60% and was the highest.Experiments for cooling water initially at 45 o C to final water temperature 27 o C showed that the cooling tower efficiencywas 54% and number of transfer unit 0.8.