The thermal pollution problem is associated with

Chapter 7, Problem 7.140

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The thermal pollution problem is associated with dis-charging warm water from an electrical power plant orfrom an industrial source to a natural body of water.Methods for alleviating this problem involve coolingthe warm water before allowing the discharge tooccur. Two such methods, involving wet cooling tow-ers or spray ponds, rely on heat transfer from the warmwater in droplet form to the surrounding atmosphere.To develop an understanding of the mechanisms thatcontribute to this cooling, consider a spherical dropletof diameter Dand temperature T, which is moving at avelocity Vrelative to air at a temperature T?andrelative humidity ?. The surroundings are character-ized by the temperature Tsur. Develop expressionsfor the droplet evaporation and cooling rates. Calcu-late the evaporation rate (kg/s) and cooling rate (K/s)whenD?3 mm, V?7 m/s, T?40?C, T??25?C,Tsur?15?C, and ??0.60. The emissivity of wateris w? ?0.96