Cooling Tower Basics

Heat Transfer Equipments Pvt Ltd india’s best leading dry cooling tower manufacturers

The basic principle of the cooling tower operationis that of evaporative condensation and exchange ofs ensibleheat. The air and water mixturere leases latent

heat of vaporization which hasa cooling effect on water byturningacertainamountofliquidintoitsgaseousstatetherebyreleasingthelatentheatofvaporization.Thisismoreeffectivelydemonstratedbywettingthebackofyourhandwithwaterandblowingonit.Thiseffectiswhathappensinsidethecoolingtower.Theairstreamreleaseslatentheatofvaporizationtherebydroppingthetemperatureofthewateronyourskin.Theliquidchangingtoitsvaporousstateconsumesheatwhichistakenfromthewaterremaining,thusloweringitstemperature.Thereisapenaltyinvolved,andthatislossofwaterwhichgoesuptothecoolingtowerandisdischargedintotheatmosphereashotmoistvapor.Undernormaloperatingconditions,thisamountstoapproximately1.2%foreach10oFcoolingrange.Sensibleheatthatchangestemperatureisalsoresponsibleforpartofthecoolingtower’soperation.Whenwateriswarmerthattheair,thereisatendencyfortheairtocoolthewater.Theairthengetshotterasitgainsthesensibleheatofthewaterandthewateriscooledasitssensibleheatistransferredtotheair.Approximately25%ofthesensibleheattransferoccursinthetowerwhilethebalanceofthe75%coolingisduetotheevaporativeeffectoflatentheatofvaporization.

The basic principle of the cooling tower operationis that of evaporative condensation and exchange ofs ensibleheat. The air and water mixturere leases latent

heat of vaporization which has a cooling effect on water by turning a certain amount of liquid into its gaseousstate there by releasing the latent heat of vaporization.This is more effectively demonstrated by wetting the back of your hand with water and blowingonit.This effect is what happens inside the cooling tower.The air stream releases laten the at of vaporization there by dropping the temperature of the water on yourskin.The liquid changing to its vaporous state consumes heat which is taken from thewater remaining,thuslower ingits temperature.There is a penalty involved,and that is loss of water which goes up to the cooling tower and is discharged into the atmosphere as hotmoistvapor.Under normal operating conditions,this amounts to approximately foreach10oFcoolingrange.Sensible heat thatchanges temperature is a lso responsiblefor part of the cooling tower’soperation.When wateris warmer that the air,there is a tendency for the air to cool the water.The air thengetshotterasitgainsthesensibleheatofthewaterand thewateriscooled as its sensible heat is transferred to the air.Approximately25%ofthe sensible heattransfer occurs inthe towerwhilethebalanceofthe75%coolingisduetotheevaporativeeffectoflatentheatofvaporization.

The temperature of air as readon the ordinary ther mometer is called there ading when the bulb of at her mometeriscovered with a wet cloth,and the instrument is whirled aroundinasling.RHistheratioofthequantityofwatervaporpresentinacubicfeetofairtothegreatestamountofvaporwhichthataircouldholdatagiventemperature.Whentherelativehumidityis100%,theaircannotholdanymorewaterandtherefore,waterwillnotevaporatein100%humidair.WhentheRHis100%be cause thewatercannotevaporateanymore.Bu twhen the RH is lessthan 100%

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