مطالعه عددي اثر اسپري آب بر راندمان رادياتورها در برج خنك كن خشك

چكيده انگليسي :

Numerical study of effect of water spray on radiators efficiency in the dry cooling tower Ali Motahar A Motahar@me iut ac ir Date of Submission 2014 09 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisor Ahmad Saboonchi Ahmadsab@cc iut ac irAbstract As thermal power plants are one of the basic and important sections in the industry of every country investigation and simulation of different sections of a power plant aiming their improvement ofperformance and increase of efficiency seem essential condensers and cooling towers as important parts ofeach power plant are not exceptions to this generalization One of the methods of cooling the coolants usedin power plants condensers is using dry cooling towers Increase in wind velocity as well as increase inambient temperature results in decrease in efficiency of dry cooling tower In conditions with hightemperature one of the methods of increasing the efficiency of dry cooling towers is using the water sprayin order to decrease the temperature of the inlet air flow to the exchanger The water is spattered betweenradiator and louvers tower by the specific water sprayers which are setup near the tower The passing airflow is cooled by little drops of water and inters into the radiator and decreases the temperature ofoutlet water The present work has studied the previous investigations and also tried to precisely modeland simulate working conditions of Heller type cooling towers using Gambit and Fluent softwares In thepresent research the second order upwind scheme was used for discretization of the governing equations PRESTO state was used to solve pressure equation the implicit method was used for linearization of theequations the SIMPLE algorithm was used for simultaneous solving of velocity and pressure equations thestandard k turbulence model was used for the turbulence flow Radiator model was used for simulationof the heat exchangers located around the tower and finally Solid cone model was used for water spraymodeling In the present work Heller type dry cooling towers of Isfahan s Shahid Mohammad Montazerithermal power plant were simulated Inside and outside of tower was simulated in conditions with bothpresence and absence of wind Next contours of temperature pressure and velocity were analyzed Thecooling tower was simulated in different ambient temperatures Also effect of increase of ambienttemperature on the efficiency of the cooling tower in ambient temperatures of 306 35 k and 312 k with andwithout spray was studied Effects of water spray in different flow rate and different diameters and primaryvelocities of droplets were studied The effect of simultaneous presence of wind and water spray in differentflow rates and also the effect of nozzle distance to the radiator on the efficiency of the cooling tower werestudied numerically Temperature of water spray was maintained constant at 298 15k There was a goodagreement between between experimental results and the numerical results adopted in current work inabsence of wind condition Water spraying increases the average of evaporation rate relative humidity rate of heat transfer and difference of flow temperature between radiator s inlet and outlet but decreases themass fraction air on the radiator The optimumdistance between nozzles and the radiator is 2 5 m Optimalmass flow rate of water spray is 658 8 m3 hr In flow rate of water spray equal to 183 kg s 2 57 percentinlet water to tower and velocity of wind equal to 2 8 m s the rate of heat transfer on the radiator increasesby 30 23 percent compared with the condition without water spray Keywords Heller Type Dry Cooling Tower Numerical Simulation Water Spray Efficiency ofCooling Tower Fluent Radiator Model Solid Cone Spray Model

مطهر، علي

مطالعه عددي اثر اسپري آب بر راندمان رادياتورها در برج خنك كن خشك

خشك هلر , Fluent , مدل اسپري Solid cone