![]() ![]() The efficiency of this device depends essentially on climatic conditions, in particular the wet-bulb temperature and the relative humidity of the ambient air. In a natural draught cooling tower, as shown in figure the circulation of air is produced by the pressure difference of air inside and outside the cooling tower This is a very large tower in which the hot water encounters a natural draught which promotes cooling of the water by convection and evaporation. The cooling tower, generally packed with brushwood or wooden laths. Induced Draft Cooling Tower – Cross Flow type Natural draft water-cooling tower Induced Draft Cooling Tower – Counter Current Flow type The counter current tower is expected to be more efficient, but the cross flow tower can be operated with lower power requirement or higher vapour velocities. They are generally induced draft cooling tower classified as counter current or cross flow tower, descriptive of the direction of air flows relative to that of the water. The circulation of air is provided by means of fans placed at the top of the tower. In an induced draught cooling tower, as shown in below figure. The circulation of air in forced draft cooling tower is produced by means of fans placed at the base of the tower Induced draught cooling tower In a forced draught cooling tower, as shown in figure. The water flows from one stage to the next and finally arrives at the pond which forms the base of the structure, from which it is taken by the cold water pump. ![]() It falls as rain on to successive stages of boards in the form of louvres of wood, polystyrene or metal, with notches and ribs to break up the flow. The water is pumped to the top and broken up into sprays. These take the form of a large rectangular concrete structure. Mechanical draft water-cooling tower consists mainly two typesĪ) Forced draft – In this cooling tower fans located at the air inletī) Induced draft – In this cooling tower fans located at the air exhaust. This helps maximize heat transfer between the air and water. ![]() The water falls downward over surface of fills, which help increase the contact time between the air and water. These mechanical draft cooling towers utilize large fans to force air through circulated water. Mechanical draft cooling towers are more commonly used for cooling of water. Natural draft cooling tower Mechanical draft water-cooling tower: Usually Louvers are installed at an angle to the direction of air flow to the cooling tower.įundamental Concept of Cooling Tower : Heat is transferred from water drops to the surrounding atmospheric air by the transfer of latent heat and sensible heat.Ĭooling towers mainly classified into two sub-divisionsĢ. Louvers: Members installed horizontally in a cooling tower wall to provide openings through which the air enters into the system while also containing the falling water within the tower. Makeup : Water added to the circulating water in cooling tower system to replace water lost by evaporation, blowdown, drift and leakageĭrift eliminators: An assembly constructed of plastic, cement board, wood, or other material that minimize the entrained water moisture from the discharged air.Ĭooling water: W ater circulated through a cooling system to remove heat from certain areas.Įxhaust air: The mixture of air and its associated vapor leaving the cooling tower system It is normally expressed directly as ( parts per million) ppm or indirectly as mhos conductivity.Īir Blows: By the opening in cooling tower through which air enters a tower.īlowdown: Water discharged from the system of cooling tower to control concentration of salts or other impurities in the circulating waterĮvaporation loss: In the process of cooling tower system, water evaporated from the circulating water into the atmosphere. Usually concentration of liquid in cooling tower occurs due to evaporation that cools the water. Heat exchange/ Condenser – It is a device for transferring heat from one substance to another.Ĭoncentration: The process of increasing solids per unit volume of solution also the amount of material dissolved in a unit volume of solution. It is independent of water lost by evaporation. After reducing the temperature of water in cooling tower and is sent back to the condenser /exchangers or to other units for further process.ĭrift: From a cooling tower water lost due to liquid droplets entrained in the exhaust air. Hot water from heat exchangers/condenser is sent to the cooling tower. The make-up water source is used to refill water lost to evaporation. Types of cooling tower | Cooling Tower Basic CalculationsĬooling towers are a very important part of many process plants and power plants. ![]()
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