4. HOW COOLING TOWER WORKS ?
HEAT AND MASS TRANSFER.
COOLING TOWER WORKS ON THE PRINCIPLE OF EVAPORATION.
1 KG OF WATER ON EVAPORATION REMOVES APPROXIMATELY 530 KCALS OF HEAT
THE HEAT GIVEN UP BY THE WATER FALLING INSIDE THE TOWER EQUALS THE HEAT
GAINED BY THE AIR RISING THROUGH THE TOWER.
THE HOT WATER ENTERING THE TOWER IS DISTRIBUTED WITHIN THE STRUCTURE IN A
MANNER THAT EXPOSES A VERY LARGE WATER SURFACE TO THE AIR PASSING THROUGH.
WATER DISTRIBUTION IS ACCOMPLISHED BY MEANS OF SPRAY NOZZLES OR DISTRIBUTION
PANS AND BY MEANS OF VARIOUS TYPES OF “FILL”.
THIS FILL INCREASES THE EXPOSED WATER SURFACE TO MAXIMIZE CONTACT WITH THE
AIR, INCREASING THE RATE OF HEAT TRANSFER.
11. ATMOSPHERIC COOLING TOWERS
Atmospheric type known as hyperbolic cooling tower is named as per its
geometric shape.
Air flow through the tower is produced by thee density differential that exists
between the heated (less dense) air inside the stack and the relatively cool
(more dense) ambient air outside the tower.
Generally used 250000 gpm and more and occasionally in excess of 500feet
in height.
High installation cost.
13. MECHANICAL DRAFT COOLING TOWERS
TOWERS USE EITHER SINGLE OR MULTIPLE FANS TO PROVIDE
KNOWN VOLUME OF AIR THROUGH THE TOWER.
THUS THEIR THERMAL PERFORMANCE TENDS TOWARDS GREATER
STABILITY, AND IS AFFECTED BY FEWER PSYCHOMETRIC VARIABLES
THAN THAT OF THE ATMOSPHERIC TOWERS.
FURTHER CLASSIFIED INTO:
FORCED DRAFT COOLING TOWERS
INDUCED DRAFT COOLING TOWERS
19. PARTS OF COOLING TOWER
SUPER STRUCTURE / FRAME AND CASING
FILL.
COLD WATER BASIN.
DRIFT ELIMINATORS.
LOUVERS.
NOZZLES.
FLOW CONTROL VALVE.
HOT WATER DECK.
FAN DECK.
FAN STACK.
GEAR REDUCER.
FAN.
MOTOR.
