This document provides an introduction to cooling towers, including their basic principles and components. It discusses the different types of cooling towers, including natural draft towers, forced draft towers, and induced draft towers. Key terms used in the cooling tower industry are also defined, such as drift, blow-out, plume, and blow-down. The main components of a cooling tower are described as the frame and casing, fill, cold-water basin, drift eliminators, air inlet, louvers, nozzles, and fans. Different types of mechanical draft towers like forced draft, induced draft counter flow, and induced draft cross flow are illustrated.

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2. LECTURE NO. 1

3. LECTURE NO. 1
TOPIC COVER
Introduction
Types
Useful Definitions
Factors Which Effects the performance of C/T
General Discussion about C/T

4. 1. BASIC PRINCIPLE
1.1 Cooling Tower Fundamentals
Heat Transfer:
The basic principle of the cooling tower operation is that of
evaporative condensation and exchange of sensible heat.
The air and water mixture releases latent heat of
vaporization which has a cooling effect on water by turning
a certain amount of liquid into its gaseous state thereby
releasing the latent heat of vaporization.

5. 1.2 Why we need COOLING TOWER in Industries ?
Cooled water is needed for, for example, air conditioners,
manufacturing processes or power generation.
A cooling tower is an equipment used to reduce the
temperature of a water stream by extracting heat from
water and emitting it to the atmosphere..

6. 1.3 Schematic diagram of a cooling water system

7. 1.4 Some useful terms, commonly used in the COOLING TOWER Industry:
Drift - Water droplets that are carried out of the cooling tower with the exhaust air. Drift
droplets have the same concentration of impurities as the water entering the tower. The
drift rate is typically reduced by employing baffle-like devices, called drift eliminators,
through which the air must travel after leaving the fill and spray zones of the tower.
Blow-out - Water droplets blown out of the cooling tower by wind, generally at the air
inlet openings. Water may also be lost, in the absence of wind, through splashing or
misting. Devices such as wind screens, louvers, splash deflectors and water diverters are
used to limit these losses.
Plume - The stream of saturated exhaust air leaving the cooling tower. The plume is visible
when water vapor it contains condenses in contact with cooler ambient air, like the
saturated air in one's breath fogs on a cold day. Under certain conditions, a cooling tower
plume may present fogging or icing hazards to its surroundings. Note that the water
evaporated in the cooling process is "pure" water, in contrast to the very small percentage
of drift droplets or water blown out of the air inlets.
Blow-down - The portion of the circulating water flow that is removed in order to
maintain the amount of dissolved solids and other impurities at an acceptable level.
Leaching - The loss of wood preservative chemicals by the washing action of the water
flowing through a wood structure cooling tower.
Noise - Sound energy emitted by a cooling tower and heard (recorded) at a given distance
and direction. The sound is generated by the impact of falling water, by the movement of
air by fans, the fan blades moving in the structure, and the motors, gearboxes or drive
belts.

8. 1.4 Components of COOLING TOWER
The basic components of a cooling tower includes
1. Frame and casing.
2. Fill.
3. Cold-water basin.
4. Drift eliminators.
5. Air inlet.
6. Louvers.
7. Nozzles .
8. Fans.

9. 2. TYPES OF COOLING TOWER
2.1 Natural Draft Cooling Tower
a. Cross Flow N D C T
b. Counter Flow N D C T
2.2 Mechanical Draft Cooling Tower
a. Forced Draft
b. Induced Draft Cross Flow
c. Induced Draft Counter Flow

10. 3. FEATURES AND OPERATION OF VARIOUS
COOLING TOWER
3.1 Natural Draft or Hyperbolic Cooling Tower
Air flow through N D C T is due to largely difference in
DENSITY between the warm air in the tower and the
external ambient air.
Tremendous size of usually 500 ft high and 400 ft in
diameter at the base.
Generally used for water flow rates above 200,000 gal/min.
Fresh cool air is drawn into the tower through an air inlet at
the bottom.
No fan is required.

11. 3.1.1 View of Natural Draft Cooling Tower

12. 3.2 Mechanical Draft Cooling Tower
Large fans to force or draw air through circulated water.
The water falls downwards over fill surfaces, by increases the
contact time which helps maximize heat transfer between
the water and the air.
Cooling rates depend upon various parameters
such as
1. fan diameter.
2. speed of operation.
3. fills for system resistance.

13. 3.2.1 Types of Mechanical Draft Cooling Tower
a. Forced Draft
b. Induced Draft Cross Flow
c. Induced Draft Counter flow

14. 3.2.1 (a) Forced Draft Cooling Tower

15. 3.2.1 (b) Induced Draft Counter Flow

16. 3.2.1 (c) Induced Draft Cross Flow