This document discusses evaporative cooling applications and principles. Evaporative cooling uses the evaporation of recirculated water to lower the dry bulb temperature of an air stream. It is commonly used for spot cooling in industrial settings like foundries, kitchen ventilation, textile mills, and printing presses. The process works by bringing water and air into direct contact, which allows the sensible heat of the air to provide the latent heat of evaporation, keeping the total heat the same while lowering the temperature. Properly designed cooling towers and air coolers can achieve saturation efficiencies as high as 90%. The maximum theoretical cooling is to the wet bulb temperature, and performance depends on factors like the water to air ratio and configuration of the wet

1. EVAPORATIVE
COOLING

2. APPLICATIONS
 SPOT COOLING – INDUSTRIAL APPLICATIONS
a) FOUNDRIES
b) STEEL ROLLING
c) FACTORY SHEDS
 KITCHEN VENTILATION.
 TEXTILE MILLS–WEAVING OF YARN–HIGH HUMIDITY
 LAUNDRY VENTILATION
 PRINTING PRESS

3. WHAT IS EVAPORATIVE COOLING ?
IS AN AIRCONDITIONING PROCESS
THAT USES EVAPORATION OF
RECIRCULATED WATER TO COOL AN
AIR STREAM SO THAT FINAL DRY BULB
TEMPERATURE IS LOWER THAN
ENTERING AIR TEMPERATURE.

4. PRINCIPLE
 WATER EVAPORATES DIRECTLY INTO THE AIR
STREAM, THUS REDUCING DRY BULB
TEMPERATURE WHILE HUMIDIFYING THE AIR.
 SENSIBLE HEAT OF AIR PROVIDES LATENT HEAT
OF EVAPORATION & TOTAL HEAT OF AIR
REMAINS SAME.
 WATER & AIR ARE IN DIRECT CONTACT.
 PROCESS IS CALLED ADIABATIC COOLING
 COOLING TOWERS, AIR COOLERS ARE THE
APPLICATION

5. SUPPLY
WATER PIPE
AIR
AIR
OUT
DOOR

6. ENTHALPY 78°
20
10
40
30
50
130
60
70
80
90
110
100
120
170
150
140
160
180
0
12020 30 40 50 60 70 80 11090 100
POUND
GRAIN /
DRY BULB TEMPERATURE °F
WBT 82°F
A
A'
B
B'
C
C'
22% RH
90

7.  THE COOLING PROCESS AB FOLLOWS THE WET BULB
LINE / CONSTANT ENTHALPY LINE. THE
RECIRCULATED WATER TEMPERATURE ATTAINS THE
TEMPERATURE OF WET BULD.
 WET BULB DEPEND ON THE LOCATION OF THE PLACE
AND IS DEPENDENT ON WEATHER AND TIME OF THE
YEAR.
 EVAPORATIVE COOLING WORKS BETTER AND IS
SUITABLE ONLY FOR THE PLACES FAR OFF FROM
WATER BODIES OR DRY CLIMATE
e.g. GOOD FOR NORTH, BUT NOT SUITABLE FOR
COASTAL AREAS LIKE MUMBAI, KOLKATA, CHENNAI

8. WHAT IS EVAPORATIVE COOLING ?
 THEORETICALLY THE MAXIMUM DROP IN THE AIR
TEMPERATURE COULD BE EQUAL TO WET BULB
TEMPERATURE
i.e IDEALLY Ta = Te
ACTUALLY IT IS ABLE TO COOL ONLY UP TO TB,
 SAVES LOT OF ENERGY AS THIS IS A NATURAL
COOLING PROCESS

9. SATURATION EFFICIENCY DEPENDS ON
 WATER TO AIR RATIO :- i.e. RATIO OF MASS FLOW
RATE OF SPRAY WATER TO MASS FLOW RATE OF
COOLED AIR. A GREATER WATER OF AIR RATIO
PROVIDE A GREATER CONTACT AREA BETWEEN AIR
WATER & THEREFORE A HIGHER SATURATION
EFFICIENCY.
FOR HUMIDIFICATION : SPRAY 6 US GALLONS/ MIN
PER 1000 CFM
 CONFIGURATION OF WETTED SURFACE : WETTED
MEDIA THAT PROVIDE A GREATER CONTACTS SURFACE
AND A LARGE CONTACT TIME BETWEEN THE AIR AND
WATER YEILD HIGHER SATURATION EFICIENCY

10. RIGID MEDIA
1. AVAILABLE IN VARIOUS DEPTHS, 4 – 24 INCHES,
IN THE DIRECTION OF AIR AIR FLOW ( 8 – 12
INCHES IS MORE COMMON )
2. LOW AIR WAY RESISTANCE, VERY COMPACT
3. WATER CIRCULATION RATE IS LOW, LOWER PUMP
SIZE
4. LOWER ENERGY CONSUMPTION THAN SPRAY
CHAMBER

11. WATER SUMP
PERFORATED
450 1500 450
PLATE
MOISTURE
ELIMINATOR
BLADES
NOZZLES
FLOW SPRAY BANK
2 BANK, COUNTER
SPARY PUMP
AIR OUTAIR IN
WASHER LENGTH

12. 1. DESIGN FACE AREA = AIR QUANTITY,
CFM / FACE
VELOCITY
2. APPROX. STATIC PRESSURE LOSS ACROSS A/W
= 25MM WG.
3. SATURATION EFFICIENCY = 90%
4. WATER FLOW RATE, 6 USGPM / 100- CFM
5. NOZZLE PRESSURE 25 – 30 PSIG

13. OTHER APPLICATIONS
 KITCHEN EXHAUST SCRUBBING
 WET SCRUBBER - FOR FRESH AIR INTAKE
PETRO CHEMICAL ( DISSOLVES AMMONIA GAS )
 HUMIDIFICATION IN PROCESS INDUSTRIES.
EVAPORATING COOLING INVOLVES USING
100% OUT DOOR AIR AND TOTAL AIR
SHOULD BE EXHAUSTED. NO RECIRCULATION
SHOULD BE DONE

14. DUCT
SUPPLY AIR SUPPLY AIR
DUCT
EXHAUST
FANS
40 FT
ZONE OF OCCUPANCY
6 FT
FFL

16. THANK
YOU