This document discusses air conditioning processes and psychrometric charts. It defines key terms like humidification, dehumidification, and psychrometric properties. Humidification is the transfer of water vapor to air, using methods like wetted mats or spraying water droplets. Dehumidification reduces moisture in air. Psychrometric charts plot air properties like dry bulb temperature, wet bulb temperature, relative humidity, and humidity ratio to determine conditioning needs. Sensible heating and cooling change air temperature without moisture alteration, while humidifying and dehumidifying impact both temperature and moisture.

1. AIR CONDITIONING and VENTILATION SYSTEMS
NME 515
Chapter 3
Air Conditioning
Process
Engr. Charlton Inao, ME
TESDA TVET NC Level 3 RAC-CRE Certified

2. Psychrometric Chart

3. Psychrometric Chart

5. Psychrometric Process

6. Sensible heating

7. Sensible cooling

8. Humidification
 The transfer of water vapor to atmospheric
air is referred to as humidification
 Here the term latent heat transfer is used.
This process is usually accomplished by
introducing water vapor or by spraying fine
droplets of water that evaporate into the
circulating air stream. Wetted mats or plates
may also be used.

9. Dehumidification
 The opposite of humidification, which
means reducing or removing moisture
or water vapor in the air.

12. Review: Psychrometry
 Psychrometry is the science dealing
with the physical laws of air – water
mixtures.
 When designing an air conditioning
system, the temperature and moisture
content of the air to be conditioned, and
the same properties of the air needed to
produce the desired air conditioning
effect, must be known.
 Once these properties are known, the air
conditioning task can be determined.

13. Properties of Air
Dry-bulb temperature
Wet-bulb temperature
Dew-point temperature
Relative humidity
Humidity ratio(specific humidity)

14. Thermometers

15. Dew Point Temperature
 Condensation
occurs at the Dew
Point Temperature

16. Saturation temperature
 Saturation temperature occurs at 100
% RH where WB, DB and DP
temperature is the same (Fog)

17. Relative Humidity

18. Humidity Ratio

19. Air conditions at the
psychrometric chart

20. Specific volume

21. Enthalpy
 The total heat energy in one pound of air
(Btu/lb) at its present condition
Enthalpy (h) = Sensible Heat + Latent
Heat

22. Chart Exercise
 Summer Design Conditions
95°F DB (dry bulb)
78°F WB (wet bulb)
Find:
Relative Humidity
Humidity Ratio
Dew Point

23. Answer
Summer Design Conditions
95°F DB (dry bulb)7
78°F WB (wet bulb)
Find:
Relative Humidity
Humidity Ratio
Dew Point

26. Comfort Zone

27. Sensible heat

28. Sensible Cooling

29. Humidifying

30. Dehumidifying