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Presentation on HVAC: Heating
Ventilation Air Conditioning
CHITKARA UNIVERSITY CHITKARA SCHOOL OF
MECHANICAL ENGINEERING
;HARVINDER SINGH
HVAC
• Heating, Ventilation and Air
Conditioning
• Provides comfort for people
• Allows humans to exist under
adverse conditions.
Load Calculations
• Heating and Cooling
• Accuracy important!
• Design conditions
• Building shell load
• Internal load
• Ventilation load
• Infiltration
• Occupancy schedules
Refrigeration
• It is defined as the process of providing and
maintaining a temperature well below that of
surrounding atmosphere.
• In other words refrigeration is the process of
cooling substance.
Air-Conditioning Principles
• Must be a transfer
of heat for
refrigerant to
change state
– Liquid absorbs
heat as changes to
gas
– Vapor releases
heat as changes to
liquid
Heat Transfer
• Heat flows to anything with less heat
– Convection
• Heat rises
• Heat always flows from hot to cold
– Radiation
• Example: heat from the sun
– Evaporation
• Moisture absorbs heat as it is vaporized
• Example: perspiration
Refrigerators and heat pumps
• If the main purpose of the machine is to
cool some object the machine is named as
refrigerator
• If the main purpose of machine to heat a
medium warmer than the surroundings,
the machine is termed as heat pump.
Refrigerator and Heat pump
QR
Work Input
QR
Work Input
Heat
Pump
Warm Space
Cold Space
Refrig
erator
Types of Refrigerators
• Ice Refrigerators : Ice is kept in the cabinet of
refrigerators and this acts as the refrigerating
means.
• Air Refrigerators : Air is used as working agent
in these types of refrigerators.
• Vapour Refrigerators: The working agents
employed in this type of refrigerators are
ammonia, CO2, SO2, freons etc.,
Applications of Refrigeration • In chemical industries, for separating and liquefying the
gases.
• In manufacturing and storing ice.
• For the preservation of perishable food items in cold
storages.
• For cooling water.
• For controlling humidity of air manufacture and heat
treatment of steels.
• For the preservation of tablets and medicines in
pharmaceutical industries.
• For the preservation of blood tissues etc.,
• For comfort air conditioning the hospitals, theatres, etc.,
Vapour Compression Refrigeration
System
Vapour Compression Refrigeration System -
Construction
• This system consists of a compressor, condenser, a receiver tank, an expansion valve and an evaporator.
• Compressor : Reciprocating
compressors generally used.
For very big plants centrifugal
compressors directly coupled
with high speed rotating
engines (gas turbine) are used.
Vapour Compression Refrigeration System -
Construction
Compressor: For very big plants
Centrifugal compressors
directly coupled with high
speed rotating engines
(gas turbine) are used
Vapour Compression Refrigeration System -
Construction
• Condenser : It is a coil of tubes made of copper.
• Receiver tank: It is the reservoir of liquid refrigerant.
• Expansion Valve: This is a throttle valve. High pressure refrigerant is made to flow at a controlled rate through this valve.
• Evaporator : It is the actual cooler and kept in the space to be cooled. The evaporator is a coil of tubes made of copper
EVAPORATOR TUBING
Vapour Compression Refrigeration System -
Working
Working :
1. The low pressure refrigerant vapour coming out of the
evaporator flows into the compressor.
2. The compressor is driven by a prime mover.
3. In the compressor the refrigerant vapour is compressed.
4. The high pressure refrigerant vapour from the compressor is
then passed through the condenser.
5. The refrigerant gives out the heat it had taken in the
evaporator
Vapour Compression Refrigeration System -
Working
Working :
6. The heat equivalent of work done on it (w) on the compressor.
7. This heat is carried by condenser medium which may be air or
water.
8. The high pressure liquid refrigerant then enters the expansion
valve.
9. This valve allows the high pressure liquid refrigerant to flow at a
controlled rate into the evaporator.
10. While passing though this valve the liquid partially
evaporates.
Vapour Compression Refrigeration System -
Working
Working :
11.Most of the refrigerant is vapourised only in the evaporator, at a low pressure.
12. In the evaporator the liquid refrigerant absorbs its latent heat of vapourisation from the material which is to be cooled.
13. Thus the refrigerating effect is obtained.
14. Then the low pressure refrigerant enters the compressor and the cycle is repeated.
Layout of Domestic Refrigerator
Window Type Air Conditioner
Window Type Air Conditioner - Construction
• This is also called room air conditioner.
• This unit consists of the following.
1. A cooling system to cool and dehumidify the air involves a condenser, a compressor and a refrigerant coil.
2. A filter to any impurities in the air. The filter is made of mesh, glass wool or fibre.
3. A fan and adjustable grills to circulate the air.
4. Controls to regulate the equipment operation.
Humidity
• Low humidity
– Permits heat to be taken away from the human
body
• Evaporation and perspiration
• High humidity
– Makes evaporation difficult
• People feel as comfortable at 79°F with 30% humidity
as at 72°F at 90% humidity
AIR FILTERS
• Air filters
– Air cleaning and filtration
– Operating performance:
• Efficiency or effectiveness of dust removal
• Dust holding capacity
• Service life
– Types: low-, medium-, and high-efficiency filters
CLEAN ROOM CLASSIFICATION (ISO 14644)
THANKS