4. • The term refrigeration may be defined as
the process of removing heat from a
subastance under controlled conditions.
• It also includes the process of reducing
and maintaining the temperature of the
body below the normal temperature of its
surroundings
• It works on the reverse carnot cycle
1
Introduction
5. HVAC
What is the full form of HVAC ?
• Heating
• Ventilation
• Airconditioning
What is meant by 1 ton of refrigeration ?
It is the amount of heat required to remove from 1 ton
of water at 0°C in 24 hours in order to change the
phase to ice
1 TR = 232.6 kJ/min = 3.5 kJ/s = 3.5 kw
5
6. “
6
Air Conditioning
Non Central AC
Window Ac Split Ac
Floor Standing Wall Mounted
Ceiling Mounted
Exposed Typr
Semi Concelaed
Type
Concealed Type
Central AC
Package Units
Air Cooled Water Cooled
Central Plant
VRF Chilled Water
Vapour
Compression
Vapour Absorption
DX System
Types of Hvac System
7. Types Of
Refrigeration System
7
1. Vapour Compression Refrigeration
System
2. Vapour Absorption Refrigeration
System
3. Evaporative Cooling
4. Bootstrap Air Cooling System
9. 9
Components of
Refrigeration Cycle
1.Compressor
It is a mechanical device that increases the
pressure of a gas by reducing its volume
The Main Types of Compressor used in
airconditioning industry are
• Reciprocating
• Rotary
• Scroll
• Helical Rotary ( Screw )
• Centrifugal
10. 10
2.Condensor
The condensor is heat exchanger that rejects heat from
the refrigerant to air,water or some other fluid
• Aircooled Condesnor
• Watercooled Condensor
11. 11
3.Evaporator
The evaporator is the heat exchanger that
transfers heat from air,water or some
other fluid to the cool liquid refrigerant
Two common types of evaporator are
Finned Tube Evaporator ( Coil )
E.g The Coils used in the Airhandling
units
Shell and Tube Evaporator
E.g Evaporator shell in the chill
12. 12
4.Expansion Valve
It is used to maintain a pressure difference between the
high pressur and low pressure side of the system
established by the compressor
Main types are thermostatic expansion valve,capillary
tubes and orifices
14. 14
Hvac Systems in
Amaazia
Amaazia Water Park
• Variable Refrigerent Flow ( VRF ) System
• Ventilation System
• Direct Expansion System
Amaazia Club
• Chilled water system
• Direct expansion system
• Ventilation system
15. 15
Refrigerants
• The refrigerant is substance or mixture usually fluid and it undergoes
phase transitions from liquid to gas and back again
• In the early stages chlorofluorocarbons was used but due to the
hazardous effect on it on the ozone layer and due to the global
warming it was banned and currently only enviornment friendly gases
are used
• The most common refrigerants used nowadays are R134a(HFC),
• R-12(CFC), R- 410A (HFC), R-22(CFC), R-404A(HFC)
• The boiling point of R-134a is -26.3° C and melting point is -103.3° C
• The boiling point of R-410A is -48.5° C and melting point is -155° C
16. Variable Refrigerant
Flow
• Variable refrigerant flow (VRF) systems vary
the flow of refrigerant to indoor units based on
demand.
• In a VRF system, multiple indoor fan coil units
may be connected to one outdoor unit.
• The outdoor unit has one or more
compressors that are inverter driven as the
compressor speed changes so does the
amount of refrigerant delivered by the
compressor
17. 17
Each indoor fan coil unit has its own metering device
that is controlled by the indoor unit itself, or by the
outdoor unit
Each indoor unit sends a demand to the outdoor unit,
the outdoor unit delivers the amount of refrigerant
needed to meet the individual requirements of each
indoor unit
19. 19
Main Parts of VRF
Outdoor Unit
• Controls compressor speed
• Controls condenser fan speed
• Controls pressure of refrigerant to maximize
capacity and efficiency
20. 20
Indoor Units
• Sense the space temperature
• Contain a Linear Expansion Valve (LEV)
that automatically modulates
• Allow the precise amount of refrigerant
through the heat exchanger
• Filter and distributes air
22. 22
What are the benefits of VRF?
• Two-pipe System
• Inverter Technology
• Multiple Indoor Units
• Variable Capacity System
• Zoning System
• Complete Control Offering
23. 23
Maintenance of VRF
System
• Clean the filters of indoor unit periodically for the economical operation
• Clean the dust particles accumulated at the outdoor unit
• Clean the fins of the outdoor unit periodically
• Check the drain pan of the indoor units
• Clean the evaporator fins regulary
• Check the alignment of fan motor of the FCU
• Check if the running ampere and voltage is normal or not
• Check the tightness of the electrical connection
24. 24
• The term direct refers to the position of the evaporator with the airside
loop
• In the DX systems the air is cooled with the refrigerant passing through
the tubes of the cooling coil
• DX system may be air cooled and water cooled
• Window airconditioners,package units and split units are the examples
of the DX systems
Direct Expansion
System
25. 25
• Hermitically Sealed Compressor
• Evaporator
• Supply air fan
• Filter
• Condensor
• Expansion Valve
Main Parts of DX
System
26. 26
Ventilation System
Ventilation means changing the air in an enclosed space
to
• Supply the fresh air and preserve the correct level of
oxygen in the air
• Control the amount of carbon dioxide
• Lowering the heat level
• Remove the dust and odours
Adult man has the frequency of breathing typically 16 times
per minute - 8 litres/min
Oxygen consumption varies between 250-350 ml/min
27. 27
Type of Ventilation
1.Natural Ventilation
It is the process of supplying and
removing air through the indoor space
without using mechanical systems
• Wind Driven Ventilation
• Pressure Driven Ventilation
• Stack Ventilaon / Stack Effect
28. 28
2.Mechanical Ventilation
It is the process of supplying and removing air through the
indoor space with using mechanical systems such as fans,
duct etc
• Pressure balanced system
• Overpressure system
• Underpressure system
The main types of fan used in the forced ventilation system
are as follows
29. 29
1. Propeller Fan
It does not create much air difference and has
limited effect in the ductwork
Ideal for use at air opening in windows and walls
2. Axial Flow Fan
It can develop high pressure and is used for moving
air through long sections of ductwork.
30. 30
3. Centrifugal Fan
It can produce high pressure and has the capacity for
large volumes of air
It is used mainly in the hvac applications
31. 31
Filters
It is a device composed of fibrous or porous materials
which removes the solid particles such dust, pollen, mold
and bacteria from the air
It can be mainly classified as follow
• Dry Filters
• Viscous Filters
• Electrostatic Filters
• Activated Carbon Filters
• HEPA Filters
32. 32
Maintenance of
Ventilation System
• Clean the filters of fresh air unit periodically for
the economical operation
• Check for the noise and vibration of the unit
• Check the alignment of motor and blower pulley
• Grease the bearings periodically
• Check and ensure the motor terminals are
properly cleaned terminal box is properly closed
• Check if the running ampere and voltage is
normal or not
• Check the tightness of the electrical connection
