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Definition of air conditioning

• Refrigerating a region in reference to the
human comfort is called air conditioning.
• Thus, air conditioning refers to maintaining a
space for the human comfort i.e. temperature,
humidity and ventilation are the parameters
to be controlled.
Room comfort range

Relative humidity (rh): 40% to 50%

Temperature: 21oC to 24oC

(rh) is the percent of moisture in the air as compared to 100 percent of the
moisture that air at that temperature 3
 Air conditioning
• Equipment used for air conditioning are called
air conditioners. The air conditioning of space
may also be the requirement of various goods,
equipment's and processes etc.
• When air conditioning is done for human
comfort then it is called comfort air
conditioning while when it is done for
industrial purposes then it is called industrial
air conditioning .

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 Comfort and industrial air conditioning

• Comfort air conditioning is extensively used in

residential buildings, hospitals, offices, working
spaces, vehicles, trains, aeroplanes etc.
• Industrial air conditioning is used for spot
cooling/heating, environmental laboratories,
printing industry, textile industry, precision parts
manufacturing, photographic product handling,
computer rooms, control rooms of power plants
etc.

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 Parts of the window air conditioner

Capillary tube is one of the

most commonly used
throttling devices (used in the
expansion valve devices) in
the refrigeration and the air
conditioning systems. The
capillary tube is a copper tube
of very small internal diameter.

Suction accumulator prevents

liquid refrigerant returning to
the compressor

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 Types of Air Conditioning Systems
• The choice of which air conditioner system to use
depends upon a number of factors including how large
the area is to be cooled, the total heat generated inside
the enclosed area, etc. An HVAC designer would
consider all the related parameters and suggest the
system most suitable for your space.
• There are four types of air conditioning units:
1. Window,
2. Split,
3. Packaged, and
4. Central

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 1- Window Air Conditioner

• Window Air Conditioner is the most

commonly used air conditioner for single
rooms.
• In this air conditioner all the components,
namely the compressor, condenser, expansion
valve or coil, evaporator and cooling coil are
enclosed in a single box.
• This unit is fitted in a slot made in the wall of
the room, or more commonly a window sill.

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Window Air Conditioner

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 2- Split Air Conditioner
• The split air conditioner comprises of two parts: the
outdoor unit and the indoor unit.
• The outdoor unit, fitted outside the room, houses
components like the compressor, condenser and expansion
valve.
• The indoor unit comprises the evaporator or cooling coil
and the cooling fan.
• For this unit you don t have to make any slot in the wall of
the room.
• Further, present day split units have aesthetic appeal and
do not take up as much space as a window unit.
• A split air conditioner can be used to cool one or two
rooms.

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Split Air Conditioner

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 3- Packaged Air Conditioner
• An HVAC designer will suggest this type of air conditioner if you
want to cool more than two rooms or a larger space at your home
or office.
• There are two possible arrangements with the package unit. In the
first one, all the components, namely the compressor, condenser
(which can be air cooled or water cooled), expansion valve and
evaporator are housed in a single box.
• The cooled air is thrown by the high capacity blower, and it flows
through the ducts laid through various rooms. In the second
arrangement, the compressor and condenser are housed in one
casing.
• The compressed gas passes through individual units, comprised of
the expansion valve and cooling coil, located in various rooms.

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 Packaged Air Conditioner

Package Air Conditioner

Air Cooled Condenser

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Package AC with Water Cooled Condenser

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4- Central Air Conditioning System
• Central air conditioning is used for cooling big
buildings, houses, offices, entire hotels, gyms, movie
theaters, factories etc.
• If the whole building is to be air conditioned, HVAC
engineers find that putting individual units in each of
the rooms is very expensive making this a better
option.
• A central air conditioning system is comprised of a
huge compressor that has the capacity to produce
hundreds of tons of air conditioning. Cooling big halls,
malls, huge spaces, galleries etc is usually only feasible
with central conditioning units.

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Central Air Conditioning System
Air distribution ducts

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 Absorption Refrigeration System
• The vapor absorption refrigeration system comprises of
all the processes in the vapor compression
refrigeration system like compression, condensation,
expansion and evaporation.
• In the vapor absorption system the refrigerant used is
ammonia, water or lithium bromide.
• The refrigerant gets condensed in the condenser and it
gets evaporated in the evaporator. The refrigerant
produces cooling effect in the evaporator and releases
the heat to the atmosphere via the condenser.

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Absorption Refrigeration System

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Absorption Refrigeration System

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 How Simple Absorption System Works?

1) Condenser: Just like in the traditional condenser

of the vapor compression cycle, the refrigerant
enters the condenser at high pressure and
temperature and gets condensed. The condenser is
of water cooled type.
2) Expansion valve or restriction: When the
refrigerant passes through the expansion valve, its
pressure and temperature reduces suddenly. This
refrigerant (ammonia in this case) then enters the
evaporator.

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 How Simple Absorption System Works?

3) Evaporator: The refrigerant at very low

pressure and temperature enters the evaporator
and produces the cooling effect. In the vapor
compression cycle this refrigerant is sucked by
the compressor, but in the vapor absorption
cycle, this refrigerant flows to the absorber that
acts as the suction part of the refrigeration
cycle.

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 How Simple Absorption System Works?

4) Absorber: The absorber is a sort of vessel consisting of

water that acts as the absorbent, and the previous
absorbed refrigerant. Thus the absorber consists of the
weak solution of the refrigerant (ammonia in this case)
and absorbent (water in this case). When ammonia from
the evaporator enters the absorber, it is absorbed by the
absorbent due to which the pressure inside the absorber
reduces further leading to more flow of the refrigerant
from the evaporator to the absorber. At high temperature
water absorbs lesser ammonia, hence it is cooled by the
external coolant to increase it ammonia absorption
capacity.

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 How Simple Absorption System Works?

5) Pump: When the absorbent absorbs the

refrigerant strong solution of refrigerant-
absorbent (ammonia-water) is formed. This
solution is pumped by the pump at high
pressure to the generator. Thus pump increases
the pressure of the solution to about 10bar.

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 How Simple Absorption System Works?

6) Generator: The refrigerant-ammonia solution in the

generator is heated by the external source of heat. This is
can be steam, hot water or any other suitable source. Due
to heating the temperature of the solution increases. The
refrigerant in the solution gets vaporized and it leaves the
solution at high pressure. The high pressure and the high
temperature refrigerant then enters the condenser,
where it is cooled by the coolant, and it then enters the
expansion valve and then finally into the evaporator
where it produces the cooling effect. This refrigerant is
then again absorbed by the weak solution in the
absorber.

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 Assignment # 8
1. What are the main types of Air Conditioning
Systems?
2. Explain with drawing the main parts of the
window air conditioner?
3. Explain with drawing the main principles of
absorption refrigeration system?

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