Air Conditioning System

AIR CONDITIONING: WORKING, AND TYPES

Submitted to-
Ar Umadhar Kamti
Submitted by-
Sumit Ranjan (AR/12/834)
Yuvraj Chopra (AR/12/836)
6th Sem.
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1. What is meant by “Air
conditioning”?
2. Human Comfort
3. Why do we need A.C.?
4. Advantages and
Disadvantage of A.C.
5. Ideal room temperature
6. some terminology-
 Dry-bulb temperature
 Wet-bulb temperature:
 Dew point
 Latent heat
 Absolute humidity
 Relative humidity
 Specific humidity
 Sensible heat
 Evaporating Cooling
 Condensation
 Enthalpy
 Entropy
7.Classfication of air conditioners
8.Windows AC- advantages
Parts of the Window Air Conditioners
Working
 the refrigeration system,
 air circulation system-room air cycle and
the hot air cycle.
 ventilation system,
 control system,
 electrical protection system.
9.Split or Ductless AC-
advantages, parts indoor and outdoor,
types-
 Wall mounted
 Floor mounted/Tower AC
 Ceiling mounted/Cassette AC
 Multi Split ACs
10.Central Air Conditioning System
Advantages and disadvantages
11. Key differences between
"Window", "Split" and a
"cassette" air conditioners.
12. Cooling capacity
13. Energy Efficiency
14.Energy Consumption
15.Energy Efficiency Ratio
16.Energy Saving Methods
17.Some AC brands

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 Air conditioning (often referred to as A/C or AC ) is the
process of altering the properties
of air (primarily temperature and humidity) to more
comfortable conditions, typically with the aim of distributing
the conditioned air to an occupied space to improve thermal
comfort and indoor air quality .
 Air conditioning is defined as a process which cools (or heat) ,
clean, circulates, freshen air, and controls its moisture content
simultaneously.
 Most of the air conditioning, particularly in India and such
other countries, is about cooling : i.e. removal of heat from an
enclosed space.
 In the most general sense, air conditioning can refer to any
form of technology that modifies the condition of air (heating,
cooling, (de-)humidification,cleaning, ventilation, or air
movement).

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The four atmospheric condition which affect human comforts are-
Temperature, Humidity, Air purity & Air
movements.
 An air conditioner controls the above factors for us to achieve human comfort.
 Most people (90%) are comfortable when the air temperature is between 18-22°C and the %sat is between 40-65%.

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 In a well climatically designed building human comfort factors are controlled naturally, that
is the best solution.
 In big building/complexes it is not possible to design entire building comfortably by natural
energy sources like sun, wind, orientation etc.
 In such cases we have to take the help of mechanical mean for obtaining comfortable
conditions inside the building.
 The science & practice of creating a controlled climate in indoor space is called Air-
conditioning.
 Outside air is quite likely to be at a different condition from the required comfort zone
condition. In order to bring its condition to within the comfort zone we may need to do one
or more of the following:-heat it; cool it; dehumidify it; humidify it; or mix it.

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Advantages:
 Increased comfort level.
 In extreme heat, air-conditioning can be a
life saver.
 Most air conditionersalso reduce the
humidity level, which helps both comfort, and
reduces mold growth.
 Less noise as the windows will be closed
 Prevents the dust entering the room as the
windows will be closed
 Gives constant temperature
 Attractive design
 Simple control
 Easy maintenance
 Easy installation
Disadvantage
 Most air conditionersuse a substantial amount of
energy,
 High cost money
 Contributing to pollution from power plants.
 Older models contain chemicals that can damage the
environmentif they escape.
 Encourages laziness,
 Habitant spending time indoors instead of out
 Habitants have less contact with nature.
 Too cool temperatureswill lead to improper blood
circulation
 Effects the environment by releasing the cfc's.

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s. n Type of Space Summer(°C) Winter(°C)
1. Residences, apartments, hotel and motel guest rooms , offices, conference rooms,
classrooms, courtrooms, and hospital patient rooms
23–26 20–22
2. Theaters , auditoriums, churches, chapels, synagogues, assembly halls, lobbies, and lounge 24–27 21–22
3. Restaurants, cafeterias, and bars 22–26 20–21
4. Retail shops and supermarkets 23–27 18–20
5. Medical intensive care rooms 22–26 22–26
6. Factories and industrial shops 27–29 18–20
7. Machinery spaces, foundries, boiler shops, and garages - 10–16
8. Kitchens and laundries 24–27 18–20

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Dry-bulb temperature:
 It is the temperature of air measured by a thermometer
freely exposed to the air but shielded from radiation
and moisture.
 Dry bulb temperature is the temperature that is usually
thought of as air temperature, and it is the true
thermodynamic temperature.
 It is the temperature measured by a regular thermometer
exposed to the airstream.
 It is the temperature shown by a dry sensing element
such as mercury in a glass tube thermometer.
 This is actual temperature.
 When people refer to the temperature of the air, they
are normally referring to its dry bulb temperature.
 The Dry Bulb Temperature refersbasically to the
ambient air temperature. It is called "Dry Bulb" because
the air temperature is indicated by a thermometernot
affected by the moisture of the air.
 It is a type of temperature measurement
that reflects the physical propertiesof a
system with a mixture of a gas and a
vapour , usually air and water vapour .
 Wet bulb temperatureis the lowest
temperature that can be reached by the
evaporation of water only.
 This is the temperature indicated by a
moistened thermometerbulb exposed to
the air flow.
 The wet bulb temperature is always
lower than the dry bulb temperaturebut
will be identical with 100% relative
humidity.
 This is the temperature we feel.
Wet-bulb temperature:

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 The dew point is a saturation temperature.
 The temperature at which the air is saturated
(100% RH) and further cooling manifests in
condensation fromwater in the air.
 The dew point is the temperature at which
water vapour starts to condense out of the
air (the temperature at which air becomes
completely saturated).
 Above this temperature the moisture will stay
in the air.
 If the dew-point temperature is close to the
dry air temperature - the relative humidity is
high
 If the dew point is well below the dry air
temperature - the relative humidity is low
Dew point:
Latent heat :
 All pure substances in nature are able to
change their state.
 Solids can become liquids (ice to water) and
liquids can become gases (water to vapor)
but changes such as these require the
addition or removal of heat.
 The heat that causes these changes is called
latent heat.
 Heat energy added or removed as a
substance
changes state, whilst temperature remains
constant,
 E.G. Water changing to steam at 100ƒc and
atmospheric pressure (W).

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Absolute humidity:
Absolute humidity is the total amount of water
vapour present in a given volume of air. It does
not take temperature into consideration.
 Relative humidity (RH) is the ratio of water
contained in air at a given dry bulb
temperature, as a percentage of the
maximum amount of water that could be held
in air at that temperature.
 Thus the relative humidity of air is a function
of both water content and temperature.
Relative humidity:
 specific humidity is the mass of water vapour
present in a unit mass of air.
 Where temperaturesare high and rainfall is
excessive, the specific humidity of the air
reaches high proportions.
 This is also called “moisture content” .
Specific humidity:
Sensible heat gain:
 when an object is heated, its temperature rises
as heat is added. The increase in heat is called
sensible heat.
 Similarly, when heat is removed from an object
and its temperature falls, the heat removed is
also called sensible heat.
 Heat that causes a change in temperature in an
object is called sensible heat.

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Evaporative cooling produces effective cooling
by combining a natural process - water
evaporation - with a simple, reliable air-moving
system.
Evaporative cooling :
Condensation is the change of the physical
state of matter from gaseous phase into liquid
phase, and is the reverse of evaporation.
Condensation :
Enthalpy:
Total heat energy, i.E. Sensible heat + latent heat.
Specific enthalpy (kj/kg dry air).
Measure of total heat energy in a refrigerant
for every degree of temperature (kj/kgƒc)
Entropy:

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Classification based on major function:-
(a) Comfort A.C.: Creating atmospheric conditions conductive to
human health, comfort & efficiency. A.C. in home, offices, stores,
restaurants, theatres, hospitals etc. are of these types.
(b) Industrial A.C.: The purpose of these system is to control
atmospheric conditions primarily for proper conduct of research &
manufacturing e.g. electronics & computer industries, paper mills,
textile mills, candy factories, photo processing etc.
Classification based on season of
the year:
a) Winter A.C.: system: These systems,
when properly designed & installed
maintain indoor atmosphericconditions for
winter comfortable, namely temperature,
humidity. Air purity & air
movements, when outside temperature is
very cold.
b) Summer A.C.: Maintains indoor
condition comfortable when outside
atmospheric conditions are not comfortable,
but it is very hot & dry.
c) All year round A.C.: Maintains
indoor temperature comfortable throughout
the year, while outside temperature may be
very cold or hot.
Classification based on equipments arranged:
a) Unitary or “packed” A.C.
b) Spit A.C.
c) Central A.C.
d) Combination of above.

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Classification based on installation position
Windows AC
Split or Ductless AC
Centralised AC
Windows AC
• These types of AC are designed to be
fitted in window sills.
• A single unit of Window Air Conditioner
houses all the necessary components,
namely the compressor, condenser,
expansion valve or coil, evaporator and
cooling coil enclosed in a single box.
• Since a window AC is a single unit, it
takes less effort to install as well as for
maintenance.
• This is the most commonly used air
conditioner for single rooms.
Advantages
•Single unit air conditioner
•Less effort needed for installation
•Costs lesser in comparison to other
varieties

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The whole assembly of the
window air conditioner can
be divided into two
compartments:
 the room side, which is
also the cooling side and
 the outdoor side from
where the heat absorbed
by the room air is
liberated to the
atmosphere.
The room side and outdoor
side are separated from
each other by an insulated
partition enclosed inside the
window air conditioner
assembly
 In the front of the
window air conditioner
on the room side there
is beautifully decorated
front panel on which the
supply and return air
grills are fitted (the
whole front panel itself
is commonly called as
front grill).
 The louvers fitted in the
supply air grills are
adjustable so as to
supply the air in desired
direction.
 There is also one
opening in the grill that
allows access to the
control panel or
operating panel in front
of the window air
conditioner.
Parts of the Window
Air Conditioners

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The various parts of the
window air conditioner can
be divided into following
categories:
 the refrigeration
system,
 air circulation system,
 ventilation system,
 control system,
 electrical protection
system.

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The REFRIGERATION SYSTEM of the window air conditioner comprises of all the important parts of the refrigeration
cycle. These include
 the compressor,
 condenser,
 expansion valve and
 the evaporator.
 The refrigerant used in most of the window air conditioners is R22.
 The compressor used in the window air conditioners is hermetically sealed type, which is portable one. This compressor has
long life and it carries long warranty periods. The condenser is made up of copper tubing and it is cooled by the
atmospheric air. The condenser is covered with the fins to enable faster heat transfer rate from it.
 The capillary tubing made up of various rounds of the copper coil is used as the expansion valve in the window air
conditioners. Just before the capillary there is drier filter that filters the refrigerant and also removes the moisture
particles, if present in the refrigerant.
 Like condenser, the evaporator is also made up of copper tubing of number of turns and is covered with the fins.
 The evaporator is also called as the cooling coil since the rooms air passes over it and gets cooled. Just in front of the
evaporator there is air filter fitted in the front panel or front grill.
 As the room air is absorbed, it is first passed over the filter so that it gets filtered. The filtered air is then blown over the
cooling coil and the chilled air is passed into the room.
 The refrigerant after leaving the cooling coil enters the accumulator where it is accumulated and then it is again sucked by
the compressor for recirculation over the whole cycle.

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The air circulation system of the window air conditioner
comprises of the following parts.
1) Blower: This is the small blower that is fitted behind
the evaporator or cooling coil inside the assembly of the
window air conditioner system. The blower sucks the air
from the room which first passes over the air filter and
gets filtered. The air then passes over the cooling coil and
gets chilled. The blower then blows this filtered and chilled
air, which passes through the supply air compartment
inside the window air conditioner assembly. This air is then
delivered into the room from the supply air grill of the
front panel.
2) Propeller fan or the condenser fan: The condenser fan is
the forced draft type of propeller fan that sucks the atmospheric
air and blows it over the condenser. The hot refrigerant inside
the condenser gives up the heat to the atmospheric air and its
temperature reduces.
3) Fan motor: The motor inside the window air conditioner
assembly is located between the condenser and the evaporator
coil. It has double shaft on one side of which the blower is fitted
and on the other side the condenser fan is fitted. This makes the
whole assembly of the blower, the condenser fan and the motor
highly compact.

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The working of window air
conditioner can be explained
by separately considering the
two cycles of air:
 room air cycle and
 the hot air cycle.
Room air cycle
 The air moving inside the room and in the front part of the air conditioner where the
cooling coil is located is considered to be the room air. When the window AC is started
the blower starts immediately and after a few seconds the compressor also starts. The
evaporator coil or the cooling gets cooled as soon as the compressor is started.
 The blower behind the cooling coil starts sucking the room air, which is at high
temperature and also carries the dirt and dust particles. On its path towards the blower,
the room air first passes through the filter where the dirt and dust particles from it get
removed.
 The air then passes over the cooling coil where two processes occur. Firstly, Due to this the
temperature of the room air becomes very low, that is the air becomes chilled. Secondly,
due to reduction in the temperature of the air, relative humidity reduces.
 This air at low temperature and low humidity is sucked by the blower and it blows it at
high pressure. The chilled air then passes through small duct inside the air conditioner
and it is then thrown outside the air conditioner through the opening in the front panel or
the grill. This chilled air then enters the room and chills the room maintaining low
temperature and low humidity inside the room.
 The cool air inside the room absorbs the heat and also the moisture and so its
temperature and moisture content becomes high. This air is again sucked by the blower
and the cycle repeats. Some outside air also gets mixed with this room air. Since this air
is sent back to the blower, it is also called as the return room air. In this way the cycle of
this return air or the room air keeps on repeating.

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Hot air cycle
 The hot air cycle includes the atmospheric air that is
used for cooling the condenser. The condenser of the
window air conditioner is exposed to the external
atmosphere.
 The propeller fan located behind the condenser sucks
the atmospheric at high temperature and it blows the
air over the condenser.
 The refrigerant inside the condenser is at very high
temperature and it has to be cooled to produce the
desired cooling effect.
 When the atmospheric air passes over the condenser, it
absorbs the heat from the refrigerant and its
temperature increases. The atmospheric air is already
at high temperature and after absorbing the
condenser heat, its temperature becomes even higher.
Since the temperature of this air is very high, this is
called as hot air cycle.
 The refrigerant after getting cooled enters the
expansion valve and then the evaporator. On the other
hand, the hot mixes with the atmosphere and then the
fresh atmospheric air is absorbed by the propeller fan
and blown over the condenser. This cycle of the hot air
continues.
Setting the Room Temperature with
Thermostat
 The temperature inside the room can be set by using the
thermostat knob or the remote control.
 When the desired temperature is attained inside the room, the
thermostat stops the compressor of the AC.
 After some time when the temperature of the air becomes higher
again, the thermostat restarts the compressor to produce the
cooling effect.
 One should set the thermostat at the required temperature and
not keep it at very low temperature to avoid high electricity bills.
Air Filter
The filter is a very important part of the AC since it cleans the air
before it enters the room. For proper functioning of the filter it is very
important to clean it every two weeks.

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 These are kits of 2 units, one internal and another external.
 The indoor unit installed inside a room intakes warm air and throws in
cold air.
 The outdoor unit on the other hand is installed out of the house. It
contains the compressor and is linked to the internal unit via drain
pipes and electric cables.
 This external unit throws out the warm air.
 Split air conditioners are used for small rooms and halls, usually in
places where window air conditioners cannot be installed. However,
these days many people prefer split air conditioner units even for
places where window air conditioners can be fitted.
 The split air conditioner takes up a very small space of your room,
looks aesthetically cool and makes very little noise.
Advantages
 Internal unit takes up less space for installation
 Usually more silent than window ACs
 Minimally affect your home decor
 Can be installed in room with no windows
Split AC
:

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There are two main parts of the split air
conditioner. These are:
1) Outdoor unit:
 This unit houses important components
of the air conditioner like the
compressor, condenser coil and also
the expansion coil or capillary tubing.
 This unit is installed outside the room
or office space which is to be cooled.
 The compressor is the maximum noise
making part of the air conditioner,
and since in the split air conditioner, it
is located outside the room, the major
source of noise is eliminated.
 In the outdoor unit there is a fan that
blows air over the condenser thus
cooling the compressed Freon gas in it.
 This gas passes through the expansion
coil and gets converted into low
pressure, low temperature partial gas
and partial liquid Freon fluid.
2) Indoor unit:
 It is the indoor unit that produces the cooling
effect inside the room or the office.
 This is a beautiful looking tall unit usually
white in color, though these days a number of
stylish models of the indoor unit are being
launched.
 The indoor unit houses the evaporator coil or
the cooling coil, a long blower and the filter.
 After passing from the expansion coil, the
chilled Freon fluid enters the cooling coil.
 The blower sucks the hot, humid and filtered
air from the room and it blows it over the
cooling coil.
 As the air passes over cooling coil its
temperature reduces drastically and also
loses the excess moisture.
 The cool and dry air enters the room and
maintains comfortable conditions of around
25-27 degree Celsius as per the
requirements.

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 Wall mounted
 Floor mounted/TowerAC
 Ceiling mounted/Cassette AC
 Multi Split ACs
Wall mounted
 Wall mounted split ACs
are the most popular.
 The indoor unit is placed
in the room and duct
cannot be concealed.
 It is generally for small
rooms which can be
cooled uniformly easily.
Floor mounted/Tower
AC/vertical AC
 These are also known as floor-standing air
conditioners.
 Like split ACs, a tower AC set consists of 2 units-
one internal and an external.
 However, the indoor unit doesn’t need wall
installation. It rather occupies some space on the
floor.
 Tower air conditioners usually have high cooling
capacity and suitable for very large rooms.
 These are useful in rooms where you cannot
mount the AC in your wall.
 These are generally more expensive than wall
mounted ACs and hence less popular for homes.
Advantages
 Suitable for high capacity cooling
 Ideal for large rooms at home and in offices
 Doesn't need windows or wall installation

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Ceiling mounted/Cassette AC
 These space-saving ACs are shaped like cassettes and are
designed to be installed on ceilings.
 The panel of these air conditioners is designed to blend with
all kinds of home décor.
 They are stylish, and are known to deliver fantastic
performances.
 Most cassette type air conditioners require no ducting.
 They are perfect for large spaces where windows or split AC
may not reach out.
 They look aesthetically beautiful as the unit is concealed,
however this needs a false ceiling.
 The price for this type of AC is higher than wall mounted or
floor mounted split ACs.
 These are also known as concealed ACs.
Advantages
 Best at saving space
 Able to cool large areas where other ACs don’t reach out
 Blends with decor

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 Multi-splits are multiple split
ACs connected to one outdoor
unit.
 The indoor units can be used
individually or at the same
time as needed if this is
supported. If both the units
are used then the capacity of
the ACs will be divided. The
fan and condenser of the
outdoor unit will be controlled
based on the signals from
indoor units.
 This primary saves cost as
instead of 2 split ACs you can
use this type of AC.
Multi Split ACs
Advantages of multi-split ACs
 Saves installation space
 Can be used individually or
simultaneously
 Independent control
 Compact Design
 Good EER
 Saves on running costs
 Convenient and economical
Disadvantages of multi-split ACs
 Expensive compared to a single unit
split AC
 Limited range of capacities and models
 More prone to leakage as number of
indoor units increases

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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
 central air conditioner unit is an energy moving or converted
machines that are designed to cool or heat the entire house.
 It does not create heat or cool. It just removes heat from one
area, where it is undesirable, to an area where it is less
significant.
 Central air conditions has a centralize duct system.
 It uses Ac refrigerant (we may know it as Freon) as a
substance to absorb the heat from indoor evaporator coils
and rejects that heat to outdoor condenser coils or vice verse.
Chilled Water Central Air Conditioning
 The chilled water types of central air conditioning
plants are installed in the place where whole large
buildings, shopping mall, airport, hotel, etc,
comprising of several floors are to be air
conditioned.
 While in the direct expansion type of central air
conditioning plants, refrigerant is directly used to
cool the room air; in the chilled water plants the
refrigerant first chills the water, which in turn chills
the room air.
 In chilled water plants, the ordinary water or brine
solution is chilled to very low temperatures of about
6 to 8 degree Celsius by the refrigeration plant.
 This chilled water is pumped to various floors of the
building and its different parts.
 In each of these parts the air handling units are
installed, which comprise of the cooling coil, blower
and the ducts. The chilled water flows through the
cooling coil. The blower absorbs return air from the
air conditioned rooms that are to be cooled via the
ducts.

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Chilled Water Central
Air Conditioning

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Key differences between "Window", "Split" and a "cassette" air
conditioners
AC Parameters Window AC Split AC Cassette AC
Suitable For Small rooms with a window sill Any room with or without a
window
Large indoor spaces
Noise Relatively on the higher side Minimal noise Silent operation
Capacity range 0.75 ton to 2 ton 0.8 to 2 ton 1 ton to 4 ton
Advanced features Humidity control, dust filter Humidity control, dust filter,
bacteria filter
Humidity control, dust filter,
bacteria filter
Interference with home decor Slight possibility to interfere
with window curtains and
drapes
Designer indoor units blend
well with wall decor
Barely interferes with interior
decor
Ease of installation Minimal effort required Indoor and outdoor units
need some amount of effort
for installation
Needs specialised false
ceiling

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The cooling capacity is the most important feature of an air conditioner, this
primarily defines the price of the AC. Most air conditioners are rated by tonnage.
One ton is equal to 12,000 BTU per hour. The cooling capacity needed depends
on factors like:
 Size of the room: The cooling capacity required depends on the area of the
room where the AC will be installed.
 Average ambient temperature: Higher temperature of the air outisde your
house, higher is the cooling capacity needed.
 Number of people: The more the people that will be in the room, the higher
will be the cooling capacity required.
 Exposure: Direct exposure of any wall of the room to sun leads to higher
requirement in cooling capacity. Glass windows which let sunlight inside the
room also increases the need for cooling capacity.
 Proximity of your room to kitchen: If the room is close to the kitchen the
cooling capacity needed would be higher due to higher temperature of the
kitchen.
Rooms Size (Sq
ft)
Tonnage
Capacity
Up to 90 sq ft 0.8 Ton

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 Today's best air conditioners use
30% to 50% less energy than
1970s
 Even if your air conditioner is only
10 years old, you may save 20%
to 40% of your cooling energy
costs by replacing it with a newer,
more efficient model .
Energy Efficiency
 Air conditioners are rated by the
number of British Thermal Units (Btu)
of heat they can remove per hour.
Another common rating term for air
conditioning size is the "ton," which is
12,000 Btu per hour.
 Room air conditioners range from
5,500 Btu per hour to 14,000 Btu
per hour.
Energy Consumption
Energy Efficiency Ratio
 EER represents the amount of cooling an air conditioner can
provide per watt of electricity it consumes.
 Bureau of Energy Efficiency rates air conditioners on its star
rating based on EER of air conditioners.
 Higher the EER of air conditioner higher the star rating it will
have.
 So a 5 star rated air conditioner provides more cooling per watt
of electricity used.
 For central air conditioners, it is the Seasonal Energy Efficiency
Ratio, or SEER
Energy Saving Methods
 Locate the air conditioner in a window or wall area near the
center of the room and on the shadiest side of the house.
 Minimize air leakage by fitting the room air conditioner
snugly into its opening and sealing gaps with a foam weather
stripping material.

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Some AC brands
Voltas
Samsung
Daikin
LG
Whirlpool
Vidiocon
Bluestar
Hitachi
Haier
O general

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Thank you!
Sumit Ranjan
Architecture student
at College of Architecture, Bhaddal, Ropar ,
Email-ar.sumitranjan@gmail.com
www.facebook.com/sumiran46.muz

Air Conditioning System

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Air Conditioning System