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 conditioners also 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 conditioners use a substantial amount of

energy,

High cost money

Contributing to pollution from power plants.

Older models contain chemicals that can damage the

environment if they escape.

Encourages laziness,

Habitant spending time indoors instead of out

Habitants have less contact with nature.

Too cool temperatures will 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 refers basically to the

ambient air temperature. It is called "Dry Bulb" because

the air temperature is indicated by a thermometer not

affected by the moisture of the air.

It is a type of temperature measurement

that reflects the physical properties of a

system with a mixture of a gas and a

vapour , usually air and water vapour .

Wet bulb temperature is the lowest

temperature that can be reached by the

evaporation of water only.

This is the temperature indicated by a

moistened thermometer bulb exposed to

the air flow.

The wet bulb temperature is always

lower than the dry bulb temperature but

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 from water 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 temperatures are 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 atmospheric conditions 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 FilterThe 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/Tower AC

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

Up to 120 sq ft 1.0 Ton

Up to 180 sq ft 1.5 Ton

Up to 220 sq ft 2.0 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