Air-conditioning

systems

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Faculty Name: Prof. Ajaypalsinh G. BaradBranch: MechanicalSemester: 6th

Name of Subject: Refrigeration and Air Conditioning

Coverage

• Introduction

• Classification

• System components

• All air systems

• All water systems

• Air water systems

• Room air conditioners

• Packaged air conditioning plant

• Central air conditioning systems

• Split air conditioning systems2

Introduction:

• The air conditioning is defined as “ The process of

treating air in an indoor environment (room or space)

to establish and maintain required standards of

temperature, humidity, cleanliness and motion of air .”

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Introduction:

The complete process of air conditioning includes

following processes:

• Cooling or heating the air as per requirement of

temperature

• Addition of moisture in air (Humidification) or removal of

moisture from air (Dehumidification).

• Controlling movement of air (air motion)

• Purification of air (cleaning or filtering)

• Addition of fresh air from outside (ventilation)

• Distribution of air

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Classification of Air Conditioning System:

• Based on way of air cooling:

– Direct cooling system

– Indirect cooling system

• Based on major function

– Comfort air conditioning system

– Industrial air conditioning system

• Based on season of year

– Winter air conditioning system

– Summer air conditioning system

– Year round air conditioning system

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Classification of Air Conditioning System:

• Based on arrangement of equipments

– Unitary air conditioning system

• Window air conditioner

• Split air conditioner

• Package air conditioner

– Central ail - conditioning system

• All air system

• All water (hydronic) system

• Air-water system

– Zoned system

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Air conditioning system components:

• An air conditioning system is an assembly of differentparts of the system used to produce a specified conditionof air within a required space or building.

• Air conditioning system has following components:

– Cooling source

– Heating element

– Control system

– Distribution system

– Fans

– Filter

– Grille

– Tray

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Room (Window) air conditioners:

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Limitation of window air conditioner:

• It produces noise in the room because of compressor

is very near to the room.

• The evaporator and condenser is enclosed in single

unit. Therefore evaporator cannot be used as an

interior of room because condenser requires outside

air for cooling.

• It requires appropriate size of window or hole in wall

in order to fit the conditioner.

Room (Window) air conditioners:

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• First part: Includes the evaporator, filter, evaporator

fan and grille. They placed inside the room.

• Second part: Includes condenser, fan, and compressor.

This placed outside the room.

Split Air Conditioner:

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• First part: Includes the evaporator, filter, evaporator

fan and grille. They placed inside the room.

• Second part: Includes condenser, fan, and compressor.

This placed outside the room.

Split Air Conditioner:

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Advantages of Split AC over Window AC:

• The compressor is outside of the room, therefore no

compressor noise, and vibration in the room or space

to be conditioned.

• No window opening and fixing needed.

• The first part can be located in the room with

decorative display. It can be mounted on floor, ceiling,

and wall or behind a decorative structure.

Split Air Conditioner:

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The Advantages of unit:

• It is fully factory made and hence proper selection and

balance of components is possible.

• All the manufacturing and testing processes like assembly,

leak testing, processing and charging carried out under

factory conditions.

• Inspection and testing of the complete unit before it leaves

the factory. Hence, better quality is maintained.

• Delivery of unit to the site with full assembly and in

working order, hence avoiding site delays for materials.

• Fully assembled unit requires less time for installation and

hence minimum of inconvenience and cost.

Package Air Conditioning System:

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• It is fully

Summer air conditioning system:

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• It is fully

Winter air conditioning system:

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• It is fully

Year round air conditioning system:

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The system may be classified as follows:

• All air system

• All water system

• Air water system

Central air conditioning system

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• Single duct, single zone, CV

All air system

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• Single duct, Multi zone, CV

All air system

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• Duel duct, Multi zone, CV

All air system

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• Single duct, Multi zone, VAV

All air system

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Advantages:

• Possible to use a wide variety of air filters and avoid

noise in the conditioned space.

• Complete absence of drain pipes, electrical wiring, and

filters at the conditioned space.

• In case of dual duct systems, it is possible to provide

simultaneous cooling and heating.

• Seasonal change over is very simple and easy to

automate.

• Very flexible heating and cooling can occur in different

zones simultaneously

All air system

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Disadvantages:

• It requires more space, reduces the available floor

space.

• Due to space constraints it may be difficult to provide

air conditioning in high rise buildings with the plant on

the ground floor or basement.

• Due to the space requirement retrofitting may not

always be possible.

• Balancing of air may be difficult in case of large and

particularly with variable air volume systems.

All air system

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All Water system

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FCU-terminal

All Water system

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Advantages:

• The plant size is small due to the absence of large

supply air fans.

• It is easier to retrofit to existing buildings.

• The thermal distribution system requires very less

space compared to all air systems.

• In case of four pipe system, simultaneous cooling and

heating is possible.

• Solar or waste heat can be utilized for winter heating.

All Water system

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Disadvantages:

• It requires higher maintenance compared to all air

system.

• The filters are small, low in efficiency and require

frequent replacement.

• The ventilation depends on wind and hence, it is

difficult to ensure positive ventilation under all

circumstances when ventilation is provided by opening

windows or wall apertures.

• Control of humidity, particularly during summer is

difficult using chi lied water control valves.

All Water system

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Air - Water system

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• FCU for Air-Water

Air - Water system

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Advantages:

• Rooms can be individually controlled at relatively low cost,

which control either the secondary water flow rate or the

secondary air (in fan coil units) or both.

• The amount of primary air supplied is less than that of an

all air systems therefore, space requirement is reduced.

• There is no latent heat transfer is required in the cooling

coil placed in the conditioned space, and its life thereby

increases.

• Terminal units in case of induction unit does not have fans,

motors, or compressors and hence service of indoor units is

relatively simpler compared to all water systems.

Air - Water system

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Disadvantages:

• Need for handling and controlling both air and water,

operation and control are complicated.

• The water coils in the conditioned space can become dirty if

the quality of filters used in the room units is not good.

• Initial cost could be high compared to all air systems.

• Shutting down the supply of primary air to unoccupied

spaces is not possible because constant amount of primary

air is supplied to conditioned space, and room control is

only through the control of room cooling / heating coils.

Air - Water system

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