This document discusses different types of air compressors. It describes positive displacement compressors like reciprocating compressors which work on the principle of a bicycle pump and have pistons that compress air. Rotary compressors are also positive displacement compressors that provide continuous airflow. Dynamic compressors like centrifugal compressors use a rotating impeller to transfer energy and compress incoming air without boundaries containing it. Centrifugal compressors are commonly used for medium pressure applications and produce smooth compressed air output.

1. Unit No:02
Energy Conversion Devices
Prof. Yash B. Parikh
M.Tech (Computer Integrated Manufacturing)
B.E.(Mechanical Engineering)
Assistant Professor
Department of Mechanical Engineering

2. Air Compressors
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3. Air Compressors
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 A compressor is a machine capable of compressing
and delivering the air at desires pressure.
 It is driven by a prime mover (Engine or an electric
motor).
 A compressor takes in atmospheric air,
compresses it and delivers the high pressure air
to a receiver(storage vessel) from which it may be
conveyed by a pipeline.

4. Applications of Compressed Air
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• For operating pneumatic hand tools such as drills.
• Painting and Spraying.
• For driving mining tools.
• To supply the air in blast furnace.
• To operate air brakes in automobiles.
• To inflate automobile tiers.
• To clean machines and work shop floor.

5. Applications of Compressed Air
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• Refrigerators and Air conditioners.
• Gas turbine power plants.
• Conveying materials like sand and concrete along a
pipe.
• Driving Air Motors.

6. Classification of Air Compressors
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7. Positive Displacement Type of Air Compressors
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 Reciprocating Compressors :
In industry, these are the most widely used.
• They work on the principles of a
bicycle pump.

8. Reciprocating Compressors
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9. Reciprocating Compressors
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• It has a piston sliding in a cylinder similar to
I.C.Engines.
• The air is compressed due to positive displacement.
• They can produce large pressure ratios with low
volume flow rate.
• They are of two types :
i) Single Acting Reciprocating Compressor
ii) Multistage Compressor

10. Single Stage v/s Multistage Compressors
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• A compressor is considered to be single stage when
the entire compression is accomplished with a single
cylinder.
• The compression of air in single stage has many
disadvantages and its use is limited where low
delivery pressure is required.
• Advantages of multistage compression is that it
provides a facility to install an inter cooler between
the stages.

11. Single Stage v/s Multistage Compressors
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• Less power is required to deliver the same quantity
of air at the same delivery pressure.
• Better lubrication due to lower temperature.
• Multistage are used for high pressures and have
lower discharge temperature (140 to 160 C)
compared to single stage (205 to 240 C)
• A multistage compression is more efficient and
mostly employed for high pressures.

12. Single Acting Reciprocating Air Compressors
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13. Rotary Compressors
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14. Rotary Compressors
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• Rotary compressors have rotors in place of pistons
and gives a continuous pulsation free discharge.
• They operate at high speed and generally provide
higher throughput than reciprocating compressors.
• Their capital costs are low, they are compact in size,
have low weight, and are easy to maintain.
• For this reason they have gained popularity with
industry.

15. Dynamic Compressors
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• In this type of compressor the air is not trapped
within the specified boundaries, but it flows at a
steady rate continuously.
Centrifugal Compressor :

16. Centrifugal Compressor
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• The centrifugal air compressor is a dynamic
compressor.
• It consists of an impeller which rotates at a very high
speed (as high as 30,000 rpm).
• Which produces centrifugal head on the air within
and causes the air to flow from surroundings axially.
• Due to transfer of energy from a rotating impeller to
the air get compressed.

17. Centrifugal Compressor
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• Centrifugal compressors are most frequently used for
medium volume and medium pressure air delivery.
• One advantage of a centrifugal pump is the smooth
discharge of the compressed air.
• The centrifugal force is utilized by the centrifugal
compressor.
• The air particles enter the eye of the impeller,
designated D.
• As the impeller rotates, air is thrown against the
casing of the compressor.

18. Centrifugal Compressor
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• The air becomes compressed as more and more air is
thrown out to the casing by the impeller blades.
• The air is pushed along the path designated A, B,
and C in Figure.
• The pressure of the air is increased as it is pushed
along this path.
• Centrifugal compressors can use a variety of blade
orientation including both forward and backward
curves as well as other designs.
• There may be several stages to a centrifugal air
compressor, and the result would be the same; a
higher pressure would be produced.