Elements of mechinical Engineering

1. GANDHINAGAR INSTITUTE OF
TECHNOLOGY
ACTIVE LEARNING ASSIGNMENT
ELEMENTS OF MECHANICAL ENGINEERING(2110006)
AIR COMPRESSORS
PREPARED BY: GUIDED BY:
Jay Chovatiya (150120116011) PROF. Sajan Chourasia
BRANCH: INFORMATION TECHNOLOGY- D-D1
SEMESTER:2 (EVEN)

2. GOALS:
Introduction
Classification
Terminology
Reciprocating compressor
Application

3. AIR COMPRESSORS
• An air compressor is a device that converts
power into potential energy by forcing air into
a smaller volume and thus increasing its
pressure.
• The energy in the compressed air can be stored
while the air remains pressurized.

4. CLASSIFICATION:
Air Compressors are classified on various categories,
according to the:
 Principle of Working:
1. Positive displacement
2. Dynamic(Negative displacement)
 Number of Stages:
1. Single stage - pressure ratio upto 5 – 6.
2. Multi stage – pressure ratio more than 6.

5.  Acting of Piston:
1. Single Acting 2. Double Acting
 Number of Cylinders:
1. Single Cylinder 2. Double Cylinder
 Pressure Ratio:
1. Fan- pressure ratio upto 1.1
2. Blower- pressure ratio 1.1 to 2.5
3. Compressor- pressure ratio more than 2.5
 Method of Cooling:
1. Air cooled 2. Water cooled

6.  According to the Arrangement of Cylinder:
1. Vertical 3. V-type
2. Horizontal 4. Radial

7. AIR COMPRESSOR TERMINOLOGY
 SINGLE ACTING COMPRESSOR:
Compressor in which suction, compression and delivery of air
takes place only in one side of piston.
 DOUBLE ACTING COMPRESSOR:
Compressor in which suction, compression and delivery of air
takes place on both sides of piston.
 SINGLE STAGE COMPRESSOR:
Compressor in which compression of air from suction pressure to
delivery pressure takes place in one cylinder .

8.  MULTI STAGE CYLINDER:
Compressors in which compression of air from suction pressure
to delivery pressure takes place in more than one cylinder.
 COMPRESSION RATIO:
It is defined as a ratio of an absolute discharge pressure to
absolute suction pressure.
 VOLUMETRIC EFFICIENCY:
Defined as the ratio of actual volume of air taken in the
compressor to the swept volume of the compressor.
 COMPRESSOR CAPACITY:
Volume of the air delivered by the compressor.
Expressed in cubic metre per minute or cubic metre per second.

9. RECIPROCATING COMPRESSORS
• A reciprocating compressor or piston compressor is
a positive-displacement compressor that uses pistons driven by
a crankshaft to deliver gases at high pressure
• The intake gas enters the suction manifold, then flows into the
compression cylinder where it gets compressed by a piston
driven in a reciprocating motion via a crankshaft, and is then
discharged.
• It also consists of inlet valve and delivery valve and they
operated because of the pressure difference across it.

10. RECIPROCATING AIR COMPRESSOR

11. Working:
• When piston moves downward during suction stroke, the
compressed air left in the cylinder expands and due to expansion,
the pressure inside the cylinder falls below atmospheric pressure
which result in the opening of inlet valve opens and delivery valve
remains closed and fresh air is sucked into the cylinder.
• At the time of upward stroke, there is slight increase in pressure
which closes the inlet valve and when both the valves are closed the
pressure inside the valve increases.
• So when the pressure inside the cylinder increases above the
compressed air pressure on outside of delivery valve,the delivery
valve remain open and compressed air is delivered into the receiver.
So, at the end piston move downward and as pressure decreases
delivery valve remain closed.
• When pressure falls below atmospheric once again inlet valve opens
and thus the cycle is repeated.

12. Application:
• Applications include oil refineries, gas pipelines, chemical
plants, natural gas processing plants and refrigeration plants.
One specialty application is the blowing of plastic bottles
made of polyethylene terephthalate (PET).

13. THANK
YOU 