Differentiate between : (i) Reciprocating and rotary air compressor (ii) Centrifugal and axial flow compressor

Differentiate between : (i) Reciprocating and rotary air compressor (ii) Centrifugal and axial flow compressor
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1 Answer

Answer :

(i) Reciprocating and rotary air compressor:

Sr. No.
Reciprocating air compressor 
Rotary air compressor 
1 It is having to and fro motion.
It is having rotary motion 
2 Air supply is intermittent.
Air supply is continuous.
3 Lubrication system is complicated.
Lubrication system is simple.
4 Maximum delivery pressure is upto 1000 bar
Maximum delivery pressure is upto 10 bar.
5 Maximum free discharge is about 300 m3/min.
Maximum free discharge is about 3000 m3/min
6 Speed is lesser
Speed is higher
7 Balancing is major problem
No balancing problem
8 Frictional losses are more
Frictional losses are less
9 Size of compressor is large for the given discharge
Size of compressor is small for the given discharge
10 It is suitable for low discharge and high pressure
It is suitable for high discharge and low pressure
11 Application- Auto workshop, service stations, air brake system etc. 
Application- Torbocharger, supercharger, Blower, Hair Drier etc.


(ii) Centrifugal and axial flow compressor:

Sr. No
Centrifugal compressor 
Axial Flow Compressor
1 Flow is perpendicular to axis of compressor. 
Flow of air is parallel to the axis of compressor.
2 Low manufacturing and running cost.
High manufacturing and running cost.
3 Requires low starting torque. 
Requires high starting torque.
4 Not suitable for multi-staging. 
Suitable for multi-staging. 
5 Requires large frontal area for given rate of flow. 
Requires less frontal area for given rate of flow.
6 Pressure ratio per stage is 4:1.
Pressure ratio is 1.1 to 1.2 
7 Isentropic efficiency is 70%
Isentropic efficiency is 80%
8 Used in supercharging I.C. engine and for refrigerants and industrial gases.
Used universally with large gas turbine. 
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