Which of the following statement is wrong?
In a two stage reciprocating air compressor with complete intercooling, maximum work is saved.
The minimum work required for a two stage reciprocating air compressor is double the work required for each stage.
The ratio of the volume of free air delivery per stroke to the swept volume of the piston is called volumetric efficiency.
None of the above
Correct Answer :
D. None of the above
Related Questions
In a high pressure compressor, the delivery pressure is
1 to 5 bar
5 to 8 bar
8 to 10 bar
10 to 15 bar
Volumetric efficiency is
The ratio of stroke volume to clearance volume
The ratio of the air actually delivered to the amount of piston displacement
Reciprocal of compression ratio
Index of compressor performance
Pick up the false statement
Gas turbine is a self starting unit
Gas turbine does not require huge quantity of water like steam plant
Exhaust losses in gas turbine are high due to large mass flow rate
Overall efficiency of gas turbine plant is lower than that of a reciprocating engine
A rocket engine for the combustion of its fuel
Carries its own oxygen
Uses surrounding air
Uses compressed atmospheric air
Does not require oxygen
The compression ratio for the compressor is always __________ unity.
Equal to
Less than
More than
None of these
A closed cycle gas turbine works on
Carnot cycle
Rankine cycle
Ericsson cycle
Joule cycle
Surging is the phenomenon of
Air stream blocking the passage
Motion of air at sonic velocity
Unsteady, periodic and reversed flow
Air stream not able to follow the blade contour
Rotary compressors are suitable for
Large discharge at high pressure
Low discharge at high pressure
Large discharge at low pressure
Low discharge at low pressure
The work ratio of simple gas turbine cycle depends on
Pressure ratio
Maximum cycle temperature
Minimum cycle temperature
All of the above
An ideal air compressor cycle without clearance on PV diagram can be represented by following processes
One adiabatic, two isobaric, and one constant volume
Two adiabatic and two isobaric
Two adiabatic, one isobaric and one constant volume
One adiabatic, one isobaric and two constant volumes
The efficiency of the vane blower is (where W₁ = Workdone due to compression, and W₂ = Workdone due to back flow)
W₁/(W₁ + W₂)
W₂/(W₁ + W₂)
(W₁ + W₂)/W₁
(W₁ + W₂)/W₂
The thrust on the rotor in a centrifugal compressor is produced by
Radial component
Axial component
Tangential component
None of the above
The ratio of specific weight/h.p. of gas turbine and I.C engines may be typically of the order of
1 : 1
2 : 1
4 : 1
1 : 6
The ratio of the increase in pressure in rotor blades to total increase in pressure in the stage is called
Pressure ratio
Pressure coefficient
Degree of reaction
Slip factor
The pressure ratio for an open cycle gas turbine compared to closed cycle gas turbine of same h.p. is
Low
High
Same
Low/high depending on make and type
Clearance volume in actual reciprocating compressors is essential
To accommodate Valves in the cylinder head
To provide cushioning effect
To attain high volumetric efficiency
To provide cushioning effect and also to avoid mechanical bang of piston with cylinder head
Volumetric efficiency of a compressor with clearance volume
Increases with increase in compression ratio
Decreases with increase in compression ratio
In not dependent upon compression ratio
May increase/decrease depending on compressor capacity
Pick up the wrong statement
Large gas turbines employ axial flow compressors
Axial flow compressors are more stable than centrifugal type compressors but not as efficient
Axial flow compressors have high capacity and efficiency
Axial flow compressors have instability region of operation
The overall efficiency of the compressed air system is the
Ratio of shaft output of the air motor to the shaft input to the compressor
Ratio of shaft input to the compressor to the shaft output of air motor
Product of shaft output of air motor and shaft input to the compressor
None of the above
In a jet propulsion
The propulsive matter is ejected from within the propelled body
The propulsive matter is caused to flow around the propelled body
Its functioning does not depend upon presence of air
None of the above
Only rocket engines can be propelled to space because
They can generate very high thrust
They have high propulsion efficiency
These engines can work on several fuels
They are not air breathing engines
The ratio of outlet whirl velocity to blade velocity in case of centrifugal compressor is called
Slip factor
Velocity factor
Velocity coefficient
None of the above
The capacity of compressor will be highest when its intake temperature is
Lowest
Highest
Anything
Atmospheric
The specific output per kg mass flow rate of a gas turbine (having fixed efficiencies of compressor and turbine and fixed higher and lower temperature) with increase in pressure ratio will
Increase first at fast rate and then slow
Increase first at slow rate and then fast
Decrease continuously
First increase, reach maximum and then decrease
A closed cycle gas turbine consists of a
Compressor
Heating chamber
Cooling chamber
All of these
For minimum work in multistage compression, assuming same index of compression in all stages
Work done in first stage should be more
Work done in subsequent stages should increase
Work done in subsequent stages should decrease
Work done in all stages should be equal
The degree of reaction is usually kept ________ for all types of axial flow compressors.
0.2
0.3
0.4
0.5
The air power of the compressor is also known as
Indicated power
Brake power
Frictional power
None of these
Out of the following, from where you will prefer to take intake for air compressor
From an air conditioned room maintained at 20°C
From outside atmosphere at 1°C
From coal yard side
From a side where cooling tower is located nearby
More than one stage will be preferred for reciprocating compressor if the delivery pressure is more than
2 kg/cm²
6 kg/cm²
10 kg/cm²
14.7 kg/cm²