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
Correct Answer :
D. Work done in all stages should be equal
Related Questions
Intercooling in gas turbines
Decreases net output but increases thermal efficiency
Increases net output but decreases thermal efficiency
Decreases net output and thermal efficiency both
Increases net output and thermal efficiency both
Volumetric efficiency of a compressor decreases with ________ in compression ratio.
Decrease
Increase
Remain same
Does not change
Losses in a centrifugal compressor are due to
Inlet losses
Impeller channel losses
Diffuser losses
All of the above
The temperature of air at the beginning of the compression stroke is ________ the atmospheric temperature.
Equal to
Less than
More than
None of these
1 m of air at atmospheric condition weighs approximately
0.5 kg
1.0 kg
1.3 kg
2.2 kg
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
Isothermal compression efficiency can be attained by running the compressor
At very high speed
At very slow speed
At average speed
At zero speed
Water gas is produced by
Carbonisation of coal
Passing steam over incandescent coke
Passing air and a large amount of steam over waste coal at about 65°C
Partial combustion of coal, eke, anthracite coal or charcoal in a mixed air steam blast
Work ratio of a gas turbine plant is ratio of
Net work output and work done by turbine
Net work output and heat supplied
Work done by turbine and heat supplied
Work done by turbine and net work output
Rotary compressor is best suited for
Large quantity of air at high pressure
Small quantity of air at high pressure
Small quantity of air at low pressure
Large quantity of air at low pressure
Adiabatic compression is one in which
Temperature during compression remains constant
No heat leaves or enters the compressor cylinder during compression
Temperature rise follows a linear relationship
Work done is maximum
The ratio of work done per cycle to the swept volume in case of compressor is called
Compression index
Compression ratio
Compressor efficiency
Mean effective pressure
In the aircraft propellers
The propulsive matter is caused to flow around the propelled body
Propulsive matter is ejected from within the propelled body
Its functioning does not depend on presence of air
All of the above
The fuel consumption in gas turbines is accounted for by
Lower heating value
Higher heating value
Heating value
Higher calorific value
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
The main purpose of reheating in gas turbine is to
Increase temperature
Reduce turbine size
Increase power output
Increase speed
Pick up wrong statement. Surging phenomenon in centrifugal compressor depends on
Mass flow rate
Pressure ratio
Change in load
Stagnation pressure at the outlet
A closed cycle gas turbine consists of a
Compressor
Heating chamber
Cooling chamber
All of these
Free air is the air at
Atmospheric conditions at any specific location
20°C and 1 kg/cm² and relative humidity of 36%
0°C and standard atmospheric conditions
15°C and 1 kg/cm²
The workdone on a compressor will be minimum if air is taken from
The atmosphere
A source at 0°C
A source of low temperature air
A source of high temperature air
A 3 m³/min compressor means that it
Compresses 3 m³/min of standard air
Compresses 3 m³/ min of free air
Delivers 3 m³/ min of compressed air
Delivers 3 m³/ min of compressed air at delivery pressure
If the clearance ratio for a reciprocating air compressor is 'K', then its volumetric efficiency is given by
1 - k + k (p₁/p₂)1/n
1 + k - k (p₂/p₁)1/n
1 - k + k (p₁/p₂) n- 1/n
1 + k - k (p₂/p₁) n-1/n
During base load operation, the best method of controlling compressor is
Start-stop motor
Constant speed unloader
Relief valve
Variable speed
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
After-cooler is used to
Cool the air
Decrease the delivery temperature for ease in handling
Cause moisture and oil vapour to drop out
Reduce volume
If the flow of air through the compressor is perpendicular to its axis, then it is a
Reciprocating compressor
Centrifugal compressor
Axial flow compressor
Turbo compressor
Which of the following plants is smallest and lightest for generating a given amount of power?
Gas turbine plant
Petrol engine
Diesel engine
Solar plant
The volumetric efficiency for reciprocating air compressors is about
10 to 40 %
40 to 60 %
60 to 70 %
70 to 90 %
The ratio of the net work obtained from the gas turbine plant to the turbine work is known as
Compression ratio
Work ratio
Pressure ratio
None of these
The minimum work required for a three stage reciprocating air compressor is ________ the work required for each stage.
Equal to
Double
Three times
Six times