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4

Efficiency of gas turbine is increased by

A. Reheating

B. Inter cooling

C. Adding a regenerator

D. All of the above

Correct Answer :

C. Adding a regenerator


Related Questions

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4

The output of a gas turbine is 300 KW and its efficiency is 20 percent, the heat supplied is

A. 6000 KW

B. 15 KW

C. 600 KW

D. 150 KW

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4

The ratio of specific weight/h.p. of gas turbine and I.C engines may be typically of the order of

A. 1 : 1

B. 2 : 1

C. 4 : 1

D. 1 : 6

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4

Which is false statement about advantages of multistage compressor in comparison to single stage compressor?

A. Less power requirement

B. Better mechanical balance

C. Less loss of air due to leakage past the cylinder

D. Lower volumetric efficiency

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4

Ram compression in turbojet involves

A. Reduction of speed of incoming air and conversion of part of it into pressure energy

B. Compression of inlet air

C. Increasing speed of incoming air

D. Lost work

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4

Clearance volume in actual reciprocating compressors is essential

A. To accommodate Valves in the cylinder head

B. To provide cushioning effect

C. To attain high volumetric efficiency

D. To provide cushioning effect and also to avoid mechanical bang of piston with cylinder head

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4

For a two stage reciprocating compressor, compression from p₁ to p₃ is with perfect intercooling and no pressure losses. If compression in both the cylinders follows the same polytropic process and the atmospheric pressure is pa, then the intermediate pressure p₂ is given by

A. p₂ = (p₁ + p₃)/2

B. p₂ = p₁. p₃

C. P₂ = Pa × p₃/p₁

D. p₂ = Pa p₃/p₁

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4

Atmospheric pressure is 1.03 kg/cm and vapour pressure is 0.03 kg/cm. The air pressure will be

A. 1.03 kg/cm²

B. 1.06 kg/cm²

C. 1.00 kg/cm²

D. 0.53 kg/cm²

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4

Propulsion efficiency of the following order is obtained in practice

A. 34 %

B. 50 %

C. 60 %

D. 72 %

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4

Separators in compressor installations are located

A. Before intercooler

B. After intercooler

C. After receiver

D. Between after-cooler and air receiver

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4

Rotary compressors are used for delivering

A. Small quantities of air at high pressures

B. Large quantities of air at high pressures

C. Small quantities of air at low pressures

D. Large quantities of air at low pressures

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4

The efficiency and work ratio of a gas turbine plant can be increased by

A. Adding heat exchanger

B. Injecting water in/around combustion chamber

C. Reheating the air after partial expansion in the turbine

D. All of the above

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4

Maximum work is done in compressing air when the compression is

A. Isothermal

B. Adiabatic

C. Polytropic

D. None of the above

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4

In a high pressure compressor, the delivery pressure is

A. 1 to 5 bar

B. 5 to 8 bar

C. 8 to 10 bar

D. 10 to 15 bar

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4

Free air is the air at

A. Atmospheric conditions at any specific location

B. 20°C and 1 kg/cm² and relative humidity of 36%

C. 0°C and standard atmospheric conditions

D. 15°C and 1 kg/cm²

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4

Losses in a centrifugal compressor are due to

A. Inlet losses

B. Impeller channel losses

C. Diffuser losses

D. All of the above

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4

The overall efficiency of the compressed air system is the

A. Ratio of shaft output of the air motor to the shaft input to the compressor

B. Ratio of shaft input to the compressor to the shaft output of air motor

C. Product of shaft output of air motor and shaft input to the compressor

D. None of the above

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4

The ratio of isentropic work to Euler work is known as

A. Pressure coefficient

B. Work coefficient

C. Polytropic reaction

D. Slip factor

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4

The degree of reaction in an axial flow compressor is defined as the ratio of static enthalpy rise in the

A. Rotor to static enthalpy rise in the stator

B. Stator to static enthalpy rise in the rotor

C. Rotor to static enthalpy rise in the stage

D. Stator to static enthalpy rise in the stage

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4

The degree of reaction of an axial flow turbine is the ratio of isentropic temperature drop in a blade row to the

A. Adiabatic temperature drop in the stage

B. Total temperature drop

C. Total temperature drop in the stage

D. Total adiabatic temperature drop

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4

Isothermal compression efficiency, even when running at high speed, can be approached by using

A. Multistage compression

B. Cold water spray

C. Both (A) and (B) above

D. Fully insulating the cylinder

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4

Water is injected in gas turbine cycle to

A. Control temperature

B. Control output of turbine

C. Control fire hazards

D. Increase efficiency

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4

Propulsive efficiency is defined as ratio of

A. Thrust power and fuel energy

B. Engine output and propulsive power

C. Propulsive power and fuel input

D. Thrust power and propulsive power

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4

Pick up the wrong statement about advantages of multistage compression

A. Better lubrication is possible advantages of multistage

B. More loss of air due to leakage past the cylinder

C. Mechanical balance is better

D. Air can be cooled perfectly in between

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4

The thrust of a jet propulsion power unit can be increased by

A. Injecting water into the compressor

B. Burning fuel after gas turbine

C. Injecting ammonia into the combustion chamber

D. All of the above

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4

In n₁ and n₂ are the indices of compression for the first and second stage of compression, then the ratio of workdone on the first and second stages (W₁/W₂) with perfect intercooling is given by

A. W₁/W₂ = n₂(n₁ - 1)/n₁(n₂ - 1)

B. W₁/W₂ = n₁(n₂ - 1)/n₂(n₁ - 1)

C. W₁/W₂ = n₁/n₂

D. W₁/W₂ = n₂/n₁

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4

In a single stage, single acting reciprocating air compressor, without clearance, the workdone on the air during isentropic compression is ________ the heat required to raise the temperature of air from T₁ to T₂ at a constant pressure.

A. Equal to

B. Less than

C. Greater than

D. None of these

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4

Euler's equation is applicable for

A. Centrifugal compressor

B. Axial compressor

C. Pumps

D. All of the above

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4

In jet propulsion power unit, the inlet duct of diverging shape is used in order to

A. Collect more air

B. Convert kinetic energy of air into pressure energy

C. Provide robust structure

D. Beautify the shape

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4

Work ratio of a gas turbine plant is ratio of

A. Net work output and work done by turbine

B. Net work output and heat supplied

C. Work done by turbine and heat supplied

D. Work done by turbine and net work output

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4

In a double acting compressor, the air is compressed

A. In one cylinder

B. In two cylinders

C. In a single cylinder on both sides of the piston

D. In two cylinders on both sides of the piston