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4

Adiabatic compression is one in which

A. Temperature during compression remains constant

B. No heat leaves or enters the compressor cylinder during compression

C. Temperature rise follows a linear relationship

D. Work done is maximum

Correct Answer :

B. No heat leaves or enters the compressor cylinder during compression


Related Questions

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4

Pick up the correct statement

A. Closed cycle gas turbine is an I.C engine

B. Gas turbine uses same working fluid over and over again

C. Ideal efficiency of closed cycle gas turbine plant is more than Carnot cycle efficiency

D. Thrust in turbojet is produced by nozzle exit gases.

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4

In open cycle turbojet engines used in military aircraft, reheating the exhaust gas from the turbine by burning, more fuel is used to increase the

A. Thrust and range of aircraft

B. Efficiency of the engine

C. Both (A) and (B)

D. None of these

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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

The pressure ratio of an ideal vaned compressor with increase in mass flow rate

A. Increases

B. Decreases

C. Remain constant

D. First decreases and then increases

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4

As the turbine inlet temperature increases, the thermal efficiency of gas turbine for the optimum pressure ratio

A. Increases

B. Decreases

C. Remain same

D. First increases and then decreases

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4

Work ratio of a gas turbine may be improved by

A. Decreasing the compression work

B. Increasing the compression work

C. Increasing the turbine work

D. Both (A) and (C) above

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4

The overall isothermal efficiency of the compressor is defined as the ratio of

A. Work required to compress the air isothermally to the actual work required to compress the air for the same pressure ratio

B. Isothermal power to the shaft power or B.P. of the motor or engine required to drive the compressor

C. Volume of free air delivery per stroke to the swept volume of the piston

D. Isentropic power to the power required to drive the compressor

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4

The compression ratio for the compressor is always __________ unity.

A. Equal to

B. Less than

C. More than

D. None of these

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4

Reheating in gas turbine results in

A. Increase of work ratio

B. Decrease of thermal efficiency

C. Decrease of work ratio

D. Both (A) and (B) above

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4

The propulsive power of the rocket is (where v₁ = Jet velocity, and v₂ = Aircraft velocity)

A. (v₁² -v₂²)/2g

B. (v₁ - v₂)²/2g

C. (v₁² -v₂²)/g

D. (v₁ - v₂)²/g

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4

In air breathing jet engine, the jet is formed by expanding

A. Highly heated atmospheric air

B. Solids

C. Liquid

D. Plasma

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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

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

Volumetric efficiency of air compressors is of the order of

A. 20 - 30 %

B. 40 - 50 %

C. 60 - 70 %

D. 70 - 90 %

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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

In a single stage, single acting reciprocating air compressor, without clearance volume, the workdone is minimum during

A. Isothermal compression

B. Isentropic compression

C. Polytropic compression

D. None of these

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4

The criterion of the thermodynamic efficiency for rotary compressor is

A. Isentropic compression

B. Isothermal compression

C. Polytropic compression

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

The clearance volume of the air compressor is kept minimum because

A. It allows maximum compression to be achieved

B. It greatly affects volumetric efficiency

C. It results in minimum work

D. It permits isothermal compression

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4

The net work input required for compressor with increase in clearance volume

A. Increases

B. Decreases

C. Remains same

D. Increases/decreases depending on compressor capacity

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4

When air is to be compressed at a high pressure, then it is advantageous to use

A. Single stage compression

B. Multistage compression without intercooling

C. Multistage compression with intercooling

D. None of these

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4

In an axial flow compressor, the ratio of pressure in the rotor blades to the pressure rise in the compressor in one stage is known as

A. Work factor

B. Slip factor

C. Degree of reaction

D. Pressure coefficient

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4

In air compressors, free air delivery means the

A. Actual volume of the air delivered by the compressor when reduced to normal temperature and pressure conditions

B. Volume of air delivered by the compressor

C. Volume of air sucked by the compressor during its suction stroke

D. None of the above

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4

Cylinder clearance in a compressor should be

A. As large as possible

B. As small as possible

C. About 50% of swept volume

D. About 100% of swept volume

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4

For minimum work in multistage compression, assuming same index of compression in all stages

A. Work done in first stage should be more

B. Work done in subsequent stages should increase

C. Work done in subsequent stages should decrease

D. Work done in all stages should be equal

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4

Which one of the following is the effect of blade shape on performance of a centrifugal compressor?

A. Backward curved blades has poor efficiency

B. Backward curved blades lead to stable performance

C. Forward curved blades has higher efficiency

D. Forward curved blades produce lower pressure ratio

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4

In turbo fan engine, the jet velocity as compared to turbojet engine is

A. Less

B. More

C. Same

D. May be less or more depending upon speed

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4

In a single acting reciprocating compressor, the suction, compression and delivery of air takes place in ________ of the piston.

A. One stroke

B. Two strokes

C. Three strokes

D. Four strokes

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4

Gas turbine works on

A. Brayton or Atkinson cycle

B. Carnot cycle

C. Rankine cycle

D. Erricson cycle

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4

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

A. Increase first at fast rate and then slow

B. Increase first at slow rate and then fast

C. Decrease continuously

D. First increase, reach maximum and then decrease