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4

In gas turbines, high thermal efficiency is obtained in

A. Closed cycle

B. Open cycle

C. Both of the above

D. Closed/open depending on other considerations

Correct Answer :

A. Closed cycle


Related Questions

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4

The maximum delivery pressure in a rotary air compressor is

A. 10 bar

B. 20 bar

C. 30 bar

D. 50 bar

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4

If p₁ is the pressure of air entering the L.P, cylinder and p₃ is the pressure of air leaving the H.P. cylinder, then the ratio of cylinder diameters for a single acting, two stage reciprocating compressor with complete intercooling is given by

A. D₁/D₂ = (p₁ p₃)1/2

B. D₁/D₂ = (p₁/p₃)1/4

C. D₁/D₂ = (p₁ p₃)1/4

D. D₁/D₂ = (p₃/p₁)1/4

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4

The volumetric efficiency of a compressor falls roughly as follows for every 5°C increase in atmospheric temperature

A. 0.1 %

B. 0.5 %

C. 1 %

D. 5 %

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4

Axial flow compressor resembles

A. Centrifugal pump

B. Reciprocating pump

C. Turbine

D. Sliding vane compressor

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4

Producer gas is produced by

A. Carbonisation of coal

B. Passing steam over incandescent coke

C. Passing air and a large amount of steam over waste coal at about 65°C

D. Partial combustion of coal, coke, anthracite coal or charcoal in a mixed air steam blast

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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 compressor capacity with decrease in suction temperature

A. Increases

B. Decreases

C. Remain unaffected

D. May increase or decrease depending on compressor capacity

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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 weight per horse power ratio for gas in Turbine as compared to I.C. engine and steam turbine is

A. Same

B. Higher

C. Lower

D. None of these

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4

A jet engine works on the principle of conservation of

A. Mass

B. Energy

C. Flow

D. Linear momentum

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4

Standard air is the air at ________ and relative humidity of 36 percent.

A. 0.1 bar and 20°C

B. 1 bar and 20°C

C. 0.1 bar and 40°C

D. 1 bar and 40°C

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4

A closed cycle gas turbine consists of a

A. Compressor

B. Heating chamber

C. Cooling chamber

D. All of these

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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

Reciprocating air compressor is best suited for

A. Large quantity of air at high pressure

B. Small quantity of air at high pressure

C. Small quantity of air at low pressure

D. Large quantity of air at low pressure

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4

Ratio of compression is the ratio of

A. Gauge discharge pressure to the gauge intake pressure

B. Absolute discharge pressure to the absolute intake pressure

C. Pressures at discharge and suction corresponding to same temperature

D. Stroke volume and clearance volume

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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

Water gas is produced by

A. Carbonisation of coal

B. Passing steam over incandescent coke

C. Passing air and a large amount of steam over waste coal at about 65°C

D. Partial combustion of coal, eke, anthracite coal or charcoal in a mixed air steam blast

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4

High air-fuel ratio is used in gas turbines

A. To increase the output

B. To increase the efficiency

C. To save fuel

D. To reduce the exit temperature

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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

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 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

The pressure and temperature conditions of air at the suction of compressor are

A. Atmospheric

B. Slightly more than atmospheric

C. Slightly less than atmospheric

D. Pressure slightly less than atmospheric and temperature slightly more than atmospheric

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4

A rocket engine uses ________ for the combustion of its fuel.

A. Surrounding air

B. Compressed atmospheric air

C. Its own oxygen

D. None of these

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4

To avoid moisture troubles, the compressed air main line should

A. Rise gradually towards the point of use

B. Drop gradually towards the point of use

C. Be laid vertically

D. Be laid exactly horizontally

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4

The type of rotary compressor used in gas turbines, is of

A. Centrifugal type

B. Axial flow type

C. Radial flow type

D. None of these

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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

Pick up the wrong statement

A. Centrifugal compressors deliver practically constant pressure over a considerable range of capacities

B. Axial flow compressors have a substantially constant delivery at variable pressures

C. Centrifugal compressors have a wider stable operating range than axial flow compressors

D. Axial flow compressors are bigger in diameter compared to centrifugal type

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4

During base load operation, the best method of controlling compressor is

A. Start-stop motor

B. Constant speed unloader

C. Relief valve

D. Variable speed

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4

The volume of air delivered by the compressor is called

A. Free air delivery

B. Compressor capacity

C. Swept volume

D. None of these

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4

A jet engine has

A. No propeller

B. Propeller in front

C. Propeller at back

D. Propeller on the top