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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

Correct Answer :

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


Related Questions

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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

The air-fuel ratio in gas turbines is of the order of

A. 7 : 1

B. 15 : 1

C. 30 : 1

D. 50 : 1.

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4

The ratio of isentropic work to Eulers work is known as

A. Compressor efficiency

B. Isentropic efficiency

C. Euler's efficiency

D. Pressure coefficient

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4

For supplying intermittent small quantity of air at high pressure, following compressor is best suited

A. Centrifugal

B. Reciprocating

C. Axial

D. Screw

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4

The compressed air may be used

A. In gas turbine plants

B. For operating pneumatic drills

C. In starting and supercharging of I.C. engines

D. All of the above

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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

An ideal air compressor cycle without clearance on PV diagram can be represented by following processes

A. One adiabatic, two isobaric, and one constant volume

B. Two adiabatic and two isobaric

C. Two adiabatic, one isobaric and one constant volume

D. One adiabatic, one isobaric and two constant volumes

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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 following is true for an open cycle gas turbine having exhaust heat exchanger. Atmospheric air before entering the compressor is

A. Heated

B. Compressed air before entering the combustion chamber is heated

C. Bled gas from turbine is heated and readmitted for complete expansion

D. Exhaust gases drive the compressor

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4

Actual compression curve is

A. Same as isothermal

B. Same as adiabatic

C. Better than isothermal and adiabatic

D. In between isothermal and adiabatic

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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

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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

When the temperature of air leaving the intercooler, in a two stage compression with intercooler, is ________ the original atmospheric air temperature, then the intercooling is known as perfect or complete intercooling.

A. Equal to

B. Less than

C. More than

D. None of these

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4

The work done per unit mass of air in compression will be least when n is equal to

A. 1

B. 1.2

C. 1.3

D. 1.4

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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

Propulsion efficiency of the following order is obtained in practice

A. 34 %

B. 50 %

C. 60 %

D. 72 %

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4

In a centrifugal compressor, the flow of air is ________ to the axis of compressor.

A. Parallel

B. Perpendicular

C. Inclined

D. None of these

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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

An aftercooler is used to

A. Remove impurities from air

B. Reduce volume of air

C. Cause moisture and oil vapour to drop out

D. Cool the air

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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

Gas turbine cycle with regenerator

A. Increases thermal efficiency

B. Allows high compression ratio

C. Decreases heat loss is exhaust

D. Allows operation at very high altitudes

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4

Mining industry usually employs following motive power

A. A.C. electric motor

B. Compressed air

C. Petrol engine

D. Diesel engine

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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

Which of the following statement is wrong?

A. In a two stage reciprocating air compressor with complete intercooling, maximum work is saved.

B. The minimum work required for a two stage reciprocating air compressor is double the work required for each stage.

C. The ratio of the volume of free air delivery per stroke to the swept volume of the piston is called volumetric efficiency.

D. None 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 material commonly used for air craft gas turbine is

A. Stainless steel

B. High alloy steel

C. Duralumin

D. Timken, Haste alloys

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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

In jet engines, for the efficient production of large power, fuel is burnt in an atmosphere of

A. Vacuum

B. Atmospheric air

C. Compressed air

D. Oxygen alone

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4

Which of the following statement is correct?

A. The reciprocating compressors are best suited for high pressure and low volume capacity

B. The effect of clearance volume on power consumption is negligible for the same volume of discharge

C. Both (A) and (B)

D. None of these

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4

In a jet propulsion

A. The propulsive matter is ejected from within the propelled body

B. The propulsive matter is caused to flow around the propelled body

C. Its functioning does not depend upon presence of air

D. None of the above