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Current Affairs January 2024

What is the correct answer?

4

More than one stage will be preferred for reciprocating compressor if the delivery pressure is more than

A. 2 kg/cm²

B. 6 kg/cm²

C. 10 kg/cm²

D. 14.7 kg/cm²

Correct Answer :

A. 2 kg/cm²


Related Questions

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4

A compressor at high altitude will draw

A. More power

B. Less power

C. Same power

D. More/less power depending on other factors

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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

When the outlet angle from the rotor of a centrifugal compressor is more than 90°, then the blades are said to be

A. Forward curved

B. Backward curved

C. Radial

D. None of these

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4

Pick up the wrong statement

A. Large gas turbines employ axial flow compressors

B. Axial flow compressors are more stable than centrifugal type compressors but not as efficient

C. Axial flow compressors have high capacity and efficiency

D. Axial flow compressors have instability region of operation

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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

Pick up the false statement

A. Gas turbine is a self starting unit

B. Gas turbine does not require huge quantity of water like steam plant

C. Exhaust losses in gas turbine are high due to large mass flow rate

D. Overall efficiency of gas turbine plant is lower than that of a reciprocating engine

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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 efficiency of jet engine is

A. Lower at low speed

B. Higher at high altitudes

C. Same at all altitudes

D. Higher at high speed

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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

Reheating in multistage expansion gas turbine results in

A. High thermal efficiency

B. Reduction in compressor work

C. Decrease of heat loss in exhaust

D. Maximum work output

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4

There is a certain pressure ratio (optimum) for a gas turbine at which its thermal efficiency is maximum. With increase in turbine temperature, the value of pressure ratio for the peak efficiency would

A. Remain same

B. Decrease

C. Increase

D. None of the above

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4

The compressor performance at higher altitude compared to sea level will be

A. Same

B. Higher

C. Lower

D. Dependent on other factors

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4

Standard air is the air at

A. Atmospheric conditions at any specific location

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

C. 0°C and standard atmospheric conditions

D. 15°C and 1 kg/cm²

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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 closed cycle gas turbine, the air is compressed

A. Isothermally

B. Polytropically

C. Isentropically

D. None of these

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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

Axial flow compressor has the following advantage over centrifugal compressor

A. Larger air handling ability per unit frontal area

B. Higher pressure ratio per stage

C. Aerofoil blades are used

D. Higher average velocities

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4

The thermal efficiency of a gas turbine as compared to a diesel plant is

A. Same

B. More

C. Less

D. Depends on other factors

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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

Which is false statement about multistage compression?

A. Power consumption per unit of air delivered is low

B. Volumetric efficiency is high

C. It is best suited for compression ratios around 7:1

D. The moisture in air is condensed in the intercooler

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4

Pick up the correct statement

A. Large gas turbines use radial inflow turbines

B. Gas turbines have their blades similar to steam turbine

C. Gas turbine's blade will appear as impulse section at the hub and as a reaction section at tip

D. Gas turbines use both air and liquid cooling

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4

The air power of the compressor is also known as

A. Indicated power

B. Brake power

C. Frictional power

D. None of these

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4

The maximum propulsion efficiency of a turbojet is attained at around following speed

A. 550 km/hr

B. 1050 km/hr

C. 1700 km/hr

D. 2400 km/hr

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4

A simple turbojet engine is basically

A. A propeller system

B. Gas turbine engine equipped with a propulsive nozzle and diffuse

C. Chemical rocket engine

D. Ramjet engine

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4

Stalling of blades in axial flow compressor is the phenomenon of

A. Air stream blocking the passage

B. Motion of air at sonic velocity

C. Unsteady periodic and reversed flow

D. Air stream not able to follow the blade contour

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4

In a reciprocating air compressor, the compression work per kg of air

A. Increases as clearance volume increases

B. Decreases as clearance volume increases

C. Is independent of clearance volume

D. Increases as clearance volume decreases

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4

With the decrease in compression ratio, the volumetric efficiency

A. Does not change

B. Increases

C. Decreases

D. First decrease and then increase

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4

Choose the correct statement

A. Gas turbine requires lot of cooling water

B. Gas turbine is capable of rapid start up and loading

C. Gas turbines has flat efficiency at part loads

D. Gas turbines have high standby losses and require lot of maintenance

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4

A compressor mostly used for supercharging of I.C. engines is

A. Radial flow compressor

B. Axial flow compressor

C. Roots blower

D. Reciprocating compressor

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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