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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

Correct Answer :

A. Equal to


Related Questions

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The temperature of air at the beginning of the compression stroke is ________ the atmospheric temperature.

A. Equal to

B. Less than

C. More than

D. None of these

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The capacity of a compressor is expressed in

A. kg/m²

B. kg/m³

C. m³/min

D. m³/kg

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4

Which of the following plants is smallest and lightest for generating a given amount of power?

A. Gas turbine plant

B. Petrol engine

C. Diesel engine

D. Solar plant

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The air is delivered ________ in one revolution in case of a three lobbed rotor.

A. Two times

B. Three times

C. Four times

D. Six times

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A rotary compressor is driven by an

A. Electric motor

B. Engine

C. Either (A) or (B)

D. None of these

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For perfect intercooling in a two stage compressor

A. p₂/p₁ = p₃/p₂

B. p₁/p₃ = p₂/p₁

C. p₁ = p₃

D. p₁ = p₂ p₃

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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 ratio of the indicated power to the shaft power or brake power of the motor or engine required to drive the compressor, is called

A. Compressor efficiency

B. Volumetric efficiency

C. Isothermal efficiency

D. Mechanical efficiency

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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

Which of the following statement is correct relating to rocket engines?

A. The combustion chamber in a rocket engine is directly analogous to the reservoir of a supersonic wind tunnel

B. The stagnation conditions exist at the combustion chamber

C. The exit velocities of exhaust gases are much higher than those in jet engine

D. All of the above

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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

In jet engines, paraffin is usually used as the fuel because of its

A. High calorific value

B. Ease of atomisation

C. Low freezing point

D. Both (A) and (C) above

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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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Gas turbines use following type of air compressor

A. Centrifugal type

B. Reciprocating type

C. Lobe type

D. Axial flow type

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Mechanical efficiency of gas turbines as compared to I.C engines is

A. Higher

B. Lower

C. Same

D. None of the above

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A closed cycle gas turbine works on

A. Carnot cycle

B. Rankine cycle

C. Ericsson cycle

D. Joule cycle

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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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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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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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The efficiency of roots blower ________ with the increase in pressure ratio.

A. Decreases

B. Increases

C. Does not change

D. None of these

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The mean effective pressure of the compressor is 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

Phenomenon of choking in compressor means

A. No flow of air

B. Fixed mass flow rate regardless of pressure ratio

C. Reducing mass flow rate with increase in pressure ratio

D. Increased inclination of chord with air steam

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The efficiency of the vane blower is (where W₁ = Workdone due to compression, and W₂ = Workdone due to back flow)

A. W₁/(W₁ + W₂)

B. W₂/(W₁ + W₂)

C. (W₁ + W₂)/W₁

D. (W₁ + W₂)/W₂

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Axial flow compressor resembles

A. Centrifugal pump

B. Reciprocating pump

C. Turbine

D. Sliding vane compressor

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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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Rotary 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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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 air entry velocity m a rocket as compared to aircraft is

A. Same

B. More

C. Less

D. Zero

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

A. Same

B. Higher

C. Lower

D. Dependent on other factors