Thermodynamics Mcqs

Q:

In an adiabatic irreversible process, extra work is done to overcome friction.

A) true B) false
 
Answer & Explanation Answer: A) true

Explanation: This increases the temperature and enthalpy of gas.

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16
Q:

For uncooled rotary compressor, compression process is ____ while ideal process is ____

A) isothermal, adiabatic B) isentropic, adiabatic
C) adiabatic, isentropic D) adiabatic, isothermal
 
Answer & Explanation Answer: C) adiabatic, isentropic

Explanation: The isentropic process is reversible and adiabatic.

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20
Q:

Which of the following is true for an axial-flow compressor?

A) blades are arranged in same manner as in reaction turbine B) flow of air is along the axis of compressor
C) velocity of air changes when it passes through the blades D) all of the mentioned
 
Answer & Explanation Answer: D) all of the mentioned

Explanation: This is the working of an axial-flow compressor.

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28
Q:

Which of the following is true for a centrifugal compressor?

A) rotation of impeller compresses the air B) diffuser converts part of KE into internal energy
C) typical pressure ratio is around 1.4 to 1 D) all of the mentioned
 
Answer & Explanation Answer: D) all of the mentioned

Explanation: This is the working of a centrifugal compressor.

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19
Q:

The centrifugal and axial flow compressor are the types of

A) displacement compressor B) steady-flow compressor
C) both of the mentioned D) none of the mentioned
 
Answer & Explanation Answer: B) steady-flow compressor

Explanation: These are the two types of steady-flow compressors.

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12
Q:

The vane type compressor requires ____ the Roots blower.

A) equal work input B) more work input
C) less work input D) none of the mentioned
 
Answer & Explanation Answer: C) less work input

Explanation: This is true for given air flow and pressure ratio.

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16
Q:

For a Root blower, as pressure ratio increases, efficiency ____

A) increases B) decreases
C) remains constant D) none of the mentioned
 
Answer & Explanation Answer: B) decreases

Explanation: This can be seen by taking pressure ratios and calculating efficiencies for them.

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14
Q:

The Roots blower and vane-type compressor are the types of

A) displacement compressor B) steady-flow compressor
C) both of the mentioned D) none of the mentioned
 
Answer & Explanation Answer: A) displacement compressor

Explanation: These are the two types of rotary positive displacement machines.

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