In case of compression of one kg of air, the work done will be the least, when the value of polytropic index 'n' is

The expression for the work done for a reversible polytropic process can be used to obtain the expression for work done for all processes, except reversible __________ process.

A

Isobaric

B

Isothermal

C

Adiabatic

D

None of these

For a two stage compressor, if index of compression for higher stage is greater than index of compression for lower stage, then the optimum pressure as compared to ideal case will

A

Increase

B

Decrease

C

Remain unaffected

D

Other factors control it

The polytropic index (n) is given by

A

$$\frac{{\log \left( {{{\text{p}}_1}{{\text{p}}_2}} \right)}}{{\log \left( {{{\text{v}}_1}{{\text{v}}_2}} \right)}}$$

B

$$\frac{{\log \left( {\frac{{{{\text{p}}_2}}}{{{{\text{p}}_1}}}} \right)}}{{\log \left( {\frac{{{{\text{v}}_1}}}{{{{\text{v}}_2}}}} \right)}}$$

C

$$\frac{{\log \left( {\frac{{{{\text{v}}_1}}}{{{{\text{v}}_2}}}} \right)}}{{\log \left( {\frac{{{{\text{p}}_1}}}{{{{\text{p}}_2}}}} \right)}}$$

D

$$\log \left( {\frac{{{{\text{p}}_1}{{\text{v}}_1}}}{{{{\text{p}}_2}{{\text{v}}_2}}}} \right)$$

For minimum work in multistage compression, assuming same index of compression in all stages

A

Work done in first stage should be more

B

Work done in subsequent stages should increase

C

Work done in subsequent stages should decrease

D

Work done in all stages should be equal

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

The value of work index does not change materially from one equipment to another. If the value of work index determined for close circuit grinding is Wi, then the same for open circuit grinding will be

A

0.5 Wi

B

Wi

C

1.34 Wi

D

3.34 Wi

The work done in isothermal compression compared to that in adiabatic compression will be

A

Less

B

More

C

Same

D

More or less depending upon the extent of work done

If value of n is infinitely large in a polytropic process pVn = C, then the process is known as constant

A

Volume

B

Pressure

C

Temperature

D

Enthalpy

Multistage compression of air as compared to single stage compression offers the advantage of

A

Power saving per unit weight of air delivered

B

Moisture elimination in the inter-stage cooler

C

Increased volumetric efficiency

D

All of the above

Maximum work is done in compressing air when the compression is

A

Isothermal

B

Adiabatic

C

Polytropic

D

None of the above

In case of compression of one kg of air, the work done will be the least, when the value of polytropic index 'n' is

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