Inter-cooling in multistage compressors is done

When the temperature of air leaving the inter-cooler, in a two stage compression with inter-cooler, 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

Why is multistage compression with intercooling adopted?

A

using a single stage with high pressure ratio decreases volumetric efficiency

B

high pressure ratio with dry compression gives high compressor discharge temperature

C

the refrigerant is damaged

D

all of the mentioned

Centrifugal compressors compared to reciprocating compressors

A

Require less space

B

Have quieter operation

C

Have lower operating costs

D

All of the above

Multistage compressors are used in industry, because they

A

Reduce the cost of compressor

B

Reduce the size requirement

C

Resemble closely to isothermal compression

D

Are easy to control

Three friends A, B and C worked together to complete the work. A takes 4 days more to complete same work done by A and B. Work done by C in 4 days is equal to the work done by A in one day. Work done by B in 3 days is equal to the work done by C in 8 days. Find the time in which work will be completed if all three worked together.

A

110/27 days

B

118/25 days

C

110/23 days

D

120/23 days

In n₁ and n₂ are the indices of compression for the first and second stage of compression, then the ratio of work-done 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

Intercooling is done in ___________

A

CI Engines

B

SI Engines

C

Gas Turbines

D

None of the mentioned

The water intercooling reduces the work to be done in low pressure compression.

A

True

B

False

In n₁ and n₂ are the indices of compression for the first and second stage of compression, then the ratio of work-done on the first and second stages $$\left( {\frac{{{{\text{W}}_1}}}{{{{\text{W}}_2}}}} \right)$$ with perfect intercooling is given by

A

$$\frac{{{{\text{W}}_1}}}{{{{\text{W}}_2}}} = \frac{{{{\text{n}}_2}\left( {{{\text{n}}_1} - 1} \right)}}{{{{\text{n}}_1}\left( {{{\text{n}}_2} - 1} \right)}}$$

B

$$\frac{{{{\text{W}}_1}}}{{{{\text{W}}_2}}} = \frac{{{{\text{n}}_1}\left( {{{\text{n}}_2} - 1} \right)}}{{{{\text{n}}_2}\left( {{{\text{n}}_1} - 1} \right)}}$$

C

$$\frac{{{{\text{W}}_1}}}{{{{\text{W}}_2}}} = \frac{{{{\text{n}}_1}}}{{{{\text{n}}_2}}}$$

D

$$\frac{{{{\text{W}}_1}}}{{{{\text{W}}_2}}} = \frac{{{{\text{n}}_2}}}{{{{\text{n}}_1}}}$$

In a single casing, multistage pump running at constant speed, the capacity rating is to be slightly lowered. It can be done by

A

Designing new impeller

B

Trimming the impeller size to the required size by machining

C

Not possible

D

Some other alterations in the impeller

Inter-cooling in multistage compressors is done

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