Volumetric efficiency of a compressor with clearance volume

A gas engine has a swept volume of 300 cm³ and clearance volume of 25 cm³. Its volumetric efficiency is 0.88 and mechanical efficiency is 0.90. The volume of the mixture taken in per stroke is

A

248 cm³

B

252 cm³

C

264 cm³

D

286 cm³

Volumetric efficiency of a compressor without clearance volume

A

Increases with increase in compression ratio

B

Decreases with increase in compression ratio

C

Is not dependent upon compression ratio

D

May increase/decrease depending on compressor capacity

Consider the following statements: The volumetric efficiency of a reciprocating compressor can be improved by 1. decreasing the clearance volume 2. cooling the intake air 3. heating the intake air Which of the above statements is/are correct?

A

2 only

B

3 only

C

1 and 2

D

1 and 3

If the clearance ratio for a reciprocating air compressor is 'K', then its volumetric efficiency is given by

A

$$1 - {\text{K}} + {\text{K}}{\left( {\frac{{{{\text{p}}_1}}}{{{{\text{p}}_2}}}} \right)^{\frac{1}{{\text{n}}}}}$$

B

$$1 + {\text{K}} - {\text{K}}{\left( {\frac{{{{\text{p}}_2}}}{{{{\text{p}}_1}}}} \right)^{\frac{1}{{\text{n}}}}}$$

C

$$1 - {\text{K}} + {\text{K}}{\left( {\frac{{{{\text{p}}_1}}}{{{{\text{p}}_2}}}} \right)^{\frac{{{\text{n}} - 1}}{{\text{n}}}}}$$

D

$$1 + {\text{K}} - {\text{K}}{\left( {\frac{{{{\text{p}}_2}}}{{{{\text{p}}_1}}}} \right)^{\frac{{{\text{n}} - 1}}{{\text{n}}}}}$$

For a fixed clearance, as the pressure ratio is increased, the volumetric efficiency of a compressor

A

decreases

B

increases

C

remains constant

D

none of the mentioned

A database of research articles in a journal uses the following schema. (VOLUME, NUMBER, STARTPAGE, ENDPAGE, TITLE, YEAR, PRICE) The primary key is (VOLUME, NUMBER, STARTPAGE, ENDPAGE) and the following functional dependencies exist in the schema. (VOLUME, NUMBER, STARTPAGE, ENDPAGE) → TITLE (VOLUME, NUMBER) → YEAR (VOLUME, NUMBER, STARTPAGE, ENDPAGE) → PRICE The database is redesigned to use the following schemas. (VOLUME, NUMBER, STARTPAGE, ENDPAGE, TITLE, PRICE) (VOLUME, NUMBER, YEAR) Which is the weakest normal form that the new database satisfies, but the old one does not?

A

1NF

B

2NF

C

3NF

D

BCNF

Various efficiencies of a centrifugal pump are related as (where, ηm = mechanical efficiency ηv = volumetric efficiency. ηma = manometric efficiency ηo = overall efficiency)

A

ηma x ηm x ηv = ηo

B

ηm = ηv . ηma

C

ηma = ηm x ηv

D

ηv = ηm x ηma

The hydraulic efficiency of a Francis turbine is 90%, the mechanical efficiency is 95% and the volumetric efficiency is assumed to be 100%. Fine the overall efficiency (in %)?

A

80

B

85.5

C

87.5

D

83.3

The hydraulic efficiency of a Kaplan turbine is 95%, the mechanical efficiency is 93% and the volumetric efficiency is assumed to be 100%. Fine the overall efficiency (in %)?

A

80.05

B

93.15

C

87.55

D

88.35

Various efficiencies of a centrifugal pump are related as (where, η_m = mechanical efficiency η_v = volumetric efficiency. η_ma = manometric efficiency η_o = overall efficiency)

A

η_ma × η_m × η_v = η_o

B

η_m = η_v × η_ma

C

η_ma = η_m × η_v

D

η_v = η_m × η_ma

Volumetric efficiency of a compressor with clearance volume

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