Horsepower increase of a centrifugal gas compressor without altering the volumetric flow rate will __________ the gas discharge pressure.

Two centrifugal pumps P and R are available for use in a pipe flow system and their head-discharge characteristics are as follows. Pump P Pump R Discharge (cumecs) Head (m) Discharge (cumecs) Head (m) 0 40 0 45 0.12 35 0.14 40 0.2 28 0.24 35 0.3 18 0.3 28 The following statements (S1, S2, and S3) pertain to the head and discharge values during actual operation. Neglect losses in the system. Which of the following statements are correct? S1: When the two pumps P and R are connected in parallel, the discharge is 0.36 cumecs corresponding to a head of 35 m. S2: When the two pumps P and R are connected in parallel, the discharge is 0.36 cumecs corresponding to a head of 70 m. S3: When the two pumps P and R are connected in series, the discharge is 0.3 cumecs corresponding to a head of 46 m.

A

S2 only

B

S1 and S3

C

S1 and S2

D

S2 and S3

The variable required to be known in correlations used for estimating the horse power of a centrifugal gas compressor and hence its cost are P. Inlet pressure Q. Compressor rpm R. Delivery pressure S. Volumetric flow rate at inlet.

A

P, Q and R

B

P and R

C

R and S

D

P, R and S

A pollutant P degrades according to first order kinetics. An aqueous stream containing P at 2 kmole/m³ and volumetric flow rate 1 m³/h requires a mixed flow reactor of volume V to bring down the pollutant level to 0.5 kmole/m³. The inlet concentration of the pollutant is now doubled and the volumetric flow rate is tripled. If the pollutant level is to be brought down to the same level of 0.5 kmole/m³, the volume of the mixed flow reactor should be increased by a factor of

A

7

B

6

C

3

D

$$\frac{7}{3}$$

Which of the following statements are correct? 1) Velocity compounded impulse turbine gives less speed and less efficiency. 2) For an ideal centrifugal compressor, the pressure produced depends on impeller velocity and diameter. 3) While flowing through the rotor blades in a gas turbine, the relative velocity of gas continuously decreases. 4) While flowing through the rotor blades in an axial flow compressor, the relative velocity of air continuously decreases.

A

1 and 3

B

2 and 3

C

1 and 4

D

2 and 4

Statement (I): The term surge indicates a phenomenon of instability which takes place at low flow values and which involves an entire system including not only the centrifugal compressor, but also the group of components traversed by the fluid upstream and downstream of it. Statement(II): Choking is defined as separation of fluid from the rotor blades of centrifugal compressor.

A

Both statement (I) and Statement (II) are individually true and Statement (II) is the correct explanation of Statement (I)

B

Both Statement (I) and Statement (II) are individually true but statement (II) is not the correct explanation of Statement (I)

C

Statement (I) is true but Statement (II) is false

D

Statement (I) is false but Statement (II) is true

Applying a pressure drop across a capillary results in a volumetric flow rate 'Q' under laminar flow conditions. The flow rate for the same pressure drop, in a capillary of the same length but half the radius is

A

$$\frac{{\text{Q}}}{2}$$

B

$$\frac{{\text{Q}}}{4}$$

C

$$\frac{{\text{Q}}}{8}$$

D

$$\frac{{\text{Q}}}{{16}}$$

For very low pressure and high discharge rate, the compressor used is a/an __________ compressor.

A

Axial

B

Reciprocating

C

Rotary

D

None of these

The highest pressure gas of a mixture has partial pressure p, the partial pressure of other gases decreases by factor of 2n-1, the partial pressure of second gases decreases by a factor of 2, partial pressure of third gas increases by 4, and so on, if the total pressure of gas mixture is 31p/16, how many gases are present in the mixture?

A

3

B

5

C

10

Match the following in Column X with Column Y: Column X Column Y P. In a triaxial compression test, with increase of axial strain in loose sand under drained shear condition, the volumetric strain I. decreases Q. In a triaxial compression test, with increase of axial strain in loose sand under undrained shear condition, the excess pore water pressure II. Increase R. In a triaxial compression test, the pore pressure parameter “B” for a saturated soil III. remains same S. For shallow strip footing in pure saturated clay, Terzaghi’s bearing capacity factor (Nq) due to surcharge IV. is always 0.0. V. is always 1.0. VI. is always 0.5. Which one of the following combinations is correct?

A

(P)-(I), (Q)-(II), (R)-(V), (S)-(V)

B

(P)-(II), (Q)-(I), (R)-(IV), (S)-(V)

C

(P)-(I), (Q)-(III), (R)-(VI), (S)-(IV)

D

(P)-(I), (Q)-(II), (R)-(V), (S)-(VI)

Which one of the following sets is incorrect to show the inter-relationships among price elasticity coefficient, change in price and change in total revenue ? Price elasticity coefficient Change in price Change in Total Revenue 1) Zero Increase Decrease Increase Decrease (2) Less than 1 Increase Decrease Decrease Increase (3) Equal to 1 Increase Decrease No change No change (4) More than 1 Increase Decrease Decrease Increase

A

(1)

B

(2)

C

(3)

D

(4)

Horsepower increase of a centrifugal gas compressor without altering the volumetric flow rate will __________ the gas discharge pressure.

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