Which of the following same diameter columns gives lowest pressure drop per unit height?

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

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

Which of these columns incurs the lowest pressure drop?

A

Packed column (with stacked packing)

B

Packed column (with dumped packing)

C

Bubble plate column

D

Pulse column

Diameter of bubble caps used in high pressure columns is __________ as compared to that used in identical vacuum columns.

A

Less

B

More

C

Same

D

Either A or B; no generalisation can be made

Two fluids are flowing through two similar pipes of the same diameter. The Reynold's number is same. For the same flow rate if the viscosity of a fluid is reduced to half the value of the first fluid, the pressure drop will

A

Increase

B

Decrease

C

Remain unchanged

D

Data insufficient to predict relative pressure drop

At the following point for a given packing and set of fluids, the pressure drop per metre of packed height, with variation in fluid rates and operating pressure

A

Increases

B

Decreases

C

Remains same

D

May increase or decrease depending upon the solubility of the gas in the liquid

Total pressure on the vertical face of a retaining wall of height ‘h’ per unit run exerted by the retained earth weighing ‘w’ per unit volume, is

A

$${\text{wh}}\frac{{\left( {1 - \sin \varphi } \right)}}{{\left( {1 + \sin \varphi } \right)}}$$

B

$${\text{w}}{{\text{h}}^2}\frac{{\left( {1 - \sin \varphi } \right)}}{{\left( {1 + \sin \varphi } \right)}}$$

C

$$\frac{{{\text{w}}{{\text{h}}^2}\left( {1 - \sin \varphi } \right)}}{{2\left( {1 + \sin \varphi } \right)}}$$

D

$$\frac{{{\text{w}}{{\text{h}}^2}\left( {1 - \sin \varphi } \right)}}{{3\left( {1 + \sin \varphi } \right)}}$$

For annular flow of a fluid, the ratio of the equivalent diameter for pressure drop calculation to the equivalent diameter for heat transfer calculation is

A

$$\frac{{{{\text{d}}_1}}}{{{{\text{d}}_1} + {{\text{d}}_2}}}$$

B

$$\frac{{{{\text{d}}_2}}}{{{{\text{d}}_1} + {{\text{d}}_2}}}$$

C

$$\frac{{{{\text{d}}_1} + {{\text{d}}_2}}}{{{{\text{d}}_1}}}$$

D

$$\frac{{{{\text{d}}_1} + {{\text{d}}_2}}}{{{{\text{d}}_2}}}$$

If a single tube pass heat exchanger is converted to two pass, then for the same flow rate, the pressure drop per unit length in tube side will

A

Increase by 1.8 times

B

Decrease by 22

C

Increase by 216

D

Remain unchanged

If a single tube pass heat exchanger is converted to two passes; for the same flow rate, the pressure drop per unit length in tube side will __________ times.

A

Increase by 1.8

B

Decrease by 2²

C

Increase by 2^1.6

D

None of these

Smaller sized packings are generally dumped to the packed columns, and the large ones of size greater than __________ mm are stacked individually, which provides better control over bed porosity and offers lower gas pressure drop.

A

25

B

50

C

75

D

150

Which of the following same diameter columns gives lowest pressure drop per unit height?

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