Agitation and Aeration – Section 1

1. Swirling and vortex formation can be prevented by

A. using baffles
B. using diffusion ring with turbines
C. both (a) and (b)
D. none of these

Correct Answer: C. both (a) and (b)

2. Power number is expressed as

A. P0 / N2Di3ρ
B. P0 / N3Di5ρ
C. P0 / N3Di3ρ
D. P0 / N2Di2ρ

Correct Answer: B. P0 / N3Di5ρ

3. The power consumption in a stirring vessel can be assessed by using a

A. dynamometer
B. strain gauge attached to agitator shaft
C. watt meter attached to agitator motor
D. all of these

Correct Answer: D. all of these

4. Surface renewal theory predicts that the mass transfer coefficient is

A. directly proportional to the square root of the molecular diffusivity
B. inversely proportional to the square root of the molecular diffusivity
C. directly proportional to the cube root of the molecular diffusivity
D. indirectly proportional to the cube root of the molecular diffusivity

Correct Answer: A. directly proportional to the square root of the molecular diffusivity

5. The oxygen transfer rate in a bioreactor will increase if

A. oil is added
B. antifoam is added
C. detergent like molecules are added
D. increase in the reactor temperature

Correct Answer: C. detergent like molecules are added

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