Discussion
Home ‣ Biochemical Engineering ‣ Agitation and Aeration Comments
- Question
Which of the following will have the highest surface area available for oxygen transfer?
Options- A. A shake flask
- B. A standing test tube
- C. A non-sparged stirred tank reactor agitated at 400 rpm
- D. A sparged stirred tank reactor agitated at 400 rpm
- Correct Answer
- A sparged stirred tank reactor agitated at 400 rpm
- 1. Which of the following is most likely to cause an increase in the rate of oxygen transfer into a particular aerated fermentation system?
Options- A. Addition of antifoams
- B. Increase in temperature
- C. Increase in stirrer speed
- D. Both (a) and (b) Discuss
- 2. Which of the following type(s) of stirrer can be used for microbiological processes?
Options- A. Mig
- B. Intermig
- C. Turbine
- D. All of these Discuss
- 3. Which of the following would be best described as an axial flow impeller?
Options- A. An impeller with blades pitched at 45° to the vertical
- B. An impeller which directs liquid flow towards the base of the reactor
- C. Both (a) and (b)
- D. An impeller with blades pitched at 75° to the vertical Discuss
- 4. Surface renewal theory predicts that the mass transfer coefficient is
Options- 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 Discuss
- 5. Penetration theory assumes that turbulent eddies travel from the bulk of the phase to the interface where they remain constant for a constant exposure time (te). The model correlating KL, mass transfer coefficient and DAB, diffusivity can be expressed as
Options- A. KL = 2(DAB/?te)0.25
- B. KL = 2(DAB/?te)0.5
- C. KL = 2(DAB/?te)0.75
- D. KL = 2(DAB/?te) Discuss
- 6. At 25°C, the saturation concentration of oxygen in water is 1.26 mmol/l and the partial pressure of oxygen is 1 atm. The Henry's law constant will be
Options- A. 0.793atml/mmol
- B. 0.207atml/mmol
- C. 1.26 atml/mmol
- D. 8.74 atml/mmol Discuss
- 7. The oxygen transfer rate in a bioreactor will increase if
Options- A. oil is added
- B. antifoam is added
- C. detergent like molecules are added
- D. increase in the reactor temperature Discuss
- 8. Power number is expressed as
Options- A. P0 / N2Di3?
- B. P0 / N3Di5?
- C. P0 / N3Di3?
- D. P0 / N2Di2? Discuss
- 9. Which of the following impellers will provide radial flow?
Options- A. Paddles
- B. Flat blade turbines
- C. Disk flat blade turbines
- D. All of the above Discuss
- 10. The average concentration of oxygen in the boundary layers surrounding the bubbles (Co*) in a reactor is normally determined by
Options- A. ultra-small dissolved oxygen probes
- B. laser based photographic systems
- C. measuring the steady state concentration of oxygen in the bulk liquid prior to inoculation of the reactor
- D. measuring the steady state concentration of oxygen in the bulk liquid after inoculation of the reactor Discuss
Agitation and Aeration problems
Search Results
Correct Answer: Increase in stirrer speed
Correct Answer: All of these
Correct Answer: Both (a) and (b)
Correct Answer: directly proportional to the square root of the molecular diffusivity
Correct Answer: KL = 2(DAB/?te)0.5
Correct Answer: 0.793atml/mmol
Correct Answer: detergent like molecules are added
Correct Answer: P0 / N3Di5?
Correct Answer: All of the above
Correct Answer: measuring the steady state concentration of oxygen in the bulk liquid prior to inoculation of the reactor
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