Fluidization Engineering Questions and Answers for Aptitude test on “Terminal Velocity of Particles”.
1. What is the Reynolds number range when the drag coefficient formula is 24/(Rep)?
a) Rep < 0.4
b) 0.4 < Rep < 500
c) 500 < Rep < 200,000
d) None of the mentioned
Answer: a
Clarification: Range is taken based on the experimental values.
2. What is the Reynolds number range when the drag coefficient formula is 10/(Rep)^0.5?
a) Rep < 0.4
b) 0.4 < Rep < 500
c) 500 < Rep < 200,000
d) None of the mentioned
Answer: b
Clarification: Range is taken based on the experimental values.
3. What is the Reynolds number range when the drag coefficient formula is 0.43?
a) Rep < 0.4
b) 0.4 < Rep < 500
c) 500 < Rep < 200,000
d) None of the mentioned
Answer: c
Clarification: Range is taken based on the experimental values.
4. The velocity of fluid is operated between minimum fluidizing velocity(Umf) and Pneumatic velocity in fluidized bed, true or false?
a) True
b) False
Answer: b
Clarification: It is operated between minimum fluidizing velocity and terminal velocity(Ut) in fluidized bed.
5. What is the range of Ut/Umf for flexible operation of the fluidized bed?
a) 10:1 to 90:1
b) 5:1 to 10:1
c) 90:1 to 120:1
d) 120:1 to 200:1
Answer: a
Clarification: This range provides best conditions for fluidization without much entrainment.
6. When the bed is just fluidized the height attained is maximum, true or false?
a) True
b) False
Answer: a
Clarification: Because after that height, the further increase in velocity will definitely lead to entrainment of some particles.
7. For fine solids Reynolds number should be less than?
a) 0.4
b) 4
c) 40
d) 400
Answer: a
Clarification: Since the size of particles is small, the velocity will be comparatively small. Hence the range also reduces.
8. For large solid particles Reynolds number should be greater than?
a) 10
b) 100
c) 1000
d) 10000
Answer: c
Clarification: Since the size of particles is large, the velocity will be comparatively large. Hence the range also increases.
9. When the diameter is narrower of the bed, which kind of problem is most likely to occur in the bed?
a) Chanelling
b) Slugging
c) Entrainment
d) None of the mentioned
Answer: b
Clarification: Slugging occurs due to coagulation of air bubbles without breaking.
10. What can be done in order to prevent slugging in the fluidized bed?
a) Baffles
b) Increase diameter
c) Proper design of distributor
d) All of the mentioned
Answer: d
Clarification: Placing baffles will break the bubbles, increasing the diameter will reduce chances of slugging, distributor design also decides the slugging factor.
for Aptitude test,