# Fluidization Engineering Questions and Answers – Fixed Bed – Particles of One Size

This set of Fluidization Engineering Multiple Choice Questions & Answers focuses on “Fixed Bed – Particles of One Size”.

1. What are the methods for measuring large particles of size above 5mm?
a) Calliper
b) Micrometer
c) Sieves
d) All of the mentioned

Explanation: All are used for measuring solid particles based on different principles.

2. What are the methods used for measuring particles of size < 0.04mm?
a) Settling rate
b) Brownian movement
c) Sieve analysis
d) All of the mentioned

Explanation: All are used for measuring solid particles based on different principles.

3. What does ‘-‘ sign mean in the following expression: – 150 + 200 mesh particles?
a) Pass through 150
b) Doesnt pass through 150
c) Pass through 200
d) None of the mentioned

Explanation: It represents particles which pass through 150 mesh.

4. What does ‘+’ sign mean in the following expression: – 150 + 200 mesh particles?
a) Pass through 200
b) Retained on 200
c) Retained on 150
d) None of the mentioned

Explanation: It represents particles which are retained on 200 mesh.

5. What is the relationship between sphericity and voidage?
a) Sphericity=(6(1-voidage))/(a*dp)
b) Voidage=(6(1-sphericity))/(a*dp)
c) Sphericity=(6*voidage)/(a*dp)
d) Voidage=(6*sphericity)/(a*dp)

Explanation: From the literature and formula derivation, the relation has been developed.

6. According to Brown, fractional voids in the packed bed are related to ___________ of particles?
a) Shape
b) Size
c) Sphericity
d) None of the mentioned

Explanation: From the literature, fractional voids in the packed bed are related to sphericity of particles.

7. The pressure drop through the fixed beds of uniformly sized solids has been correlated by ________
a) Ergun equation
b) Poisson equation
c) Laplace equation
d) None of the mentioned

Explanation: The pressure drop through the fixed beds has been correlated by Ergun equation.

8. Which factor is considered in Ergun equation when the Reynolds number is less 20?
a) 150
b) 1.75
c) 2.75
d) 250

Explanation: Since viscous forces predominate, 150 factor is considered.

9. Which factor is considered in Ergun equation when the Reynolds number is greater than 1000?
a) 150
b) 1.75
c) 2.75
d) 250

Explanation: Since kinetic losses are considered, 150 factor is considered.

10. Which new term is utilized for measuring non spherical particles?
a) Sphericity
b) Volume displacement
c) Geometry
d) None of the mentioned

Explanation: This new term is used to express the sphericity of non-spherical particles.

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