Question Bank • QB_EXP_APE_PNC_003 MCQ • 1 Mark

Section 6: Agricultural Process Engineering

Pneumatic Conveying & Fluidization of Solids

Subtopic: Minimum fluidization velocity Ergun equation

Question Statement:

At the onset of minimum fluidization in a granular bed, the pressure drop across the bed ($\Delta P$) equals:

Options:

  • (A) The buoyant weight of the bed particles per unit cross-sectional area: $\Delta P = L (1 - \epsilon_m) (\rho_s - \rho_g) g$
  • (B) Zero
  • (C) Atmospheric pressure multiplied by void ratio
  • (D) The dynamic pressure $\frac{1}{2} \rho_g v^2$

Answer Key:

A

Step-by-Step Solution & Explanation

Fluidization begins when upward drag force balances the net submerged weight of all bed particles: $\Delta P \cdot A = W_{submerged} \implies \Delta P = L (1 - \epsilon_{mf}) (\rho_p - \rho_f) g$.
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