A. More
B. Less
C. Equal
D. Independent of porosity
Related Mcqs:
- For Laminar flow through a packed bed, the pressure drop is proportional to (Vs is the superficial liquid velocity and Dp is the particle diameter) ?
A. Vs/Dp2
B. Vs2/Dp2
C. Vs2/Dp3
D. Vs/Dp3 - A bed of spherical particles (specific gravity 2.5) of uniform size 1500 μm is 0.5 m in diameter and 0.5 m high. In packed bed state, the porosity may be taken as 0.4. Ergun’s equation for the above fluid-particle system (in SI units) is given below: Δ P/L = 375 × 103 VOM + 10.94 × 106 V2 OM (SI units) If water is to be used as the fluidising medium, in actual operation, the above bed has a height = 1 m. What is the porosity of the fluidised bed ?
A. 0.2
B. 0.5
C. 0.7
D. 0.8 - For flow of fluids through packed bed, the superficial velocity is_________________?
A. Less than the average velocity through channels
B. More than the average velocity through channels
C. Dependent on the pressure drop across the bed
D. Same as the average velocity through channels - Bed pressure drop in an air fluidised bed of catalyst particles (ρp = 200 kg/m3, Dp = 0.05 cm) of 60 cm bed depth and bed porosity of 0.5 expressed in cm of water (manometer) is________________?
A. 90
B. 60
C. 45
D. 30 - Umf is the minimum fluidisation velocity for a bed of particles. An increase in the superficial gas velocity from 2 Umf to 2.5 Umf results in (all velocities are smaller than the entrainment velocity of the particles) no change in the_______________?
A. Drag on particles
B. Drag on column walls
C. Bed height
D. Bed voidage - A gas (density = 1.5 kg/m3, viscosity = 2 × 10‒5 kg/m.s) flowing through a packed bed (particle size = 0.5 cm, porosity = 0.5) at a superficial velocity of 2 m/s causes a pressure drop of 8400 Pa/m. The pressure drop for another gas, with density of 1.5 kg/m3and viscosity of 3 × 10‒5kg/m.s flowing at 3 m/s will be________________?
A. 8400 Pa/m
B. 12600 Pa/m
C. 18900 Pa/m
D. 16800 Pa/m - The ratio of the hydraulic radius to the diameter of the channel, for maximum mean velocity of flow in a circular channel, in open channel flow is_________________?
A. 0.3
B. 0.9
C. 0.03
D. 0.66 - The ratio of the depth of flow to the diameter of the channel for maximum discharge in a circular channel in open channel flow is________________?
A. 0.1
B. 0.55
C. 0.95
D. 1.85 - A bed of spherical particles (specific gravity 2.5) of uniform size 1500 μm is 0.5 m in diameter and 0.5 m high. In packed bed state, the porosity may be taken as 0.4. Ergun’s equation for the above fluid-particle system (in SI units) is given below : Δ P/L = 375 × 103 VOM + 10.94 × 106 V2 OM (SI units) If water is to be used as the fluidising medium, the minimum fluidisation velocity, VOM is_________________?
A. 12 mm/s
B. 16 mm/s
C. 24 mm/s
D. 28 mm/s - A 0.5 m high bed made up of a 1 mm dia glass sphere (density 2500 kg/m3 ) is to be fluidised by water (density 1000 kg/m3 ). If at the point of incipient fluidisation, the bed voidage is 40%, the pressure drop across the bed is________________?
A. 4.4 KPa
B. 2.94 KPa
C. 3.7 KPa
D. None of these
