A. Particle size
B. Fluid viscosity
C. Density of both the particle & the fluid
D. All A., B. and C.
Related Mcqs:
- 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 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 - Minimum porosity for fluidisation is____________________?
A. That corresponding to static bed
B. That corresponding to completely fluidised bed
C. The porosity of the bed when true fluidisation begins
D. Less than that of the’ static bed - Cd, Cc and Cv are related (for flow through an orifice) as (where, Cd = discharge co-efficient, Cc = co-efficient of contraction = (area of jet at vena-contracta/area of opening), Cv = co-efficient of velocity = (actual velocity at vena-contracta/theoretical velocity)?
A. Cd = Cc/Cv
B. Cd = Cc.Cv
C. Cd = Cv/ Cc
D. None of these - Specific speed of a centrifugal pump depends upon the ______________ head?
A. Suction
B. Delivery
C. Manometric
D. None of these - With decrease in particle size to be fluidised by a particular fluid, the operating range of fluidisation velocity___________________?
A. Widens
B. Squeezes
C. Does not change
D. Unpredictable from the data - Which of the following is not an advantage of fluidisation from transfer operation point of view ?
A. Intimate contact of the fluid with all parts of the solid particles
B. Lower fluid pumping power requirement
C. Minimisation of temperature variation
D. Prevention of particle segregation - 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 - When larger particles e.g., grains are subjected to fluidisation, the corresponding bed produced is termed as the _______________ bed?
A. Spouted
B. Sluggish
C. Boiling
D. Teeter - The main factor on which the behaviour of a mass of fluidised solid depends mainly is the___________________?
A. Fluid characteristics
B. Particle size
C. Both A. and B.
D. Neither A. nor B.
