Mass Transfer

The drying time between fixed moisture contents within the ‘constant rate period’ is proportional to (assuming that drying occurs from all surfaces of the solid) (where, T = thickness of the solid) ?

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The drying time between fixed moisture contents within the ‘constant rate period’ is proportional to (assuming that drying occurs from all surfaces of the solid) (where, T = thickness of the solid) ?

A. √T
B. T
C. T1.5
D. T3

In case of absorption with exothermic reaction, for fluids having ___________________?

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In case of absorption with exothermic reaction, for fluids having ___________________?

A. Pr = Sc; percentage change in heat and mass transfer flux will be the same for a given change
in the degree of turbulence
B. Pr = Sc = 1; total mass, momentum and thermal diffusivity will be the same
C. Both A. and B.
D. Pr = Sc; there won’t be any change in heat and mass transfer flux with changes in degree of
turbulence

At equilibrium the concentration of water in vapour phase (C*) in kg/m3 of air space and the amount of water (m) adsorbed per kg of dry silica gel are related by, C* = 0.0667m. To maintain dry conditions in a room of air space 100m3 containing 2.2 kg of water vapour initially, 10 kg of dry silica gel is kept in the room. The fraction of initial water remaining in the air space after a long time (during which the temperature is maintained constant) is_________________?

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At equilibrium the concentration of water in vapour phase (C*) in kg/m3 of air space and the amount of water (m) adsorbed per kg of dry silica gel are related by, C* = 0.0667m. To maintain dry conditions in a room of air space 100m3 containing 2.2 kg of water vapour initially, 10 kg of dry silica gel is kept in the room. The fraction of initial water remaining in the air space after a long time (during which the temperature is maintained constant) is_________________?

A. 0.0
B. 0.2
C. 0.4
D. 1.0