Project ForgeMass Transfer
Mass Transfer Operations
GATE 2019
Medium
In the drying of non-dissolving solids at constant drying conditions, the internal movement of moisture in the solid has a dominant effect on the drying rate during
- Athe initial adjustment period only
- Bthe constant rate period only
- the falling rate period only
- Dboth the initial adjustment and constant rate periods
Explanation
During the constant-rate period, surface moisture controls drying (external mass transfer limited). Once the surface dries out, internal moisture diffusion within the solid becomes rate-controlling — this is the falling-rate period.
Source: GATE CH 2019 (2019)
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