Project ForgeMass Transfer
Diffusion
GATE 2014
Medium
Which ONE of the following statements is CORRECT for the surface renewal theory?
- AMass transfer takes place at steady state
- Mass transfer takes place at unsteady state
- CContact time is same for all the liquid elements
- DMass transfer depends only on the film resistance
Explanation
Danckwerts' surface renewal theory models mass transfer as occurring into fluid elements that are continuously and randomly replaced (renewed) at the interface, each undergoing UNSTEADY-STATE (transient) diffusion during its variable exposure time — unlike Higbie's penetration theory, which assumes equal (fixed) contact time for all elements.
Source: GATE CH 2014 (2014)
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