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Chemical Engineering - Mass Transfer - Discussion

Discussion Forum : Mass Transfer - Section 5 (Q.No. 10)
Mass Transfer
10.
Pick out the wrong statement.
In the McCabe-Thiele diagram for binary distillation, vertical feed line represents saturated liquid feed and horizontal feed line represents saturated vapour feed.
In small columns, local efficiency is larger than Murphree efficiency; in large columns local efficiency is smaller than Murphree efficiency.
For Laminar flow over a plate of length L, the local mass transfer co-efficient at a distance L from the leading edge is 1.5 x 10-2m/s. Then the average mass transfer co-efficient for the plate is 2 x 10-2m/s.
The concentration and hydrodynamic boundary layers over a flat plate are of equal thickness, if Schmidt number is equal to unity.
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
2 comments Page 1 of 1.
Mongam Damodhar Rao said:   8 months ago
Option B is also a wrong statement because for a small diameter column, local efficiency is equal to Murphree efficiency due to the concentration gradient is zero across length of plate.

For large diameter columns Murphree efficiency is greater than local efficiency due to existence of concentration gradient.
Radhika said:   1 decade ago
It should be 3 x 10^-2m/s (i.e. kavg = klocal).
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