Number of Transfer Units Formula:
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Definition: Nog is a dimensionless parameter used to quantify the effectiveness of mass transfer in processes like absorption and distillation.
Purpose: It helps chemical engineers determine the height of packing required for a given separation in packed columns.
The calculator uses the formula:
Where:
Explanation: The difference in solute concentration is divided by the average driving force for mass transfer.
Details: Nog is crucial for designing packed columns as it directly relates to the height of packing needed (HTU × Nog = total height).
Tips: Enter the solute mole fractions (0-1 range) and log mean driving force. y1 should be greater than y2, and Δylm must be positive.
Q1: What is a typical range for Nog values?
A: Nog typically ranges from 1 to 10, with higher values indicating more difficult separations.
Q2: How is log mean driving force calculated?
A: Δylm = [(y1 - y1*) - (y2 - y2*)] / ln[(y1 - y1*)/(y2 - y2*)], where y* is equilibrium concentration.
Q3: What's the difference between Nog and Nol?
A: Nog is gas-phase based, while Nol is liquid-phase based transfer units.
Q4: When is this dilute system approximation valid?
A: When solute concentrations are below about 10% in both phases.
Q5: How does Nog relate to column height?
A: Total height = Nog × HTU (Height of a Transfer Unit), where HTU is equipment-specific.