1. What is Log Mean Driving Force?

Definition: The Log Mean Driving Force represents the effective driving force for mass transfer in separation processes like absorption and stripping.

Purpose: It provides a more accurate average driving force when the driving force changes significantly throughout the process.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( \Delta y_{lm} \) — Log mean driving force (dimensionless)
• \( y_1 \) — Solute gas mole fraction at bottom
• \( y_2 \) — Solute gas mole fraction at top
• \( y_e \) — Equilibrium gas concentration

Explanation: The formula calculates the logarithmic average of the driving forces at the two ends of the process.

3. Importance of Log Mean Driving Force

Details: It's crucial for designing mass transfer equipment like absorption towers, as it determines the required size and efficiency of the equipment.

4. Using the Calculator

Tips: Enter the mole fractions (values between 0 and 1) for the solute gas at bottom (y₁), at top (y₂), and at equilibrium (yₑ).

5. Frequently Asked Questions (FAQ)

Q1: When should I use log mean driving force?
A: Use it when the driving force varies significantly throughout the process, typically in continuous contact equipment.

Q2: What if y₁ - yₑ equals y₂ - yₑ?
A: In this special case, the driving force is constant and the arithmetic average can be used instead.

Q3: What units does this calculator use?
A: All inputs and outputs are in mole fractions (dimensionless).

Q4: How do I determine equilibrium concentration (yₑ)?
A: yₑ is typically determined from equilibrium relationships like Henry's Law or vapor-liquid equilibrium data.

Q5: Can this be used for liquid-phase concentrations?
A: Yes, the same formula applies for liquid-phase mole fractions (x) instead of gas-phase (y).