Mass Transfer Coefficient based on Wet Bulb Temperature Calculator

Mass Transfer Coefficient Formula:

\[ kY' = \frac{(T_G - T_W)}{(Y_W' - Y_A)} \times \frac{h_G}{\lambda_W} \]

Temperature of Air (T_G):

Wet Bulb Temperature (T_W):

Air Humidity at Wet Bulb (Y_W'):

kg/kg

Ambient Air Humidity (Y_A):

kg/kg

Heat Transfer Coefficient (h_G):

W/m²·K

Heat of Vaporization (λ_W):

J/kg

Mass Transfer Coefficient (kY'): mol/s·m²

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1. What is Mass Transfer Coefficient based on Wet Bulb Temperature?

Definition: This calculator determines the mass transfer coefficient of moisture in air using wet bulb temperature measurements and related thermodynamic properties.

Purpose: It's essential for designing and analyzing humidification, drying, and air conditioning systems where mass transfer plays a crucial role.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ kY' = \frac{(T_G - T_W)}{(Y_W' - Y_A)} \times \frac{h_G}{\lambda_W} \]

Where:

\( kY' \) — Mass transfer coefficient (mol/s·m²)
\( T_G \) — Temperature of air (K)
\( T_W \) — Wet bulb temperature (K)
\( Y_W' \) — Air humidity at wet bulb temperature (kg/kg)
\( Y_A \) — Ambient air humidity (kg/kg)
\( h_G \) — Heat transfer coefficient of air film (W/m²·K)
\( \lambda_W \) — Heat of vaporization at wet bulb temperature (J/kg)

Explanation: The temperature difference drives the calculation, normalized by humidity difference and scaled by the ratio of heat transfer to vaporization energy.

3. Importance of Mass Transfer Coefficient

Details: Accurate determination of mass transfer coefficients is critical for designing efficient heat and mass transfer equipment in chemical, food, and HVAC industries.

4. Using the Calculator

Tips: Enter all required parameters in consistent units. Ensure wet bulb temperature is lower than air temperature and humidity at wet bulb is greater than ambient humidity.

5. Frequently Asked Questions (FAQ)

Q1: What is the physical significance of kY'?
A: It represents how easily moisture transfers between air and water surfaces per unit driving force.

Q2: How do I measure wet bulb temperature?
A: Use a psychrometer with a thermometer wrapped in a wet wick exposed to air flow.

Q3: What's a typical value for h_G?
A: For air-water systems, it typically ranges from 10-100 W/m²·K depending on air velocity.

Q4: Why is λ_W important?
A: It accounts for the energy required for phase change, linking heat and mass transfer.

Q5: Can this be used for other vapor-liquid systems?
A: Yes, but properties (h_G, λ_W) must be for the specific system.