Average Heat Transfer Coefficient For Vapor Condensing On Plate Calculator

Formula Used:

\[ h_{avg} = 0.943 \times \left( \frac{\rho_f \times (\rho_f - \rho_v) \times [g] \times h_{fg} \times k_f^3}{L \times \mu_f \times (T_{sat} - T_w)} \right)^{0.25} \]

Density of Liquid Film (ρf):

kg/m³

Density of Vapor (ρv):

kg/m³

Latent Heat of Vaporization (hfg):

J/kg

Thermal Conductivity of Film Condensate (kf):

W/m·K

Length of Plate (L):

Viscosity of Film (μf):

Pa·s

Saturation Temperature (Tsat):

Plate Surface Temperature (Tw):

Average Heat Transfer Coefficient (havg):

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1. What is the Average Heat Transfer Coefficient for Vapor Condensing on Plate?

The average heat transfer coefficient for vapor condensing on a vertical plate is a measure of the effectiveness of heat transfer during the condensation process. It represents the rate of heat transfer per unit area per unit temperature difference between the vapor and the plate surface.

2. How Does the Calculator Work?

The calculator uses the Nusselt's condensation theory formula:

\[ h_{avg} = 0.943 \times \left( \frac{\rho_f \times (\rho_f - \rho_v) \times [g] \times h_{fg} \times k_f^3}{L \times \mu_f \times (T_{sat} - T_w)} \right)^{0.25} \]

Where:

\( \rho_f \) — Density of liquid film (kg/m³)
\( \rho_v \) — Density of vapor (kg/m³)
\( [g] \) — Gravitational acceleration (9.80665 m/s²)
\( h_{fg} \) — Latent heat of vaporization (J/kg)
\( k_f \) — Thermal conductivity of film condensate (W/m·K)
\( L \) — Length of plate (m)
\( \mu_f \) — Viscosity of film (Pa·s)
\( T_{sat} \) — Saturation temperature (K)
\( T_w \) — Plate surface temperature (K)

Explanation: This formula is derived from Nusselt's film condensation theory and provides the average heat transfer coefficient for laminar film condensation on a vertical surface.

3. Importance of Heat Transfer Coefficient Calculation

Details: Accurate calculation of heat transfer coefficient is crucial for designing heat exchangers, condensers, and other thermal systems. It helps in determining the size and efficiency of heat transfer equipment and optimizing energy consumption in industrial processes.

4. Using the Calculator

Tips: Enter all physical properties in SI units. Ensure that saturation temperature is greater than plate surface temperature for condensation to occur. All values must be positive and within reasonable physical limits.

5. Frequently Asked Questions (FAQ)

Q1: What is the range of validity for this formula?
A: This formula is valid for laminar film condensation on vertical surfaces. It assumes constant properties and negligible vapor shear stress at the liquid-vapor interface.

Q2: How does plate length affect the heat transfer coefficient?
A: The heat transfer coefficient decreases with increasing plate length due to the thickening of the condensate film along the length of the plate.

Q3: What are typical values for heat transfer coefficients in condensation?
A: For steam condensation, typical values range from 5000-15000 W/m²·K. For organic vapors, values are generally lower, ranging from 1000-3000 W/m²·K.

Q4: When is this formula not applicable?
A: This formula is not applicable for turbulent film condensation, condensation on horizontal surfaces, or when vapor velocity is significant enough to affect the condensate flow.

Q5: How does temperature difference affect the heat transfer coefficient?
A: The heat transfer coefficient decreases with increasing temperature difference due to the increased condensate film thickness that forms with higher condensation rates.