Average Heat Transfer Coefficient for Laminar Film Condensation of Tube Calculator

Average Heat Transfer Coefficient Formula:

\[ h_{avg} = 0.725 \times \left( \frac{\rho_f \times (\rho_f - \rho_v) \times [g] \times h_{fg} \times k_f^3}{D_{Tube} \times \mu_f \times (T_{Sat} - T_w)} \right)^{0.25} \]

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

Diameter of Tube (DTube):

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 Laminar Film Condensation?

The Average Heat Transfer Coefficient for Laminar Film Condensation on a tube represents the effectiveness of heat transfer during the condensation process. It quantifies the rate of heat transfer per unit area per unit temperature difference between the saturated vapor and the tube surface.

2. How Does the Calculator Work?

The calculator uses the Nusselt's theory formula for laminar film condensation:

\[ h_{avg} = 0.725 \times \left( \frac{\rho_f \times (\rho_f - \rho_v) \times [g] \times h_{fg} \times k_f^3}{D_{Tube} \times \mu_f \times (T_{Sat} - T_w)} \right)^{0.25} \]

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)
\( D_{Tube} \) — Diameter of tube (m)
\( \mu_f \) — Viscosity of film (Pa·s)
\( T_{Sat} \) — Saturation temperature (K)
\( T_w \) — Plate surface temperature (K)

Explanation: This formula accounts for the physical properties of the condensate film and the driving temperature difference for condensation heat transfer.

3. Importance of Heat Transfer Coefficient Calculation

Details: Accurate calculation of the heat transfer coefficient is crucial for designing heat exchangers, condensers, and other thermal systems involving phase change. It helps in determining the required heat transfer area and optimizing system performance.

4. Using the Calculator

Tips: Enter all physical properties in consistent SI units. Ensure that saturation temperature is higher than surface temperature for condensation to occur. All values must be positive and physically meaningful.

5. Frequently Asked Questions (FAQ)

Q1: What is laminar film condensation?
A: Laminar film condensation occurs when vapor condenses on a surface and forms a continuous, smooth liquid film that flows downward under gravity in a laminar flow regime.

Q2: When is this formula applicable?
A: This formula is valid for laminar film condensation on horizontal tubes when the condensate film flow is laminar and wave-free.

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

Q4: How does tube diameter affect the heat transfer coefficient?
A: The heat transfer coefficient increases with decreasing tube diameter due to thinner condensate films on smaller diameter tubes.

Q5: What are the limitations of this equation?
A: This equation assumes laminar flow, smooth tube surface, pure vapor, negligible vapor shear, and constant properties. It may not be accurate for turbulent film flow or when these assumptions are violated.