Film Thickness in Film Condensation Calculator

Film Thickness Formula:

\[ \delta = \left( \frac{4 \cdot \mu_f \cdot k \cdot x \cdot (T_{Sat} - T_w)}{[g] \cdot h_{fg} \cdot \rho_L \cdot (\rho_L - \rho_v)} \right)^{0.25} \]

Viscosity of Film (μf):

Pa·s

Thermal Conductivity (k):

W/m·K

Height of Film (x):

Saturation Temperature (T_Sat):

Plate Surface Temperature (T_w):

Latent Heat of Vaporization (h_fg):

J/kg

Density of Liquid (ρ_L):

kg/m³

Density of Vapor (ρ_v):

kg/m³

Film Thickness (δ):

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1. What is Film Thickness in Film Condensation?

Film thickness in film condensation refers to the thickness of the liquid film that forms on a surface during condensation. It is a critical parameter in heat transfer calculations as it affects the thermal resistance and overall heat transfer coefficient.

2. How Does the Calculator Work?

The calculator uses the film thickness formula:

\[ \delta = \left( \frac{4 \cdot \mu_f \cdot k \cdot x \cdot (T_{Sat} - T_w)}{[g] \cdot h_{fg} \cdot \rho_L \cdot (\rho_L - \rho_v)} \right)^{0.25} \]

Where:

\( \delta \) — Film thickness (m)
\( \mu_f \) — Viscosity of film (Pa·s)
\( k \) — Thermal conductivity (W/m·K)
\( x \) — Height of film (m)
\( T_{Sat} \) — Saturation temperature (K)
\( T_w \) — Plate surface temperature (K)
\( [g] \) — Gravitational acceleration (9.80665 m/s²)
\( h_{fg} \) — Latent heat of vaporization (J/kg)
\( \rho_L \) — Density of liquid (kg/m³)
\( \rho_v \) — Density of vapor (kg/m³)

Explanation: The formula calculates the thickness of the condensate film based on the balance between viscous forces and gravitational forces in the condensation process.

3. Importance of Film Thickness Calculation

Details: Accurate film thickness calculation is crucial for determining heat transfer rates in condensation processes, designing heat exchangers, and optimizing thermal systems. Thicker films increase thermal resistance and reduce heat transfer efficiency.

4. Using the Calculator

Tips: Enter all required parameters in appropriate units. Ensure temperature values are in Kelvin, viscosities in Pa·s, thermal conductivity in W/m·K, heights in meters, latent heat in J/kg, and densities in kg/m³. All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: What is film condensation?
A: Film condensation occurs when vapor condenses on a surface and forms a continuous liquid film. This is different from dropwise condensation where liquid forms discrete droplets.

Q2: Why is film thickness important in heat transfer?
A: Film thickness directly affects the thermal resistance to heat transfer. Thicker films create greater resistance and reduce the overall heat transfer coefficient.

Q3: What are typical film thickness values?
A: Film thickness typically ranges from 0.1 mm to several millimeters, depending on the fluid properties, temperature difference, and surface geometry.

Q4: Does this formula work for all fluids?
A: The formula is derived for laminar film condensation and works best for Newtonian fluids with constant properties. It may need modification for non-Newtonian fluids or turbulent conditions.

Q5: How does surface inclination affect film thickness?
A: Surface inclination affects the gravitational component. For inclined surfaces, the gravitational acceleration term should be modified to account for the angle of inclination.