Condensation Methode De Calcul

Nusselt Theory For Film Condensation Rate:

\[ \dot{m} = \frac{h D (T_s - T_\infty)}{h_{fg}} \]

Heat Transfer Coefficient (h):

W/m²K

Diameter (D):

Surface Temperature (T_s):

°C

Ambient Temperature (T_∞):

°C

Latent Heat of Vaporization (h_fg):

J/kg

Condensation Rate (ṁ):

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1. What is Nusselt Theory For Film Condensation?

Nusselt theory provides a fundamental analytical solution for laminar film condensation on vertical surfaces. It describes the condensation rate based on heat transfer principles and fluid properties.

2. How Does the Calculator Work?

The calculator uses the Nusselt condensation rate equation:

\[ \dot{m} = \frac{h D (T_s - T_\infty)}{h_{fg}} \]

Where:

\( \dot{m} \) — Condensation rate (kg/s)
\( h \) — Heat transfer coefficient (W/m²K)
\( D \) — Diameter or characteristic length (m)
\( T_s \) — Surface temperature (°C)
\( T_\infty \) — Ambient temperature (°C)
\( h_{fg} \) — Latent heat of vaporization (J/kg)

Explanation: The equation calculates the mass flow rate of condensate based on the heat transfer driving force and the energy required for phase change.

3. Importance of Condensation Rate Calculation

Details: Accurate condensation rate calculation is crucial for designing heat exchangers, refrigeration systems, and power plant condensers. It helps optimize system performance and efficiency.

4. Using the Calculator

Tips: Enter all parameters in consistent SI units. Ensure temperature difference is positive (T_s > T_∞) for condensation to occur. All values must be valid positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What are typical values for heat transfer coefficient in condensation?
A: For steam condensation, h ranges from 5,000-15,000 W/m²K. For refrigerants, it's typically 1,000-5,000 W/m²K depending on conditions.

Q2: When is Nusselt theory applicable?
A: Nusselt theory applies to laminar film condensation on vertical surfaces with smooth interfaces and negligible vapor shear effects.

Q3: What factors affect condensation rate?
A: Surface geometry, temperature difference, fluid properties, surface orientation, and presence of non-condensable gases significantly impact condensation rates.

Q4: Are there limitations to Nusselt theory?
A: Yes, it assumes constant properties, laminar flow, and neglects vapor drag and subcooling effects. More complex models are needed for turbulent flow.

Q5: How does surface orientation affect condensation?
A: Horizontal tubes generally have higher condensation rates than vertical surfaces due to better drainage of condensate film.