Heat Transfer Coefficient By Convection For Stable Film Boiling Calculator

Heat Transfer Coefficient By Convection For Stable Film Boiling Formula:

\[ h_c = 0.62 \times \left( \frac{k_v^3 \times \rho_v \times [g] \times (\rho_l - \rho_v) \times (\Delta H + (0.68 \times C_v) \times \Delta T)}{\mu_v \times D \times \Delta T} \right)^{0.25} \]

Thermal Conductivity of Vapor (k_v):

W/m·K

Density of Vapour (ρ_v):

kg/m³

Density of Liquid (ρ_l):

kg/m³

Change in Enthalpy of Vaporization (ΔH):

J/mol

Specific Heat of Vapour (C_v):

J/kg·K

Excess Temperature (ΔT):

Dynamic Viscosity of Vapour (μ_v):

Pa·s

Diameter (D):

Heat Transfer Coefficient by Convection (h_c):

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1. What is Heat Transfer Coefficient By Convection For Stable Film Boiling?

The Heat Transfer Coefficient By Convection For Stable Film Boiling is a measure of the heat transfer rate per unit area per unit temperature difference during stable film boiling conditions. It quantifies the efficiency of convective heat transfer in boiling processes where a stable vapor film forms on the heating surface.

2. How Does the Calculator Work?

The calculator uses the following formula:

\[ h_c = 0.62 \times \left( \frac{k_v^3 \times \rho_v \times [g] \times (\rho_l - \rho_v) \times (\Delta H + (0.68 \times C_v) \times \Delta T)}{\mu_v \times D \times \Delta T} \right)^{0.25} \]

Where:

\( h_c \) — Heat transfer coefficient by convection (W/m²·K)
\( k_v \) — Thermal conductivity of vapor (W/m·K)
\( \rho_v \) — Density of vapour (kg/m³)
\( [g] \) — Gravitational acceleration (9.80665 m/s²)
\( \rho_l \) — Density of liquid (kg/m³)
\( \Delta H \) — Change in enthalpy of vaporization (J/mol)
\( C_v \) — Specific heat of vapour (J/kg·K)
\( \Delta T \) — Excess temperature (K)
\( \mu_v \) — Dynamic viscosity of vapour (Pa·s)
\( D \) — Diameter (m)

Explanation: This formula calculates the convective heat transfer coefficient for stable film boiling conditions, considering various physical properties of the vapor and liquid phases.

3. Importance of Heat Transfer Coefficient Calculation

Details: Accurate calculation of heat transfer coefficient is crucial for designing efficient heat exchangers, boilers, and other thermal systems. It helps in predicting heat transfer rates, optimizing system performance, and ensuring safe operation of thermal equipment.

4. Using the Calculator

Tips: Enter all required parameters with appropriate units. Ensure all values are positive and within reasonable physical ranges for accurate results.

5. Frequently Asked Questions (FAQ)

Q1: What is stable film boiling?
A: Stable film boiling occurs when a continuous vapor film forms on the heating surface, creating a barrier between the surface and the liquid. This typically happens at high temperature differences.

Q2: Why is the gravitational acceleration constant included?
A: Gravitational acceleration affects natural convection currents and buoyancy forces that drive the boiling process, making it an essential parameter in the calculation.

Q3: What are typical values for heat transfer coefficient in film boiling?
A: Heat transfer coefficients in film boiling typically range from 100 to 1000 W/m²·K, depending on the fluid properties and operating conditions.

Q4: How does vapor density affect the heat transfer coefficient?
A: Higher vapor density generally increases the heat transfer coefficient as it affects the buoyancy forces and the stability of the vapor film.

Q5: When is this formula most applicable?
A: This formula is specifically designed for stable film boiling conditions on horizontal cylinders or tubes, where the vapor film remains stable and continuous.