Average Heat Transfer Coefficient Given Reynolds Number And Properties At Film Temperature Calculator

Formula Used:

\[ h_{avg} = \frac{0.026 \times Pr_f^{1/3} \times Re_m^{0.8} \times K_f}{D_{tube}} \]

Prandtl Number at Film Temperature (Pr_f):

Reynolds Number for Mixing (Re_m):

Thermal Conductivity at Film Temperature (K_f):

W/m·K

Diameter of Tube (D_tube):

Average Heat Transfer Coefficient (h_avg):

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1. What is the Average Heat Transfer Coefficient?

The Average Heat Transfer Coefficient is equal to the heat flow (Q) across the heat-transfer surface divided by the average temperature (Δt) and the area of the heat-transfer surface (A). It represents the overall heat transfer capability between a surface and a fluid.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ h_{avg} = \frac{0.026 \times Pr_f^{1/3} \times Re_m^{0.8} \times K_f}{D_{tube}} \]

Where:

\( h_{avg} \) — Average Heat Transfer Coefficient (W/m²·K)
\( Pr_f \) — Prandtl Number at Film Temperature
\( Re_m \) — Reynolds Number for Mixing
\( K_f \) — Thermal Conductivity at Film Temperature (W/m·K)
\( D_{tube} \) — Diameter of Tube (m)

Explanation: This empirical correlation relates the heat transfer coefficient to fluid properties and flow characteristics, accounting for both convective and conductive heat transfer mechanisms.

3. Importance of Heat Transfer Coefficient Calculation

Details: Accurate calculation of heat transfer coefficient is crucial for designing heat exchangers, cooling systems, and thermal management equipment in various engineering applications.

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 the significance of Prandtl Number in heat transfer?
A: Prandtl Number represents the ratio of momentum diffusivity to thermal diffusivity, indicating the relative thickness of momentum and thermal boundary layers.

Q2: How does Reynolds Number affect heat transfer?
A: Higher Reynolds numbers indicate more turbulent flow, which generally enhances heat transfer due to better mixing and thinner boundary layers.

Q3: What is film temperature and why is it important?
A: Film temperature is the average of surface and bulk fluid temperatures, used to evaluate temperature-dependent fluid properties in heat transfer calculations.

Q4: What are typical ranges for heat transfer coefficients?
A: Values range from 5-25 W/m²·K for natural convection of gases to 2500-100,000 W/m²·K for boiling liquids, depending on the application.

Q5: When is this correlation most applicable?
A: This correlation is particularly useful for forced convection heat transfer in tubes with turbulent flow conditions.