1. What is the Nusselt Number?

The Nusselt number (Nu) is a dimensionless number that represents the ratio of convective to conductive heat transfer across a boundary. It helps us understand how well heat is being transferred in a system compared to just conduction.

2. How Does the Calculator Work?

The calculator uses the Nusselt number equation:

Where:

• \( Nu \) — Nusselt number (dimensionless)
• \( h \) — Heat transfer coefficient (W/m²·K)
• \( L \) — Characteristic length (m)
• \( k \) — Thermal conductivity (W/m·K)

Explanation: The equation shows how the convective heat transfer (h) compares to conductive heat transfer (k) over a characteristic length (L).

3. Importance of Nusselt Number

Details: The Nusselt number is crucial in heat transfer calculations for designing cooling systems, heat exchangers, and understanding thermal processes in engineering applications.

4. Using the Calculator

Tips: Enter the heat transfer coefficient in W/m²·K, characteristic length in meters, and thermal conductivity in W/m·K. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What does a high Nusselt number mean?
A: A high Nu indicates that convection is dominating over conduction in the heat transfer process.

Q2: What are typical Nusselt number values?
A: For natural convection, Nu is typically 1-10, while for forced convection it can range from 10 to 1000 or more.

Q3: What is characteristic length?
A: It's a representative dimension of the system, like the diameter of a pipe or length of a flat plate.

Q4: Is Nusselt number always calculated this way?
A: This is the basic definition, but in practice, Nu is often found using empirical correlations for specific geometries.

Q5: Why is it called a dimensionless number?
A: Because all the units cancel out, leaving just a pure number that can be compared across different systems.