1. What is the Nusselt Number?

The Nusselt number (Nu) is a dimensionless number that represents the ratio of convective to conductive heat transfer at a boundary in a fluid. It's widely used in heat transfer calculations and thermal system design.

2. How Does the Calculator Work?

The calculator uses the Nusselt number equation:

Where:

• \( h \) — Heat transfer coefficient (W/m²·K)
• \( D \) — Characteristic diameter (m)
• \( k \) — Thermal conductivity of the fluid (W/m·K)

Explanation: The Nusselt number quantifies the enhancement of heat transfer through a fluid as a result of convection relative to conduction.

3. Importance of Nusselt Number

Details: The Nusselt number is crucial for designing heat exchangers, cooling systems, and other thermal management applications. It helps determine the efficiency of convective heat transfer processes.

4. Using the Calculator

Tips: Enter the heat transfer coefficient in W/m²·K, diameter 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 indicate?
A: A high Nu indicates more efficient convective heat transfer compared to conductive heat transfer.

Q2: What are typical Nusselt number ranges?
A: For laminar flow, Nu is typically 3-5. For turbulent flow, it can range from 10 to 1000 or more.

Q3: How does Nusselt number relate to Reynolds number?
A: In forced convection, Nu often correlates with Re (Reynolds number) and Pr (Prandtl number) through empirical relations.

Q4: Can Nu be less than 1?
A: Yes, though uncommon. Nu < 1 suggests conduction dominates over convection.

Q5: What's the difference between Nu and Biot number?
A: Both are similar ratios, but Biot number uses solid conductivity while Nu uses fluid conductivity.