1. What is Convection Coefficient?

Definition: The convection coefficient (h) quantifies the heat transfer between a surface and a fluid moving past it.

Purpose: It's essential for thermal analysis in engineering applications like heat exchangers, HVAC systems, and electronic cooling.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( h \) — Convection coefficient (W/m² K)
• \( Nu \) — Nusselt number (dimensionless)
• \( k \) — Thermal conductivity of fluid (W/m K)
• \( L \) — Characteristic length (m)

Explanation: The Nusselt number represents the ratio of convective to conductive heat transfer, which when multiplied by conductivity and divided by length gives the convection coefficient.

3. Importance of Convection Coefficient

Details: Accurate calculation of h is crucial for designing efficient thermal systems, predicting heat transfer rates, and optimizing energy consumption.

4. Using the Calculator

Tips: Enter the Nusselt number (from empirical correlations), fluid thermal conductivity, and characteristic length (typically diameter for pipes or length for plates).

5. Frequently Asked Questions (FAQ)

Q1: How do I determine the Nusselt number?
A: Nu is calculated from empirical correlations like Dittus-Boelter (for turbulent flow) or Churchill-Bernstein (for external flow) based on Reynolds and Prandtl numbers.

Q2: What are typical values for h?
A: Natural convection: 5-25 W/m²K, Forced convection: 10-500 W/m²K, Boiling/condensation: 500-10,000 W/m²K.

Q3: What's characteristic length?
A: A representative dimension of the system - pipe diameter for internal flow, plate length for external flow.

Q4: Does this work for all fluids?
A: Yes, but you must use the correct thermal conductivity (k) for your specific fluid at the operating temperature.

Q5: How accurate is this calculation?
A: Accuracy depends on correct Nu determination. Most empirical correlations are accurate within ±20% for their specified conditions.