1. What is Forced Convection Heat Transfer Coefficient?

Definition: This calculator estimates the heat transfer coefficient (h) for forced convection over a flat plate heat sink using the Pohlhausen solution.

Purpose: It helps thermal engineers and designers determine the convective heat transfer performance of heat sinks under forced airflow conditions.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( h \) — Heat transfer coefficient (W/m²K)
• \( k \) — Thermal conductivity of fluid (W/mK)
• \( L \) — Characteristic length of heat sink (m)
• \( Re \) — Reynolds number (dimensionless)
• \( Pr \) — Prandtl number (dimensionless)

Explanation: The formula accounts for fluid properties (k, Pr), flow conditions (Re), and geometry (L) to estimate convective heat transfer.

3. Importance of Heat Transfer Coefficient

Details: Accurate h values are crucial for thermal management design, ensuring components stay within safe operating temperatures.

4. Using the Calculator

Tips: Enter the thermal conductivity (k), characteristic length (L), Reynolds number (Re), and Prandtl number (Pr). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical Reynolds number for heat sinks?
A: Typically between 1,000-50,000 for forced convection cooling applications.

Q2: What's the characteristic length (L)?
A: For heat sinks, this is usually the length in the flow direction (longitudinal dimension).

Q3: What Prandtl numbers should I use?
A: For air at room temperature, Pr ≈ 0.71. For water, Pr ≈ 7.0.

Q4: What's the range of typical h values?
A: For forced air convection, h typically ranges from 10-100 W/m²K.

Q5: When is this formula valid?
A: For laminar flow (Re < 5×10⁵) over flat plates with constant surface temperature.