1. What is Thermal Diffusivity?

Thermal diffusivity (κ) is a measure of how quickly heat diffuses through a material. It represents the ratio of thermal conductivity to the heat capacity of a material. Higher values indicate faster heat propagation through the material.

2. How Does the Calculator Work?

The calculator uses the thermal diffusivity equation:

Where:

• \( \kappa \) — Thermal diffusivity (m²/s)
• \( k \) — Thermal conductivity (W/m·K)
• \( \rho \) — Density (kg/m³)
• \( c \) — Specific heat capacity (J/kg·K)

Explanation: The equation shows that thermal diffusivity increases with higher conductivity and decreases with greater density or heat capacity.

3. Importance of Thermal Diffusivity

Details: Thermal diffusivity is crucial in heat transfer analysis, material selection for thermal applications, and understanding transient heat conduction processes.

4. Using the Calculator

Tips: Enter thermal conductivity in W/m·K, density in kg/m³, and specific heat capacity in J/kg·K. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What are typical values of thermal diffusivity?
A: Metals generally have high values (10⁻⁵ to 10⁻⁴ m²/s), while insulating materials have lower values (10⁻⁷ to 10⁻⁶ m²/s).

Q2: How does thermal diffusivity relate to thermal conductivity?
A: Diffusivity considers both conductivity and heat storage capacity (ρ×c), while conductivity only measures heat transfer ability.

Q3: When is thermal diffusivity important?
A: Critical in transient heat transfer problems, thermal wave propagation, and applications where heating/cooling rates matter.

Q4: How does temperature affect thermal diffusivity?
A: Generally decreases with temperature for metals, but may increase for some non-metals as conductivity increases more than heat capacity.

Q5: What's the difference between diffusivity and effusivity?
A: Diffusivity (κ) measures heat propagation speed, while effusivity (√kρc) measures ability to exchange heat with surroundings.