1. What is Heat Diffusivity?

Heat diffusivity is the thermal conductivity divided by density and specific heat capacity at constant pressure. It represents how quickly heat spreads through a material.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Hd \) — Heat Diffusivity (m²/s)
• \( Le \) — Lewis Number (dimensionless)
• \( Md \) — Mass Diffusivity (m²/s)

Explanation: The Lewis Number is defined as the ratio of thermal diffusivity to mass diffusivity, making this relationship fundamental in heat and mass transfer analysis.

3. Importance of Heat Diffusivity Calculation

Details: Accurate heat diffusivity calculation is crucial for thermal analysis, heat transfer modeling, and designing thermal systems in various engineering applications.

4. Using the Calculator

Tips: Enter Lewis Number (dimensionless) and Mass Diffusivity in m²/s. Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is the physical significance of Lewis Number?
A: The Lewis Number indicates the relative rates of heat and mass diffusion in a fluid. When Le = 1, heat and mass diffuse at the same rate.

Q2: What are typical values for Lewis Number?
A: Lewis Number typically ranges from 0.1 to 10 for most gases and liquids, with values around 1 being common for many gas mixtures.

Q3: How does heat diffusivity relate to thermal conductivity?
A: Heat diffusivity (α) = Thermal conductivity (k) / (Density (ρ) × Specific heat capacity (Cp)).

Q4: In which applications is this calculation important?
A: This calculation is important in combustion processes, drying operations, chemical reactors, and any system involving simultaneous heat and mass transfer.

Q5: Are there limitations to this formula?
A: This formula assumes constant properties and may need modification for systems with significant property variations or complex boundary conditions.