Thermal Diffusivity Calculator

Calculate thermal diffusivity and related properties using the fundamental heat transfer equation α = k/(ρ × Cp)

Calculate Thermal Diffusivity Properties

What do you want to calculate?

Select the quantity you want to find using α = k/(ρ × Cp)

Material (Pre-loaded Properties)

Target Thermal Diffusivity

Material Properties: Water (25°C)

Thermal Conductivity

0.607 W/(m·K)

Density

997 kg/m³

Specific Heat

4182 J/(kg·K)

Thermal Diffusivity

0.146 mm²/s

Thermal Diffusivity Results

0.000000

m²/s

Thermal Diffusivity

Unit Conversions

m²/s

0.00000015

mm²/s

0.14558261

cm²/s

0.00145583

ft²/s

0.00000157

in²/s

0.00022565

Calculation Details

Formula: α = k / (ρ × Cp)

Where:

α = Thermal diffusivity (0.00000015 m²/s)

k = Thermal conductivity (0.6070 W/(m·K))

ρ = Density (997.00 kg/m³)

Cp = Specific heat capacity (4182 J/(kg·K))

α = 0.6070 / (997.00 × 4182) = 0.00000015 m²/s

Physics Analysis

🛡️ Low thermal diffusivity - material responds slowly to temperature changes

💧 High specific heat capacity - requires significant energy for temperature change

Example Calculation

Water Thermal Diffusivity

Problem: Find thermal diffusivity of water

Given:

• Thermal conductivity (k) = 0.607 W/(m·K)

• Density (ρ) = 997 kg/m³

• Specific heat (Cp) = 4,182 J/(kg·K)

Solution

α = k / (ρ × Cp)

α = 0.607 / (997 × 4,182)

α = 1.46 × 10⁻⁷ m²/s = 0.146 mm²/s

Rate of heat penetration in water

Thermal Diffusivity Formula

α = k/(ρ × Cp)

Heat Diffusion Equation

α = Thermal diffusivity (m²/s)

k = Thermal conductivity (W/(m·K))

ρ = Density (kg/m³)

Cp = Specific heat capacity (J/(kg·K))

Thermal Diffusivity Values

Silver174 mm²/s

Gold127 mm²/s

Copper111 mm²/s

Aluminum97.8 mm²/s

Iron23 mm²/s

Air22 mm²/s

Water0.146 mm²/s

Higher values = faster heat penetration

Physics Tips

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High diffusivity = rapid temperature response

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Metals have highest thermal diffusivity

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Liquids generally have low diffusivity

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Units are always area per time (m²/s)

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Critical for transient heat transfer analysis

Understanding Thermal Diffusivity

What is Thermal Diffusivity?

Thermal diffusivity (α) is a material property that measures how quickly heat spreads through a material. It represents the ratio of thermal energy transfer capability to thermal energy storage capability. Materials with high thermal diffusivity respond quickly to temperature changes.

Physical Significance

•Controls rate of temperature change in transient heating
•Determines how fast heat penetrates into materials
•Critical for thermal shock and cycling analysis
•Used in heat treatment and thermal processing

Material Categories

High Diffusivity (>50 mm²/s)

Metals like silver (174), copper (111), and aluminum (97.8) mm²/s. Rapid thermal response, excellent for heat sinks.

Medium Diffusivity (1-50 mm²/s)

Materials like air (22) and iron (23) mm²/s. Moderate thermal response for various applications.

Low Diffusivity (<1 mm²/s)

Liquids like water (0.146) and organics. Slow thermal response, good for thermal storage.

Note: Thermal diffusivity decreases with temperature for most materials. Values shown are typical at room temperature.

Engineering Applications

Transient Heat Transfer

∂T/∂t = α∇²T

Heat diffusion equation

Thermal Shock

Bi = hL/k

Biot number analysis

NDT Testing

t = L²/(π²α)

Thermographic inspection

Real-World Applications

Non-Destructive Testing

Thermographic damage detection in aerospace and automotive industries. Monitor structural health without damaging components.

Heat Treatment Processes

Design heating and cooling cycles for metal processing. Optimize thermal treatments for desired material properties.

Thermal Management

Electronic component cooling design. Building thermal analysis and energy efficiency optimization.