Thermal Conductivity
Thermal Conductivity of Perlite — Heat Transfer Mechanisms & Performance Factors
Thermal conductivity of expanded perlite ranges from 0.02–0.06 W/m·K depending on density and porosity. Heat transfer occurs through conduction, convection, and radiation within the porous structure.
1. What Is Thermal Conductivity in Perlite?
Thermal conductivity measures heat transfer through perlite. It depends on:
- 1.1 Solid Conduction: Through glass walls.
- 1.2 Gas Conduction: Through trapped air.
- 1.3 Radiation: Minor contribution.
2. Typical Thermal Conductivity Values
| Density (kg/m³) | Conductivity (W/m·K) |
|---|---|
| 30–50 | 0.02–0.03 |
| 50–80 | 0.03–0.04 |
| 80–120 | 0.04–0.06 |
3. How Thermal Conductivity Is Measured
3.1 ASTM C177
Guarded hot plate.
3.2 ASTM C518
Heat flow meter.
4. Factors Affecting Thermal Conductivity
4.1 Density
Lower density → lower conductivity.
4.2 Porosity
Higher porosity → better insulation.
4.3 Moisture
Increases conductivity.
4.4 PSD
Fine PSD → lower conductivity.
5. Application Performance
5.1 Construction
Insulating plasters.
5.2 Cryogenics
Low-temperature insulation.
5.3 Industrial Furnaces
High-temperature stability.
6. Geological Influence
- Natural porosity
- Hydration
- Glass chemistry
7. Regional Thermal Characteristics
| Region | Conductivity | Notes |
|---|---|---|
| Turkey | Low | High porosity |
| Greece | Medium | Coarse PSD |
| USA | Low | Fine PSD |
| Mexico | Variable | Mixed |
| Iran | Low | High purity |
8. FAQ
Q: Does moisture increase conductivity?
Yes — significantly.
Q: Does density affect insulation?
Yes — inversely.
Q: Why does thermal behavior vary?
Porosity and PSD differences.
