The formula to calculate the Critical Radius of Insulation (Rc) is:
\[ Rc = \frac{2 \cdot K_{\text{insulation}}}{h_{\text{outside}}} \]
Critical Radius of Insulation is the radius of insulation at which there is maximum heat transfer and increase or decrease in its value will lead to an overall decrease in heat transfer. Thermal Conductivity of Insulation is defined as the ability of insulating material to transmit heat. External Convection Heat Transfer Coefficient is the proportionality constant between the heat flux and the thermodynamic driving force for the flow of heat in case of convective heat transfer.
Let's assume the following values:
Using the formula:
\[ Rc = \frac{2 \cdot 21}{9.8} \approx 4.28571428571429 \]
The Critical Radius of Insulation is approximately 4.28571428571429 Meter.
| Thermal Conductivity (W/m·K) | Convection Coefficient (W/m²·K) | Critical Radius (Meter) |
|---|---|---|
| 10 | 9.8 | 2.040816326530612 |
| 12 | 9.8 | 2.448979591836734 |
| 14 | 9.8 | 2.857142857142857 |
| 16 | 9.8 | 3.265306122448979 |
| 18 | 9.8 | 3.673469387755102 |
| 20 | 9.8 | 4.081632653061225 |
| 22 | 9.8 | 4.489795918367347 |
| 24 | 9.8 | 4.897959183673469 |
| 26 | 9.8 | 5.306122448979592 |
| 28 | 9.8 | 5.714285714285714 |
| 30 | 9.8 | 6.122448979591836 |