Rtotal = ΣRi — series thermal resistance network for flat walls. Build any number of convection and conduction layers, see the resistance breakdown, and optionally compute heat flow Q = ΔT / Rtotal.
Heat Transfer · ConductionLayers (left → right = inner → outer):
Resistance formulas:
Cylindrical wall (tube / pipe):
Typical thermal conductivity values:
| Material | k [W/(m·K)] |
|---|---|
| Copper | 401 |
| Carbon steel | 50 |
| Concrete | 1.0 |
| Brick | 0.72 |
| Timber | 0.14 |
| Glass wool | 0.038 |
| EPS foam | 0.036 |
| Air (still) | 0.026 |
Design principle — dominant resistance:
In a series network, the largest Ri controls Q. Reducing a small resistance (e.g., from 5% to 0%) changes Rtotal by only 5%. Focus design effort on the dominant layer — often the insulation layer in buildings or the gas-side film in process heat exchangers.