KEVOS® MAKEOS · Materials
Heat Flow Through a Layered Wall
How much heat flows through this insulated wall, and what are the layer temperatures?
Overall heat transfer coefficient, heat flow and interface temperatures for conduction through up to three plane layers with optional surface film coefficients.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Hot side temperature | °C | Temperature of the hot fluid or inside surface. |
| Cold side temperature | °C | Temperature of the surroundings or cold fluid. |
| Wall area | m² | Wall area. |
| Hot side film coefficient (0 = ignore) | W/(m²·K) | Convection coefficient on the hot side; 0 to treat the hot temperature as the surface temperature. |
| Cold side film coefficient (0 = ignore) | W/(m²·K) | Convection plus radiation coefficient on the cold side (about 8–12 W/m²K for still air). |
| Layer 1 | ||
| Thickness (0 = not used) | mm | Thickness of layer 1 (hot side). |
| Thermal conductivity | W/(m·K) | Conductivity of layer 1 at its mean temperature, from material data. |
| Layer 2 | ||
| Thickness (0 = not used) | mm | Thickness of layer 2. |
| Thermal conductivity | W/(m·K) | Conductivity of layer 2 (insulation conductivity rises with temperature). |
| Layer 3 | ||
| Thickness (0 = not used) | mm | Thickness of layer 3 (cold side). |
| Thermal conductivity | W/(m·K) | Conductivity of layer 3. |
Method and formulas
- Resistance per unit area R = 1/h_in + Σ(t ÷ k) + 1/h_out (omitting zero terms).
- U = 1 ÷ R; heat flow Q = U × A × ΔT.
- Each interface temperature drops by q × (layer resistance) from the hot side.
- Example: the default wall loses 673.06 W, and its outer surface runs at 31.731 °C.
Limitations
- Steady, one-dimensional conduction through flat layers; curved walls of small radius and thermal bridges increase the loss.
- Conductivity varies with temperature; use mean-temperature values.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Estimate heat loss from an oven, tank or duct wall
- Choose insulation thickness
- Find the outside surface temperature for touch safety
Who it is for
- Process engineers
- Maintenance engineers
- Design engineers
What you get
- Overall coefficient U
- Heat flow and heat flux
- Cold-side surface temperature
- Interface temperatures
Interpreting the result
- Check the outside surface temperature against your touch-temperature or burn-protection limit.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 371–378. Topic reference; no source tables or recommended settings are reproduced.
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