What does this conduction tool represent?
This tool solves a steady one-dimensional conduction relationship for heat-transfer rate or any inverse variable in the formula.
It is helpful for insulation thickness checks, wall heat-loss estimates, material comparisons and first-pass thermal sizing.
Formulas used
- Q̇ = k × A × ΔT / L
- k = Q̇ × L / (A × ΔT)
- A = Q̇ × L / (k × ΔT)
- ΔT = Q̇ × L / (k × A)
- L = k × A × ΔT / Q̇
About the material presets
- Copper, aluminum, steel, glass, concrete, wood and air presets are provided as approximate room-condition values.
- Real conductivity can change significantly with temperature, fiber direction, moisture, alloy content and manufacturing method.
Unit reference tables
Power units
| Unit name | Symbol | SI equivalent | Typical use |
|---|
| Watt | W | 1 W | Base SI heat-transfer-rate unit |
| Kilowatt | kW | 1,000 W | Larger heat loads |
| Megawatt | MW | 1,000,000 W | Very large heat-transfer rates |
| Kilocalorie per hour | kcal/h | 1.16222222222 W | Legacy heat-load and process calculations |
| Btu per hour | Btu/h | 0.293071070172 W | HVAC and Imperial/US heat loads |
Thermal-conductivity units
| Unit name | Symbol | SI equivalent | Typical use |
|---|
| Watt per meter-kelvin | W/(m·K) | 1 W/(m·K) | Base SI thermal-conductivity unit |
| Watt per meter-degree Celsius | W/(m·°C) | 1 W/(m·K) | Practical notation with °C temperature differences |
| Milliwatt per meter-kelvin | mW/(m·K) | 0.001 W/(m·K) | Low-conductivity materials |
| Btu per hour-foot-degree Fahrenheit | Btu/(h·ft·°F) | 1.73073466637 W/(m·K) | Imperial/US thermal-conductivity tables |
Area units
| Unit name | Symbol | SI equivalent | Typical use |
|---|
| Square millimeter | mm² | 0.000001 m² | Small sections and surfaces |
| Square centimeter | cm² | 0.0001 m² | Medium-scale test surfaces |
| Square meter | m² | 1 m² | Base SI area unit |
| Square kilometer | km² | 1,000,000 m² | Very large surfaces |
| Square inch | in² | 0.00064516 m² | Imperial/US small surface areas |
| Square foot | ft² | 0.09290304 m² | Imperial/US surface areas |
Thickness units
| Unit name | Symbol | SI equivalent | Typical use |
|---|
| Millimeter | mm | 0.001 m | Thin layers and small diameters |
| Centimeter | cm | 0.01 m | Short dimensions |
| Meter | m | 1 m | Base SI length unit |
| Kilometer | km | 1,000 m | Very large distances and long layers |
| Inch | in | 0.0254 m | Imperial/US thickness measurements |
| Foot | ft | 0.3048 m | Imperial/US length measurements |
Temperature-difference units
| Unit name | Symbol | SI equivalent | Typical use |
|---|
| Kelvin difference | K | 1 K | SI temperature difference |
| Degree Celsius difference | °C | 1 K | Practical temperature-difference notation |
| Degree Fahrenheit difference | °F | 0.555555555556 K | Imperial/US temperature-difference notation |
Worked examples
Heat flow through a copper plate
For k = 401 W/(m·K), A = 0.02 m², ΔT = 15 °C and L = 0.02 m, the heat-transfer rate is 6.015 kW.
Required insulation thickness for a known load
With Q̇ = 200 W, k = 0.04 W/(m·K), A = 4 m² and ΔT = 25 °C, the required thickness is about 20 mm.
Typical applications
- Preliminary wall and insulation sizing
- Heat-loss estimates through plates and flat layers
- Quick comparison of material conductivity choices
- Educational and concept-stage one-dimensional conduction checks
Assumptions and limitations
- The formula assumes steady one-dimensional conduction with constant properties.
- Contact resistance, multilayer walls, radiation and convection are not included in this basic solution.
- Preset material values are approximate; use supplier or test data for final design work.
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