Planar Thermal Conduction Calculator

How the planar thermal conduction calculator works

Area-normalized resistance in m²·K/W is the sum of each layer’s thickness in metres divided by conductivity in W/(m·K). At least one layer must have positive thickness. Planar conductance is 1/resistance; signed heat rate in W is area × boundary surface-temperature difference ÷ resistance.

Conductivities must match the material/state. The model is steady, one-dimensional and planar with series layers. Boundary temperatures describe material surfaces, not automatically ambient air. Films, convection, radiation, bridges, moisture and cylindrical geometry are excluded. No insulation choice, condensation prediction or safe-touch temperature is determined.

Quantities use the stated units and finite bounded inputs. Whole purchases round up under the documented model; cost components round half-up to cents before totals are summed. Undefined ratios stay unavailable. π and logarithms use normal numeric precision. Display rounding does not alter the entered assumptions.

Worked example

A 100 mm layer at 0.05 W/(m·K) has resistance 2; a 200 mm layer at 1 adds 0.2. Across 10 m² and 30−10 = 20 K, heat rate is 200/2.2 ≈ 90.909 W. Raising the first surface to 40°C gives about 136.364 W.

Sources and assumptions

The source material explains the underlying calculation or pricing structure. Entered prices, costs, schedules and scenario choices are your assumptions; this tool does not obtain supplier quotes or predict actual results.

• Spirax Sarco Heat Transfer