Heat Conduction Calculator
Fourier’s law gives Q = kAΔT/L for a plane wall: a 200 mm wall with k = 0.8 W/m·K over 10 m² and 30 °C across it conducts 1200 W.
1200 W
- Thermal resistance R
- 0.025 K/W
- Heat flux q = Q/A
- 120 W/m²
Step-by-step solution
- R = L/kA = 0.2 ÷ (0.8 × 10) = 0.025 K/W
- Q = ΔT/R = 30 ÷ 0.025 = 1200 W
Heat Conduction Formula
Q = ΔT / R, R = L/kA, ln(r₂/r₁)/2πkL
composite: R = 1/hᵢA + Σ L/kA + 1/hₒA
Worked Example
A 200 mm wall (k = 0.8 W/m·K, 10 m²) with faces at 40 °C and 10 °C:
- R = L/kA = 0.2 ÷ (0.8 × 10) = 0.025 K/W
- Q = ΔT/R = 30 ÷ 0.025 = 1200 W
Heat flux q = Q/A: 120 W/m²
More Heat Transfer Calculators
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LMTD Calculator
LMTD = (ΔT₁ − ΔT₂) ÷ ln(ΔT₁/ΔT₂)
counter-flow ΔT₁ = Th,i − Tc,o, ΔT₂ = Th,o − Tc,i
Example: Counter-flow: hot 150 → 100 °C, cold 30 → 70 °C, Q = 200 kW, U = 500 W/m²·K: LMTD = 74.8888 °C.
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Fin Efficiency Calculator
η = tanh(mL)/mL, m = √(hP/kAc)
P perimeter, Ac cross-section, Q = √(hPkAc) θb tanh(mL)
Example: A 5 mm aluminium pin fin (k = 200), 50 mm long, h = 25 W/m²·K, base 100 °C in 25 °C air: Fin efficiency η = 92.4234 %.
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NTU Effectiveness Calculator
ε = [1 − e^(−NTU(1 − Cr))] ÷ [1 − Cr e^(−NTU(1 − Cr))]
NTU = UA/Cmin, Cr = Cmin/Cmax (counter-flow)
Example: UA = 3000 W/K, Ch = 4000 W/K, Cc = 2000 W/K, hot in at 120 °C, cold in at 20 °C: Effectiveness ε = 0.690785.
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Radiation Heat Transfer Calculator
Q = εσA(T₁⁴ − T₂⁴)
σ = 5.670374 × 10⁻⁸ W/m²·K⁴; plates: σ(T₁⁴ − T₂⁴)/(1/ε₁ + 1/ε₂ − 1)
Example: A 1 m² surface (ε = 0.8) at 500 K in large surroundings at 300 K: Net radiation heat transfer Q = 2467.75 W.
Frequently asked questions
How do resistances combine in a composite wall?
Layers in series add: R = Σ L/kA, plus 1/hA for each surface film.
What is the critical radius of insulation?
rc = k/h for a cylinder (2k/h for a sphere); below it, adding insulation increases heat loss.
Sources
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
Cite this page
APA
Scientific Converters. (2026, October 15). Heat Conduction Calculator. Retrieved October 25, 2026, from https://scientificconverters.com/calculators/heat-conduction-calculator/
IEEE
Scientific Converters, "Heat Conduction Calculator," scientificconverters.com. Accessed: Oct. 25, 2026. [Online]. Available: https://scientificconverters.com/calculators/heat-conduction-calculator/