Thermal Conduction (Fourier's Law) (H = KA(TC − TD)/L)
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H = KA(TC − TD)/L
What each symbol means
| Symbol | What it stands for |
|---|---|
| A | Cross-sectional area perpendicular to heat flow (m²) |
| H | Rate of heat flow or heat current (W or J/s) |
| K | Thermal conductivity of the material (W m⁻¹ K⁻¹) |
| L | Length of the conductor (m) |
| TC | Temperature of the hot end (K) |
| TD | Temperature of the cold end (K) |
When to use this
Steady-state heat conduction through a uniform bar. Assumes no heat loss from sides (fully insulated). Metals are good conductors (Cu: K ≈ 385 W/m·K), gases are poor (air: K ≈ 0.024 W/m·K). For composite bars in series: 1/K_eq = Σ(Li/Ki) normalized by total length.