Heat flows through solids by Fourier's law q=-k dT/dx.
Fourier's law q=-k dT/dx: heat flux proportional to temperature gradient, with conductivity k (copper 400, steel 50, brick 0.7, air 0.026 W/m·K). Steady 1D plane wall Q=kAΔT/L. Governing equation ∇²T=0 for steady, no generation.
A 20 cm brick wall with ΔT=20 K passes about 70 W/m².
Conduction explains how heat moves through solids, which is the basis of insulation design, electronics cooling and heat exchanger walls.
Heat flows through solids by Fourier's law q=-k dT/dx.
Conduction explains how heat moves through solids, which is the basis of insulation design, electronics cooling and heat exchanger walls.
Heat flux is proportional to the negative temperature gradient, with thermal conductivity as the constant of proportionality.
Free electrons carry thermal energy quickly, so metals have high thermal conductivity compared with most non-metals.
Typical applications include calculating the heat loss through a brick wall, estimating the temperature of a chip package from its power and choosing insulation thickness for a pipe carrying hot water.
Study "Computational fluid dynamics" first (topic 83 of 105 in Thermodynamics & Fluids). It covers the groundwork this topic builds on.
Insulators have low k. Cylindrical Q=2πkLΔT/ln(r₂/r₁). Heat generation adds a term.
A 20 cm brick wall with ΔT=20 K passes about 70 W/m².
The next topic is "Thermal resistance", which builds directly on this one.
It is classed as Advanced in Thermodynamics & Fluids (topic 84 of 105). It is an advanced topic. It assumes you are comfortable with the intermediate topics in Thermodynamics & Fluids.
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