Conductive Heat Flux
Conductive Heat Flux
Heat flux — heat flow per unit area — lets you compare insulation performance independent of size.
Fourier’s law in flux form is q = k·ΔT/L. where k is the conductivity, ΔT the temperature difference and L the thickness.
Inputs
k := 45 W/(m·K)=45 kg·m/K/s^3
dT := 100 K=100 K
L := 0.05 m=50 mm
Apply Fourier’s law per unit area.
q := k·dT/L=90000 kg/s^3
Results
Multiplying the flux by the area gives the total heat rate. A lower conductivity or greater thickness cuts the flux — the goal of insulation.
Assumptions & limitations
- Steady one-dimensional conduction.
- Constant conductivity.
- Single homogeneous layer.