Thermal Resistance of a Wall
Thermal Resistance of a Wall
Treating heat flow like an electrical circuit, each layer has a thermal resistance; series resistances simply add.
The conductive resistance of a layer is R = L/(k·A). where L is the thickness, k the conductivity and A the area.
Inputs
L := 0.2 m=200 mm
k := 0.8 W/(m·K)=0.8 kg·m/K/s^3
A := 15 m^2=15 m^2
Resistance grows with thickness and falls with conductivity and area.
R := L/(k·A)=0.02 K·s^3/kg/m^2
Results
With the resistance known, the heat flow is just ΔT/R. For a multi-layer wall, add each layer’s resistance in series to get the total.
Assumptions & limitations
- One-dimensional steady conduction.
- Single homogeneous layer.
- Surface film resistances added separately.