This calculator determines the heat flow and heat flux through a homogeneous plate as well as its absolute thermal resistance and R-value.
Illustration of Parameters
The default is 1" extruded polystyrene foam insulation.
Material | Thermal Resistance ( |
---|---|
Diamond | 2200 |
Silver | 406 |
Copper | 385 |
Aluminum | 205 |
Epoxy | 0.3 |
Fiberglass Batting | 0.043 |
Extruded Polystyrene | 0.0289 |
The equation for thermal resistance can be derived from Fourier's law:
Which for a 1D homogeneous plate can be simplified to:
Where
For heat flux which is power per area, the equation is:
Absolute thermal resistance tells you how much temperature will rise for a given heat input. This is useful for finding the temperature rise of electrical parts where you often see junction to case thermal resistance in degrees C per W:
R-value is the absolute thermal resistance per square meter of a material. This is often used for specifying insulation for building construction where it can be used to compare the effectiveness of different insulations. For example, two inch styrofoam rigid insulation has an R-value of 10 and 3.5 inches of fiberglass batting has an R-value of 13.