The thermal resistance R of a material or a structure is typically defined as the ratio of the temperature difference (ΔT) across the material or structure to the heat transfer rate (Q) through it. Mathematically, it can be expressed as:
Where:
- R is the thermal resistance (in units of K/W),
- ΔT is the temperature difference (in units of Kelvin or Celsius, K or °C),
- Q is the heat transfer rate (in units of watts, W).
This formula represents the thermal resistance in a general context. However, in specific applications or systems, there might be different formulas or expressions used to calculate thermal resistance depending on the geometry, material properties, and boundary conditions.