Thermal Resistance

Thermal resistance, abbreviated as R, measures the temperature difference by which an object or material resists a heat flow.

 

Thermal Resistance Formula
\(\large{ R = \frac{ l }{ k\;A }  }\)
Symbol	English	Metric
\(\large{ R }\) = thermal resistance	\(\large{\frac{hr-F}{Btu}}\)	\(\large{\frac{K}{W}}\)
\(\large{ A }\) = area cross-section of heat exchanger	\(\large{ft^2}\)	\(\large{m^2}\)
\(\large{ l }\) = length of material (measured on the path of the heat flow)	\(\large{ft}\)	\(\large{m}\)
\(\large{ k }\) = thermal conductivity of material	\(\large{\frac{Btu-ft}{hr-ft^2-F}}\)	\(\large{\frac{W}{m-K}}\)