Thermal Resistance

Written by Jerry Ratzlaff on . Posted in Thermodynamics

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


Thermal Resistance Formula

\(\large{ R = \frac{ l }{ k\;A }  }\) 


 Units 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 \(\large{\frac{Btu-ft}{hr-ft^2-F}}\)  \(\large{\frac{W}{m-K}}\)


P D Logo 1


Tags: Temperature Equations Heat Exchanger Equations