 Among many analogies (like Reynolds analogy, Prandtl–Taylor analogy) developed to directly relate heat transfer coefficients, mass transfer coefficients, and friction factors Chilton and Colburn J-factor analogy proved to be the most accurate.It is written as follows,

formula_1

This equation permits the prediction of an unknown transfer coefficient when one of the other coefficients is known.The analogy is valid for fully developed turbulent flow in conduits with "Re" > 10000, 0.7 < "Pr" < 160, and tubes where "L"/"d" > 60 (the same constraints as the Sieder–Tate correlation).