A new procedure for the prediction of forced convection heat transfer at near- and supercritical pressure

Based on heat transfer experiments with tubes of different inside geometry, correlations for forced convection heat transfer at near- and supercritical pressure are presented. They are of the Dittus-Boelter typeNu=CRe ^m Pr ⁿ and over the whole enthalpy range. The simple form is made possible by a new method of determining a representative specific heat capacity. At five reference temperatures heat capacities are computed with semi-empirical equations. The two highest values closest to the (pseudo-)critical state are then sorted out, because they are not relevant for turbulent flow. The average of the remaining three values represents a reasonable characteristic heat capacity. Comparisons to measurements show the very good accuracy of the new correlations. The procedure can be recommended whenever strong dependencies of fluid properties on temperature or even singularities occur.