A new model for refrigerant condensation on the outside of three-dimensional enhanced tubes

This work present procedures to compute the heat transfer coefficient when downwards flowing halogenated refrigerant vapours condense on the outside of the three-dimensional enhanced tubes. At first, single tubes are considered, and the suggested procedure takes shear, gravity and surface tension forces into account. Predictions compare very well with data taken by the present authors during condensation of refrigerants on the commercial tube Hitachi 'Thermo excel'. The second part of the paper considers other geometries of pin-fin tubes, dealing also with condensation on tube bundles; in this case the effect of inundation on heat transfer is taken in due account. The correlations compare satisfactorily against the available experimental points