A method for predicting heat transfer during boiling of mixtures in plain tubes

Methods for predicting heat transfer during boiling of mixtures inside tubes are needed for refrigeration, cryocoolers, and LNG vaporizers but published methods have been verified only with limited data. The method evaluated here consists of modifying the predictions of pure fluid correlations by applying a well-known correction factor for pool boiling in the nucleate boiling region and applying a correction factor used for condensation heat transfer to the region in which nucleate boiling has been completely suppressed. For comparison, calculations were also done using only the pool boiling correction factor. These correction factors were used together with five well-known correlations for pure fluids. These were compared to a data base consisting of 878 data points for 45 mixtures of 19 fluids from 21 independent studies. The fluids included halocarbons, hydrocarbons, nitrogen, and carbon dioxide. The data included tube diameters 0.19–14 mm, horizontal and vertical orientations, flow rates 50–930 kg/m2s, reduced pressures from 0.05 to 0.63, and temperature glides upto 156 °C. The proposed method worked well for all mixtures except LNG. LNG data were in agreement with two correlations for pure fluids without any correction.