An empirical correlation for two-phase frictional performance in small diameter tubes

Experimental two-phase pressure drop data in small diameter tubes (D<10 mm) have been collected and updated from the literature which contain eight refrigerant and three air–water datasets. Comparisons between the data and the predictions indicate that the Chisholm correlation fails to predict the data. The Friedel correlation and Souza and Pimentaʹs correlation give fair predictions for the refrigerant data, but fail to predict the air–water data due to the surface tension effect. The homogeneous model shows a better predictive ability (a mean deviation of 34.7%) than the other empirical correlations. In this regard, an empirical correlation based on the homogeneous model was developed. By introducing the Bond number and Weber number to the modified correlation, the new correlation gives a mean deviation of 19.1% based on 1484 data points.