An Improved Correlation for Void Fraction During In-Tube Condensation

A comprehensive literature research was undertaken for the available void fraction correlations and experimental void fraction data during condensation inside tubes. Comparisons between the correlations showed that slip ratio models were probably more suitable for the determination of void fraction at low mass velocity when the slip ratio was chosen appropriately. For high mass velocity, there was no apparent difference for the predictions of various models. In addition, the Froude rate parameter (dimensionless number) can be used for representing the flow characteristics during condensation inside tube and was defined in terms of mass flux and quality. Based on the observations made, a new correlation was developed through the weighted average method without resorting back to very complex expressions. This correlation was a simple model and obtained involving with the Froude rate parameter and slip ratio models. The improved correlation has been shown to be in good agreement with data ranging from low mass velocity up to very high mass velocity.