A generalized correlation for two-phase flow of alternative refrigerants through short tube orifices

The objective of this study is to develop a generalized correlation for the prediction of refrigerant flow rate through short tube orifices using alternative refrigerants. The generalized correlations for two-phase and subcooled inlet conditions are separately derived from a power law form of dimensionless parameters generated by the Buckingham Pi theorem. The database for the present correlation includes extensive experimental data for R12, R22, R134a, R407C, R410A, and R502 obtained from the open literature. For subcooled inlet conditions at the short tube entrance, the correlation yields an average deviation of 0.3% and a standard deviation of 6.1% based on the present database, while for two-phase inlet conditons it predicts the database with an average deviation of 0.2% and a standard deviation of 5.0%. The relative deviations of the predictions using the present correlations for two-phase and subcooled inlet conditions range from -21% to 18%.