Characteristics of refrigerant R-134A liquid-vapor two-phase flow in a horizontal pipe

The prediction of void fraction and two-phase flow regimes are essential for the accurate calculation of pressure drop and heat transfer in liquid-vapor two-phase flow. In the present paper, data are presented on flow regime and void fraction measurements for the ozone-safe refrigerant R-134a liquid-vapor flow in a horizontal pipe. The experiments covered a wide range of conditions that are typically encountered in refrigerating and air-conditioning equipment. The test conditions included the stratified, annular, and intermittent flow regimes. The applicability of flow regime predictive methods was assessed. The data were used for the development of void fraction correlations that can be used for design purposes. An empirical approach was used to correlate the void fraction in terms of the Martinelli parameter. Alternatively, the void fraction data for each flow regime were correlated using the drift-flux model.