The mass flow characteristics of the R-22 replacement refrigerant R-407c were measured for multiphase flow through sharp-edged short-tube orifices with length-to-diameter ratios from 6.5 to 23.2. All test conditions were a combination of condensing temperatures ranging from 35.0°C (95°F) to 51.7°C (125°F) and evaporating temperatures ranging from -1.1°C (30°F) to 10°C (50°F). Short-tube orifices 12.70 mm (0.5 in.), 19.05 mm (0.75 in.), and 25.4 mm (1.0 in.) in length with diameters ranging from 1.09 mm (0.0432 in.) to 1.94 mm (0.0763 in.) were tested. The effects of downstream pressure, upstream subcooling/quality, upstream pressure, diameter, and length on the mass flow rate of refrigerant through a given orifice geometry were presented. The R-407c data were fit to a semi-empirical model developed previously. The accuracy of the model was also discussed. 

Units: Dual