在美国，短管节流孔被用作汽车和家用空调的膨胀装置。这些系统的最佳性能设计要求在给定的操作条件下预测通过短管的正确流量特性。与传统制冷剂相比，关于任何新型替代制冷剂在短管孔中的性能，现有数据不足。在各种入口条件和短管几何形状下，将实验质量流量结果与HFC-134a和CFC-12进行比较。五个锐边短管孔，7个小于L/D小于20，1.10mm（0.0435英寸）小于D小于1.72毫米（0.0676英寸）使用HFC-134a和CFC-12进行测试。对进入短管的两相和过冷液体流动条件进行了检查，冷凝温度范围为35.4℃（96℉）至53℃。 8摄氏度（129华氏度），用于高达13.9摄氏度（25华氏度）的过冷，以及在短管入口处高达10%的质量。通过将下游压力从上游饱和压力降低至310 kPa（45 psia），也研究了下游压力的影响。对于HFC-134a，在本研究中进行了两种类型的测量——质量流量测试和孔口内的压力分布。对于CFC-12，仅进行了质量流量试验。将CFC-12的结果与上游温度条件相同的HFC-134a的结果进行了比较。根据主要操作变量（上游压力、过冷度和下游压力）和短管几何形状，对这两种制冷剂进行了比较。建立了HFC-134a和CFC-12的半经验模型，用于预测短管内的质量流量。关键词: 更换、R134a、R12、制冷剂、管道、孔口、膨胀阀、汽车、家用、热泵、单元空调、设计、优化、性能、计算、流体流动、特性、比较、实验、几何、过冷、冷凝温度、压力、测量、压差冷却:研讨会，ASHRAE Trans。1994年，第100卷，第2部分

Short-tube orifices have been used as an expansion device on automotive and residential air conditioners in the United States. The design for optimum performance of these systems requires predicting correct flow characteristics through short tubes for a given set of operating conditions. Insufficient data are available on how any of the new replacement refrigerants will perform in short-tube orifices relative to conventional refrigerants. Compares experimental mass flow results with HFC-134a and CFC-12 for a variety of inlet conditions and short-tube geometries. Five sharp-edged short-tube orifices with 7 less than L/D less than 20 and 1.10mm (0.0435 in.) less than D less than 1.72mm (0.0676 in.) were tested with HFC-134a and CFC-12. Both two-phase and subcooled liquid flow conditions entering the short tube were examined for condensing temperatures ranging from 35.4 deg C (96 deg F) to 53.8 deg C (129 deg F), for subcooling as high as 13.9 deg C (25 deg F), and for qualities as high as 10% at the inlet of the short tube. The effects of downstream pressure were also investigated by lowering the downstream pressure from the upstream saturation pressure down to 310 kPa (45 psia). For HFC-134a, two types of measurements were made during this study - mass flow tests and pressure distribution inside the orifice. For CFC-12, only mass flow tests were performed. The results with CFC-12 were compared with those of HFC-134a with the same upstream temperature conditions. A comparison of these two refrigerants was made as a function of the main operating variables (upstream pressure, subcooling, and downstream pressure) and short-tube geometry. Semi-empirical models for both HFC-134a and CFC-12 were developed for the prediction of mass flow rate through short tubes.KEYWORDS: replacing, R134a, R12, refrigerants, tubes, orifices, expansion valves, motor cars, domestic, heat pumps, unit air conditioners, designing, optimisation, performance, calculating, fluid flow, properties, comparing, experiment, geometry, subcooling, condensation temperature, pressure, measuring, pressure difference