A literature review on the two-phase flow inside plain tubes, especially for the refrigerant R1234yf, is conducted in this research. The flow boiling, condensation, and visualization of this low GWP refrigerant were examined experimentally to measure the heat transfer coefficients and pressure drop of the refrigerant, and also to present a flow pattern map. The measurements were carried out on smooth circular tubes with internal diameters of 8.2 mm for the mass velocity ranging from 95 to 410 kg m⁻² s⁻¹, vapor qualities from 0.12 to 0.92, and saturation temperatures from 26.3°C to 33.5°C. For the range of test parameters, the flow patterns were observed and compared with the work of Wojtan et al. Also, the experimental results were analyzed to evaluate the effect of mass flow and vapor quality. Generally, both parameters increase the heat transfer and pressure drop in the boiling and condensing flows. Also, the experimental results were compared with the existing models proposed to predict the heat transfer coefficient and pressure drop. Two correlations, based on the previous studies, were proposed to improve the accuracy of the heat transfer coefficient prediction. the correlation of Dobson et al. was adapted and resulted in a mean absolute error of 11.9%. Also, the Liu and Winterton model for boiling was modified to reduce its mean absolute error from 25.6% to 13.4%.

这项研究对普通管内的两相流进行了文献综述，特别是对于制冷剂R1234yf。通过实验检查了这种低GWP制冷剂的沸腾，冷凝和可视化，以测量制冷剂的传热系数和压降，并提供流型图。测量在内径为8.2 mm的光滑圆形管上进行，质量速度范围为95至410 kg m ^-2 s ^-1，蒸气质量为0.12至0.92，饱和温度为26.3°C至33.5°C。对于测试参数的范围，观察到了流型并将其与Wojtan等人的工作进行了比较。此外，还对实验结果进行了分析，以评估质量流量和蒸汽质量的影响。通常，这两个参数都会增加沸腾和冷凝流中的热传递和压降。另外，将实验结果与现有的预测传热系数和压降的模型进行了比较。在以前的研究的基础上，提出了两种相关性，以提高传热系数预测的准确性。Dobson等人的相关性。进行了调整，平均绝对误差为11.9％。还，