Saturated flow boiling and convective condensation experiments for oil-free refrigerant R22 have been carried out with a microfin tube of new design and with a smooth tube. Both tubes have the same outer diameter of 9.52 m and are horizontally operated. Two-phase flow pattern data have been obtained in addition to heat transfer coefficients and pressure drops; moreover, adiabatic tests have been also performed in order for flow pattern map to cover even the adiabatic flows. Data are for mass fluxes rangin from about 90 to 400 kg/s m~2. In boiling tests, the nominal saturation temperature is 5 deg C, with inlet quality varying from 0.2 to 0.6 and the quality change ranging from 0.1 to 0.5. In condensation, results are for saturation temperature equal to 35 deg C, with inlet quality between 0.8 and 0.4, and quality change within 0.6 and 0.2. The comparison shows a large heat transfer augmentation with a moderate increment of pressure drops, especially in evaporation where the enhancement factor comes up to 4 while the penalty factor is about 1.4 at the most. Heat transfer coefficients both in evaporation and condensation are compared to the predictions of some recent correlatiosn specifically proposed or modified for microfin tubes.
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机译：无油制冷剂R22的饱和流沸腾和对流冷凝实验已经使用新设计的微翅片管和光滑管进行了。两条管的外径相同，为9.52 m，可水平操作。除了传热系数和压降外，还获得了两相流型数据。此外，还进行了绝热测试，以使流型图甚至覆盖绝热流。数据为范围在约90至400 kg / s m〜2的质量通量。在沸腾测试中，标称饱和温度为5摄氏度，进口质量在0.2到0.6之间变化，质量变化在0.1到0.5之间。在冷凝条件下，结果是饱和温度等于35摄氏度，入口质量在0.8到0.4之间，质量变化在0.6到0.2之间。比较表明，传热增加很大，压降增加适中，特别是在蒸发中，增强因子最高为4，而惩罚因子最大为1.4。将蒸发和冷凝中的传热系数与专门针对微翅片管提出或修改的一些最新相关性的预测进行了比较。
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