Abstract The following paper presents the results of experimental research on the condensation of R134a and R404A refrigerants in horizontal tubular mini-channels during impulsive hydrodynamic instabilities. Due to the complexity of the problem, it will be presented in two parts. The first part covers the results of experimental research on the influence of impulsive instabilities during the development of condensation of R134a and R404A refrigerants in mini-channels. The second part will cover the decay of condensation for similar conditions. The paper also provides a definition and conditions of the initiation and propagation of impulsive instabilities. Special attention was paid to the possible occurrence of characteristic instabilities during condensation in mini-channels, so-called capillary blocking. The experimental investigation was based on the condensation of R134a and R404A refrigerants in horizontal tubular mini-channels with internal diameters of D = 0.64; 0.90; 1.40; 1.44; 1.92; 2.30 and 3.30 mm. Propagation of impulsive instabilities was a result of a sudden change in the refrigerant flow-rate inside mini-channels.

中文翻译：

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R134a 和 R404A 制冷剂在脉冲不稳定性过程中在管状微通道中冷凝的实验研究。第二部分

摘要 以下论文介绍了 R134a 和 R404A 制冷剂在脉冲水动力不稳定性期间在水平管状微通道中冷凝的实验研究结果。由于问题的复杂性，将分两部分介绍。第一部分涵盖了 R134a 和 R404A 制冷剂在微型通道中冷凝过程中脉冲不稳定性影响的实验研究结果。第二部分将介绍类似条件下冷凝的衰减。论文还给出了脉冲不稳定性的产生和传播的定义和条件。特别注意了在微型通道中冷凝过程中可能出现的特征不稳定性，即所谓的毛细管阻塞。实验研究基于 R134a 和 R404A 制冷剂在内径 D = 0.64 的水平管状微型通道中的冷凝；0.90; 1.40; 1.44; 1.92; 2.30 和 3.30 毫米。脉冲不稳定性的传播是微型通道内制冷剂流速突然变化的结果。