Abstract

The heat transfer during boiling of freon R-21 in vertical downflow for an element of a plate-fin heat exchanger with textured and perforated fins was studied experimentally. The experiments were carried out for mass velocities of 30 to 60 kg/m²s and heat fluxes of 900 to 1900 W/m² for a heat exchanger with 850 fins per meter. The heat exchanger fin texture at an angle of 45 degrees to the flow direction of the vapor-liquid mixture made it possible to intensify the heat transfer and suppress the deterioration of the heat transfer at a vapor quality exceeding 0.8 in comparison with perforated fins. It has been found that the heat transfer coefficient is practically independent of the heat flux density and mass velocity, which shows the decisive influence of evaporation on the liquid film surface on the heat transfer under these conditions.

中文翻译：

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垂直下流式氟利昂 R-21 沸腾传热用于倾斜结构微通道的组装

摘要

对带有纹理和穿孔翅片的板翅式换热器元件在垂直下流中氟利昂 R-21 沸腾过程中的传热进行了实验研究。 对于每米具有 850 个翅片的热交换器，实验的质量速度为 30 至 60 kg/m ² s，热通量为 900 至 1900 W/m ^{2 。}与汽液混合物的流动方向成45度角的热交换器翅片结构使得与穿孔翅片相比可以强化传热并抑制蒸汽干度超过0.8时传热的恶化。研究发现，传热系数实际上与热流密度和质量速度无关，这表明液膜表面蒸发对这些条件下的传热具有决定性影响。