Abstract

The use of mixtures as refrigerants and heat carriers in various power systems has become widespread. The thermophysical properties of mixtures differ from the properties of their components. This paper presents the results of a study of the intensity of heat transfer to a non-azeotropic alcohol-water mixture with weight concentration of the volatile component of 20% during forced circulation in a heated smooth circular channel, as well as in a channel with spiral intensifiers with a hydrophobic coating. The experiments were carried out on a closed circulation circuit at a pressure in the storage vessel of 0.04–0.055 MPa. The test section was a stainless steel tube with inner diameter of 7.6 mm and wall thickness of 0.2 mm. The heating was provided due to the electric current passed in the tube wall. The spiral intensifiers had winding pitch of 4 mm; the thickness of the PTFE sleeve was 0.9 mm. The experiments were carried out at mass flux rates of 44–46 kg/m² and 316 kg/m². The heat flux density varied in the range \(1200<q<15200\) W/m². The use of the spiral intensifiers with the hydrophobic coating during circulation of the non-azeotropic alcohol-water mixture (20%) in the circular channel led to the formation of a significant amount of the vapor-gas phase in the flow at channel wall temperatures below the saturation point of this mixture. The heat transfer coefficient in the channel with the intensifiers grew 2–5 times compared with those in a smooth channel.

中文翻译：

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非共沸醇水混合物循环过程中螺旋增强器圆形通道内的传热

摘要

在各种电力系统中使用混合物作为制冷剂和热载体已经变得广泛。混合物的热物理性质与其组分的性质不同。本文介绍了挥发性组分重量浓度为 20% 的非共沸醇-水混合物在加热光滑圆形通道和具有带有疏水涂层的螺旋增强器。实验在封闭循环回路上进行，储存容器压力为0.04-0.055 MPa。测试段为内径7.6mm、壁厚0.2mm的不锈钢管。由于电流通过管壁而提供加热。螺旋增压器的缠绕节距为4毫米；PTFE套管的厚度为0.9毫米。^{实验在质量通量率为 44–46 kg/m 2}和 316 kg/m ²下进行。热流密度在\(1200<q<15200\)  W/m ²范围内变化。在非共沸醇-水混合物（20%）在圆形通道中循环期间，使用具有疏水涂层的螺旋增强器导致在通道壁温度下在流中形成大量蒸气-气相低于该混合物的饱和点。与光滑通道相比，带有增强器通道的传热系数增加了2-5倍。