Heart Transfer Characteristics of a Heat Pipe using a Binary Mixture of Immiscible Liquids

一般来说，热管是一种有效的传热设备，在大多数情况下，它使用有机物质作为工作流体。但有机物质，如氟利昂（R11，R113等）存在热物理性能差、不利于全球环境等缺点。在这里，通过将这种有机成分与具有更高潜热和热导率的水混合来改善性能的概念成为一种有前途的技术。本工作是为了获得使用由这种有机成分和水组成的不混溶液体的二元混合物的热管的可用性和传热特性。本文以PFC C_6F_2和水为工质，对PFC C_6F_2和水的二元混合物进行了详细的实验研究，分析了PFC C_6F_2和水的二元混合物在冷却段的冷凝机理、在加热段的沸腾和蒸发机理以及从冷却段到加热段通过绝热段传热的总体特性，并考虑了这类混合物的相平衡关系<14>。可以清楚地看出蒸汽的浓度取决于上部液体层的深度和加热条件，这种水蒸气浓度和基于有机物膜状冷凝双重作用的明显冷凝现象影响着冷却段的传热特性。在此基础上，建立了一种新的混合比模型，即存在一定的混合比，尽管加热段向冷却段的传热量增加，但加热段与冷却段之间的温差和管内压力保持不变。

Generally, a heat pipe is an effective equipment for heat transportation, which uses organic substances as working fluids in most cases. But organic substances like freon (R11, R113 etc.) have some shortcomings in ther poor thermophysical properties and threads against the global environment. Here, the concept of property improvement by mixing such an organic component with water, which has a higher latent heat and thermal conductivity, comes up as a promising technique.The present work was undertaken to get the availability and heat transfer characteristics of heat pipes using a binary mixture of immiscible liquids made up of such an organic component and water. Detailed experiment, which used a binary mixture of PFC C_6F_<14> and water, have been conducted with regard to the condensation mechanism in the cooling section, the boiling and evaporation mechanism in the heating section and the overall characteristics of heat transported from the cooling to the heating section through the adiabatic section.Considering the phase equilibrium relations of this kind of mixture, it was clarified that the concentration of vapor depended on the depth of the upper liquid layr and the heating conditions, and that the heat transfer characteristics of the colling section were effected by this concentration of vapor and the distinct condensation phenomena bsed on the dual action of film condensation of the organic component and dropwise condensation of water with the diffusion layr developing along the liquid layr.Consequently, there existed a certain mixing radio of mixtures, where a temperature difference between the heated and cooled wall and the pressure in a pipe were kept constant in spite of the increase of heat transpouted from the heating section to the cooling section.