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

一般来说，热管是一种有效的热传递设备，在大多数情况下，它使用有机物作为工质。而有机物质如氟里昂(R11、R113等)有一些缺点是热物性差，不利于全球环境。在这里，通过将这种有机成分与具有较高潜热和导热系数的水混合来改善性能的概念被认为是一种很有前途的技术。本工作旨在利用由这种有机成分和水组成的不相容液体的二元混合物来获得热管的可用性和传热特性。详细实验，使用PFC C_6F_&lt；14&GT；从冷却段的冷凝机理、加热段的沸腾和蒸发机理以及通过绝热段从冷却段到加热段的热量传递的总体特征等方面进行了分析，并结合绝热段的相平衡关系，阐明了水蒸气的浓度取决于上层液层的深度和加热条件，冷却段的换热特性受这种浓度的影响，而冷凝段的冷凝现象是由于有机物的膜状冷凝和水滴状冷凝以及沿液层扩散的水滴状冷凝的双重作用而产生的。尽管加热段向冷却段输送的热量增加，但加热段和冷却段之间的温差和管内压力保持不变，存在一定的混合物混合比。

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.