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

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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.