Twenty Years of Research on Thermophysical Properties of High Temperature Fluids

Thermophysics play an important and decisive role in the characterization of materials, in particular of fluids. Among these properties, thermal conductivity and viscosity are key properties both for the elucidation of liquid structure and for the design of chemical plant equipments, in particular at high temperatures. Semiconductor industry, aerospace technology, glass manufacture, polymer technology and nuclear or solar power plants are only a few examples of technologies highly dependent on the accurate data for the thermophysical properties of the employed fluids. However, it has been proved in the past that there are significant scatter of data among the data published by different authors and different laboratories, for the properties of the same fluids, mostly caused by the difficulties in accurate measurements, including temperature. In this paper we describe twenty years of experience in the design and utilization of self constructed equipments for the measurement of thermal conductivity and viscosity of molten salts and molten alloys at the highest metrological level. Additionally some examples of data produced are given, the proposal of a reference correlation for the viscosity of molten sodium nitrate and the study of the influence of minor components in the viscosity of industrially important Zn-Al alloys.