56 research outputs found
Modeling the Thermal Conductivity of Pure and Mixed Heavy n-Alkanes Suitable for the Design of Phase Change Materials
Reference Correlation for the Density and Viscosity of Eutectic Liquid Alloys Al+Si, Pb+Bi, and Pb+Sn
In this paper, the available experimental data for the density and viscosity of eutectic liquid alloys Al+Si, Pb+Bi, and Pb+Sn have been critically examined with the intention of establishing a reference standard representation of both, density and viscosity. All experimental data have been categorized as primary or secondary according to the quality of measurement, the technique employed, and the presentation of the data, as specified by a series of carefully defined criteria. The proposal standard reference correlations for the density of liquid Al+Si, Pb+Si, and Pb+Sn are, repectively, characterized by deviations of 2.0%, 2.9%, and 0.5% at the 95% confidence level. The standard reference correlations for the viscosity of liquid Al+Si, Pb+Bi, and Pb+Sn are, repectively, characterized by deviations of 7.7%, 14.2%, and 12.4% at the 95% confidence level
Prediction of the viscosity of liquid mixtures
This paper describes the application of the theoretically based scheme of Vesovic and Wakeham, modified by making use of the hard-sphere model of Dymond and Assael, to the prediction of the viscosity of liquid mixtures. The purpose of the paper is to examine this scheme in more detail than earlier to find out in what circumstances it works well and when it fails. Hence, the scheme is employed to predict, for the first time, the viscosity of a wide range of mixtures of quite disparate liquids from groups of hydrocarbons, through combinations of alcohols and hydrocarbons, to halogenated refrigerants. It is shown that, in all cases, provided that the mass ratio of the pure components is close to unity, the predictions show excellent agreement with experiment
A novel instrument for the measurement of the thermal conductivity of molten metals. Part 1: instrument's description
The paper reports the design and construction of a new instrument for the measurement of the thermal conductivity of molten metals and salts. The apparatus is based on the transient hot-wire technique, and it is intended for operation over a wide range of temperatures, from ambient up to 1200 K. The present experimental technique overcomes problems of convection and thermal radiation, and it is demonstrated that it operates in accord with a theoretical model. The uncertainty of the thermal conductivity results is estimated to be +/-2% which is superior to that achieved in most earlier work
A novel instrument for the measurement of the thermal conductivity of molten metals. Part II: measurements
New measurements of the thermal conductivity of molten mercury, gallium, tin, and indium are reported up to 750 K. The measurements are performed in a novel transient hot-wire instrument described elsewhere. The present experimental technique overcomes problems of convection, and it is shown that it operates in an absolute way in accord with a theoretical model. The uncertainty of the thermal conductivity results is estimated to be +/- 2%, which is superior to that achieved in most earlier work. The low uncertainty of the present experimental results has allowed us to test the only significant theory for the thermal conductivity of molten metals, which relates this property to the electrical conductivity The pattern of results among the four metals indicates that further theoretical developments would be warranted
Application of the transient hot-wire technique to the measurement of the thermal conductivity of solids
A novel application of the transient hot-wire technique for thermal conductivity measurements is described. The new application is intended to provide an accurate means of implementation of the method to the determination of the thermal conductivity of solids exemplified by a standard reference ceramic material. The methodology makes use of a soft-solid material between the hot wires of the technique and the solid of interest. Measurements of the transient temperature rise of the wires in response to an electrical heating step in the wires over a period of 20 ? s to 10 s allows an absolute determination of the thermal conductivity of the solid. The method is based on a full theoretical model with equations solved by finite-element method applied to the exact geometry. The uncertainty achieved for the thermal conductivity is better than ±1%, and for the product (? C p) about ±3%. The whole measurement involves a temperature rise less than 4 K
Thermal conductivity of suspensions of carbon nanotubes in water
The enhancement of the thermal conductivity of water in the presence of carbon-multiwall nanotubes (C-MWNT) was investigated. Sodium dodecyl sulfate (SDS) was employed as the dispersant, and a 0.6 vol% suspension of C-MWNT in water was used in all measurements. The thermal conductivity was measured with a transient hot-wire instrument built for this purpose, and operated with a standard uncertainty better than 2 The maximum thermal conductivity enhancement obtained was 38 %. In an attempt to explain the experimental observations, a number of micro-structural investigations have been carried out and those results are presented here along with the analysis
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