Document type
Journal articles
Document subtype
Full paper
Title
Correct Use of Oscillating-Cup Viscometers for High-Temperature Absolute Measurements of Newtonian Melts
Participants in the publication
Valentim M. B. Nunes (Author)
Maria José V. Lourenço (Author)
Dep. Química e Bioquímica
CQE
Carlos A. Nieto de Castro (Author)
Dep. Química e Bioquímica
CQE
Summary
Oscillating-body viscometers have been used in the past to measure, in an absolute way, the viscosity of molten materials at high temperatures, from salts, metals, alloys, and semiconductors. However, the simultaneous use of basic mathematical models, that mimic the experiment, and the engineering solutions for the design and operation of the instruments, conducted in the past to high discrepancies between the data obtained in several laboratories. This is caused by the incorrect use of the method’s theory, less accurate solutions of the complex solutions, that involve solid state and fluid mechanics, and unreal instrument design. \\nFrom these types of viscometers, oscillating-cup instruments have had the most success in measuring viscosity at high temperatures, and they will be the object of this paper. It was written as a resource for workers interested in transport properties of materials when considering its use for the absolute measurement of fluids viscosity in their work, or in judging the results of others' work when comparing data with their own. \\nThe paper starts with the most accurate theory of the method’s description, followed by a discussion of its validity, application to instrument design, and consequent operation. Several constraints were identified and recommendations were made to minimize them. Finally, a discussion about the uncertainty budget calculations for a real experiment is made.\\nIf all these points are followed in the design and operation of the instrument, results with global uncertainties Ur (eta) between 0.02 and 0.04 are possible to obtain, up to high temperatures. If these constraints are neglected, erroneous measurements can be made, making comparisons and quality assessment difficult.
Date of Publication
2024-04-05
Institution
FACULDADE DE CIÊNCIAS DA UNIVERSIDADE DE LISBOA
Where published
International Journal of Thermophysics
Publication Identifiers
ISSN - 0195-928X
Publisher
Springer Science and Business Media LLC
Document Identifiers
DOI -
https://doi.org/10.1007/s10765-024-03355-x
URL -
https://doi.org/10.1007/s10765-024-03355-x
Rankings
Web Of Science Q2 (2023) - 2.5 - THERMODYNAMICS
SCOPUS Q2 (2023) - 4.1 - Chemical Engineering (miscellaneous)