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Speed-of-Sound Measurements and a Fundamental Equation of State for Propylene Glycol



Eisenbach Tim, Christian Scholz, Roland Span, Diego Cristancho, Monika Thol, Eric W. Lemmon


A fundamental equation of state was developed for propylene glycol. It is written in terms of the Helmholtz energy with the independent variables temperature and density. Due to its fundamental nature, it can be used to calculate all thermodynamic state properties from the Helmholtz energy and its derivatives with respect to the independent variables. Special attention was paid not only to accurately reproduce the available experimental data, but also to correct extrapolation. Therefore, this equation can be used for the application in mixture models. For the development of the present equation of state, the available literature data were supplemented with new experimental speed-of-sound measurements. High accuracy was achieved by applying the well-established double-path length pulse-echo technique and a careful sample preparation.
Journal of Physical and Chemical Reference Data


equation of state, experimental measurements, extrapolation, Helmholtz energy, propylene glycol, speed of sound


Tim, E. , Scholz, C. , Span, R. , Cristancho, D. , Thol, M. and Lemmon, E. (2021), Speed-of-Sound Measurements and a Fundamental Equation of State for Propylene Glycol, Journal of Physical and Chemical Reference Data, [online],, (Accessed April 24, 2024)
Created June 9, 2021, Updated November 29, 2022