<abstract xml:lang="en" xmlns="http://www.w3.org/1999/xhtml"><p>Different thermodynamic properties (the vapour density, the liquid density and the saturation pressure) were calculated by the model based on the Nakamura-Breedveld-Prausnitz equation of state (NBP EOS). Since the original form of the NBP EOS often generates inaccurate results for liquids, it was modified to describe this phase better. The calculations were realized in the subcritical region. So far, the temperature-dependent NBP EOS parameters have been obtained by special correlations. Their constants were fitted to a lot of experimental data. In this paper the equation of state temperature-dependent parameters were obtained by a new method which was based at piecewise cubic Hermite interpolating polynomials (PCHIPs). In the proposed method some experimental data (called the key ones) were used, thus reducing the experimental effort. Seven substances were chosen for the test calculations. Each of them is common in industry. The calculation results were compared with the experimental data. The new method has made an accurate description of vapour-liquid equilibrium for the considered pure substances over a wide temperature range possible.</p></abstract>

Different thermodynamic properties (the vapour density, the liquid density and the saturation pressure) were calculated by the model based on the Nakamura-Breedveld-Prausnitz equation of state (NBP EOS). Since the original form of the NBP EOS often generates inaccurate results for liquids, it was modified to describe this phase better. The calculations were realized in the subcritical region. So far, the temperature-dependent NBP EOS parameters have been obtained by special correlations. Their constants were fitted to a lot of experimental data. In this paper the equation of state temperature-dependent parameters were obtained by a new method which was based at piecewise cubic Hermite interpolating polynomials (PCHIPs). In the proposed method some experimental data (called the key ones) were used, thus reducing the experimental effort. Seven substances were chosen for the test calculations. Each of them is common in industry. The calculation results were compared with the experimental data. The new method has made an accurate description of vapour-liquid equilibrium for the considered pure substances over a wide temperature range possible.

Optimization of the quintic equation of the state based model for the calculations of different thermodynamic properties

Faculty of Chemistry, Division of Chemical and Biochemical Processes, Technical University of Wroclaw, Norwida 4/6, 50-373 Wroclaw, Poland

Polish Journal of Chemical Technology

Different thermodynamic properties (the vapour density, the liquid density and the saturation pressure) were calculated by the model based on the...

Optimization of the quintic equation of the state based model for the calculations of different thermodynamic properties

Published Online: Apr 03, 2008

Page range: 6 - 10

DOI: https://doi.org/10.2478/v10026-008-0002-x

Keywords
NBP equation of state, vapour-liquid equilibrium, cubic Hermite polynomials

This content is open access.

Optimization of the quintic equation of the state based model for the calculations of different thermodynamic properties

Published Online: Apr 03, 2008

Page range: 6 - 10

DOI: https://doi.org/10.2478/v10026-008-0002-x

KeywordsNBP equation of state, vapour-liquid equilibrium, cubic Hermite polynomials

This content is open access.

Keywords
NBP equation of state, vapour-liquid equilibrium, cubic Hermite polynomials