Fundamental equation of state for chlorobenzene
DOI: 10.17586/1606-4313-2025-24-4-73-80
UDC 536.71
Berkova Elena A. , Alexksandrov Igor S., Gerasimov Anatoly A. , Grigoriev Boris A.
Keywords: chlorobenzene, fundamental equation of state, thermodynamic properties, density, heat capacity.
UDC 536.71
Fundamental equation of state for chlorobenzene
For citation: Berkova E.A., Aleksandrov I.S., Gerasimov А.А., Grigoriev B.А. Fundamental equation of state for chlorobenzene. Journal of International Academy of Refrigeration. 2025. No 4. p. 73-80. DOI: 10.17586/1606-4313-2025-24-4-73-80 (in Russian)
Abstract
The article solves the problem of constructing the fundamental equation of state (FES) for chlorobenzene which is a technically important substance and is actively used in industry. An array of heterogeneous experimental data, formed during the analysis of the published works, served as a basis for optimizing the form and determining the constants of the equation. The range of state parameters within which the FES reliably describes the thermodynamic surface of chlorobenzene is by temperature – from the triple point to 700 K, and by pressure – up to 100 MPa. The thermodynamic potential, in the form of which the equation of state is expressed, is free energy. The structure of the excess part of the potential, which was optimized on an array of experimental data, contains 15 terms, of which five are polynomial, five are exponential and five are Gaussian terms for describing the properties in a wide vicinity of the critical point. Despite its empirical basis, the new equation of state physically correctly describes the behavior of the derivatives of the thermodynamic potential and, as a consequence, the surface of state of chlorobenzene. This was achieved by using a modern optimization algorithm, the advantage of which is the joint processing of heterogeneous data in its own variables, excluding the linearization procedure associated with the inevitable loss of accuracy. In addition, the algorithm allows for the correct course of isolines outside the experimentally studied parameter areas. Average relative deviations of the calculated data from the experiment: for the density of the liquid phase – ±0.34%, for the pressure of saturated vapors – ±1.2%, the density of the saturated liquid phase – ±0.05%, the isobaric heat capacity of the liquid phase – ±1.4%; the speed of sound of the liquid phase – ±0.46% and the speed of sound of the saturated liquid – ±0.5%.
Abstract
The article solves the problem of constructing the fundamental equation of state (FES) for chlorobenzene which is a technically important substance and is actively used in industry. An array of heterogeneous experimental data, formed during the analysis of the published works, served as a basis for optimizing the form and determining the constants of the equation. The range of state parameters within which the FES reliably describes the thermodynamic surface of chlorobenzene is by temperature – from the triple point to 700 K, and by pressure – up to 100 MPa. The thermodynamic potential, in the form of which the equation of state is expressed, is free energy. The structure of the excess part of the potential, which was optimized on an array of experimental data, contains 15 terms, of which five are polynomial, five are exponential and five are Gaussian terms for describing the properties in a wide vicinity of the critical point. Despite its empirical basis, the new equation of state physically correctly describes the behavior of the derivatives of the thermodynamic potential and, as a consequence, the surface of state of chlorobenzene. This was achieved by using a modern optimization algorithm, the advantage of which is the joint processing of heterogeneous data in its own variables, excluding the linearization procedure associated with the inevitable loss of accuracy. In addition, the algorithm allows for the correct course of isolines outside the experimentally studied parameter areas. Average relative deviations of the calculated data from the experiment: for the density of the liquid phase – ±0.34%, for the pressure of saturated vapors – ±1.2%, the density of the saturated liquid phase – ±0.05%, the isobaric heat capacity of the liquid phase – ±1.4%; the speed of sound of the liquid phase – ±0.46% and the speed of sound of the saturated liquid – ±0.5%.
Keywords: chlorobenzene, fundamental equation of state, thermodynamic properties, density, heat capacity.
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