Supercritical fluid reactors and supercritical fluid separators are used in chemical manufacturing when they can potentially provide an efficient use of energy and materials. To achieve an optimum performance level, process models are used, which call for a detailed knowledge of supercritical fluid thermodynamics.[1] A major challenge is that, in the supercritical fluid region, the fluid is in the vicinity of a critical point, where thermodynamic properties undergo changes leading to an anomaly. From a theoretical perspective, we understand this behavior of the anomaly as the temperature and pressure where the correlation length extends to infinity and isochoric heat capacity grows to infinity. A series of calorimetric experiments on 2-propanol [2] and 17 other substances has established the conformity of the Yang-Yang critical anomaly as a thermodynamic model for supercritical fluids. Presently we seek to generalize the Yang-Yang model and an equation of state for supercritical fluids.

[1] Abdulagatov I. M., Magee, J. W., Polikhronidi, N. G. and Batyrova, R. G. "Yang-Yang Critical Anomaly" Ch. 15 in Enthalpy and Internal Energy: Liquids, Solutions and Vapours, Trevor Letcher and Emmerich Wilhelm, Editors, Cambridge: Royal Society of Chemistry, September 12, 2017, pp. 380-410 [DOI: 10.1039/9781788010214].

[2] Polikhronidi, N. G., Batyrova, R. G., Magee, J. W. and Abdulagatov I. M., "One- and Two-Phase Isochoric Heat Capacities and Saturated Densities of 2-Propanol in the Critical and Supercritical Regions," J. Chem. Thermodyn. 135: 155-174 (2019) [DOI: 10.1016/j.jct.2019.03.023].