Determination of fluid thermodynamics properties of fluids. Pure fluids

Information concerning the thermodynamics of equilibria between phases under pressure is essential in chemical and energy engineering. Indeed, many industrial processes and energy systems operate under pressure: separation processes (distillation, supercritical fluid extraction, etc.), geochemical processes (underground gas and energy storage), natural gas treatment, refrigeration and heat pumps, engines, ORC cycles and waste heat recovery, etc. To date, many models have been proposed (pure bodies and mixtures) for the faithful representation of thermodynamic properties, taking into account the behavior of the various systems commonly encountered in the industrial field. However, thanks to the precise information provided by laboratory experiments, new, even more accurate thermodynamic models can be developed. These models are used to reduce the number of experimental points to be determined (predictive models) and to size units or unit operations, as well as to improve understanding of the physical phenomena involved. Process energy assessment also requires highly accurate thermodynamic models, enabling energy, entropy and exergy balances to be calculated and evaluated. When calculating the coefficient of performance of a refrigeration cycle, for example, it is not sufficient to use thermodynamic models whose density calculation uncertainty is too great. Similarly, the use of the perfect gas is very limited.