Application of thermodynamics at different scales to describe the behaviour of fast reacting binary mixtures in vapour-liquid equilibrium

Lasala, Silvia; Samukov, Konstantin; Polat, H.M.; Lachet, Véronique; Herbinet, Olivier; Privat, Romain; Jaubert, Jean Noël; Moultos, O.; De Ras, Kevin; Vlugt, T.J.H.

doi:10.1016/j.cej.2024.148961

Application of thermodynamics at different scales to describe the behaviour of fast reacting binary mixtures in vapour-liquid equilibrium

Title

Application of thermodynamics at different scales to describe the behaviour of fast reacting binary mixtures in vapour-liquid equilibrium

Author

Lasala, Silvia (Lorraine University)
Samukov, Konstantin (Lorraine University)
Polat, H.M. (TU Delft Engineering Thermodynamics)
Lachet, Véronique (IFP Energies Nouvelles)
Herbinet, Olivier (Lorraine University)
Privat, Romain (Lorraine University)
Jaubert, Jean Noël (Lorraine University)
Moultos, O. (TU Delft Process and Energy)
De Ras, Kevin (Universiteit Gent)
Vlugt, T.J.H. (TU Delft Process and Energy)

Department

Process and Energy

Date

2024

Abstract

The use of reactive working fluids in thermodynamic cycles is currently being considered as an alternative to inert working fluids, because of the preliminarily attested higher energy-efficiency potential. The current needs to simulate their use in thermodynamic cycles, which may operate in liquid, vapour or vapour-liquid state, are an accurate real-fluid equation of state and ideal gas thermochemical properties of each molecule constituting the mixture, to calculate the equilibrium constant. To this end, the appeal to a multi-scale theoretical methodology is paramount and its definition represents the objective of the present work. This methodology is applied and validated on the system N₂O₄ ⇌ 2NO₂. Firstly, the equations solved for simultaneous two-phase and reaction equilibrium are presented. Secondly, ideal gas thermochemical properties of N₂O₄ and NO₂ are computed at atomic scale by quantum mechanics simulations. Then, to apply the selected cubic equation of state, pure-component properties of the species forming the reactive mixture (critical point coordinates and acentric factor) are required as input. However, these properties are not measurable, since NO₂ and N₂O₄ do not exist in nature as pure components. To get around this difficulty, the methodology relies on molecular Monte Carlo simulations of the pure N₂O₄ and NO₂, as well as on the reactive N₂O₄ ⇌ 2NO₂, enabling the determination of those missing pure-component properties and thus the calculation, on a macroscopic scale, of the reactive mixture properties. Finally, the comparison of calculated mixture properties with available experimental data leads to validate the accuracy of the proposed methodology.