An accurate thermodynamic model to characterise dissociating N2O4 at vapour-liquid equilibrium states

Published

May 10, 2025

Author(s)

Samukov Konstantin, David Vega-Maza, Eric Lemmon, Vladimir Diky, Silvia Lasala

Abstract

A new thermodynamic model is presented, capable of accurately representing the vapour-liquid equilibrium pressures and densities of dissociating dinitrogen tetroxide (N2O4 ⇄ 2NO2). The model is based on the Peng-Robinson equation of state coupled with advanced mixing rules. The required but non-measurable critical coordinates of pure components in the reactive mixtures are optimized, within a variability range defined in a previous study, to fit experimental vapour-liquid equilibrium data. A parametric sensitivity analysis was previously undertaken, and only the reaction N2O4 ⇄ 2NO2 was considered. The optimized parameters and method were validated by comparing calculated thermodynamic properties with available experimental data in both subcritical and supercritical regions. The negligible impact in the model of the higher temperature reaction (2NO2 ⇄ 2NO + O2) was also proven within the temperature and pressure range. The resulting model was also compared with the currently most accurate available equation of state, showing comparable results when considered for both the scatter in available experimental data and the relative simplicity of the proposed equation of state. In particular, the proposed model demonstrates the unprecedented capability of a cubic equation of state to accurately reproduce both saturation pressures and saturation densities without requiring volume translation.

Citation

International Journal of Thermophysics

Volume

46

Pub Type

Journals

Download Paper

https://doi.org/10.1007/s10765-025-03565-x

Local Download

Keywords

dinitrogen tetroxide, reactive mixtures, vapour-liquid equilibrium, chemical equilibrium, equation of state

Citation

Konstantin, S. , Vega-Maza, D. , Lemmon, E. , Diky, V. and Lasala, S. (2025), An accurate thermodynamic model to characterise dissociating N2O4 at vapour-liquid equilibrium states, International Journal of Thermophysics, [online], https://doi.org/10.1007/s10765-025-03565-x, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=959350 (Accessed October 9, 2025)