Accurate experimental ($p$, $\rho$, $T$) data of the ($CO_{2}$ + $O_{2}$) binary system for the development of models for CCS processes

TL;DR

This paper presents new high-precision experimental density data for CO₂ + O₂ mixtures across various pressures, temperatures, and compositions, aiding the development of thermodynamic models for carbon capture and storage processes.

Contribution

It provides the first extensive experimental density data for specific CO₂ + O₂ mixtures, and compares these results with existing equations of state to evaluate their accuracy.

Findings

EOS-CG predicts densities more accurately than GERG-2008.

EOS-CG shows no systematic temperature dependence in predictions.

GERG-2008's temperature dependence is less consistent.

Abstract

The limited availability of accurate experimental data in wide ranges of pressure, temperature, and composition is the main constraining factor for the proper development and assessment of thermodynamic models and equations of state. In the particular case of carbon capture and storage (CCS) processes, there is a clear need for data sets related to the (carbon dioxide + oxygen) mixtures that this work aims to address. This work provides new experimental ($p$, $\rho$, $T$) data for three binary ($CO_{2}$ + $O_{2}$) mixtures with mole fractions of oxygen $x$($O_{2}$) = (0.05, 0.10, and 0.20) mol/mol, in the temperature range $T$ = (250 to 375) K and pressure range $p$ = (0.5 to 13) MPa. The measurements were performed with a high-precision single-sinker densimeter with magnetic suspension coupling. The density data were obtained with estimated expanded relative uncertainties of 0.02% for the highest densities and up to 0.3% for the lowest ones.The results were compared to the corresponding results calculated by the current reference equations of state for this kind of mixtures, namely the EOS-CG (combustion gases) and the GERG-2008 equation of state, respectively. The EOS-CG yields better estimations in density than the GERG-2008 equation of state. The results from the EOS-GC model show no systematic temperature dependence. For the GERG-2008 model, however, this criterion is significantly less fulfilled.