Thermophysical Properties and Phase Behavior of CO2 with Impurities: Insight from Molecular Simulations

TL;DR

This study uses molecular simulations to accurately determine thermophysical properties of CO2 with impurities, aiding in the design of safer CO2 transportation systems by providing extensive property data across various conditions.

Contribution

The paper presents a comprehensive molecular simulation dataset of CO2 with impurities, revealing how impurities affect thermophysical properties across different phases.

Findings

Impurities decrease thermal expansion, compressibility, heat capacity, Joule-Thomson coefficient in gas phase.

Impurities increase speed of sound in gas phase, decrease it in liquid and supercritical phases.

Good agreement with existing equations of state validates the simulation approach.

Abstract

Experimentally determining thermophysical properties for various compositions commonly found in CO2 transportation systems is extremely challenging. To overcome this challenge, we performed Monte Carlo (MC) and molecular dynamics (MD) simulations of CO2 rich mixtures to compute thermophysical properties such as densities, thermal expansion coefficients, isothermal compressibilities, heat capacities, Joule-Thomson coefficients, speed of sound, and viscosities at temperatures (235-313) K and pressures (20-200) bar. We computed thermophysical properties of pure CO2 and CO2 rich mixtures with N2, Ar, H2, and CH4 as impurities (1-10) mol% and showed good agreement with available equations of state (EoS). We showed that impurities decrease the values of thermal expansion coefficients, isothermal compressibilities, heat capacities, and Joule-Thomson coefficients in the gas phase, while these values increase in the liquid and supercritical phases. In contrast, impurities increase the value of speed of sound in the gas phase and decrease it in the liquid and supercritical phases. We present an extensive data set of thermophysical properties for CO2 rich mixtures with various impurities, which will help to design the safe and efficient operation of CO2 transportation systems.