Viscosities, thermal conductivities and diffusion coefficients of CO2 mixtures:Review of experimental data and theoretical models

摘要

Accurate experimental data on the thermo-physical properties of CO2-mixtures are pre-requisites fordevelopment of more accurate models and hence, more precise design of CO2 capture and storage (CCS)processes. A literature survey was conducted on both the available experimental data and the theoreticalmodels associated with the transport properties of CO2-mixtures within the operation windows ofCCS. Gaps were identified between the available knowledge and requirements of the system design andoperation. For the experimental gas-phase measurements, there are no available data about any transportproperties of CO2/H2S, CO2/COS and CO2/NH3; and except for CO2/H2O(/NaCl) and CO2/amine/H2Omixtures, there are no available measurements regarding the transport properties of any liquid-phasemixtures. In the prediction of gas-phase viscosities using Chapman–Enskog theory, deviations are typically<2% at atmospheric pressure and moderate temperatures. The deviations increase with increasingtemperatures and pressures. Using both the Rigorous Kinetic Theory (RKT) and empirical models in theprediction of gas-phase thermal conductivities, typical deviations are 2.2–9%. Comparison of popularempirical models for estimation of gas-phase diffusion coefficients with newer experimental data forCO2/H2O shows deviations of up to 20%. For many mixtures relevant for CCS, the diffusion coefficientmodels based on the RKT show predictions within the experimental uncertainty. Typical reported deviationsof the CO2/H2O system using empirical models are below 3% for the viscosity and the thermalconductivity and between 5 and 20% for the diffusion coefficients. The research community knows littleabout the effect of other impurities in liquid CO2 than water, and this is an important area to focus infuture work.