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The Viscosity of Carbon Dioxide
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1998
Year
Carbon DioxideEngineeringFluid MechanicsExperimental ThermodynamicsGas-liquid FlowThermodynamic ModellingFluid PropertiesMolecular ThermodynamicsExcess ViscosityRheologyThermodynamicsCo2 Miscible FloodingRepresentative EquationsSupercritical FlowHeat TransferMultiphase FlowSupercritical Co2Viscoplastic FluidGas PhaseThermo-fluid Systems
In 1990, inconsistencies in experimental liquid viscosity data for CO₂ highlighted the need for new measurements. The study aims to revise existing CO₂ viscosity equations using two new measurement sets to improve liquid‑phase accuracy. The authors replaced the previous two‑equation, blended representation with a single equation for excess viscosity across all phases. The new single‑equation model accurately predicts CO₂ viscosity over 200–1500 K, up to 1400 kg m⁻³ and 300 MPa (30 MPa above 1000 K), with uncertainties from ±0.3 % to ±5 % and accompanying tables for validation.
When representative equations for the viscosity of carbon dioxide were published in 1990, it was recognized that, owing to inconsistencies among the available experimental liquid viscosity data which could not be resolved, new measurements were necessary. Since then, two new sets of measurements have been performed and it is appropriate to revise the published equations in order to improve their performance in the liquid region. In the previous work, the excess viscosity was represented by two separate equations, one for the gas phase and the other, a provisional one, for the liquid phase. Both equations were joined by a blending function. In the present work, the excess viscosity for the whole thermodynamic surface is represented by one equation. The resulting overall viscosity representation for carbon dioxide covers the temperature range 200 K⩽T⩽1500 K and densities up to 1400 kg m−3. In terms of pressure, the viscosity representation is valid up to 300 MPa for temperatures below 1000 K, whereas for higher temperatures and owing to the limitation of the equation of state used, the upper pressure limit is restricted to 30 MPa. The uncertainties associated with the proposed representation vary from ±0.3% for the viscosity of the dilute gas near room temperature to ±5.0% at the highest pressures. Tables of viscosity generated by the representative equations are included for easy reference and to assist validation of computer coding.