Thermophysical Properties of a CCUS Candidate Fluid

Comprehensive measurements of density, viscosity, hydrate equilibrium temperature, bubble and dew points, and water content were obtained for a representative CCUS candidate fluid comprising approximately 96 mol % CO2. Experiments were conducted across wide ranges of pressure and temperature to capture the thermodynamic and transport conditions characteristic of the full CCUS value chain. Complementing the experimental program, molecular dynamics simulations were employed to predict density and viscosity, enabling a direct comparison between molecular-level predictions and laboratory measurements The experimentally measured and simulated properties were systematically compared with predictions from relevant thermodynamic and transport models. Density predictions were evaluated using the Peng–Robinson (PR) equation of state and a multiparameter Helmholtz energy equation of state (MFHEA). Viscosity predictions were assessed using the residual entropy scaling (SRES) model, Lennard–Jones (LJ) theory, and SUPERTRAPP (ST). Hydrate equilibrium temperatures were modeled using the simplified cubic-plus-association equation of state (CPA-SRK-72). Vapor–liquid equilibrium (bubble and dew points) was described using MFHEA and sCPA models, while water content predictions were evaluated using CPA and SRK equations of state. Overall, this integrated experimental–computational study provides a rigorous evaluation of thermophysical property models for CO2-rich CCUS candidate fluids and offers validated data sets essential for benchmarking process design, simulation, and risk assessment across carbon capture, utilization, and storage operations.