Densities and Viscosities of Carbon Dioxide and Hydrogen Binary Systems: Experimental and Modeling

Density and viscosity data for CO₂ + H₂ systems are needed for optimum safe and efficient design of carbon capture and storage (CCS) processes, transport, and underground storage of hydrogen gas. A densimeter was used to measure the densities of the CO₂ + H₂ systems from 278 to 348 K and up to 55 MPa. The measured densities were compared against the predictions of the Multi-Fluid Helmholtz Energy Approximation (MFHEA) and the Peng-Robinson (PR) equations of states. Overall, MFHEA and PR are applicable for predicting the densities of the CO₂ + H₂ systems within the experimental uncertainty. Also, a capillary tube viscometer was used to measure the viscosities of CO₂ + H₂ binary systems from 273.62 to 323.37 K and up to 29 MPa. The measured viscosities were compared against the predictions of the Lennard-Jones (LJ), SUPERTRAPP (ST), residual entropy viscosity (SRES), and Pedersen models. Generally, it was observed that SRES, LJ, Pedersen, and ST are adequate in evaluating the measured viscosity of CO₂-rich systems, while for the H₂-rich systems, the LJ model showed relative weakness. Density and viscosity data, and models, considered at the gas, liquid, and supercritical regions are critical for optimizing CCS strategies and other hydrogen management processes.