Experimental determination and modelling of hydrate phase equilibria for systems containing heptane, nonane, and hexadecane with or without <scp>TBAB</scp>

Abstract In this work, we report hydrate phase equilibria data for CO₂ + H₂O + C 7 H 16 + C 9 H 20 + C 16 H 34 systems with TBAB () and its modelling using a modified Chen–Guo model, which incorporates a modification to the Helmholtz molar free energy term and a polynomial equation in terms of temperature and/or solubility of the compounds. The experimental data were obtained using the non‐visual isochoric method by pressure search over a temperature range of 273.69–292.03 K and a pressure interval of 1.32–4.59 MPa using several hydrocarbon mixtures (C 7 H 16 + C 9 H 20 + C 16 H 34 ) with mass fraction composition, namely (). The combined experimental uncertainties were estimated for temperature and pressure conditions to be 0.15 K and 0.02 MPa, respectively, while the relative standard uncertainty in composition (mass fraction) was 0.0020. The present modified model represented quite well the measured hydrate‐phase equilibria data, yielding an average absolute percentage deviation () of 0.033% (without TBAB) and 0.023% (with TBAB) meanwhile a maximum absolute percentage deviation () of 0.085% (without TBAB) and 0.044% (with TBAB).