Joule-Thomson Effect on a CCS-Relevant (CO2 + N2) System

The Joule-Thomson effect is a key chemical thermodynamic property that is encountered in several industrial applications for CO2 capture and storage (CCS). An apparatus was designed and built for determining the Joule-Thomson effect. The accuracy of the device was verified by comparing the experimental data with the literature on nitrogen and carbon dioxide. New Joule-Thomson coefficient (mu(JT)) measurements for three binary mixtures of (CO2 + N-2) with molar compositions x(N2) = (0.05, 0.10, 0.50) were performed in the temperature range between 298.15 and 423.15 K and at pressures up to 14 MPa. Three equations of state (GERG-2008 equation, AGA8-92DC, and the Peng-Robinson) were used to calculate the mu(JT) compared with the corresponding experimental data. All of the equations studied here except PR have shown good prediction of mu(JT) for (CO2 + N-2) mixtures. The relative deviations with respect to experimental data for all (CO2 + N-2) mixtures from the GERG-2008 were within the +/- 2.5% band, and the AGA8-DC92 EoSs were within +/- 3%. The Joule-Thomson inversion curve (JTIC) has also been modeled by the aforementioned EoSs, and a comparison was made between the calculated JTICs and the available literature data. The GERG-2008 and AGA8-92DC EoSs show good agreement in predicting the JTIC for pure CO2 and N-2. The PR equation only matches well with the JTIC for pure N-2, while it gives a poor prediction for pure CO2. For the (CO2 + N-2) mixtures, the three equations all give similar results throughout the full span of JTICs. The temperature and pressure of the transportation and compression conditions in CCS are far lower than the corresponding predicted P-inv,P-max and T-inv,T-max for (CO2 + N-2) mixtures.