Application of Peng-Robinson Equation of State for Calculating Solid-Vapor and Solid-Liquid Equilibrium of CH4-CO2 System

Abstract

In this study, the performances of Peng-Robinson Equation of State combined with the classical mixing rules were evaluated to calculate solid-vapor equilibrium (SVE) and solid-liquid equilibrium (SLE) of CH 4 -CO 2 system. The evaluation was performed by comparing the calculated values with the literature data. In the calculation of SVE, the new binary interaction parameter values (k ij ) of CH 4 -CO 2 mixtures were proposed in this work based on the experimental data. The proposed k ij obtained in this work might increase the accuracy of Peng-Robinson Equation of State by reducing average absolute deviation in the temperatures between calculated values and literature data from (2.18% to 0.26%), (0.88% to 0.70%) and (0.61% to 0.44%) at CO 2 composition of 1%, 1.91% and 2.93%, respectively. Significant improvement was found at CO 2 composition of 1%. In the calculation of SLE, new parameters were not proposed since the calculation using the existing (literature) k ij gives good results with an average absolute deviation of 0.5%.

CO2 Frost Phenomenon for Binary System of Methane-Carbon Dioxide Mixtures

“…Prediction of CO 2 freezing points for mixtures of CO 2 -CH 4 under cryogenic conditions using the standard Peng-Robinson equation of state [10] was done by ZareNezhad [11] and ZareNezhad and Eggeman [12]. In our previous work [13], we investigated the performance of the Peng-Robinson equation of state in the prediction of the solid-vapor and the solid-liquid equilibrium of the CH 4 -CO 2 system and we proposed an interaction parameter for a CO 2 concentration of 1% to improve the accuracy. However, for CO 2 concentrations of more than 1%, ZareNezhad and Eggemen's parameters [12] were adequate.…”