CO₂ frost phenomenon for binary system of methane-carbon dioxide mixtures

In the present study, the CO₂ frost phenomenon of CH₄-CO₂ mixtures has been observed for the rational design of CO₂ removal from natural gas using a controlled freeze out area. The CO₂ frost conditions were estimated using the ZNE method and process simulation software (Aspen HYSYS® v7.3). The experiment was carried out using a double pipe heat exchanger (DPHE) with the concentration of CO₂ in the gas mixture at 5 and 10% and pressure of the gas mixture from 1 to 20 bar. The equilibrium temperature predictions of the ZNE method and the process simulation software only had a slight difference, with a magnitude deviation of less than 1% for pressures below 20 bar and 3% for pressures in the range of 20-30 bar, respectively. In the experimental study, CO₂ frost formation was detected at pressures of 1, 5, 10 and 20 bar. The locations of the initial CO₂ frost formation were determined using a pressure drop indicator associated with the predicted frost temperatures obtained from the ZNE method and the process simulation software. For all studied variables, the locations of initial CO₂ frost formation were found at 0.887-1.531 m from the inlet.