High pressure phase behavior of the system ethane+orange peel oil

High-pressure vapor–liquid equilibria of ethane+orange peel oil was determined experimentally by a synthetic method. No liquid–liquid immiscibility was observed in this system. Bubble and dew points were measured at ethane mass fractions ranging from 0.1 to 0.9988 and within temperature and pressure ranges of 282–363 K and 1–10 MPa, respectively. Critical points were also determined experimentally for ethane mass fractions of 0.75–0.9988. At very high ethane concentrations, the experimental results showed double retrograde vaporization behavior, in which the dew point curve has a double-domed shape. In this limited region, increasing the pressure at fixed concentration results in triple- or quadruple-valued dew points. The bubble and dew point data of this work were also compared with those of ethane+lemon peel oil and ethane+limonene, indicating an almost perfect match between all three systems. Even the double retrograde behavior of the orange oil system showed good agreement with that of ethane+limonene, even though the oil is composed of numerous components. The experimental data were correlated with the Stryjek–Vera modified version of the Peng–Robinson equation of state using the Mathias–Klotz–Prausnitz mixing rule with two binary interaction parameters. The results showed fairly good agreement with the data.