Speed of Sound Data in Pure Refrigerants R-116 and R-218 and Their Mixtures: Experiment and Modeling

We present our latest research on speed of sound in mixtures of fluorocarbons that are used as unconventional refrigerants in various applications within high-technology electronics installations, in particle detectors, and elsewhere in the electronics industry. A new automated apparatus for speed of sound measurements has been prepared, and the experimental data that were gathered were compared to three equations of state. Actual speed of sound measurements were carried out in two fluorocarbons, R-218 (C3F8) and R-116 (C2F6), their mutual mixture, and mixtures of C3F8 with nitrogen. In total, more than 600 data points along 15 isotherms from 250 to 324 K and pressures up to 0.5 MPa were obtained. The range of the obtained speed of sound was from 102.5 to 144.8 m.s(-1). The sPC-SAFT, SAFT-BACK, and one cubic equation of state were evaluated in terms of speed of sound prediction accuracy in both liquid and vapor phases using our own data and data adopted from literature.