Measurements of the Speed of Sound for Mixtures of Methane + Butane with a Particular Focus on the Critical State

Abstract

The speed of sound in binary mixtures of methane + butane has been measured in the subcritical, nearcritical, and supercritical regions as a function of pressure at 311 K. The measurements were based on an acoustic pulse technique using a high-pressure vessel equipped with two 1-MHz transducers to generate and receive the ultrasonic wave. The results showed that the speed of sound decreased with decreasing pressure for mixtures in the subcritical region, whereas it passed through a minimum in the supercritical region.

Accurate Values of Some Thermodynamic Properties for Carbon Dioxide, Ethane, Propane, and Some Binary Mixtures

“…The experimental values of speed of sound obtained for water were compared with those from the reference EoS, and the precision (MRD( u )) obtained was better than 0.06%. The values of MRD( u ) obtained in this work are comparable with those from the literature − determined with pulsed ultrasonic systems operating in most of the cases up to pressures lower than those reached in this work. Using the same technique, Gedanitz et al measured sound velocity in fluids up to 30 MPa in the temperature range between 250 and 350 K, and the deviations observed in their measurements are better than those given above.…”

Comment on “Molecular Simulation Prediction of Sound Velocity for a Binary Mixture near Miscible Conditions”

“…For this mixture, FB reported a molecular simulation deviation of ∼5% and a minimum deviation of 54.2% for the PR values. The new calculated values are reported in Table 2 and require some discussion that also could include experimental data from Plantier et al 2 In the singlephase region, PR values are quite near the experimental data (2%À5% error) and similar to those calculated with the LK and GERG models. When the two-phase boundary is crossed, the calculated speed of sound decreases almost discontinuously; the PR error increases sharply to an average value of 33%, remaining however consistent with LK and GERG calculated values.…”

“…This doubt has been confirmed by recalculating their values with a process simulator developed by the author: the new calculated values are largely different from those presented by FB. This work presents updated values of the speed of sound evaluated using the PR equation of state and compares them with the original experimental values of Plantier et al 2 For validation, calculated values using the PR equation are also compared with those generated by other noncubic and more-complex equations of state.…”

“…Sonic Speed for the Methane (x = 0.724) and n-Butane Mixture a Experimental data from Plantier et al2 …”

Reply to “Comment on ‘Molecular Simulation Prediction of Sound Velocity for a Binary Mixture near Miscible Conditions’”

“… a Experimental data taken from Plantier et al b The relative error of the results presented by Raimondi c The relative error of our computed results via the Peng–Robinson equation of state. d The relative error of our computed results via the Peng–Robinson equation of state, considering the volume shift. …”