Gaseous speed of sound and virial coefficients for 2,3,3,3-tetrafluoropropene (R1234yf) + 1,1,1,2-tetrafluoroethane (R134a) binary mixture

Acoustic Properties and Derived Virial Coefficients for Gaseous Mixtures of 2,3,3,3-Tetrafluoropropene (R1234yf) + Hexafluoropropylene (R1216)

“…The fixed-path acoustic resonance method, which was comprehensively introduced in the study by Moldover, was selected as the experimental method to measure the speed of sound. The method is currently one of the most accurate for measuring the gaseous speed of sound, and it has been used for determining the Boltzmann constant ( k B ) and redefining the thermodynamic temperature reference in SI. , Our previous studies demonstrated that this method is suitable for measuring the speed of sound in HFOs and their blends. ,− Briefly, an acoustic standing wave is formed in a fixed cylindrical or spherical cavity, and then the speed of sound is calculated using the measured resonance frequency and the calibrated cavity length according to the wave equation. For a cylindrical cavity, the speed of sound ( w ) is calculated according to eq . w = 2 π ( f N − ∑ j normalΔ f j ) / true( l π L true) 2 + true( χ m n a true) 2 where f N is the measured resonant frequency, Δ f j is the shift in the measured resonant frequency from the ideal frequency owing to the nonidealities, l ,| m |, n = (0, 1, 2···) are characteristic numbers of the axial, angular, and radial vibrations, respectively, indicating the number of half-waves in each direction, L and a are the length and radius of the resonant cavity, respectively, and χ mn is the zeros of the first derivative of the cylindrical Bessel function.…”

“…The receiver transducer was linked to a lock amplifier (SR830). The received electrical signal was processed using the Levernberg–Marquardt algorithm to acquire the resonant frequency within a relative expanded uncertainty ( k = 2) of 5 × 10 –6 . However, as shown in eq , the nonidealities, such as the boundary layer, adsorption, sample impurity, and cavity vibration, caused the f N peak to shift from the ideal peak frequency and resulted in a half-width.…”

“…First, mixture samples were prepared in the two-phase region with a mass of 10 times the total experimental amount, as described in previous work . Briefly, a bottle containing R1234yf was placed on an electronic balance, and another bottle containing pure R1216 was heated and turned upside down, causing R1216 to slowly flow into the R1234yf bottle to form a mixture.…”

“…Although thermodynamic research has been conducted on several pure HFOs, there is still a strong demand for the investigation of other HFOs and their mixtures. − So far, research on mixtures containing HFOs has been mostly restricted to the vapor–liquid equilibrium in the two-phase region and density in the single-phase region . For the speed of sound, another important single-phase region property, very little is known in the liquid phase, ,,− and no previous studies have addressed the gaseous speed of sound except for our recent study on an azeotropic mixture of R1234yf(1) + R134a(2) . Owing to the small composition difference between the gaseous and liquid phases and the low slide temperature, azeotropic mixtures can realize high heat transfer and component ratio stability while reducing the defects of pure fluids.…”

“…The speed of sound is a fundamental thermodynamic property characterizing the physical system and is widely used as indispensable basic data in the design of compressors, engines, and nozzles. − Furthermore, using the speed of sound data, one can construct intermolecular potential models and calculate virial coefficients, which can then be used to derive other thermodynamic properties including density, ideal-gas heat capacity, compressibility coefficients, , and equations of state (EoS) . For mixtures, high-accuracy speed of sound data can be used to describe intermolecular interactions, sensitively verify the mixing model and other thermodynamic properties, and determine the molar fraction. − Therefore, the measurement of the speed of sound is extremely important in scientific research and engineering fields.…”