Acoustic Determination of Thermophysical Properties and Critical Parameters for the Mixture (51 wt % R143a + 49 wt % R125) and Critical Line of xCO₂ + (1 − x)(51 wt % R143a + 49 wt % R125)

Abstract

The thermophysical properties and critical parameters for the alternative refrigerant (51 wt % of 1,1,1-trifluoroethane (R143a) + 49 wt % of pentafluoroethane (R125))svery close to the composition of R507 (50 wt % of each mixture component)swere investigated using two different acoustic techniques. The critical behavior of the system xCO 2 + (1x)(51 wt % R143a + 49 wt % R125) was also investigated. Experimental data of speed of sound in liquid (51 wt % R143a + 49 wt % R125) from T ) (253 to 338) K and pressures up to 65 MPa were measured using a pulse-echo method. Derived thermodynamic properties were calculated, combining our experimental data with density and isobaric heat capacity values published by other authors. Measurements of the critical temperature T c and pressure p c on (51 wt % R143a + 49 wt % R125) and mixtures of xCO 2 + (1x)(51 wt % R143a + 49 wt % R125) were performed using another simple ultrasonic time-delay technique. The binary critical line was determined over the whole composition range showing that this system deviates only slightly from ideality since the critical line is a continuous line. The Peng-Robinson equation of state with conventional mixing and combining parameters was used to correlate the binary experimental data.

CHAPTER 13. Ultrasonics 2: High Pressure Speed of Sound, Isentropic Compressibility

“…Dzida and co-workers have studied u(T,P) for n-alkanes, alcohols and their mixtures, and have discussed their results from a physical chemistry point of view. The research groups of Lago et al, [91][92][93][94][95][96][97][98][99][100] Kabelac et al, [101][102][103][104] Guedes et al, [106][107][108][109] Trusler et al [110][111][112] and others 105,113,114 have reported measurements of u(T,P) on compounds such as: water, hydrocarbons, refrigerants, oils over a wide range of temperature and pressure. Research on the u(T,P) for biomassderived fuels and related compounds has recently been reported.…”