Critical (p , ρ , T) properties of CH2F2, {xCO2+(1−x) SF6}, {xSF6+(1−x) CH2F2}, and {xCHF3+(1−x) CH2F2}

Near critical measurements of HmEandVmE for { xCO2+ (1 −x)SF6} and measurements made over the pressure range 2.5 to 10.0 MPa at the temperature T= 301.95 K

“…The critical temperature (x, T c ) locus and the critical pressure (x, p c ) for {xCO 2 + (1 − x) SF 6 } have been measured by Diefenbacher and Turk (9) These data generate the ( p c , T c ) locus for (carbon dioxide + sulfur hexafluoride) shown in figure 1. For carbon dioxide the critical temperature and pressure are T c = 304.19 K and p c = 7.386 MPa, and for sulfur hexafluoride the values are T c = 318.74 K and p c = 3.755 MPa.…”

“…(4) In table 2 we report 39 measurements of H E m and 36 measurements of V E m at x = 0.5 made over the pressure range 10.0 MPa to 2.5 MPa at the temperature 301.95 K. The V E m and H E m measurements are shown plotted as a function of the pressure in figures 10 and 11. The T c (x) measurements of Diefenbacher and Turk (9) give T c (x = 0.5) = (300.6 ± 0.2) K and p c (x = 0.5) = (5.15 ± 0.5) MPa. This information was not available when our excess function measurements were made, but we now know that our experimental temperature was 1.35 K greater than T c (0.5), 2.26 K below the critical temperature of carbon dioxide, and 16.75 K below the critical temperature of sulfur hexafluoride.…”

CO2-based mixtures as working fluids for geothermal turbines.

“…As with CO 2 /SF 6 , NIST has not incorporated a specific model for CO 2 /Ne mixtures. Rather, predictions are based on other generalized models [8], and inaccuracies can be expected. Pure neon has a much lower critical temperature than CO 2 , at 44K (-380°F); therefore, even a small amount was expected by models to sharply decrease the mixture critical point.…”