Vapor pressure, speed of sound, and density of the refrigerant mixture R-134a–R227ea in vapor phase

Using an ultrasonic interferometer and a piezometer of constant volume in the temperature range from $293$ to $373$ K and at pressures from $0.06$ to $0.4$–$3.6$ MPa, vapor pressure at the bubble line, speed of sound, and density of the gaseous mixed refrigerant R-134a $(48.66\%)$–R-227ea $(51.34\%)$ were investigated. Measurement errors of temperature, pressure, speed of sound and density were $\pm20$ mK, $\pm4$ kPa, $\pm(0.1$–$0.3)\%$ and $\pm(0.2$–$0.4)\%$, respectively. Approximation dependences of the vapor density and its pressure on the bubble lines were obtained. Experimental data were compared with calculations by the REFPROP program.