Study on the PVT x Properties for Mixtures of Alternative Refrigerants

点击翻译按钮获取中文摘要

The PVT properties in the liquid phase for binary mixtures of HFC32 +HFC125, +HFC134a, and HFC125 + HFC134a were measured at from 283K to 353K and from near the saturated pressure to about 20 MPa.The method used in this work was the new direct-weighing technique. The sample vessel (about 64cm<@D13@>D1) was suspended to an electric balance (1200(]SY.+-。[)0.001g), and the densities were observed by direct weighing the gross weight of vessel contained the sample. The pressure generated by a hand oil pump was transmitted to the sample through the capillary tube. The suspension mechanism including the sample vessel was immersed in a liquid thermostat controlled within (]SY.+-。[)0.02K.The temperature was measured by a quartz thermometer. The pressure was measured by two precision strain gauges of maximum pressure : 5(]SY.+-。[)0.003 MPa and 25(]SY.+-。[)0.008 MPa.The volume in the sample vessel was obtained from the specific volume of methanol measured at 298.15K and 0.1MPa. The densities of pure HFC32, HFC125, HFC134a and HFC152a (purity : better than 99.6%) having the different density were observed at several temperatures and pressures, and the reliability of densimeter were confirmed to be measure an uncertainty within (]SY.+-。[)0.002g/m<@D13@>D1 compared with reference values.The mixtures were prepared by weighing with an uncertainty of within (]SY.+-。[)0.0003 mole, and the densities of liquid binary mixtures of HFC32/HFC125, HFC32/HFC134a and HFC125/HFC134a were measured at several temperatures and pressures. The bubble point pressures for these systems required to estimate the saturated liquid density were also measured by the instrument for ultrasonic speed measurement. Among these mixtures, They for HFC32/HFC125 were measured in detail for narrow interval concentrations, because that system has an azeotropic mixture. These results were correlated by the Fuller's equation of state and the Peng-Robinson's equation of state with a reasonable accuracy.