STUDY ON THE THERMOPHYSICAL PROPERTIES IN MIXTURES OF NON-CHLORINE HYDROCARBON REFRIGERaNTS

在氟氯烃中，氯氟烃、二氟氯甲烷、氯氟化碳_2(HCFC22，临界温度T_c=369.30 K；临界压力p_c=4.988 Mpa)是当今空调制冷技术中广泛使用的工质。据推测，由于氟氯烃的演变，臭氧消耗潜能，与氯氟化碳的消耗潜能相比，相对较低。然而，随着包括氯原子在内的氟氯烃-22的大量使用，在不久的将来给地球环境带来的各种有害影响令人担忧。CHCIF_2的合适替代化合物可能是三氟甲烷、CHF_3(HFC-23)、二氟甲烷、CH_2F_2(HFC-32)、五氟乙烷CHF_2CF_3(HFC-125)和1，1，1，2-四氟乙烷、CF_3CH_2F(HFC-134a)，它们的蒸汽压和临界参数与CHCIF_2和/或它们的二元混合物几乎相同。在243~333K等温线上测量了CHF_3CF_3CH_2F和CH_2F_2CF_3CH_2F二元混合物在243~333K，压力达30 Mpa时，在液相中的声速和密度。采用回旋技术测量蒸汽压和超声速。用直接称重法观察密度(PVT)。这些值的温度、压力和/或组成的变化被发现为测量每个二元混合物体系的热物理性质提供了有力的线索。在CH_2F_2CF_3CH_2F体系的下部得到的结果表明，它们的性质几乎相同，可能是氯二氟甲烷CHCIF_2的替代流体。

Among hydrochlorofluorocarbons, HCFCls, chlorodifluoromethane, CHCIF_2 (HCFC-22, critical temperature, T_c=369.30 K ; critical pressure, p_c=4.988MPa) is widely used today as working fluidsinair-conditioning and refrigeration technology. The ozone depletion potential, ODP, due to the evolution of HCFCs, is presumed to be the comparatively lower compared with those for chlorofluorocarbons, CFCs. However, wity the use in a large quantity of HCFC-22 including chlorine atom, the various harmful influences giving to the earth environmental are anxious in the near future. Suitable replacement compounds for CHCIF_2 may be trifluoromethane, CHF_3 (HFC-23), difluoromethane, CH_2F_2 (HFC-32), pentafluoroethane CHF_2CF_3 (HFC-125) and 1,1,1,2-tetrafluoroethane, CF_3CH_2F (HFC-134a), which those have nearly the same vapor pressures and critical parameters with those for CHCIF_2, and/or their binary mixtures.In this project, the vapor pressure, ultrasonic speed and density (PVT) in the liquid phase for binary mixtures of CHF_3+CF_3CH_2F and CH_2F_2+CF_3CH_2F were measured along isotherms from 243 to 333 K and at pressures up to about 30MPa. A sing-around technique were used for the measurement of vapor pressure and ultrasonic speed. And the density (PVT) was observed by a direct weighing technique. The temperature, pressure and/or composition variations for these values are found to give a powerful clue to measure the thermophysical properties for each system of binary mixtures. The results obtained in the lower region of CH_2F_2 + CF_3CH_2F system, which indicated the nearly same properties, may be noted as a alternative fluid of chlorodufluoromethane CHCIF_2.