Study on the Vapor-Liquid Equilibria using a Composition Analysis Technique from Ultrasonic speed for Hydrofluorocarbon Mixtures.

流体混合物的汽液平衡是衡量体系性质和进行工艺设计的重要热力学性质。对几种混合物的汽液平衡的研究已在其他地方报道过。通过对气相色谱图的分析，观察了这些研究中体系的组成。然而，该技术很难在比室温低得多或高得多的温度下测量汽液平衡。由于样品室和气相色谱仪进样条件（压力和/或温度）的不同，给体系的成分测定带来了不规律性，特别是在那些具有较高的气泡压力或露点压力的情况下，在临界条件下可以准确地测量流体中的超声速度。在以前的作品中。Takagi报道了通过声吸收测量的相同氢氟烃的蒸气压和泡点压力， ...更多信息 n技术在较宽的温度范围内。在这项工作中。建立了新的汽液平衡测定装置。本文采用的方法是利用超声波速度分析氢氟烃混合物的组成。在不锈钢SUS 316制成的高压平衡池中，平行设置用于测量气相（上侧）和液相（下侧）中的超声波速度的两个腔室。为了验证新装置的可靠性，对（1-x）HFC 32 + xHFCI 34 a的汽液平衡进行了研究。其在两种纯物质之间具有大的蒸气压差。在几个温度下测量。243.15 ~ 333.15K的温度范围内，X.与文献值比较，泡点压力的不确定度在2.5%以内，露点压力的不确定度在7%以内。对于（1-x）HFC 32 + x HFC 125，纯物质之间的蒸气压差很小。还在上述相同条件下测量VLE。该系统的实验误差。它们有一个异色体。尤其是露点压力的变化幅度较大。少

The vapor-liquid equilibria for fluid mixture is important thermodynamic properties to measure the characteristics of system and to design the process. The studies on the vapor-liquid equilibria for several mixtures have been reported elsewhere. The composition of systems in these studies has been observed by analyzing on the gas clomatogram. However, this technique was very difficult to measure the vapor-liquid equilibria at very lower or higher temperatures than the room temperature. Because the different of conditions (pressure and/or temperature) between the sample chamber and the injection of gas-chlomatograph give rise to irregularity to the composition determination for systems, especially in the cases of those having higher bubble or dew points pressures.The ultrasonic speeds in fluid can be measured accurately at critical conditions. In the previous works. Takagi reported the vapor pressure and bubble point pressure for same hydrofluorocarbons measured by an acoustic absorptio … More n technique in the wide temperature ranges. In this work. the new apparatus for measurement the vapor-liquid equilibria was constructed. The method used here was the composition analysis technique from the ultrasonic speed in the hydrofluorocarbon mixtures. In the high pressure equilibrium cell made stainless steel, SUS3 16, two chambers to measure the ultrasonic speed in gas (upper side) and liquid (lower side) phases were set up in parallel. Also this vessel have two optical windows to observe the condition of cell inside.In order to confirm the reliability of new apparatus, the VLE for (1-x)HFC32 + x HFCI34a. which have the large difference in the vapor pressures between both pure substances. were measured at several temperatures. from 243.15 to 333.15 K, and compositions. x. The uncertainties of VLE obtained are within 2.5% for the bubble point pressure and 7% for the dew point pressure by comparison with the references data. For (1-x) HFC32 + x HFC 125, the vapor pressure difference between the pure substances was small. the VLE were also measured at same conditions described above. The experimental errors for this system. which have an azeotrope. were a larger than those for former system, especially for dew point pressure. Less