In the present work, new VLE data of biphenyl in supercritical binary mixture (solvent) of (0.527propane/0.473n-butane) are reported for three selected isotherms of (403, 423, and 443) K for pressures up to 6.65 MPa. The VLE property (PTxy) measurements were performed using a new recently developed high-pressure and high-temperature optical cell with a volume of 117 cm³. The concentrations of the liquid and gas equilibrium phases were measured independently without breaking the phase equilibrium (PT) conditions during the sampling procedure from each phase. This allows considerable increase the accuracy of the concentration determination of the equilibrium phases using gravimetric method, especially for vapor phase. The values of the critical parameters$T_{\text{C}}=403\pm 0.2\text{K}$,$P_{\text{C}}=4.25\pm 0.03\text{MPa,}$$x=0.051\pm \text{0.006}$ mole fraction of biphenyl; $T_{\text{C}}=423\pm \text{0.2 K,}$$P_{\text{C}}=5.55\pm 0.03\text{MPa,}$$x=0.06\pm \text{0.006}$ mole fraction of biphenyl; and $T_{\text{C}}=443\pm 0.2\text{K,}$$P_{\text{C}}=6.80\pm 0.03\text{MPa,}$$x=0.09\pm \text{0.006}$ mole fraction of biphenyl for the mixture (0.527 propane / 0.473 n-butane) + biphenyl have been estimated from the experimental VLE data near the critical point. The measured VLE properties (PTxy relationship) of (0.527 propane / 0.473 n-butane) + biphenyl mixture was presented in various projections $P-x$ for different isotherms, $T-x$for various isobars, and $P-T$projection. The combined expanded uncertainty of the temperature, pressure, and concentration measurements at 0.95 confidence level with a coverage factor of k = 2 is estimated to be 0.15 K, 0.22 % (or 0.0022P), and 0.03, respectively.

在目前的工作中，联苯在（0.527 丙烷/0.473正丁烷）的超临界二元混合物（溶剂）中的新 VLE 数据报告了（403、423和 443）K 的三个选定等温线，压力高达 6.65 MPa。VLE 特性 ( PTxy ) 测量是使用最近开发的新型高压高温光学池进行的，体积为 117 cm ³。在不破坏相平衡 ( PT) 的情况下独立测量液相和气相平衡相的浓度) 每个阶段的采样过程中的条件。这可以显着提高使用重量法测定平衡相浓度的准确度，特别是对于气相。关键参数的值${吨}_{\text{C}}=403\pm 0.2\text{钾}$,${磷}_{\text{C}}=4.25\pm 0.03\text{兆帕，}$$X=0.051\pm \text{0.006}$ 联苯的摩尔分数； ${吨}_{\text{C}}=423\pm \text{0.2K，}$${磷}_{\text{C}}=5.55\pm 0.03\text{兆帕，}$$X=0.06\pm \text{0.006}$联苯的摩尔分数；和${吨}_{\text{C}}=443\pm 0.2\text{克，}$${磷}_{\text{C}}=6.80\pm 0.03\text{兆帕，}$$X=0.09\pm \text{0.006}$混合物 (0.527 丙烷 / 0.473正丁烷) + 联苯的摩尔分数已从临界点附近的实验 VLE 数据估计。(0.527 丙烷 / 0.473正丁烷) + 联苯混合物的测量 VLE 特性（PTxy关系）以各种预测形式呈现$磷——X$ 对于不同的等温线， $吨——X$对于各种等压线，和 $磷——吨$投影。在 0.95 置信水平和k = 2的覆盖系数下，温度、压力和浓度测量的组合扩展不确定性估计分别为 0.15 K、0.22 %（或 0.0022 P）和 0.03。