Liquid Viscosity and Interfacial Tension of Binary Mixtures of <i>n</i>‑Pentane, <i>n</i>‑Decane, <i>n</i>‑Hexadecane, or Squalane with Dissolved Carbon Dioxide or Propane by Surface Light Scattering

The present study investigates the influence of dissolved gases on the liquid viscosity ηL and interfacial tension σ of linear and branched alkanes under saturated conditions by using surface light scattering (SLS). Five binary mixtures consisting of n-pentane, n-decane, n-hexadecane, or 2,6,10,15,19,23-hexamethyltetracosane (squalane) with dissolved propane or carbon dioxide are studied at temperatures T between 255.7 and 423.15 K, pressures p up to 7.8 MPa, and solute amount fractions up to 0.79. Using SLS, ηL and σ were determined with an average expanded experimental uncertainty (coverage factor k = 2) of 2.0%. Polarization-difference Raman spectroscopy was simultaneously applied to SLS experiments to determine the liquid-phase composition. The influence of the dissolved gas is discussed by comparing the thermophysical properties of the mixtures to those of the pure solvents. It could be observed that the molecular characteristics of the solute have a minimal influence on ηL of the mixture, which is primarily determined by the solvent’s characteristics. In contrast, the molecular characteristics of the solvent and solute strongly influence σ. Overall, the results of this study contribute to expanding the database for ηL and σ for binary mixtures, which can be considered surrogate mixtures for refrigeration oil–refrigerant systems.本研究采用表面光散射（surface light scattering, SLS）技术，探究了饱和条件下溶解气体对直链与支链烷烃的液体黏度（η_L）与界面张力（σ）的影响。本研究针对五种二元混合物开展实验，这些混合物分别由正戊烷、正癸烷、正十六烷或2,6,10,15,19,23-六甲基二十四烷（角鲨烷，squalane）与溶解的丙烷或二氧化碳组成，实验温度T介于255.7 K至423.15 K之间，压力p最高可达7.8 MPa，溶质物质的量分数最高为0.79。通过表面光散射技术，本研究测得的液体黏度与界面张力的平均扩展实验不确定度（覆盖因子k=2）为2.0%。本研究同时将偏振差拉曼光谱法应用于表面光散射实验，以确定液相组成。通过对比二元混合物与纯溶剂的热物理性质，分析了溶解气体的影响。研究结果表明，溶质的分子特性对混合物的液体黏度影响极小，液体黏度主要由溶剂的特性决定；与之相反，溶剂与溶质的分子特性均会对界面张力产生显著影响。总体而言，本研究的实验结果有助于扩充二元混合物的液体黏度与界面张力数据库，此类二元混合物可作为制冷机油-制冷剂系统的替代混合体系。