Abstract:

Viscosity, as one of the transport properties, is essential information of fluids in industrial and scientific areas. In order to develop a practical viscosity model based on Eyring's absolute rate theory, which is simultaneously applicable to both pure and mixture fluids at high pressures, a mixing rule is presented to extend our previously proposed viscosity model to the mixture calculations. Then, in order to verify the reliability of the present model, 27 pure fluids including alkanes, aromatics, esters, and alcohols are selected and their viscosities are correlated to obtain the model parameters. After that, the viscosity model coupled with the proposed mixing rule is applied to 27 binary mixtures and 3 ternary mixtures. For each binary mixture, an extra binary interaction parameter is introduced, which can be obtained by fitting to its viscosity data. While for ternary mixtures, no additional parameter is required. The results show that the present model gives rather high accuracy for all fluids. The average absolute relative deviations for the viscosities of pure fluids, binary mixtures, and ternary mixtures are 1.54%, 2.35%, and 3.86%, respectively, and the maximum deviations are 8.62%, 12.9%, and 19.7%, respectively. Such performance indicates the present model can be an effective tool for viscosity estimations in both industry and research. Finally, the proposed model is compared with the free volume model, which has higher computational accuracy than the latter for both high viscosity and interassociative fluids.

Key words: absolute rate theory, mixtures, high pressure, viscosity, model

摘要：

为了建立起一个统一的、可同时应用于纯质与混合物高压黏度计算的绝对速率理论模型，基于此前已有的纯质黏度模型，提出了相应的混合法则，将其扩展至对混合流体的计算当中。为验证模型精度，首先选取了27种纯质流体，通过拟合其黏度数据得到模型参数。随后，对27种二元混合物以及3种三元混合物的黏度进行了计算。其中，对于二元混合物，仍需要引入额外的二元交互参数，可通过拟合混合体系黏度数据得到。结果表明，该黏度模型对所选纯质、二元混合物和三元混合物的黏度均有着较高的计算精度，其相对偏差的平均绝对值分别为1.54%、2.35%和3.86%，最大偏差为8.62%、12.9%和19.7%。最后，将本文模型与自由体积模型进行了比较，其对高黏度和互缔合流体的计算精度均高于后者。

关键词: 绝对速率理论, 混合物, 高压, 黏度, 模型