Abstract In this work, a simple temperature- and density-effective diameter expression recently published in the literature was combined with a new set of universal constants for the perturbed chain-statistical association fluid theory equation of state (PC- SAFT EoS). Then, the resulting PC- SAFT version was used to perform thermodynamic calculations of Brown's first- order ideal curves, phase behavior for simple hydrocarbon binary mixtures (critical loci), cloud-points (CP) for ternary polymeric mixtures, and asphaltene onset pressures (AOPs) for ill- and well-defined hydrocarbon mixtures prone to precipitate asphaltenes. In addition, the new PC- SAFT version was used to predict the crossover temperatures of one of the ill-defined petroleum mixtures under the injection of different amounts of CO2. This modified PC- SAFT model predicted both AOPs and CPs lower than those found by using the original universal constants by Gross and Sadowski (GS). The predictive calculations with both GS and Liang- Kontogeorgis (LK) universal constants produced as a result that a temperature- and density-dependent effective diameter significantly modifies the predictions for dense and complex systems, while does not generate an important impact on the calculation of properties of systems made-up by simple molecules under ordinary conditions.

中文翻译：

---

四种不同 PC-SAFT 版本的比较，用于预测低温下聚合物和沥青质系统的液-液平衡

摘要 在这项工作中，最近发表在文献中的一个简单的温度和密度有效直径表达式与一组新的通用常数相结合，用于扰动链统计关联流体理论状态方程 (PC-SAFT EoS)。然后，所得的 PC-SAFT 版本用于执行布朗一阶理想曲线的热力学计算、简单烃二元混合物的相行为（临界轨迹）、三元聚合物混合物的浊点 (CP) 和沥青质起始压力（ AOPs) 用于易于沉淀沥青质的定义不明确和定义明确的烃混合物。此外，新的 PC-SAFT 版本用于预测在注入不同数量的 CO2 下一种不明确的石油混合物的交叉温度。这种修改后的 PC-SAFT 模型预测的 AOP 和 CP 低于使用 Gross 和 Sadowski (GS) 使用原始通用常数发现的那些。使用 GS 和 Liang-Kontogeorgis (LK) 通用常数进行预测计算的结果是，与温度和密度相关的有效直径显着修改了对密集和复杂系统的预测，而不会对计算在普通条件下由简单分子组成的系统的性质。