Alkhatib Ismail I I, Albà Carlos G, Li Yuting, Stephan Simon, Llovell Fèlix, Vega Lourdes F
Research and Innovation Center on CO2 and Hydrogen (RICH Center) and Chemical and Petroleum Engineering Department, Khalifa University of Science and Technology, PO Box 127788, Abu Dhabi, United Arab Emirates.
Department of Chemical Engineering, ETSEQ, Universitat Rovira i Virgili (URV), Campus Sescelades, Av. Països Catalans 26, 43007 Tarragona, Spain.
J Phys Chem C Nanomater Interfaces. 2025 Aug 4;129(32):14622-14637. doi: 10.1021/acs.jpcc.5c04188. eCollection 2025 Aug 14.
Interfacial anomalies such as the formation of an aneotrope have been well-established for binary refrigerant blends with polar and nonpolar compounds. This remains largely unexplored for mixtures of polar refrigerants. This study investigates the phase equilibria and interfacial properties of pure refrigerants and their binary mixtures, specifically focusing on the molecular origin of interfacial anomalies. The polar soft-SAFT equation coupled with density gradient theory (DGT) was used to model the interfacial properties of 16 pure refrigerants, as well as phase equilibria and surface tension of selected binary mixtures with available data. Once the model was validated, the phase equilibria and interfacial tension for mixtures with R134a were systematically predicted with emphasis on azeotrope and aneotrope formation. It was determined that, unlike polar + nonpolar refrigerant mixtures, the occurrence of azeotropy is not a strict prerequisite for manifesting aneotropic-like behavior. The aneotrope composition was always consistent with the composition at which zero relative adsorption was observed rather than the composition of the azeotrope. Distinct interfacial enrichment in these mixtures was absent, indicating a subtle preferential adsorption rather than significant accumulation at the interface. This research provides a deeper understanding of interfacial anomalies and molecular-level insights for the rational design of sustainable next-generation refrigerants.
对于含有极性和非极性化合物的二元制冷剂混合物，诸如形成非共沸物之类的界面异常现象已得到充分证实。而对于极性制冷剂混合物，这方面在很大程度上仍未得到探索。本研究调查了纯制冷剂及其二元混合物的相平衡和界面性质，特别关注界面异常现象的分子起源。采用极性软统计缔合流体理论（soft-SAFT）方程结合密度梯度理论（DGT）来模拟16种纯制冷剂的界面性质，以及所选二元混合物的相平衡和表面张力（针对有可用数据的情况）。一旦模型得到验证，就对与R134a的混合物的相平衡和界面张力进行了系统预测，重点是共沸物和非共沸物的形成。结果表明，与极性+非极性制冷剂混合物不同，共沸现象的出现并非表现出非共沸物样行为的严格先决条件。非共沸物组成始终与观察到零相对吸附时的组成一致，而非与共沸物的组成一致。这些混合物中不存在明显的界面富集现象，表明存在微妙的优先吸附，而非在界面处有显著积累。本研究为界面异常现象提供了更深入的理解，并为可持续下一代制冷剂的合理设计提供了分子层面的见解。
