Vargas, Francisco M2019-05-162019-05-162017-082017-08-10August 201Wang, Fei. "Thermophysical Properties and Solution Thermodynamics of Hydrocarbon Systems at High Tempeartures and Pressures." (2017) Diss., Rice University. <a href="https://hdl.handle.net/1911/105514">https://hdl.handle.net/1911/105514</a>.https://hdl.handle.net/1911/105514Hydrocarbon liquids and solutions are widely used in industry to produce different chemical products. Their thermophysical properties and phase behavior are important for enhancing production, improving operational efficiency and also increasing environmental sustainability. Easier, faster and more accurate approaches for property evaluations and solubility behavior predictions are in need, especially for complex hydrocarbon systems under extreme conditions, to which current methods may not be successfully applied. The solubility parameter is an inherent property of a material and also a key input parameter in solution models. Accurate evaluations of solubility parameters at high temperatures and pressures are not feasible by the conventional methods. Current correlations between solubility parameters and other properties are limited to ambient condition. The pressure effect on solubility parameter is usually ignored in previous research work. A novel approach to calculate solubility parameters using volumetric properties is proposed in this work. The temperature and pressure dependence equations of solubility parameter are derived based on fundamental thermodynamic relations. The proposed equations are applied to various hydrocarbon systems with great accuracy. The composition effects on solubility parameter of mixtures are also investigated for mixtures consisting of components different in shapes and sizes, for which the regular solution theory provides unsatisfactory predictions. A binary constant is introduced in this work, with which the solubility parameter of the mixture and excess Gibbs energy can be more accurately predicted. Easier and faster method to evaluate volumetric properties using optical property, refractive index, is proposed in this work. The correlations between thermal expansivity and isothermal compressibility with refractive index are developed based on Lorenz-Lorentz equation and a saturation density correlation. The new approach allows volumetric property evaluations using only refractive index measurements for pure hydrocarbons, their mixtures, and crude oils, which significantly reduces the complexity of experiments. Applications to crude oil systems are also provided to predict asphaltene precipitation and deposition tendency using refractive index measurements. The work presented in this dissertation aims to stimulate new approaches to correlate different thermophysical properties of non-polar hydrocarbons to optical properties, such as refractive index. A variety of advantages of using the proposed approach over the conventional density-based method have been discussed, including but not limited to easier and faster experimental procedure, significantly less sample required and less fouling problems.application/pdfengCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.Solubility ParameterThermal Expansion CoefficientRefractive IndexDensityNon-polar HydrocarbonsSolution ModelPhase BehaviorThesis2019-05-16