无机类化合物蒸气压数学模型的研究

通过对无机类化合物蒸气压估算方法的研究,利用手册或软件中的数据库,来查找无机类化合物的蒸气压数据,运用一定的数学分析方法和Ofigin软件对已有的蒸气压数据进行回归,给出最大相对误差、最小相对误差,提高了计算数据的准确度,为生产、设计提供了依据。     

新型制冷工质HFO-1234ze(E)蒸气压方程

为了更完善地认识新型制冷剂HFO-1234ze(E)的热物性,在公开发表的HFO-1234ze(E)饱和蒸气压实验数据的基础上,通过仔细分析各个实验数据的精确程度,筛选出一套由118组数据点组成的综合数据,经过拟合得到一系列蒸气压方程,对比各个方程对拟合数据的绝对偏差和相对偏差,得到一个适用范围较宽(232.990—380.002 K)且精度良好的四项Wanger型HFO-1234ze(E)蒸气压专用方程。该方程对拟合数据的平均相对偏差为-0.02%。同时,通过新方程计算得到HFO-1234ze(E)的正常沸点以及偏心因子,可以供物性计算和工程运用,具有较高的实际应用价值。     

煤液化油窄馏分饱和蒸气压研究进展

为了获得煤液化油窄馏分准确的物性参数——蒸气压,比较分析了物质蒸气压的测量、关联及估算方法。详细分析了几种测定方法的理论依据、设备要求及使用范围。根据煤液化油窄馏分的组分特性,提出了适用于其馏分饱和蒸气压测量关联及估算的方法。研究发现:窄馏分蒸气压的测量宜选择拟静态法,也可以参照石油馏分蒸气压的测量选用雷德法和参比法。其蒸气压与温度的关联应使用三参数Antoine方程;修正的MB关联式和Riedel方程适用于煤液化油窄馏分蒸气压估算。     

五种酯类化合物极微蒸气压的扭转法测定

<正> 引言 物质的饱和蒸气压是最重要的物性数据之一.在化工设计、生产与科学研究中,如农药、化肥的储存,香料的挥发速度,橡胶、塑料中增塑剂的有效寿命等,对有机酯类化合物低蒸气压数据要求迫切.由于测定难度以及数据准确性等问题,目前极微蒸气压的数据非常缺乏.测定方法主要有Knudsen隙透法和同位素示踪法,后者由于实验条件苛刻而很少     

松节油体系组分饱和蒸气压研究进展

本文综述了松节油体系组分的饱和蒸气压研究现状,根据松节油由双环单萜和倍半萜组成的特性,提出了适用于松节油体系组分饱和蒸气压的测定原理、测量方法、数据关联及估算方法。松节油体系组分是沸点相近的萜类同分异构体,难以分离得到纯度很高的松节油组分,利用稀溶液溶剂符合Raoult定律的原理,间接测定蒎烷、顺式蒎烷、对孟烷和长叶烯的饱和蒸气压。Antoine方程的三参数形式适用于松节油组分饱和蒸气压与温度的关联;对应态基团贡献法可应用于松节油组分饱和蒸气压数据的估算。     

六氟化铀及氟化物汽液相平衡数据预测及精馏过程模拟

精馏技术提纯六氟化铀是铀转化工艺的重要环节,该精馏工艺的模拟可为工艺设计及操作优化提供关键支撑。然而,由于六氟化铀及氟化物汽液相平衡数据及物性数据的缺乏,六氟化铀提纯精馏工艺的建模和模拟难以开展。为此,利用COSMOtherm和Turbomole软件,预测UF₆与TiF₄二元体系汽液相平衡数据。通过预测已知的WF₆-UF₆二元体系汽液相平衡实验数据以间接验证COSMO-RS模型预测的准确性。利用Aspen Plus软件的物性常数估算系统(property constant estimation system),估算出缺失的无限稀释水溶液Gibbs生成能等物性参数。文献中UF₆饱和蒸气压实验数据与模拟值进行对比,相对误差在1.76%以内。根据文献中的实验数据和预测的汽液相平衡数据,利用Aspen Plus软件回归NRTL模型的二元交互作用参数。针对六氟化铀及氟化物的分离,设计直接分离序列和间接分离序列提纯UF₆的两种方案。设定UF₆产品...     

基团贡献法估算偏心因子的可行性探讨

本文提出一种新的估算偏心因子方法,当某一化合物缺少饱和蒸气压或沸点等数据时,可用基团贡献法估算出偏心因子。     

道路运输液体危险货物罐式车辆金属常压罐体出厂检验问题探讨

在常压罐车出厂检验中发现设计文件中汽油饱和蒸气压错误,查找原因后发现其数据来源于《GB18564.1—2006〈道路运输液体危险货物罐式车辆第1部分:金属常压罐体技术要求〉实施指南》。通过对比计算发现,饱和蒸气压数据错误对一般车型罐体壁厚影响不大,但对罐车出厂检验时气密性压力、水压试验压力及软管试验压力影响较大,应及时改正该错误数据,避免由此带来安全隐患。     

有机化合物物性估算系统软件的开发(Ⅰ)——有机化合物物性的估算

介绍了有机化合物物性估算系统软件的有机物性估算及模型选用,描述了其主要物性的估算模型及输入参数和适用范围。根据当前最新的物性研究成果,系统建立了基础物性数据库,并为大部分物性提供了多种估算模型,以予互相补充。在物性估算过程中,系统将显示出待估算物性的每种估算模型的适用范图、输入参数和估算精度等信息,用户可根据自己的实际情况选择一种或几种模型进行物性估算,迅速得到满意的计算结果。     

有机化合物物性估算系统软件的开发(Ⅰ)--有机物性的估算

介绍了有机化合物物性估算系统软件的有机物性估算及模型选用,描述了其主要物性的估算模型及输入参数和适用范围。根据当前最新的物性研究成果,系统建立了基础物性数据库,并为大部分物性提供了多种估算模型,以予互相补充。在物性估算过程中,系统将显示出待估算物性的每种估算模型的适用范图、输入参数和估算精度等信息,用户可根据自己的实际情况选择一种或几种模型进行物性估算,迅速得到满意的计算结果。     

The effect of structure and isomerism on the vapor pressures of organic molecules and its potential atmospheric relevance

Knudsen Effusion Mass Spectrometry (KEMS) was used to find the solid state vapor pressures of a range of atmospherically relevant organic molecules from 298?K to 333?K. The selection of species analyzed allowed for the effect of structural isomerism, specifically positional isomerism, and stereoisomerism, specifically geometric isomerism, on solid state vapor pressure to be investigated. In addition, the effect of varying the number of carboxylic acid groups present within a molecule’s structure and of varying alkyl chain length was assessed. The solid state vapor pressures were converted to subcooled liquid vapor pressures using experimental heat of fusion and melting point values. The resulting subcooled liquid vapor pressures were found to be up to 7 orders of magnitude lower than the vapor pressures estimated from models. Some of this variation between experimentally determined subcooled liquid vapor pressures and predicted vapor pressures, which use group contribution methods, can be attributed to the effects of isomerism which are largely not taken into account in models. Whilst these techniques might have both structural and parametric uncertainties, of the compound classes tested, a general inverse relationship between melting point and solid state vapor pressure was observed. Within each compound class the variations in vapor pressure can be attributed to the number and size of functional groups present and the relative positions of those functional groups to each other both positionally and geometrically. These two factors impact upon both the molecules’ dipole moments and upon their ability to interact both intramolecularly and intermolecularly via hydrogen bonding, thus explaining the differences in observed vapor pressure. Partitioning calculations using a range of condensed mass loadings show that whilst using vapor pressure values derived from models would put most of the compounds in the vapor phase, using the experimental values obtained here would mean a significant fraction of the organic molecules would be in the condensed phase. This could have a significant impact upon the formation and nature of atmospheric aerosol, and comparisons with ambient data obtained from other mass spectrometry techniques during bonfire night in Manchester in 2016 are made in an attempt to assess this potential atmospheric importance.     

ESTIMATION OF VAPOR PRESSURES OF ORGANIC NITROGEN AND SULFUR COMPOUNDS BY A GROUP-CONTRIBUTION METHOD

The group-contribution method for vapor pressures of hydrocarbons and organic compounds containing nitrogen or sulfur, based on the kinetic theory of fluids, is revised and extended to include new groups containing nitrogen or sulfur. Good representation is obtained for vapor pressure data in the region 1.30-270 kPa. The method may be used to estimate vapor pressures and enthalpies of vaporization for those organic fluids containing nitrogen or sulfur, where no experimental data are available.     

基团对应状态法(CSGC)用于纯物质饱和蒸气压的估算

将对应态原理与基团贡献法相结合,引入拟临界性质的概念,提出基团对应状态法(Correspounding State with Group Contribution,简称CSGC)。并将其与Riedel方程相结合用于饱和蒸气压的估算,提出新的蒸气压估算方程(CSGC-PR方程)。88种基团的参数由包括饱和烃、不饱和烃、环烃、芳烃、含氧化合物、含硫化合物、含氮化合物、含卤化合物等350种物质5255个饱和蒸气压实验数据关联获得。新模型的估算精度优于现有的对应状态法,不仅对于高碳数分子有良好的估算精度,并对非极性物质能较好地外推高压下的饱和蒸气压。     

Rapid measurements of boiling point and vapor pressure of short-chain triglycerides by thermogravimetric analysis

Temperature dependence of vapor pressure and the boiling points for tricaproin (Tcap) and tricaprylin (Tcpy) were measured by a new rapid thermogravimetric analysis (TGA) method. Results were in agreement with data from other references. The Clausius/Clapeyron model fitted Tcap and Tcpy vapor pressure data with errors of 6% or less for pressures ranging from ambient down to 20 mmHg. This agreement with the model suggests that the vapor of these compounds has a large degree of ideal gas behavior and that their vaporization enthalpies are nearly constant from 25 to 400°C. Comparable accuracy and precision were obtained with TGA and differential scanning calorimetry methods for the compounds tested; however, TGA plots had significantly straighter baselines, which made vapor pressure determinations more convenient.     

Prediction of pure‐component flash points for organic compounds

Published flash point prediction methods are evaluated for accuracy against experimental data from the DIPPR ^® 801 database. The most accurate methods require a vapor pressure correlation, which is often not available. Two new methods are presented, one that uses the vapor pressure, and one based on the normal boiling point and enthalpy of vaporization at the normal boiling point. The vapor pressure method shows little improvement over the previous methods unless group contributions are implemented. The boiling point method predicts the flash point within an absolute average deviation of 1.3% when compared with data for more than 1000 compounds. The previous most accurate method that was not based on vapor pressure exhibited an absolute average deviation of 1.84% for the same test set. Copyright © 2010 John Wiley & Sons, Ltd.     

Prediction of adsorption equilibrium using a modified D-R equation: organic-water vapor mixtures on BPL carbon

Methods to describe and predict adsorption equilibrium using the D-R equation are presented in this paper. We focus on adsorption of organic-water vapor binary mixtures on BPL activated carbon. By adjusting the partial pressure of the organic component in the binary mixture, the effects of the presence of water vapor on adsorption of the organic component are quantitatively expressed using one term in a modified form of the D-R equation. The developed models have broad application ranges that are not limited by organic type and the loadings of the organic and water vapor. They can be used for coadsorption of water-immiscible or water-miscible organic compounds with water vapor on BPL activated carbon in the cases of small or large organic loading with low or near-saturation relative humidity. Compared with other methods for the adsorption of organic-water vapor binary mixtures, our models are simple and do not require iteration.     

Estimation of solid vapor pressures from supercritical CO2 + biomolecule systems using a PSO algorithm

A method to estimate the solid vapor pressures of biomolecules using a biologically deriver algorithm is presented. The solid vapor pressure is usually small for most solid compounds and in many cases available experimental techniques cannot be used to obtain accurate values. Therefore, estimation methods must be used to obtain these data. Five binary gas-solid phase systems of supercritical CO₂ + biomolecule containing caffeine, artemisinin, capsaicin, cholesterol, and β-carotene are considered in this study. Particle swarm optimization is used for minimize the difference between calculated and experimental solubility. Then, the solid vapor pressures of biomolecules are calculated from solubility data. The Peng-Robinson equation of state with the Wong-Sandler mixing rules are used to evaluate the fugacity coefficient on the systems. The results show that the method presented is reliable enough and can be used with confidence to estimate the solid vapor pressure of any organic biomolecule.     

Pervaporation and Vapor Permeation Tutorial: Membrane Processes for the Selective Separation of Liquid and Vapor Mixtures

Pervaporation and vapor permeation are membrane-based processes proposed as alternatives to conventional separation technologies. Applications range from organic solvent removal from water, ethanol, or butanol recovery from fermentation broths, solvent/biofuel dehydration to meet dryness specifications, and organic-organic separations such as the removal of sulfur compounds from gasoline. Unlike membrane filtration processes, which rely on an applied liquid pressure gradient and size sieving to accomplish a separation, pervaporation and vapor permeation separate compounds based on a chemical activity driving force and the sorption and diffusion of the compounds through the membrane. These properties enable the separation of even miscible liquid mixtures.     

TRANSPORT PROPERTY DATA QUALIFICATION FOR VARYING FUNCTIONAL GROUPS

A qualitative study of the accuracy and consistency of transport property experimental data was undertaken for compounds which are not categorized in particular homologous series but contain a common hydrocarbon chain and differing functional groups. The behaviors of liquid and vapor viscosity and vapor thermal conductivity were observed over a reasonable temperature range. Plots of property against temperature or reduced temperature were analyzed for consistent alignment among different properties and groups of compounds. Trends were similar to past work on thermodynamic properties. Results of the study provide methods to verify data accuracy, predict positioning of data within functional group categories, and allow rough prediction for multifunctional compounds.