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汽液平衡二相组成与温度间的相互关系 总被引:1,自引:0,他引:1
汽液平衡时液相分子仍不断地从液相蒸发到汽相,那些从液相蒸发到汽相中的分子与滞留在液相中的同类分子相比具有较高的能量。通过考虑液相中分子能量的分布以及分子相互之间碰撞对汽液相分子分布的影响,从新的角度探讨了汽液二相平衡时汽液相组成与温度之间的相互关系。 相似文献
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采用双循环汽液平衡釜测定了异丙醇—异丙醚二元体系在常压下的汽液平衡数据,实验结果经Herrington方法检验符合热力学一致性。应用Margules、Van Laar、Wilson、NRTL4种方程对其进行关联,求出模型参数,利用所得模型参数计算相应的汽相组成,并与实验值比较,两者符合良好。 相似文献
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采用泵式沸点仪测定了吗啡啉-正丁醇二元体系在常压下的汽液平衡数据,并用间接法由TPX推算了与之平衡的汽相组成,用最小二乘法求出了该系统的液相活度系数模型参数,由模型参数推算的泡点与实验值符合良好,所得数据通过了热力学一致性检验。 相似文献
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综述了国内外FT合成气汽液平衡研究的新进展,主要包括FT合成液相溶剂的性质、溶解度实验研究、模型关联及汽液平衡规律 相似文献
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确定流动汽液平衡釜总压的直接法 总被引:1,自引:0,他引:1
本文提出了两种由体系温度(T)及汽液相组成(y,x)推算二元系总压(P)的直接法。并用T,x,y,P均已知的氯仿-乙醇、异戊二烯-乙腈二个二元体系数据,对所得公式进行验算,结果计算值与实验值吻合。此法可直接确定用流动平衡釜测汽液平衡时的总压;对同时测定了T,x,y,P的体系可进行逐点的P检验。 相似文献
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用改进Rose釜测定了乙酸-乙酸丁酯、水-乙酸-乙酸丁酯(完全互溶区)体系在101.33 kPa下的汽液平衡数据。考虑乙酸的缔合效应,利用维里方程和Hayden-O'Connell(HOC)模型计算各组分的汽相逸度系数,校正汽相的非理想性,液相的非理想性全部归结到液相活度系数中予以校正。用NRTL,UNIQUAC模型对乙酸-乙酸丁酯的汽液平衡数据进行关联,并得到相应的模型参数、温度偏差和汽相组成偏差。比较二元体系的关联结果,用NRTL模型参数预测了三元汽液平衡数据,计算值与实验值吻合良好,预测精度较好,说明采用的模型参数是可靠的,能够为精馏的设计和模拟计算提供基础热力学数据。 相似文献
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The time series of the physical parameters in boiling evaporators with vapor‐liquid (V‐L) two‐phase and vapor‐liquid‐solid (V‐L‐S) three‐phase external natural circulating flows exhibit nonlinear features. Hence, proper system evolution models may be built from the point of view of nonlinear dynamics. In this work, genetic programming (GP) was utilized to find the nonlinear modeling functions necessary to develop global explicit two‐variable iteration models, using wall temperature signals measured from the heated tube in ordinary two‐phase and three‐phase fluidized bed evaporators. The model predictions agree well with the experimental data of the time series, which means that the models established with GP can adequately describe the dynamic evolution behavior of multi‐phase flow boiling systems. 相似文献
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采用静态法测定了NH_3-H_3PO_4-H_2O体系在NH_3/H_3PO_4分子比为1.0-1.4,相应温度范围为75-175℃时的汽液平衡数据,并把实验数据关联成数学式.根据热力学理论,对NH_3-H_3PO_4-H_2O体系的热力学平衡计算的模型作了初步探讨.液相活度及活度系数采用扩充Pitzer方程,汽相逸度系数采用根据极性修改的RK方程.根据Edwards提出的弱电解质溶液的分子热力学,基于质量平衡、化学平衡、电荷平衡及汽液平衡理论,提出了NH_3-H_3PO_4-H_2O体系汽液平衡计算的热力学模型.计算结果表明:摩尔浓度低于25mol/kg H_2O时,模型计算结果与实验数据吻合得较好. 相似文献
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Caroline Dang Thomas Bannan Petroc Shelley Michael Priestley Stephen D. Worrall John Waters 《Aerosol science and technology》2013,47(9):1040-1055
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. 相似文献
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甲醇-乙酸-丙酸多元体系汽液平衡 总被引:1,自引:1,他引:0
用新型泵式沸点仪测定了在100kPa下甲醇-乙酸、甲醇-丙酸、乙酸-丙酸3个二元体系以及甲醇-乙酸-丙酸三元系在不同液相组成时的沸点,并用间接法T-p-x(温度、压力和液相摩尔分数)推算了3个二元体系的汽相平衡组成。3个二元体系活度系数分别用Wilson模型、NRTL模型、Margules模型和van Laar模型进行关联,用最小二乘法求出了它们的液相活度系数模型参数,同时,用这些模型参数来计算它们的汽相摩尔分数。所得的液相活度系数来计算3个二元体系的过量吉布斯自由能函数,且所研究的所有体系中各组分之间不存在共沸点。用3个二元体系Wilson模型参数对所测的三元体系数据进行关联,建立该系统汽液平衡的热力学模型并计算平衡时的汽相摩尔分数和泡点温度。由面积积分法检验这些模型参数计算的3个二元体系相平衡数据,得到很好的热力学一致性。 相似文献
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汽液相平衡计算是化工过程开发及优化设计的基础。汽液相平衡计算的核心是确定体系处于平衡状态时,温度T、压力p、液相组成x及汽相组成y 4个变量之间的关系。在这4个变量中,汽相组成一般难以准确测定,低浓度汽相组成的测定偏差更为明显,因此一般实验测定T、p、x,用热力学方法推算y。由T、p、x数据推算y的方法分为模型法和无模型法两种,无模型法由于不需要考虑各种活度系数模型的使用限制条件而备受国内外学者的关注。通过分析无模型法的原理,按照直接法和间接法两部分对目前无模型法的发展历程进行归纳综述,着重比较了各方法的适用体系、收敛速度和计算精度等方面,总结了几种常用方法的应用情况,并对无模型法未来的研究方向进行了展望。 相似文献
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R. Davarnejad 《Journal of the Chinese Institute of Chemical Engineers》2008,39(4):343-352
Solubility data of a mixture containing 94.2% ethanol and 5.8% octane was measured in carbon dioxide solvent using a high-pressure type phase equilibrium apparatus at pressures up to 103.5 bar and at temperature of 75 °C. The results showed that considerable separation was not achieved in this ethanol and octane ratio. However, the experimental data were then compared with the theoretical data which were obtained from two models which are regular solution theory and Redlich-Kwong equation of state. Regular solution theory is employed to each phase by applying activity coefficient expressions. Redlich-Kwong equation of state is employed to the vapor phase and then with applying fugacity coefficient, liquid phase data is obtained. The regular solution theory as a novel model approach has been found to be encouraging for the prediction of phase equilibria solubilities. It concluded that the regular solution theory model could predict two phases equilibrium data better than Redlich-Kwong equation of state. 相似文献
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《Chemical Engineering and Processing: Process Intensification》1988,24(2):93-103
A theoretical and experimental study has been carried out on the dynamics of two-phase counter-current flow with interfacial transfer in a packed bed absorption column. An eight-parameter model has been formulated consisting of axially dispersed plug flow for the gas phase and a piston-diffusion exchange model for the liquid phase. In addition, three limiting cases of this model have been analysed. Solutions of the models have been obtained in the Laplace domain with four possible transfer functions for each model as a result. Only two of these transfer functions have been found useful for an experimental study of the absorption of a poorly soluble gas. Experimental measurements of these two transfer functions, in the form of frequency characteristics, have been carried out in a 0.105 m diameter column packed to a height of 2.1 m by glass spheres 0.01 m in diameter. The absorption system studied was water—air—oxygen. Evaluation of the parameters of the formulated models was carried out in the frequency domain. The results showed that models with a stagnant liquid zone are considerably better than axially dispersed models. For a more reliable assessment of the various models, however, combination of several independent measurements is recommended. 相似文献
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Alireza Afsharpour 《中国化学工程学报》2022,44(4):521-527
Two bi-part combined models containing reaction equilibrium thermodynamic model and an equation of state (EoS) including cubic plus association (CPA) or modified Soave-Redlich-Kwong (SRK), were employed to correlate H2S solubility in ionic liquids [emim][Lac], [bmim][Ac] and [emim][Pro]. RETM and CPA/mSRK are responsible for chemical and phase equilibria calculations, respectively. The RETM defines a complex formation reaction between an H2S and two IL molecules into the liquid phase so that a complex in the form of H2S(IL)2 is probable to produce. On the other side, CPA/mSRK EoSs perform phase equilibria computations to find pressure and vapor phase concentrations. In the case of CPA, both of H2S and the ionic liquids were considered as self-associating components which pursue 4C and 2B schemes, respectively. This model computes the pure IL parameters using experimental density data. In this work, critical properties were estimated through the modified Lydersen-Joback-Reid method, Eotvos and Guggenheim relations. Afterward, the binary systems were investigated by applying RETM. CPA presents average absolute deviations (AADs) equal to 2.41%, 13.42% and 3.52% for [emim][Lac], [bmim][Ac], and [emim][Pro], respectively. Moreover, the AADs obtained by mSRK are 3.75%, 5.07%, and 6.06%, respectively. As it is evident from the results, the combination of RETM with both CPA and mSRK EoSs will result in good correlation accuracy. 相似文献