Thermophysical Properties of Gas Mixtures and Solutions

Vargaftik, N. B.

doi:10.1007/978-3-642-52504-9_13

Cited by 238 publications

(237 citation statements)

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“…12. The intermolecular potential parameters are optimized to provide the best description of the experimental vapor-liquid equilibria and surface tension data; 102,103 in the case of ethane the parameters obtained from vapor-liquid equilibria alone give a good description of the surface tension. As one would expect, the surface tension becomes progressively larger as the degree of molecular association in the system is increased from the nonassociating system ͑ethane͒ to the four-site associating system ͑water͒.…”

Section: Resultsmentioning

confidence: 99%

An accurate density functional theory for the vapor-liquid interface of associating chain molecules based on the statistical associating fluid theory for potentials of variable range

Gloor

Jackson

Blas

et al. 2004

The Journal of Chemical Physics

119

134

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A Helmholtz free energy density functional is developed to describe the vapor-liquid interface of associating chain molecules. The functional is based on the statistical associating fluid theory with attractive potentials of variable range ͑SAFT-VR͒ for the homogenous fluid ͓A. Gil-Villegas, A. Galindo, P. J. Whitehead, S. J. Mills, G. Jackson, and A. N. Burgess, J. Chem. Phys. 106, 4168 ͑1997͔͒. A standard perturbative density functional theory ͑DFT͒ is constructed by partitioning the free energy density into a reference term ͑which incorporates all of the short-range interactions, and is treated locally͒ and an attractive perturbation ͑which incorporates the long-range dispersion interactions͒. In our previous work ͓F. J. Blas, E. Martín del Río, E. de Miguel, and G. Jackson, Mol. Phys. 99, 1851 ͑2001͒; G. J. Gloor, F. J. Blas, E. Martín del Río, E. de Miguel, and G. Jackson, Fluid Phase Equil. 194, 521 ͑2002͔͒ we used a mean-field version of the theory ͑SAFT-HS͒ in which the pair correlations were neglected in the attractive term. This provides only a qualitative description of the vapor-liquid interface, due to the inadequate mean-field treatment of the vapor-liquid equilibria. Two different approaches are used to include the correlations in the attractive term: in the first, the free energy of the homogeneous fluid is partitioned such that the effect of correlations are incorporated in the local reference term; in the second, a density averaged correlation function is incorporated into the perturbative term in a similar way to that proposed by Toxvaerd ͓S. Toxvaerd, J. Chem. Phys. 64, 2863 ͑1976͔͒. The latter is found to provide the most accurate description of the vapor-liquid surface tension on comparison with new simulation data for a square-well fluid of variable range. The SAFT-VR DFT is used to examine the effect of molecular chain length and association on the surface tension. Different association schemes ͑dimerization, straight and branched chain formation, and network structures͒ are examined separately. The surface tension of the associating fluid is found to be bounded between the nonassociating and fully associated limits ͑both of which correspond to equivalent nonassociating systems͒. The temperature dependence of the surface tension is found to depend strongly on the balance between the strength and range of the association, and on the particular association scheme. In the case of a system with a strong but very localized association interaction, the surface tension exhibits the characteristic ''s shaped'' behavior with temperature observed in fluids such as water and alkanols. The various types of curves observed in real substances can be reproduced by the theory. It is very gratifying that a DFT based on SAFT-VR free energy can provide an accurate quantitative description of the surface tension of both the model and experimental systems.

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Section: Resultsmentioning

confidence: 99%

An accurate density functional theory for the vapor-liquid interface of associating chain molecules based on the statistical associating fluid theory for potentials of variable range

Gloor

Jackson

Blas

et al. 2004

The Journal of Chemical Physics

119

134

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“…The values of nitrogen compressibility [138] given in Table 5.1 for different gas temperatures and pressures may be used in calculations and at the same time allow for a conclusion on the necessity of real gas state equations utilization in the analysis of pneumatic dampers operated in a wide range of pressures and temperatures. Expressions (5.1), (5.2) and the Table above are convenient for calculation of static piston movement resistance characteristics at the gas chamber volume change.…”

Section: Pneumatic Return Mechanisms In Shock Absorbers and Oscillatimentioning

confidence: 99%

“…The author applies the ideal gas polytropic expression to calculate the gas pressure. The polytropy index is derived from the differential equation using the heat-balance equation.In this Section, the problem of modeling the pneumatic support bearings or pneumatic shock absorbers operation for the cases of stationary and non-stationary heat processes is solved using incremental methods of numerical integration of differential equations [145; 147].As the models considered in this section are related to shock absorbers when the pressure in a liquid or a gas varies in a big range and reaches 100 and more megapascals, the equations of state used for the calculation purpose have the form of , ( , )Where p and V are the pressure in the cavity with gas and its value, respectively; z(p,T) is determined experimentally [138] tabulated function characterizing the real gas compressibility; v is the number of moles of gas in the cavity; R and T are the universal gas constant and absolute temperature in degrees by Kelvin, respectively, R = 8. . Value v is calculated as v = ρ 0 (p 0 ,T 0 )V 0 /µ, where ρ is the gas density, index 0 stands for the state at filling the chamber with initial volume V 0 with gas having temperature T 0 until the pressure reaches p 0 ; µ is the weight of one mole of the gas.…”

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confidence: 99%

“…The parameters describing the gas state in chamber 14 -the receiver -are designated similarly, but indexed 2. To determine the gas pressure in chambers the equation of the real gas state is used:where z i (p i ,T i ) is the compressibility coefficient for real gas determined experimentally and presented either in tables [138] or in diagrams [150; 151]. First, let us determine the gas temperature due to the change of the working chamber volume, the gas overflow from one chamber to another, the heat exchange and heat transfer.…”

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confidence: 99%

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Oscillation Dampers and Shock Absorbers in Railway Vehicles (Mathematical Models)

Manashkin¹,

Мямлин²,

Мямлін³

et al. 2007

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The Monograph deals with the simulation of oscillation damping units -the shock absorbers and oscillation dampers. Various types of draft gears are considered including their structural features and mathematical models describing their operation. The test methods for oscillation dampers and draft gears are described together with the test results processing techniques.The book is issued for the scientists and designers researching and developing various shock absorbing units in railway vehicles. It may be useful for postgraduate, master degree and other students studying the structure and dynamics of the railways rolling stock and industrial transport. INTRODUCTIONThis monograph brings to the experts' notice the mathematical modeling of draft gears and shock absorbers. The mathematic description of these units functioning that can be used when studying the vehicles dynamics is connected with the specific features of their structure.Wedged friction draft gears with steel friction elements tend to lock if friction is not stabilized. Therefore, when modeling dynamic process in a train, it was typical to assume the gears compression forces subject to the identification of their qualitative and quantitative train dynamic process parameters, but not the forces that resulted directly from the specific features of their structure. In some publications [3,101,102], these parameters are called integral. The same publications showed that, actually, they were just some static characteristic of the gears. The experience of transitional train motion modes (standing start, braking, motion in vertical track alignment breaks, coupled cars collisions) dynamic processes simulation evidences the appropriateness of such characteristics utilization when determining the forces acting on the train vehicles.The design of Mark plate type spring friction draft gears described in Freight Car Draft Arrangements Manual, 2003 Wabtec Corporation, and (PMK) draft gears [103] include elements (special lubrication and metal-ceramic parts) that significantly increase the energy capacity and stabilizing functioning of these draft gears. The correlation of these elements geometry with the gears force characteristics in general is detailed in publication [103].The ideas of a friction draft gear mathematical simulation presented in Chapter 2 are used in Chapter 3 when building the flat and spatial car bogie friction shock absorber model. The fundamental correlation of vertical and transverse horizontal oscillation produced by friction forces is shown.When modeling hydraulic and pneumatic (Chapters 4-9) draft gears, shock absorbers and dampers, stationary and non-stationary thermodynamic processes in the respective environment are considered. The processes occurring in the real gas and in the systems with variable working body weight are analyzed. The difference in draft gears and shock absorbers modeling results arising due to real gas environment versus ideal gas environment is demonstrated. New, formally derived, approximating equation and calculat...

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“…For CO 2 , there exist discrepancies in different tables (see Table 1); the influence of these discrepancies on our results is illustrated in Table 1. Data are based on Vargaftig 9 and Altunin. 10 The evident differences are admissible first approximations.…”

Section: The Ocdopus Plantmentioning

confidence: 99%

95/05436 A zero emission combustion power plant for enhanced oil recovery

1995

Fuel and Energy Abstracts

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-We have studied an internal combustion CO 2 power plant to enhance oil recovery. The plant has air separation of O 2 for combustion and of N 2 for injection, a combustion chamber, a turbine, a compressors, a recuperator, and a cooling tower. The oil-derived gases are used to produce liquid CO 2 , highly compressed N 2 , process steam and, if necessary, power. No exhaust gases are released. The plant design is presented along with efficiency calculations. The plant should be of interest for offshore oil production.

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Thermophysical Properties of Gas Mixtures and Solutions

Cited by 238 publications

References 0 publications

An accurate density functional theory for the vapor-liquid interface of associating chain molecules based on the statistical associating fluid theory for potentials of variable range

An accurate density functional theory for the vapor-liquid interface of associating chain molecules based on the statistical associating fluid theory for potentials of variable range

Oscillation Dampers and Shock Absorbers in Railway Vehicles (Mathematical Models)

95/05436 A zero emission combustion power plant for enhanced oil recovery

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