Numerical Calculation of the Diffusion Process in Multicomponent Hydrocarbon Gas Mixtures

Knowledge of the laws of diffusion is necessary in the description, design and calculation of the mass transfer process in the production, operation and transportation of gaseous fuels. In this article, the calculation of diffusion processes for five natural hydrocarbon gas mixtures into the air was carried out. The effective diffusion coefficients and matrix coefficients of multicomponent diffusion were determined. Also the advantages of using effective coefficients in the description of mass transfer were shown.

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PATTERNS OF THE VARIATION OF PARAMETERS OF TRANSFER PROCESSES FOR MULTICOMPONENT HYDROCARBON GAS MEDIA UNDER SEPARATION

Vestnik Tomskogo gosudarstvennogo universiteta Matematika i mekhanika ◽

10.17223/19988621/66/7 ◽

2020 ◽

pp. 86-95

Author(s):

A.V. Dmitriev ◽

◽

P.N. Zyatikov ◽

Keyword(s):

Mass Transfer ◽

Heat And Mass Transfer ◽

Heterogeneous Media ◽

Oil And Gas ◽

Oil And Gas Industry ◽

Gas Mixtures ◽

Transfer Processes ◽

Mass Transfer Processes ◽

Hydrocarbon Gas ◽

Property Changes

A detailed study of the evolution of local and integral parameters of momentum, heat, and mass transfer processes in hydrocarbon gas mixtures under separation conditions at given temperature and pressure values in working media is carried out within the framework of the principles of equilibrium thermodynamics using the Aspen HYSYS software package, namely, the Peng-Robinson equation of state for real gas mixtures, the principles of statistical mechanics, the approaches of corresponding states, the Chapman-Enskog and the Golubev methods, and the theory of similarity and dimensional analysis. The limits of similarity method applicability in quantitative estimates and qualitative forecasts of the mechanisms and configurations of convective heat and mass transfer in oil treatment units are established. The paper also discusses results of the analog method application in separation process modeling for momentum, heat and mass transfer processes in the problems of oil and gas industry. The conclusions about the aspects of property changes in complex mixtures and about heat and mass transfer intensity during separation, which violate a triple analogy in non-isothermal homogeneous and heterogeneous media, are recommended to take into account when designing real equipment.

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Experimental Determination of Polymers and Polymer-Based Composite Materials Diffusion Properties

Materials Science Forum ◽

10.4028/www.scientific.net/msf.945.401 ◽

2019 ◽

Vol 945 ◽

pp. 401-406

Author(s):

V. Dmitriev ◽

G. Baronin ◽

E. Sergeeva

Keyword(s):

Mass Transfer ◽

Diffusion Coefficient ◽

Composite Materials ◽

Effective Diffusion ◽

Mass Transfer Process ◽

Polymer Materials ◽

Zonal Method ◽

Kinetic Problem ◽

Humidity Dependence ◽

Diffusion Properties

The widespread use of polymer composite materials makes it necessary to study their physical properties. Particular attention is given to polymers reacted with water and other low molecular weight compounds in their preparation as well as during operation. Most studies have been devoted in the diffusion properties of materials in the form of films, while operating materials often have a different shape, for example pellets. Well at small sizes of granules is impossible to use stationary methods. In this paper, the diffusion coefficient is determined by the zonal method based on the integration of the diffusion equation. A significant increase in the effective diffusion coefficient with an increase in the diffusant concentration associated with the plasticizing action of water was detected. Temperature-humidity dependence of diffusion effective coefficient is approximated by the refined formula which helps to calculate mass transfer process kinetics and carry out theoretical analysis of water diffuse properties in polymer matrix. With the movement of individual particles of polymer materials in real dryers, it is expedient to break the kinetic problem of mass transfer into external and internal one. The validity of the two-level consideration of the kinetic problem of granular polymer materials deep drying and the applicability of the data obtained for their diffusion properties are shown. The microkinetics of a single particle drying is considered, it is the determining condition for the accuracy of the kinetic calculation.

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Effective Diffusion Coefficients during Osmotic Dehydration of Vegetables with Different Initial Porosity

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.258-260.575 ◽

2006 ◽

Vol 258-260 ◽

pp. 575-585

Author(s):

Luis Mayor ◽

Ramón Moreira ◽

Francisco Chenlo ◽

Alberto M. Sereno

Keyword(s):

Mass Transfer ◽

Osmotic Dehydration ◽

Effective Diffusion ◽

Food Material ◽

Transfer Rates ◽

Sodium Chloride Solutions ◽

Effective Coefficients ◽

Sucrose Solutions ◽

Diffusional Model ◽

Transfer Mechanisms

Chesnut and pumpkin fruits were dehydrated with osmotic solutions of sucrose and NaCl at 25°C. These food materials have different structure, composition and porosity. Water loss and solids gain kinetics were experimentally determined and modeled using a diffusional model. In spite of the several mass transfer mechanisms taking place along with diffusion during osmotic dehydration, the modeling was satisfactory and involved effective coefficients of diffusion useful to quantify the different mass transfer fluxes. Water and sucrose transfer rates during osmotic dehydration with sucrose solutions are independent on the initial food material characteristics; however they seem to be related with the permeability of these components to a sucrose layer formed in the surface of the samples. In the case of osmotic dehydration with sodium chloride solutions, the coefficients of diffusion show a dependence on food material characteristic and higher values of these coefficients for pumpkin (more porous material) were found.

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Nitrocarburising in ammonia-hydrocarbon gas mixtures

HTM Journal of Heat Treatment and Materials ◽

10.3139/105.110090 ◽

2011 ◽

Vol 66 (2) ◽

pp. 76-81 ◽

Cited By ~ 3

Author(s):

H. Pedersen ◽

T. L. Christiansen ◽

M. A. J. Somers

Keyword(s):

Gas Mixtures ◽

Hydrocarbon Gas

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Simulation of volumetric heating of a moist medium with allowance for fluid mobility

Proceedings of the Mavlyutov Institute of Mechanics ◽

10.21662/uim2012.1.017 ◽

2012 ◽

Vol 9 (1) ◽

pp. 91-93

Author(s):

U.R. Ilyasov ◽

A.V. Dolgushev

Keyword(s):

Mass Transfer ◽

Porous Medium ◽

Numerical Solution ◽

Heat And Mass Transfer ◽

Transfer Process ◽

Thermal Action ◽

Mass Transfer Process ◽

Low Permeability ◽

Volumetric Heating ◽

Drying Regime

The problem of volumetric thermal action on a moist porous medium is considered. Numerical solution, the influence of fluid mobility on the dynamics of the heat and mass transfer process is analyzed. It is established that fluid mobility leads to a softer drying regime. It is shown that in low-permeability media, the fluid can be assumed to be stationary.

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Certain problems with the application of stochastic diffusion processes for description of chemical engineering phenomena; Kolmogorov and classic diffusion equations

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19881181 ◽

1988 ◽

Vol 53 (6) ◽

pp. 1181-1197

Author(s):

Vladimír Kudrna

Keyword(s):

Mass Transfer ◽

Partial Differential Equations ◽

Differential Equations ◽

Chemical Engineering ◽

Diffusion Processes ◽

Parabolic Type ◽

Diffusion Equations ◽

Stochastic Motion ◽

Energy Component ◽

Classic Form

The paper presents alternative forms of partial differential equations of the parabolic type used in chemical engineering for description of heat and mass transfer. It points at the substantial difference between the classic form of the equations, following from the differential balances of mass and enthalpy, and the form following from the concept of stochastic motion of particles of mass or energy component. Examples are presented of the processes that may be described by the latter method. The paper also reviews the cases when the two approaches become identical.

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Free Convective Mass Transfer at Isosceles Triangular Surfaces of Varying Inclination

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20032080 ◽

2003 ◽

Vol 68 (11) ◽

pp. 2080-2092 ◽

Cited By ~ 1

Author(s):

Martin Keppert ◽

Josef Krýsa ◽

Anthony A. Wragg

Keyword(s):

Mass Transfer ◽

Transfer Rate ◽

Mass Transfer Rate ◽

Mass Transfer Process ◽

Sulfate Solution ◽

Convective Mass Transfer ◽

Varying Length ◽

Inclined Surface ◽

Vertical Case ◽

Limiting Diffusion Current

The limiting diffusion current technique was used for investigation of free convective mass transfer at down-pointing up-facing isosceles triangular surfaces of varying length and inclination. As the mass transfer process, copper deposition from acidified copper(II) sulfate solution was used. It was found that the mass transfer rate increases with inclination from the vertical to the horizontal position and decreases with length of inclined surface. Correlation equations for 7 angles from 0 to 90° were found. The exponent in the ShL-RaL correlation ranged from 0.247 for the vertical case, indicating laminar flow, to 0.32 for inclinations of 60 to 90°, indicating mixed or turbulent flow. The general correlation ShL = 0.358(RaL sin θ)0.30 for the RaL sin θ range from 7 × 106 to 2 × 1011 and inclination range from 15 to 90° was obtained.

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A Semi-Theoretical Model for Water Condensation: Dew Used in Conservation of Earthen Heritage Sites

Water ◽

10.3390/w13010052 ◽

2020 ◽

Vol 13 (1) ◽

pp. 52

Author(s):

Xiang He ◽

Sijia Wang ◽

Bingjian Zhang

Keyword(s):

Mass Transfer ◽

Theoretical Model ◽

Field Experiments ◽

Environmental Control ◽

Mass Transfer Process ◽

Formation Processes ◽

Heritage Sites ◽

Dew Formation ◽

The Difference ◽

Two Parameter

Dew is a common but important phenomenon. Though water is previously considered to be a threat to earthen heritage sites, artificial dew is showing potential in relic preservation. A model of dew prediction on earthen sites will be essential for developing preventive protection methods, but studies of dew formation processes on relics are limited. In this study, a two parameter model is proposed. It makes approximations according to the features of earthen heritage sites, assuming that a thin and steady air layer exists close to the air–solid interface. This semi-theoretical model was based on calculations of the mass transfer process in the air layer, and was validated by simulations of laboratory experiments (R > 0.9) as well as field experiments. Additionally, a numerical simulation, performed by the commercial software COMSOL, confirmed that the difference between fitting parameter δ and the thickness of assumed mass transfer field was not significant. This model will be helpful in developing automatic environmental control systems for stabilizing water and soluble salts, thus enhancing preventive protection of earthen heritage sites.

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