Two modeling problems for the motion of an aggressive liquid in a porous medium

Пеньковский, В. И.

doi:10.1007/bf00912888

Cited by 3 publications

(4 citation statements)

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“…Models of porosity reduction in granular beds were proposed in [195] for ball packing under mechanical pressure, in [196] for graph structures, and in [197] for hydrate-saturated rocks. The dynamics of porous media dissolving in a flowing liquid were studied theoretically and experimentally in [198][199][200]. The models of melting powder particles under intense radiation (laser) were proposed in [201,202]; filtration models in media undergoing phase transitions were proposed in [203][204][205].…”

Section: Filtration In Reactive Mediamentioning

confidence: 99%

Particle Agglomeration of Biomass and Plastic Waste during Their Thermochemical Fixed-Bed Conversion

Donskoy

2023

Energies

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The article provides state-of-the-art research on agglomeration processes during fixed-bed combustion and gasification of low-grade fuels such as biomass and waste (primarily plastic-containing waste). Such fuels demonstrate complex thermal behaviour: their decomposition and combustion are multistage, accompanied by phase transitions, and may lead to fixed-bed mechanical instability and the non-uniformity of air distribution over the cross-section. To clarify the role of physicochemical factors (fuel composition and properties, reactor conditions), data from different sources are compared. The review shows that the fixed-bed agglomeration regimes can, in a rough approximation, be classified by the sintering mechanism (due to the melting of the mineral part or the organic part), with the following search for each mechanism realisation conditions by comparing the fuel properties and characteristic temperatures. Attempts to theoretically describe and numerically simulate the agglomeration phenomenon as a change in the structure of a reacting dispersed medium are also considered: the main directions in which such approaches can be developed are indicated.

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Section: Filtration In Reactive Mediamentioning

confidence: 99%

Particle Agglomeration of Biomass and Plastic Waste during Their Thermochemical Fixed-Bed Conversion

Donskoy

2023

Energies

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“…This model can be derived from the condition of heat and mass balance in two continua with specific laws of energy and mass transfer and with a postulated law of energy and mass exchange between the components (see, e.g., [1][2][3][4][5][6][7]). A more generic approach is the use of methods of mechanics of continuous media for finding relations between interpenetrating continua, where the necessary closing relations are found from the corresponding problems with microscopic scales for the basic variables (see, e.g., [8][9][10][11]).…”

Section: Introductionmentioning

confidence: 99%

“…Finally, we consider the case with D 1 → 0 in Eq. (5). Here, it is reasonable to use T 3 = b −2 and l 3 = U /b 2 as the time and length scales.…”

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Mathematical model of heat and mass transfer in a bidisperse porous material

Moshinskii

2009

J Appl Mech Tech Phy

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A model of heat and mass processes in a body with two types of pores is considered. This model describes the initial stage of substance penetration into the porous system (or the inverse process, namely, substance extraction from the system) and takes into account convective transport in large channels. A kinetic function of impregnation (extraction) of the porous medium and the substance flux density are found for a problem with additional conditions. Introduction.A two-component transport model is usually used to describe a number of heat-and masstransfer processes, including convective motion of the transported substance. This model can be derived from the condition of heat and mass balance in two continua with specific laws of energy and mass transfer and with a postulated law of energy and mass exchange between the components (see, e.g., [1][2][3][4][5][6][7]). A more generic approach is the use of methods of mechanics of continuous media for finding relations between interpenetrating continua, where the necessary closing relations are found from the corresponding problems with microscopic scales for the basic variables (see, e.g., [8][9][10][11]). A two-component (bidisperse) model of heat and mass transfer is usually used when the results predicted by a simpler one-component model differ significantly from experimental data because of an oversimplified presentation of the medium in the form of a homogeneous continuum or when the physical phenomenon has an essentially two-component character. Specific features of hydrodynamics of transport process and chemical kinetics can be often explained by using a model of a body containing pores of difference sizes (fissuredporous systems) [12,13]. For instance, mass transfer in some media forms zones with quantitatively and qualitatively different mass exchange with the ambient medium (cavities, pockets, stagnant zones, etc.). Despite the large variety of transport phenomena (washing of sediments, desalinization of soils, heat transfer in a heterogeneous medium, filtration in bidisperse or fissured-porous media, adsorption, etc.), the models have much in common, which allows one to use the results for studying similar processes.The solution of problems of this class is usually based on equations that describe processes occurring within sufficiently large time intervals, whereas the behavior of the heat-and mass-transfer characteristics at the initial stage (short times) has not been adequately studied. Moreover, the problem considered usually involves several dimensionless parameters (criteria) and characteristic times; therefore, the analysis is rather complicated. The initial stage of the process evolution is analyzed in the present work on the basis of a two-component model, and analytical solutions are found.Construction of the Model and Formulation of the Problem. Construction of models of hydrodynamics and heat and mass transfer in multispecies media usually involves averaging, for instance, over the volume [8] or over the ensemble of system configurations [10]...

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