Mathematical model of the volume dissociation of gas-phase hydrates in a porous medium with water-phase mobility

1992 ◽  
Vol 62 (1) ◽  
pp. 60-64 ◽  
Author(s):  
A. M. Maksimov
Keyword(s):  
Mathematical Model ◽  
Porous Medium ◽  
Gas Phase ◽  
Water Phase ◽  
Phase Mobility

Modeling of aerated upflow fixed bed reactors for nitrification

1999 ◽  
Vol 39 (4) ◽  
pp. 85-92 ◽  
Author(s):  
J. Behrendt
Keyword(s):  
Mathematical Model ◽  
Mass Transfer ◽  
Liquid Phase ◽  
Gas Phase ◽  
Fixed Bed ◽  
Fixed Bed Reactor ◽  
Bulk Liquid ◽  
Initial Value ◽  
Fixed Bed Reactors ◽  
Number Of Cells

A mathematical model for nitrification in an aerated fixed bed reactor has been developed. This model is based on material balances in the bulk liquid, gas phase and in the biofilm area. The fixed bed is divided into a number of cells according to the reduced remixing behaviour. A fixed bed cell consists of 4 compartments: the support, the gas phase, the bulk liquid phase and the stagnant volume containing the biofilm. In the stagnant volume the biological transmutation of the ammonia is located. The transport phenomena are modelled with mass transfer formulations so that the balances could be formulated as an initial value problem. The results of the simulation and experiments are compared.

scholarly journals Numerical Simulation of Diffusion Absorption Refrigerator

2021 ◽  
Vol 233 ◽  
pp. 01044
Author(s):  
Guoyan Zhang ◽  
Shengyong Liu ◽  
Jie Lu ◽  
Jiong Wang ◽  
Yongtao Ma
Keyword(s):  
Numerical Simulation ◽  
Mathematical Model ◽  
Gas Phase ◽  
Radial Direction ◽  
Tube Length ◽  
Lifting Capacity ◽  
Fluent Software ◽  
Lower Temperature ◽  
Absorption Refrigerator ◽  
Diffusion Absorption

Based on Fluent software, a mathematical model of thermosyphon pump is established and numerical simulation is carried out to study the influence of riser tube length, tube diameter and immersion ratio on liquid lifting capacity and efficiency. The results showed that: the liquid lifting volume increased with the increase of immersion ratio, whereas the lifting efficiency showed a trend of increasing followed by decreasing. The highest lifting efficiency for a 340mm long, 6mm diameter riser achieved when the immersion ratio is 0.35. With the increasing of the height in riser, the velocity of the gas phase close to the wall in the thermosyphon pump was higher than the velocity along the radial direction. In order to enhance fluid interchange, corners of the refrigeration box were designed to be arc-shaped with a higher corner speed and lower temperature.

Dynamic Analysis of a Three-Dimensional Poroelastic Beam Using the Boundary-Element Method

2018 ◽  
Vol 769 ◽  
pp. 329-335
Author(s):  
Andrey Petrov ◽  
Leonid A. Igumnov
Keyword(s):  
Mathematical Model ◽  
Porous Medium ◽  
Boundary Element Method ◽  
Boundary Element ◽  
Three Dimensional ◽  
Element Solution ◽  
Harmonic Force ◽  
Porosity And Permeability ◽  
Beam Thickness ◽  
Element Method

The problem of the effect of a normal harmonic force on a porous beam in a 3D formulation is solved using the boundary-element method. A homogeneous fully saturated elastic porous medium is described using Biot’s mathematical model. The effect of the porosity and permeability parameters on the deflection of the beam and the distribution of pore pressure over the beam thickness is investigated. The comparison of the boundary-element solution with a 2D numerical-analytical one is given.

scholarly journals Numerical Simulation of a New Porous Medium Burner with Two Sections and Double Decks

Processes ◽  
2018 ◽  
Vol 6 (10) ◽  
pp. 185 ◽  
Author(s):  
Zhenzhen Jia ◽  
Qing Ye ◽  
Haizhen Wang ◽  
He Li ◽  
Shiliang Shi
Keyword(s):  
Numerical Simulation ◽  
Mathematical Model ◽  
Porous Medium ◽  
Industrial Development ◽  
High Efficiency ◽  
Methane Combustion ◽  
Combustion Mechanism ◽  
Gas Mixture ◽  
Temperature And Pressure ◽  
Save Energy

Porous medium burners are characterized by high efficiency and good stability. In this study, a new burner was proposed based on the combustion mechanism of the methane-air mixture in the porous medium and the preheating effect. The new burner is a two-section and double-deck porous medium with gas inlets at both ends. A mathematical model for the gas mixture combustion in the porous medium was established. The combustion performance of the burner was simulated under different equivalence ratios and inlet velocities of premixed gas. The methane combustion degree, as well as the temperature and pressure distribution, was estimated. In addition, the concentrations of emissions of NOx for different equivalence ratios were investigated. The results show that the new burner can not only realize sufficient combustion but also save energy. Furthermore, the emission concentration of NOx is very low. This study provides new insights into the industrial development and application of porous medium combustion devices.

A mathematical model for the flotation of waste activated sludge

2002 ◽  
Vol 46 (11-12) ◽  
pp. 203-208
Author(s):  
K. Fujisaki ◽  
M. El-Zahar
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Gas Phase ◽  
Solid Phase ◽  
Growth Curves ◽  
Vertical Axis ◽  
Waste Activated Sludge ◽  
Flotation Process ◽  
Hindered Settling ◽  
Similar Character

A mathematical model that describes a batch flotation process is presented. The model employed a similar method to the hindered settling of flocculated material. This idea is based on our experimental results that the time growth curves of separated liquor zone showed a similar character to the settling curve of flocculated material, when the vertical axis reversed. In this model, it is also assumed that the gas phase and solid phase have the same movement, that is microbubbles and solid sludge particles joined to form aggregated floc. By comparing the numerical prediction with experimental data, the usefulness of the model is confirmed and some examples of flotation simulation are demonstrated.

The effect of hydrodynamic dispersion on reactive flows in porous media

2001 ◽  
Vol 12 (5) ◽  
pp. 557-569 ◽  
Author(s):  
J. CHADAM ◽  
P. ORTOLEVA ◽  
Y. QIN ◽  
R. STAMICAR
Keyword(s):  
Mathematical Model ◽  
Porous Medium ◽  
Critical Value ◽  
Reactive Flow ◽  
Hydrodynamic Dispersion ◽  
Reaction Interface ◽  
Shape Stability ◽  
Linearized Problem ◽  
New Feature ◽  
Moving Free Boundary

The shape stability of the reaction interface for reactive flow in a porous medium is investigated. Previous work showed that the Reaction-Infiltration Instability could cause the reaction zone to lose stability when the Peclet number exceeded a critical value. The new feature of this study is to include a velocity-dependent hydrodynamic dispersion. A mathematical model for this phenomenon is given in the form of a moving free-boundary problem. The spectrum of the linearized problem is obtained, and the related analysis and numerical calculations show that the onset of the instability is not eliminated by the new dispersive terms. The details of analysis show that the instability is reduced especially by the transverse dispersion.

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