Numerical Analysis of Depollution of Smoke Produced by Household Wastes Incineration

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
K. N’Wuitcha ◽  
M. Banna ◽  
S. W. Igo ◽  
B. Zeghmati ◽  
K. Palm ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Radiative Transfer Equation ◽  
Simple Algorithm ◽  
Velocity Fields ◽  
Algebraic Equations ◽  
Governing Equations ◽  
Thomas Algorithm ◽  
Cylindrical Furnace ◽  
Volume Method ◽  
Double Diffusive

This study reports the results on a numerical investigation of the depollution of smokes produced by the incineration of household wastes in a cylindrical furnace. Transfers are described by double-diffusive mixed convection equations, associated to radiative transfer equation, and a global kinetics model. The governing equations are discretized using finite volume method and the resulting algebraic equations are solved by THOMAS algorithm. The linkage between the pressure and velocity fields is assumed by SIMPLE algorithm. Results are presented as streamlines, isotherms, isoconcentrations for different Reynolds number (300 ≤ Re ≤ 1800). Effects of Reynolds number, relative height opening, aspect ratio, excess air ratio, and radiative transfers on gas pollutants (CO, CH4, C2H4…) destruction are investigated in detail.

Effect of Thermal Conductivity Ratio on Laminar Double-Diffusive Free Convection in a Porous Cavity

2017 ◽  
Vol 139 (10) ◽  
Author(s):  
Paulo H. S. Carvalho ◽  
Marcelo J. S. de Lemos
Keyword(s):  
Free Convection ◽  
Thermal Equilibrium ◽  
Control Volume ◽  
Simple Algorithm ◽  
Thermal Conductivity Ratio ◽  
Control Volume Method ◽  
Algebraic Equations ◽  
Square Cavity ◽  
Volume Method ◽  
Double Diffusive

This work presents a study on double-diffusive free convection in a porous square cavity using the thermal equilibrium model. Transport equations are discretized using the control-volume method, and the system of algebraic equations is relaxed via the SIMPLE algorithm. The effect of ks/kf on average Nusselt and Sherwood values was investigated. Results show that increasing ks/kf affects Nuw and Shw boosting mass transfer at the expense of reducing overall heat transport across the enclosure.

The Structure of Turbulence in a Moving Bed as a Function of Flow and Medium Properties

2014 ◽  
Author(s):  
Marcelo J. S. de Lemos
Keyword(s):  
Reynolds Number ◽  
Turbulent Flows ◽  
Control Volume ◽  
Mechanical Energy ◽  
Simple Algorithm ◽  
Darcy Number ◽  
Control Volume Method ◽  
Governing Equations ◽  
Bed Porosity ◽  
Volume Method

This article presents simulations for turbulent flows in a moving permeable bed making use of a macroscopic turbulence model. Intra-pore turbulence is considered by means of a two-equation closure. Governing equations for mean and turbulent flows are volume-averaged. The resulting set of transport equations is discretized using the control-volume method and the obtained algebraic equation set is relaxed via the SIMPLE algorithm. Results indicate that for larger values of Reynolds number, a greater amount of available mechanical energy is converted into turbulence. Simulations further indicate that for lower values of Darcy number and bed porosity, higher levels of turbulence kinetic energy are calculated.

Effect of position and height of a shield on convective heat transfer performances of plate fin heat sink

2015 ◽  
Vol 25 (5) ◽  
pp. 1047-1063 ◽  
Author(s):  
Rachid Bouchenafa ◽  
Rachid Saim ◽  
Said Abboudi ◽  
Hakan F. Öztop
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Sink ◽  
Dynamic Performance ◽  
Simple Algorithm ◽  
Governing Equations ◽  
Enhancement Of Heat Transfer ◽  
Content Type ◽  
The One ◽  
Volume Method

Purpose – The purpose of this paper is to examine the thermal and dynamic performance of the plate-fin heat sink fitted with a shield in the bypass. Design/methodology/approach – The governing equations were solved using the finite volume method based on the SIMPLE algorithm. The k-ω Shear Stress Transport was used to model turbulence. The thermal and dynamic results were presented in term of average Nusselt number and friction factor, respectively. The effect of the height (Hs=6, 10 and 13) and the position (X=0, 1/3, 1/2, 2/3 and 3/4) of the shield was studied for a Reynolds number ranging from 2×103 to 12×103 and compared with a heat sink without shield. To evaluate the performance of different heat sink geometries, the efficiency was presented and discussed. Findings – By adding a shield in the bypass, a greater amount of air is injected between the heat sink fins, which improves the heat transfer (advantage) of the one part, and increases the friction on the other hand (disadvantage). The efficiency of the heat sink varies inversely proportional with the Reynolds number. Originality/value – The originality of this work is the method for enhancement of heat transfer.

A Thermo-Mechanical Model for a Counterflow Biomass Gasifier

2014 ◽  
Vol 354 ◽  
pp. 227-235
Author(s):  
Marcelo J.S. de Lemos
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Control Volume ◽  
Simple Algorithm ◽  
Thermal Capacity ◽  
Macroscopic Model ◽  
Algebraic Equations ◽  
Medium Permeability ◽  
Mechanical Approach ◽  
Volume Method

This article presents a thermo-mechanical approach to investigate heat transfer between solid and fluid phases in a model gasifier. A two-temperature equation approach is applied in addition to a macroscopic model for laminar flow through a porous moving bed. Transport equations are discretized using the control-volume method and the system of algebraic equations is relaxed via the SIMPLE algorithm. The effects on inter-phase heat transfer due to variation of medium permeability, thermal conductivity and thermal capacity are analyzed. Results indicate that for smaller medium permeabilities, as well as for higher solid-to-fluid thermal capacity and thermal conductivity ratios, enhancement of heat transfer between phases is observed.

Numerical Simulation of Laminar Confined Impinging Jet in a Composite Channel

2008 ◽  
Author(s):  
Marcelo J. S. de Lemos
Keyword(s):  
Porous Layer ◽  
Control Volume ◽  
Numerical Technique ◽  
Simple Algorithm ◽  
Local Distribution ◽  
Governing Equations ◽  
Stagnation Region ◽  
Volume Method ◽  
Material Porosity ◽  
Macroscopic Equations

This work shows numerical results for a jet impinging onto a flat plane covered with a layer of a porous material. Porosity of the porous layer is varied in order to analyze its effect on the local distribution of Nu. Macroscopic equations for mass and momentum ae obtained based on the volume-average concept. The numerical technique employed for discretizing the governing equations was the control volume method with a boundary-fitted non-orthogonal coordinate system. The SIMPLE algorithm was used to handle the pressure-velocity coupling. Results indicate that inclusion of a porous layer decreases the peak in Nu avoiding excessive heating or cooling near the stagnation region.

Laminar Natural Convection Inside a Wavy Enclosure Heated From Top and Uniformly Cooled From the Bottom and Both Sides

2005 ◽  
Author(s):  
Amaresh Dalal ◽  
Manab Kumar Das
Keyword(s):  
Natural Convection ◽  
Simple Algorithm ◽  
Governing Equations ◽  
Square Cavity ◽  
Integral Forms ◽  
Nusselt Number Distribution ◽  
Laminar Natural Convection ◽  
Lower Temperature ◽  
Volume Method ◽  
Spatially Varying

In the present paper, natural convection inside a square cavity with one and three undulations on the top wall has been carried out. The top wall is heated by a spatially varying temperature and other three walls are kept constant lower temperature. The integral forms of the governing equations are solved numerically using finite-volume method in non-orthogonal body-fitted coordinate system. SIMPLE algorithm with higher-order up-winding scheme are used. The streamlines and isothermal lines are presented for different Rayleigh number (103-106) and a fluid having Prandtl number 0.71. Results are presented in the form of local and average Nusselt number distribution for two different undulations (1 and 3) with wave amplitude of 0.05.

scholarly journals Velocity and stress fields in grounded glaciers: a simple algorithm for including deviatoric stress gradients

1995 ◽  
Vol 41 (138) ◽  
pp. 333-344 ◽  
Author(s):  
Heinz Blatter
Keyword(s):  
Method Of Lines ◽  
Three Dimensional ◽  
Simple Algorithm ◽  
Velocity Fields ◽  
Deviatoric Stress ◽  
Shear Stresses ◽  
Algebraic Equations ◽  
Field Equations ◽  
Stress Gradients ◽  
The Method Of Lines

AbstractA new and efficient algorithm for computing the three-dimensional stress and velocity fields in grounded glaciers includes the role of deviatoric stress gradients. A consistent approximation of first order in the aspect of ratio of the ice mass gives a set of eight field equations for the five stress and three velocity components and the corresponding boundary conditions. A coordinate transformation mapping the local ice thickness on to unity and approximating the derivatives in the horizontal direction by centered finite-differences yields five ordinary differential and three algebraic equations. This allows use of the method of lines, starting the integration with prescribed stress and velocity components at the base, and a simple iteration procedure converges rapidly.The algorithm can be used for a wide rangе of stress-strain-rate relations, as long as strain only depends on deviatoric and shear stresses and on temperature. Sensitivity tests using synthetic and realistic ice geometries show the relevance of normal deviatoric stresses in the solutions for the velocity components even for ice sheets. Stress and velocity fields may deviate substantially from the widely used shallow-ice approximation.

scholarly journals Isotherms and Streamlines for 2D Lid Driven Square Cavity

2021 ◽  
Vol 10 (11) ◽  
pp. 97-99
Author(s):  
Garepally Srinivas ◽  
◽  
A. V. Ramana Kumari ◽  
Narayana Vekamulla ◽  
◽  
...  
Keyword(s):  
Reynolds Number ◽  
Richardson Number ◽  
Thermal Characteristics ◽  
Cavity Flow ◽  
Control Parameters ◽  
Governing Equations ◽  
Square Cavity ◽  
Isothermal Temperature ◽  
Vertical Walls ◽  
Volume Method

Analysis of lid driven square cavity flow of air with three different ranges of Ri and Re are analyzed using numerically. Adiabatic temperature is maintained at horizontal walls and isothermal temperature is established at the vertical walls in which the top wall is assumed to slide with a uniform speed. Finite volume method techniques have used to solve non dimensional governing equations. To visualize the flow and thermal characteristics, the control parameters, the Richardson number (Ri) and Reynolds number (Re) and in the range of 0.001 ≤ Ri ≤ 10 and 100 ≤ Re ≤ 400 are used for streamlines and isotherms.

scholarly journals Numerical Analysis of Turbulent Flow Around Two-Dimensional Bodies Using Non-Orthogonal Body-Fitted Mesh

2019 ◽  
Vol 24 (2) ◽  
pp. 387-410
Author(s):  
Md. Shahjada Tarafder ◽  
M. Al Mursaline
Keyword(s):  
Turbulent Flow ◽  
Computational Cost ◽  
Numerical Procedure ◽  
Simple Algorithm ◽  
Two Dimensional ◽  
Governing Equations ◽  
Wall Functions ◽  
Relaxation Factors ◽  
Volume Method ◽  
Naca 0012

Abstract This paper deals with the numerical simulation of a turbulent flow around two-dimensional bodies by the finite volume method with non-orthogonal body-fitted grid. The governing equations are expressed in Cartesian velocity components and solution is carried out using the SIMPLE algorithm for collocated arrangement of scalar and vector variables. Turbulence is modeled by the k- ε turbulence model and wall functions are used to bridge the solution variables at the near wall cells and the corresponding quantities on the wall. A simplified pressure correction equation is derived and proper under-relaxation factors are used so that computational cost is reduced without adversely affecting the convergence rate. The numerical procedure is validated by comparing the computed pressure distribution on the surface of NACA 0012 and NACA 4412 hydrofoils for different angles of attack with experimental data. The grid dependency of the solution is studied by varying the number of cells of the C-type structured mesh. The computed lift coefficients of NACA 4412 hydrofoil at different angles of attack are also compared with experimental results to further substantiate the validity of the proposed methodology.

Influence of Coil Inclined around Y Axis on Thermomagnetic Convection of Air in a Porous Cubic Enclosure under Zerogravity

2011 ◽  
Vol 354-355 ◽  
pp. 24-28 ◽  
Author(s):  
Chang Wei Jiang ◽  
Xian Feng Zhu ◽  
Er Shi ◽  
Zhen Zhou
Keyword(s):  
Heat Transfer ◽  
Magnetic Force ◽  
Vertical Wall ◽  
Simple Algorithm ◽  
Darcy Number ◽  
The Other ◽  
Governing Equations ◽  
Left Hand ◽  
Thermomagnetic Convection ◽  
Volume Method

Thermomagnetic convection of air in a porous cubic enclosure with a electric coil inclined around the Y axis is numerically investigated under zerogravity environment. The porous cubic enclosure is heated isothermally from left-hand side vertical wall and cooled isothermally from opposing wall while the other four walls are thermally insulated. The governing equations in primitive variables are discretized by the finite-volume method and solved by the SIMPLE algorithm. The results show that the overall heat transfer is enhanced gradually with the increase of magnetic force number and Darcy number. The resulted convection is symmetrical in terms of the angle at yeuler =0 when the range of inclination angle is from -90 to 90.

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