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.

Turbulent Double-Diffusive Free Convection in a Porous Square Cavity Simulated With the Two Temperature Approach

2016 ◽  
Author(s):  
Marcelo J. S. de Lemos ◽  
Paulo H. S. Carvalho
Keyword(s):  
Solid Phase ◽  
Control Volume ◽  
Chemical Species ◽  
Simple Algorithm ◽  
Fluid Phase ◽  
Solid Matrix ◽  
Thermal Conductivity Ratio ◽  
Algebraic Equations ◽  
Square Cavity ◽  
Volume Method

This work investigates the influence of thermal conductivity ratio on energy and mass transport across a porous square cavity. Modeling of heat transfer from side to side of the enclosure assumed the hypothesis of thermal non-equilibrium between the solid matrix and the fluid phase. Transport equations were discretized using the control-volume method and the system of algebraic equations obtained was relaxed via the SIMPLE algorithm. Results showed that Shw, mass flux of chemical species and heat flux in the solid phase are strongly dependent of ks/kf, significantly increasing their values as such ratio increases.

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.

Free convective of a linear heterogeneous liquid in a square cavity at side heating

2020 ◽  
pp. 108-116
Author(s):  
K.V. Moiseev ◽  
◽  
V.S. Kuleshov ◽  
R.N. Bakhtizin ◽  
◽  
...  
Keyword(s):  
Control Volume ◽  
Three Dimensional ◽  
Simple Algorithm ◽  
Double Diffusion ◽  
Boussinesq Approximation ◽  
Square Cavity ◽  
Cell Height ◽  
Volume Method ◽  
Dimensional Statement ◽  
Stratified Liquid

In this work the problem of free convection of the Newtonian poorly stratified liquid in the cell warmed up from left and cooled from right with the heat-insulated horizontal boarders is presented. Liquid with small concentration of salt and initial linear stratification on cell height is considered. The model of double diffusion in a Boussinesq approximation is applied to model the process. The problem is solved both in two - and three-dimensional statement by means of a control volume method and a SIMPLE algorithm. It is shown that vortex structures at the layered mode of convection have quasi-two-dimensional character.

Simulation of Free Convection in a Porous Enclosure Using the One-Temperature Approach

2014 ◽  
Author(s):  
Marcelo J. S. de Lemos ◽  
Paulo H. S. Carvalho
Keyword(s):  
Nusselt Number ◽  
Control Volume ◽  
Simple Algorithm ◽  
Fluid Phase ◽  
Solid Material ◽  
Solid Matrix ◽  
Thermal Conductivity Ratio ◽  
Turbulent Regime ◽  
Algebraic Equations ◽  
The One

This article investigates the influence of porosity and thermal conductivity ratio on the Nusselt number in a heated vertical cavity. Heat transfer modeling across the enclosure assumed the hypothesis of thermal equilibrium between the solid matrix and the fluid phase. Transport equations were discretized using the control-volume method and the system of algebraic equations was relaxed via the SIMPLE algorithm. Results showed that, when using the one temperature model under the turbulent regime, the cavity Nusselt number is reduced for higher values of the ratio ks/kf as well as when the material porosity is increased. In both cases, conduction through the solid material overwhelms convection across the medium.

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.

scholarly journals Innovations in Heat Pump Design Using Computational Fluid Dynamics with Control Volume Method

2020 ◽  
Author(s):  
Cemil Koyunoğlu
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Heat Pump ◽  
Industry 4.0 ◽  
Control Volume ◽  
Control Volume Method ◽  
Algebraic Equations ◽  
Ansys Fluent ◽  
Control Volumes ◽  
Volume Method

Mathematical modeling of the heat pump as a result of continuity, momentum, and energy equations is obtained. To solve these equations numerically, the problem is divided by a finite number of control volumes. Then the differential equations in these control volumes integrated and converted into algebraic equations. The importance of computational fluid dynamics in Industry 4.0 applications is to make current applications more efficient in heat pump applications. In this study, the book section is composed of the application of computational fluid dynamics by the control volume method using Ansys fluent program, which will benefit readers from industry 4.0 perspective, especially in energy efficiency issues according to the volume method of controlling correct heat pump designs.

Laminar Heat Transfer in a Parallel Plate Channel With Solid and Porous Baffles

2004 ◽  
Author(s):  
Marcelo J. S. de Lemos ◽  
Nicolau B. Santos
Keyword(s):  
Laminar Flow ◽  
Parallel Plate ◽  
Control Volume ◽  
Computational Domain ◽  
Control Volume Method ◽  
Algebraic Equations ◽  
Simple Method ◽  
Volume Method ◽  
Plate Channel ◽  
Elementary Representative Volume

Simulations are presented for laminar flow in a channel containing fins made with solid (impermeable) and porous materials. The equations of mass continuity, momentum and energy are written for an elementary representative volume yielding a set of equations valid for the entire computational domain. These equations are discretized using the control volume method and the resulting system of algebraic equations is relaxed with the SIMPLE method. The presented numerical results for the friction factor f and the Nusselt number Nu were compared with available data indicating that results herein differ by less than 5% in relation to published results. Further simulations comparing the effectiveness of the porous material used showed that no advantages are obtained for using low porosity baffles in the laminar flow regime.

Use of Foam-Like Materials to Enhance Heat Transfer From Surfaces Subjected to Impinging Jets

2009 ◽  
Author(s):  
Marcelo J. S. de Lemos ◽  
Cleges Fischer
Keyword(s):  
Thermal Conductivity ◽  
Porous Layer ◽  
Control Volume ◽  
Simple Algorithm ◽  
Impinging Jets ◽  
Thermal Conductivity Ratio ◽  
Conductivity Ratio ◽  
System Pressure ◽  
Volume Method ◽  
Range Of Values

In this paper, numerical simulation of a jet impinging against a flat plane covered with a layer of a porous material is presented. The plate is kept at a temperature higher than that of the incoming fluid. Macroscopic transport equations are obtained based on a volume average concept. Discretization of such governing equations is accomplished by means of the control volume method applied with a boundary-fitted nonorthogonal coordinate system. Pressure-velocity coupling is treated with the use of the SIMPLE algorithm. Parameters such as permeability, thickness of the porous layer and thermal conductivity ratio are varied in order to analyze their effects on the local distribution of Nu. Results indicate that inclusion of a porous layer decreases the peak in Nu avoiding excessive heating or cooling at the stagnation point. Also found was that the integral heat flux from the wall is enhanced for certain range of values of layer thickness, porosity, and thermal conductivity ratio.

Influence of Micro Trapezoidal-Groove on Behavior of Sliding Tribopairs

2010 ◽  
Vol 37-38 ◽  
pp. 544-549 ◽  
Author(s):  
Pei Yun Zhang ◽  
Yan Hu Zhang ◽  
Xiao Li Wang ◽  
Xi Jun Hua ◽  
Yong Hong Fu
Keyword(s):  
Hydrodynamic Lubrication ◽  
Control Volume ◽  
Turbulence Models ◽  
Simple Algorithm ◽  
Tribological Performance ◽  
Control Volume Method ◽  
Supporting Capacity ◽  
Continuity Equations ◽  
Isosceles Trapezoid ◽  
Volume Method

The effect of various micro isosceles-trapezoid grooves on improvement of tribological performance is discussed. It is accomplished through the CFD-approach where the momentum and continuity equations are solved separately, one of low Reynolds turbulence models-Abid index and SIMPLE algorithm in theory of Control Volume Method are adopted. For different width and depth of micro isosceles-trapezoid grooves, the load supporting capacity of oil-film are compared. The results show that the widths has more influence than the depths on hydrodynamic lubrication, and relative parameters change monotonously with the depth of micro-groove. The effect of texturing arc-grooves on improvement of tribological properties is conspicuous if w1= 40μm, w2= 10μm and hp= 10μm for micro isosceles-trapezoid grooves.

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