Geometric Optimization of C-Shaped Cavities According to Bejan's Theory: General Review and Comparative Study

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
G. Lorenzini ◽  
C. Biserni ◽  
L. A. O. Rocha
Keyword(s):  
Aspect Ratio ◽  
Solid Wall ◽  
Convection Heat Transfer ◽  
Internal Heat ◽  
Thermal Conditions ◽  
Geometric Optimization ◽  
Square Cavity ◽  
Conducting Wall ◽  
Optimal Shapes ◽  
The One

The aim of this paper is to consider, by means of the numerical investigation, the geometric optimization of a cavity that intrudes into a solid with internal heat generation. The objective is to minimize the maximal dimensionless excess of temperature between the solid and the cavity. The cavity is rectangular, with fixed volume and variable aspect ratio. The cavity shape is optimized for two sets of boundary conditions: isothermal cavity and cavity cooled by convection heat transfer. The optimal cavity is the one that penetrates almost completely the conducting wall and proved to be practically independent of the boundary thermal conditions, for the external ratio of the solid wall smaller than 2. As for the convective cavity, it is worthy to know that for values of H/L greater than 2, the best shape is no longer the one that penetrates completely into the solid wall, but the one that presents the largest cavity aspect ratio H0/L0. Finally, when compared with the optimal cavity ratio calculated for the isothermal C-shaped square cavity, the cavities cooled by convection highlight almost the same optimal shape for values of the dimensionless group λ ≤ 0.01. Both cavities, isothermal and cooled by convection, also present similar optimal shapes for ϕ0 < 0.3 and ϕ0 > 0.7. However, in the range 0.3 ≤ ϕ0 ≤ 0.7, the ratio (H0/L0)opt calculated for the cavities cooled by convection is greater than the one presented by isothermal cavities. This difference is approximately 17% when λ = 0.1 and ϕ0 = 0.7, and 20% for λ = 1 and ϕ0 = 0.5.

scholarly journals CONSTRUCTAL DESIGN AND SIMULATED ANNEALING EMPLOYED FOR GEOMETRIC OPTIMIZATION OF A Y-SHAPED CAVITY INTRUDED INTO CONDUCTIVE WALL

2015 ◽  
Vol 14 (1) ◽  
pp. 79
Author(s):  
G. V. Gonzales ◽  
E. D. Dos Santos ◽  
L. R. Emmendorfer ◽  
L. A. Isoldi ◽  
E. S. D. Estrada ◽  
...  
Keyword(s):  
Genetic Algorithm ◽  
Simulated Annealing ◽  
Solid Wall ◽  
Internal Heat ◽  
Optimization Methods ◽  
Optimization Method ◽  
Internal Heat Generation ◽  
Geometric Optimization ◽  
Constructal Design ◽  
Optimal Shapes

he problem study here is concerned with the geometrical evaluation of an isothermal Y-shaped cavity intruded into conducting solid wall with internal heat generation. The cavity acts as a sink of the heat generated into the solid. The main purpose here is to minimize the maximal excess of temperature (θmax) in the solid. Constructal Design, which is based on the objective and constraints principle, is employed to evaluate the geometries of Y-shaped cavity. Meanwhile, Simulated Annealing (SA) algorithm is employed as optimization method to seek for the best shapes. To validate the SA methodology, the results obtained with SA are compared with those achieved with Genetic Algorithm (GA) and Exaustive Search (ES) in recent studies of literature. The comparison between the optimization methods (SA, GA and ES) showed that Simulated Annealing is highly effective in the search for the optimal shapes of the studied case.

scholarly journals CONSTRUCTAL THEORY APPLIED TO THE GEOMETRIC OPTIMIZATION OF ELLIPTICAL CAVITIES INTO A SOLID CONDUCTING WALL

2008 ◽  
Vol 7 (2) ◽  
pp. 81
Author(s):  
L. A. O. Rocha ◽  
C. Biserni ◽  
E. Lorenzini
Keyword(s):  
Solid Wall ◽  
Thermal Conditions ◽  
Geometric Optimization ◽  
Constructal Theory ◽  
Design Parameters ◽  
Cavity Volume ◽  
Cavity Shape ◽  
Elliptical Cavity ◽  
Conducting Wall ◽  
Geometrical Shapes

This work reports, according to Bejan’s Constructal theory, the geometric optimization of an elliptical cavity that intrudes into a solid conducting wall. The objective is to minimize the global thermal resistance between the solid and the cavity. There is uniform heat generation on the solid wall. The cavity is optimized for two sets of thermal conditions: isothermal cavity and cavity bathed by a steady stream of fluid. The solid conducting wall is isolated on the external perimeter. The total volume and the elliptical cavity volume are fixed while the geometry of the cavity is free to vary. The results show that the optimized geometrical shapes are relatively robust, i.e., insensitive to changes in some of the design parameters: the cavity shape is optimal when penetrates the conducting wall almost completely.

scholarly journals GEOMETRIC OPTIMIZATION OF “+”-SHAPED CAVITY USING CONSTRUCTAL THEORY

2017 ◽  
Vol 16 (1) ◽  
pp. 75
Author(s):  
P. A. Avendaño ◽  
J. A. Souza ◽  
D. F. Adamatti ◽  
E. D. dos Santos
Keyword(s):  
Solid Body ◽  
Degrees Of Freedom ◽  
Internal Heat ◽  
Thermal Conditions ◽  
Geometric Optimization ◽  
Optimal Performance ◽  
Constructal Theory ◽  
Maximum Temperature ◽  
Constructal Design ◽  
Better Than

In this work it is applied the Constructal Theory for the study of the geometry of an “+”-shaped isothermal cavity inserted in a conductive solid body. Main goal is to minimize the maximum temperature in the solid. The total volume of the solid and the total volume of the cavity are kept fixed while the dimensions of the cavity geometry vary according to constraints and degrees of freedom defined by the Constructal Design. The solid body has internal heat generation and its external surfaces are insulated. Cavity walls are isothermal with constant temperature Tmin. Obtained results indicate that the optimal performance of “+”-shape cavity is 37.2% better that the optimal performance of “C”-shape cavity and 10.8% better than the “T”-shaped cavity for the same thermal conditions.

scholarly journals Effects of an adiabatic fin on the mixed convection heat transfer in a square cavity with two ventilation ports

2014 ◽  
Vol 18 (2) ◽  
pp. 377-389 ◽  
Author(s):  
Fatih Selimefendigil ◽  
Hakan Öztop
Keyword(s):  
Heat Transfer ◽  
Mixed Convection ◽  
Thermal Performance ◽  
Convection Heat Transfer ◽  
Flow Characteristics ◽  
Square Cavity ◽  
Fluid Flow Characteristics ◽  
The One ◽  
Convection Dominated ◽  
Fin Length

In this study, a square cavity with two ventilation ports in the presence of an adi-abatic fin of different lengths placed on the walls of the cavity is numerically analyzed for the mixed convection case for a range of Richardson numbers (Ri=0.1,1, 10, 100) and at Reynolds number of 300. The effect of the fin height, placement of the fin on each of the four walls of the cavity and Richardson number on the heat transfer and fluid flow characteristics is numerically analyzed. The results are presented in terms of streamlines, isotherm plots and averaged Nusselt number plots. It is observed that for the convection dominated case, fin length and its position on the one of the four walls of the cavity do not alter the thermal performance whereas when the buoyancy effects become important thermal performance increases for high fin length.

Constructal Design Applied to the Geometric Optimization of Y-shaped Cavities Embedded in a Conducting Medium

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
G. Lorenzini ◽  
C. Biserni ◽  
L. A. Isoldi ◽  
E. D. dos Santos ◽  
L. A. O. Rocha
Keyword(s):  
Thermal Resistance ◽  
Degrees Of Freedom ◽  
Vertical Direction ◽  
Optimization Procedure ◽  
Power Laws ◽  
Geometric Optimization ◽  
Constructal Design ◽  
Conducting Wall ◽  
Geometric Conditions ◽  
Optimal Shapes

In this paper, we rely on the Constructal method to optimize the geometry of a Y-shaped cavity embedded into a solid conducting wall. The structure has four degrees of freedom. The objective is to minimize the global thermal resistance between the solid and the cavity. The optimization procedure has demonstrated that for larger solids, a cavity shaped as T led to a minimization of the global thermal resistance, while the opposite effect is observed for tall solids, where the optimal shapes are reached when the bifurcated branches deeply penetrates the solid in the vertical direction, according to the Constructal principle of “optimal distribution of imperfections”. The three times minimized global thermal resistance of the Y-shaped cavity has been correlated by power laws as a function of its corresponding optimal configurations. Finally, the performance of the Y-shaped intrusion proved to be superior to that of other basic geometries: the optimized global thermal resistances of the Y-shaped cavities obtained for H/L = 1.0, 2.0, and 5.0 were, respectively 66.61%, 55.37%, and 19.05% lower than the optimal T-shaped cavities under the same thermal and geometric conditions. Furthermore, in comparison with the “finger cavity” shaped as C, the Y-shaped cavities increased the thermal performance in 109.12%, 84.45%, 59.32%, and 20.10% for H/L = 0.5, 1.0, 2.0, and 5.0, respectively.

scholarly journals Natural Convection in a Square Cavity in the Presence of Heated Plate

2007 ◽  
Vol 12 (2) ◽  
pp. 203-212 ◽  
Author(s):  
P. Kandaswamy ◽  
J. Lee ◽  
A. K. Abdul Hakeem
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Aspect Ratio ◽  
Thin Plate ◽  
Convection Heat Transfer ◽  
Working Fluid ◽  
Heated Plate ◽  
Square Cavity ◽  
Aspect Ratios ◽  
Alternating Direction

Natural convection heat transfer in a square cavity induced by heated plate is studied numerically. Top and bottom of the cavity are adiabatic, the two vertical walls of the cavity have constant temperature lower than the plate’s temperature. The flow is assumed to be two-dimensional. The discretized equations were solved by finite difference method using Alternating Direction Implicit technique and Successive OverRelaxation method. The study was performed for different values of Grashof number ranging from 103 to 105 for different aspect ratios and position of heated plate. Air was chosen as a working fluid (Pr = 0.71). The effect of the position and aspect ratio of heated plate on heat transfer and flow were addressed. With increase of Gr heat transfer rate increased in both vertical and horizontal position of the plate. When aspect ratio of heated thin plate is decreased the heat transfer also decreases. For the vertical situation of thin plate heat transfer becomes more enhanced than for horizontal situation.

Study on Coupled Conduction and Convection Heat Transfer Based on Internal Heat Source

2011 ◽  
Vol 90-93 ◽  
pp. 3001-3004
Author(s):  
Yong An Li ◽  
Ya Nan Gao ◽  
Ming Wang ◽  
Xue Lai Liu
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Heat Source ◽  
Solid Wall ◽  
Convection Heat Transfer ◽  
Internal Heat ◽  
Internal Heat Source ◽  
Heat Transfer Process ◽  
Horizontal Distance ◽  
Computational Fluid Dynamics Cfd

A computational fluid dynamics (CFD) model is proposed to simulate numerically conjugated heat transfer process of fluid washing out solid with evenly internal heat source in the pipe. Temperature field and velocity field inside the pipe and outside solid are gained by calculation. Based on numerical simulation, the varying regularity of Nusselt number between fluid and solid wall surface is obtained and analyzed. The results show that there are two symmetrical vortexes in the back of solid. The Nusselt number and heat exchange rate dramatically decrease with increasing horizontal distance of top and bottom of solid.

Numerical Prediction of Contaminant Removal from Cavity in Horizontal Channel by Constrained Interpolated Profile Method

2014 ◽  
Vol 695 ◽  
pp. 384-388
Author(s):  
Nor Azwadi Che Sidik ◽  
A.S. Ahmad Sofianuddin ◽  
K.Y. Ahmat Rajab
Keyword(s):  
Reynolds Number ◽  
Aspect Ratio ◽  
Removal Rate ◽  
Contaminant Removal ◽  
Square Cavity ◽  
Profile Method ◽  
Aspect Ratios ◽  
Contaminants Removal ◽  
Parabolic Flow ◽  
High Removal Rate

In this paper, Constrained Interpolated Profile Method (CIP) was used to simulate contaminants removal from square cavity in channel flow. Predictions were conducted for the range of aspect ratios from 0.25 to 4.0. The inlet parabolic flow with various Reynolds number from 50 to 1000 was used for the whole presentation with the same properties of contaminants and fluid. The obtained results indicated that the percentage of removal increased at high aspect ratio of cavity and higher Reynolds number of flow but it shows more significant changes as increasing aspect ratio rather than increasing Reynolds number. High removal rate was found at the beginning of the removal process.

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