scholarly journals Constructal Design Applied to the Geometric Evaluation of a T-Shaped Earth-Air Heat Exchanger

2021 ◽  
Vol 16 (2) ◽  
pp. 207-217
Author(s):  
Gerusa C. Rodrigues ◽  
Giulio Lorenzini ◽  
Lucas C. Victoria ◽  
Igor S. Vaz ◽  
Luiz A.O. Rocha ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Degrees Of Freedom ◽  
Analytical Approach ◽  
Design Method ◽  
Performance Parameters ◽  
Search Technique ◽  
Constructal Design ◽  
Reference Installation ◽  
Flow Pressure ◽  
Straight Duct

An Earth-Air Heat Exchanger (EAHE) is a device that consists of one or more buried ducts through which air is forced to flow. The surrounding soil is responsible for enabling thermal exchanges along with the installation, making the temperature at the outlet milder than the inlet. The objective of this work is to ally a numerical-analytical approach with the Constructal Design method and Exhaustive Search technique to minimize the soil volume occupation (V), minimize the air flow pressure drop (PD), and maximize the thermal potential (TP) of a T-shaped EAHE. Starting from a conventional EAHE composed of a straight duct, called Reference Installation (RI), two degrees of freedom (DOF) were considered: the ratio between the length of the bifurcated branch and the length of the main branch (L1/L0) and the ratio between the diameter of the bifurcated branch and the diameter of the main branch (D1/D0). Comparing with RI, different T-shaped EAHE geometries were identified to reduce V by 23% and PD by 62% and to increase TP by 21%; and when these three performance parameters were concomitantly considered another T-shaped EAHE geometric configuration allowed to reach an improvement of around 27% when compared with the RI.

Analysis of Geometric Variation of Three Degrees of Freedom through the Constructal Design Method for a Oscillating Water Column Device with Double Hidropneumatic Chamber

2019 ◽  
Vol 396 ◽  
pp. 22-31
Author(s):  
Yuri T.B. Lima ◽  
Mateus das Neves Gomes ◽  
Camila F. Cardozo ◽  
Liércio André Isoldi ◽  
Elizaldo D. Santos ◽  
...  
Keyword(s):  
Water Column ◽  
Degrees Of Freedom ◽  
Numerical Study ◽  
Design Method ◽  
Geometric Optimization ◽  
Oscillating Water Column ◽  
Constructal Design ◽  
Wave Energy Converters ◽  
Volume Method ◽  
Geometric Variation

This paper presents a biphasic two-dimensional numerical study of sea wave energy converters with operating principle being Oscillating Water Column (CAO) devices with two couples chambers. For the study of the geometric optimization, the Constructal Design method is applied in association with the exhaustive search method to determine the geometric arrangement that leads to the greatest hydropneumatic power available. The objective function is the maximization of hydropneumatic power converted by the device. The constraints of the problem are the inflow volumes of the hydropneumatic chamber (VE1, VE2), the total volumes (VT1, VT2) and the thicknesses of the device columns (e1, e3). The degrees of freedom analyzed were H1/L1(ratio between height and length of the hydropneumatic chamber of the first device), H2/L2 (ratio between height and length of the hydropneumatic chamber of the second device), H2 (height of the column dividing the two devices) and e2 (thickness of the column dividing the devices). In the present work the degree of freedom H6 (depth of immersion of the device) is kept constant and equal to H6 = 9.86 m. The Finite Volume Method (FVM) was used in the numerical solution of the equations employed. For the treatment of the interaction between the air and water phases, the Volume of Fluid (VOF) method was applied. The results show that the maximum hydropneumatic power available was 5715.2 W obtained for degrees of freedom H1/L1 = H2/L2 = 0.2613 and e2 = 2.22 m. The case of lower performance has a power value equal to 4818.5 W with degrees of freedom equal to H1/L1 = H2/L2 = 0.2613 and e2 = 0.1 m.

scholarly journals GEOMETRIC EVALUATION OF FOUR STAGGERED CYLINDERS ARRAY SUBJECTED TO FORCED CONVECTIVE FLOWS BY MEANS OF CONSTRUCTAL DESIGN

2019 ◽  
Vol 18 (1) ◽  
pp. 57
Author(s):  
A. P. D. Aghenese ◽  
F. B. Teixeira ◽  
L. A. O. Rocha ◽  
L. A. Isoldi ◽  
J. F. Prolo Filho ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Numerical Study ◽  
Design Method ◽  
Fluid Dynamic ◽  
Working Fluid ◽  
Convective Flows ◽  
Constructal Design ◽  
Staggered Arrangement ◽  
Forced Convective Flow ◽  
Volume Method

This work presents a numerical study on the geometric evaluation of forced convective flows over four staggered arrangement of four cylinders. The forced convective flow is considered incompressible, two-dimensional, laminar and unsteady. Geometry varies according to Constructal Design method. The objectives are the maximization of Nusselt number (NuD) and minimization of drag coefficient (CD) between the cylinders and the surrounding flow. Simulations were performed considering Reynolds numbers of ReD = 10, 40 and 150 and air as working fluid, i.e., Prandtl number is assumed Pr = 0.71. The problem presents three degrees of freedom: ST/D (ratio between transversal pitch of the intermediate cylinders and the cylinders diameter), SL1/D (ratio between the frontal and intermediate cylinders longitudinal pitch and the cylinders diameter) and SL2/D (ratio between the intermediate and posterior cylinders longitudinal pitch and the cylinders diameter). However, SL1/D and SL2/D measures were kept fixed at 1.5 and ST/D varies in the range 1.5 ≤ ST/D ≤ 5.0. The conservation equations of mass, momentum and energy conservation are solved with the Finite Volume Method (FVM). Optimal results for fluid-dynamic study in all ReD cases occurred for the lowest values of ST/D, i.e., (ST/D)o,f = 1.5. For thermal analysis, NuD behavior was assessed, where optimal results for ReD = 10 and 40 occurred for the highest values of ST/D, whilst, for ReD = 150, the optimal value was achieved for the intermediate ratio of ST/D = 4.0.

Geometric Evaluation of Forced Convective Flows across an Arrangement of Four Circular Cylinders

2017 ◽  
Vol 372 ◽  
pp. 110-121
Author(s):  
Martim dos Santos Pereira ◽  
Bruno Costa Feijó ◽  
Filipe Branco Teixeira ◽  
Liércio André Isoldi ◽  
Luiz Alberto Oliveira Rocha ◽  
...  
Keyword(s):  
Nusselt Number ◽  
Degrees Of Freedom ◽  
Design Method ◽  
Great Influence ◽  
Circular Cylinders ◽  
Constructal Design ◽  
Prandtl Numbers ◽  
Forced Convective Flow ◽  
Volume Method ◽  
Four Cylinders

The present study consists in a numerical evaluation of an arrangement formed by four cylinders submitted to an unsteady, two-dimensional, incompressible, laminar and forced convective flow. The geometric evaluation is performed through the Constructal Design method. The problem has two restrictions given by the sum of the area of ​​the cylinders and one occupation area and has three degrees of freedom: ST1/D (the ratio between the transverse pitch of the frontal cylinders and the diameter of the cylinders), ST2/D (the ratio between the transverse pitch of the posterior cylinders and the diameter of the cylinders) and SL/D (ratio between the longitudinal pitch of the frontal and posterior cylinders and the diameter of the cylinders). For all simulations the Reynolds number is kept constant, ReD = 100, and two different Prandtl numbers of Pr = 0.71 and 5.83 are considered, which simulates respectively the use of air and water as a fluid. The conservation equations of mass, momentum and energy are solved with the Finite Volume Method (FVM). The main objective is to evaluate the effect of the degrees of freedom on the drag coefficient (CD) and the Nusselt number (NuD) between the cylinders and the surrounding flow, as well as the optimal ST2/D values ​​for three ratios of ST1/D = 1.5, 3.0 and 4.0, these results being obtained for ratios of SL/D = 1.5 and 4.0. Results showed that the ratio changes of ST1/D and ST2/D have a great influence on the drag coefficients and on the Nusselt number of the arrangement formed by the four cylinders, as well as on the geometries leading to the best fluid dynamics and thermal performance.

Numerical investigation about the improvement of the thermal potential of an Earth-Air Heat Exchanger (EAHE) employing the Constructal Design method

2015 ◽  
Vol 80 ◽  
pp. 538-551 ◽  
Author(s):  
Michel Kepes Rodrigues ◽  
Ruth da Silva Brum ◽  
Joaquim Vaz ◽  
Luiz Alberto Oliveira Rocha ◽  
Elizaldo Domingues dos Santos ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Numerical Investigation ◽  
Design Method ◽  
Constructal Design ◽  
Thermal Potential

scholarly journals Geometric Evaluation of Stiffened Steel Plates Subjected to Transverse Loading for Naval and Offshore Applications

2019 ◽  
Vol 7 (1) ◽  
pp. 7 ◽  
Author(s):  
João Pedro T. P. De Queiroz ◽  
Marcelo L. Cunha ◽  
Ana Pavlovic ◽  
Luiz Alberto O. Rocha ◽  
Elizaldo D. Dos Santos ◽  
...  
Keyword(s):  
Design Method ◽  
Steel Plates ◽  
Stiffened Plates ◽  
Geometrical Configuration ◽  
Ansys Software ◽  
Search Technique ◽  
Constructal Design ◽  
Longitudinal Stiffeners ◽  
Stiffened Steel ◽  
Reference Plate

This work searched for the optimal geometrical configuration of simply supported stiffened plates subjected to a transverse and uniformly distributed load. From a non-stiffened reference plate, different geometrical configurations of stiffened plates, with the same volume as the reference plate, were defined through the constructal design method. Thus, applying the exhaustive search technique and using the ANSYS software, the mechanical behaviors of all the suggested stiffened plates were compared to each other to find the geometrical configuration that provided the minimum deflection in the plate’s center when subjected to this loading. The optimum geometrical configuration of stiffeners is presented at the end of this work, allowing a reduction of 98.57% for the central deflection of the stiffened plate if compared to the reference plate. Furthermore, power equations were adjusted to describe the deflections for each combination of longitudinal and transverse stiffeners as a function of the ratio between the height and the thickness of the stiffeners. Finally, a unique equation for determining the central deflections of the studied stiffened plates based only on the number of longitudinal stiffeners without significantly losing accuracy has been proposed.

Constructal Design Applied to a Channel with Triangular Fins Submitted to Forced Convection

2017 ◽  
Vol 372 ◽  
pp. 152-162 ◽  
Author(s):  
Bruno Costa Feijó ◽  
Martim dos Santos Pereira ◽  
Filipe Branco Teixeira ◽  
Liércio André Isoldi ◽  
Luiz Alberto Oliveira Rocha ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Forced Convection ◽  
Degrees Of Freedom ◽  
Numerical Study ◽  
Design Method ◽  
Convection Heat Transfer ◽  
Lower Surface ◽  
Worst Case ◽  
Constructal Design

The purpose of this work is to present a numerical study of a two-dimensional channel with two triangular fins submitted to a laminar flow with forced convection heat transfer, evaluating the geometry of the first fin through the Constructal Design method. The main objectives are to maximize the heat transfer rate and minimize the pressure difference between the inlet and outlet flow of the channel for different dimensions of the first channel fin, considering the same Reynolds (ReH = 100) and Prandtl numbers (Pr = 0.71). The problem is subjected to three constraints given by the channel area, fin area and maximum occupancy area of ​​each fin. The system has three degrees of freedom. The first is given by the ratio between height and length of the channel, which is kept fixed, H/L = 0.0625. The other two are the ratio between height and width of the upstream fin base (H3/L3) positioned on the lower surface of the channel, and the ratio between height and width of the downstream fin (H4/L4) positioned on the upper surface of the channel, which is also kept fixed, H4/L4 = 1.11. The problem is simulated for three different values ​​of the fraction area of upstream fin (φ1 = 0.1, 0.2 and 0.3). For the numerical approach of the problem, the conservation equations of mass, momentum and energy are solved using the finite volume method (MVF). The results showed that a ratio of φ1 = 0.2 is the one that best meets the proposed multi-objective. It was also observed that φ1 = 0.1 led to a better fluid dynamics performance with a ratio between the best and the worst performance for fluid dynamics case of 25.2 times. For φ1 = 0.3, the best thermal performance is achieved, where the optimal case has a performance 65.75% higher than that reached for the worst case.

CONSTRUCTAL DESIGN OF A T-SHAPED EARTH-AIR HEAT EXCHANGER INSTALLED AT RIO GRANDE CITY

2020 ◽  
Author(s):  
Lucas Costa Victoria ◽  
Igor Vaz ◽  
Luiz Alberto Oliveira Rocha ◽  
Elizaldo dos Santos ◽  
Michel Kepes Rodrigues ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Rio Grande ◽  
Constructal Design
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