JÁ

Jeferson Ávila Souza

Universidade Federal do Rio Grande

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Elizaldo Domingues dos Santos

Universidade Federal do Rio Grande

Liércio André Isoldi

Universidade Federal do Rio Grande

Luíz Alberto Oliveira Rocha

Universidade Federal do Rio Grande

Sandro Campos Amico

Universidade Federal do Rio Grande do Sul

Juan C. Ordóñez

Florida State University

JOSÉ VIRIATO COELHO VARGAS

Universidade Federal do Paraná

Mateus das Neves Gomes

Instituto Federal de Educação Ciência e Tecnologia do Paraná

Crístofer Hood Marques

Universidade Federal do Rio Grande

Jaifer Corrêa Martins

Universidade Federal do Rio Grande

Max Letzow

Universidade Federal do Rio Grande

Cooperative Institutions

Universidade Federal do Rio Grande

Universidade Federal do Rio Grande do Sul

University of Rio Grande and Rio Grande Community College

Universidade Federal do Paraná

Universidade Federal de Pelotas

Florida State University

Petrobras (Brazil)

Universidade Federal de Campina Grande

Universidade de São Paulo

Universidade Federal do Rio de Janeiro

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FINNED ELLIPTIC TUBES HEAT EXCHANGERS IN THE TURBULENT REGIME CONSTRUCTAL DESIGN

Manuel Pereira Jeferson Ávila Souza JOSÉ VIRIATO COELHO VARGAS Diogo B. Pitz Juan C. Ordóñez

This work seeks numerically the heat exchanger structure direction of evolution in time, i.e., the general optimal that maximizes the total heat transfer rate between a fixed volume arrangement of finned tubes and a turbulent external flow governed by a pressure difference, both for circular and elliptic tube arrays. In this way, the dynamic, ever-changing heat exchanger design that provides easier access to the currents that flow through it is sought for any time reality (e.g., geometry, materials, environment), according to Constructal law. The optimization procedure began by recognizing the limited availability of the design space as a fixed volume constraint. The three-way optimized (3wo) arrangement concerning tube-to-tube distance, eccentricity, and fin density was found as (S/2b, e, ϕf)3wo ≅ (0.5; 0.4; 0.094). A relative heat transfer gain of up to 38% was noted with the elliptic compared to the 3wo circular arrangement, demonstrating that elliptical tube arrangements have potential for considerably better performance and lower cost than traditional circular arrangements.

Constructal law

10.59277/clc.2024.31

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Estudo numérico da influência de condições de contorno na modelagem computacional de trocador de calor solo-ar

Scientia Plena (2015)

Michel Kepes Rodrigues Jeferson Ávila Souza Joaquim Vaz Ivoni Carlos Acunha Luíz Alberto Oliveira Rocha

<div><p class="SPabstract">O trocador de calor solo-ar (TCSA) é um dispositivo utilizado para a melhoria da condição térmica de ambientes construídos, contribuindo na diminuição no consumo de energia elétrica dos equipamentos tradicionais de condicionamento de ar. Assim, os objetivos deste trabalho são de avaliar a influência da condição de contorno térmica de fluxo prescrito nulo no potencial térmico (PT) do TCSA, que é imposta nas superfícies laterais do domínio computacional, e de estudar a efeito do tipo de condição de contorno térmica imposta na superfície inferior do domínio computacional no tempo de processamento da simulação numérica de um TCSA. Para isso, um modelo computacional, validado e verificado, desenvolvido no software FLUENT, que é baseado no Método dos Volumes Finitos (MVF), foi empregado. Os resultados mostraram que o PT das instalações de TCSA analisadas é afetado para um espaçamento horizontal, entre o duto e a parede do domínio computacional, inferior a 2,00 m. Além disso, foi observado que a utilização da condição de contorno de temperatura prescrita imposta na superfície inferior do domínio computacional contribuiu para a redução do tempo de processamento da simulação numérica em 18%, quando comparada com a utilização da condição de contorno térmica de fluxo prescrito nulo.</p></div>

10.14808/sci.plena.2015.081334

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Citations (6)

Overtopping device numerical study: Openfoam solution verification and evaluation of curved ramps performances

International Journal of Heat and Mass Transfer (2018)

Dante Vinícius Eloy Barbosa Andrei Luís Garcia Santos Elizaldo Domingues dos Santos Jeferson Ávila Souza

Control volume

10.1016/j.ijheatmasstransfer.2018.11.071

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Citations (22)

Numerical study on natural, forced and mixed convection of a hybrid photovoltaic inverter

Journal of the Brazilian Society of Mechanical Sciences and Engineering (2024)

Otavio Duarte Aires Heckler Rafael Christiano Annunziato Welington Fernando Lima Desan Marcus Vinicius Alves Pereira Jeferson Ávila Souza

Forced convection

10.1007/s40430-024-05218-w

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The self-gravity model of longitudinal span of Neptune main arc Fraternite

arXiv (Cornell University) (2009)

K. H. Tsui Jeferson Ávila Souza

According to recent works [Tsui PSS \textbf{55}, 237-242 (2007), \textbf{55}, 2042-2044 (2007)], the Neptune Adams ring main arc Fraternite is regarded as captured by the corotation elliptic resonance (CER) potential of Galatea. The minor arcs Egalite(2,1), Liberte, and Courage are located at positions where the time averaged forces, due to the 42-43 corotation-Lindblad resonances under the central field of Neptune, vanish. With adequately chosen Fraternite mass and Galatea eccentricity, this model gives minor arc locations compatible to observed positions, and allows a dynamic transport of materials among arcs. To complement this model, the effect of self-gravity of Fraternite, with a distributed mass, is evaluated together with the CER potential to account for its $10^{0}$ longitudinal span. Although self-gravity is the collective action of all the particles in the arc, each individual particle will see the self-potential with a central maximum as an external potential generated by other particles.

Eccentricity (behavior)

Neptune

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THERMAL ANALISYS AND GEOMETRIC OPTIMIZATION OF A TUBULAR ARRAY USING CONSTRUCTAL DESIGN

Proceedings of the ... International Congress of Mechanical Engineering (2015)

Vagner Andrade Pedrotti Jeferson Ávila Souza Elizaldo Domingues dos Santos Liércio André Isoldi

Constructal law

10.20906/cps/cob-2015-2214

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Modelagem numérica da infusão de resina em um meio poroso

RETEC - Revista de Tecnologias (2017)

Laísa Luiz Soares Jeferson Ávila Souza Liércio André Isoldi Elizaldo Domingues dos Santos Sandro Campos Amico

Compositos fabricados pelo processo de RTM (Resin Transfer Molding) tem sido largamente utilizados em diversos segmentos industriais (naval, automotivo, etc.). Este processo combina, geralmente, os custos reduzidos de producao com boas propriedades mecânicas para a peca fabricada. Alem disso, o processo de RTM produz pequenas quantidades de residuos e e adequado para a producao de pecas com geometrias, tanto simples como complexas. O reforco fibroso utilizado dentro do molde para a fabricacao dos compositos e, na verdade, uma pilha de tecidos fibrosos ou mantas fibrosas, cortados no tamanho e forma da peca e posicionados dentro da cavidade do molde. A fim de investigar os padroes de escoamento da resina no interior do molde, este trabalho apresenta a simulacao numerica do processo de RTM, utilizando o software OpenFOAM. Foi investigado o tempo de cura da resina e o tempo total de preenchimento do molde. A viscosidade nao foi considerada constante e, uma equacao que relaciona a sua variacao em funcao do tempo, foi utilizada para prever esta mudanca. Os resultados mostraram que o controle das variaveis do processo, no caso pressao de injecao e permeabilidade do meio, sao de fundamental importância para uma injecao bem-sucedida. Alem disso, destaca-se que a modelagem numerica do RTM pode auxiliar na determinacao dessas variaveis. Palavras-chave: RTM, simulacao numerica, tempo de injecao.

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A Simplified Numerical Model to Predict the Velocity Field in a Catalytic Cracking Unity in Oil Refineries

Jeferson Ávila Souza JOSÉ VIRIATO COELHO VARGAS Oscar F. von Meien D. Vlassov

Abstract This paper introduces a general computational model for determining the velocity field in either reacting or non-reacting duct flows. The model is then applied to a catalytic cracking unit (FCC) of an oil refinery, to determine the velocity field inside the riser, where reactions take place to convert heavy petroleum fractions in lighter products, like middle distillates and light olefins, with high rates of conversion and productivity. The correct approach to simulate this process is to avoid the plug flow assumption and to solve the full fluid flow problem, based on the mass and momentum conservation equations in a complete formulation, which are shown in the literature to be computationally very expensive and time consuming, mainly in a three-dimensional (3-D) simulation. Since, the main objective of the simulation is the accurate determination of the concentration of the noble products, a very accurate velocity field is not mandatory. Therefore, bidimensional flow is assumed, and a modified set of unsteady mass and momentum conservation equations is proposed and the resulting 2-D differential equations are discretized in space using an upwind cell centered finite differences method, and the equations integrated in time with an implicit backward Euler scheme. The coarsest possible mesh is determined such that the solution relative error is within 5 % when compared to a steady state accurate finite element solution, which was obtained with a 2-D isoparametric, four-noded, linear element that was implemented to solve the complete Navier-Stokes equations for the finite element analysis program, FEAP [1]. The objective of this work is to propose an alternative technique that gives a simplified treatment to the velocity field, to make possible the numerical calculation of the products concentrations in the riser and future application in optimization and real time control. Each cell, in this specific situation, can be understood as a perfect mixing reactor.

Conservation of mass

Momentum (technical analysis)

Fluid catalytic cracking

10.1115/imece2001/htd-24301

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Numerical study of three-dimensional microchannel using the Constructal Law

International Communications in Heat and Mass Transfer (2023)

Alex Maliska de Moura Elizaldo Domingues dos Santos Jeferson Ávila Souza

Constructal law

Microchannel

10.1016/j.icheatmasstransfer.2023.106891

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ENERGY AND EXERGY THERMODYNAMIC ANALYSIS OF A TWO-STAGE COMPRESSION REFRIGERATION SYSTEM INTEGRATED WITH AN ABSORPTION SYSTEM (NH3+H2O)

Revista de Engenharia Térmica (2008)

Guayanay Correa Jeferson Ávila Souza Carlos Prentice-Hernández Luíz Alberto Oliveira Rocha

This work proposes an energetic and exergetic thermodynamic analysis of two refrigeration systems: one is a conventional two stages cooling system by steam compression of ammonia and the other is named integrated refrigeration system. The conventional system, used as reference, is largely employed in cooling fish industry. The integrated refrigeration system is similar to the conventional one, although it uses in the intermediate cooling, between the stages of high and low pressure, cold water in closed circuit. The cold water is supplied by ammonia-water absorption system integrated to the conventional compression system. The calorific energy supplied is obtained from waste exceeding of the fish meal production thus the energy delivered tothe integrated refrigeration system is considered of zero cost. Numeric simulation is employed to compare the behavior of both systems. The results obtained in this comparison show that the integrated refrigeration system operates with a reduction of up to 19.73 % in COP. However, the integratedrefrigeration system presented an increase of up to 25.57% in exergetic efficiency and 33.09% in frigorific capacity in relation to the conventionalsystem. These results, added to the decrease of operational cost which will bequantified in a further study, will make very attractive the use of the integrated refrigeration system.

Absorption refrigerator

Coefficient of performance

Cooling capacity

Exergy efficiency

10.5380/reterm.v7i1.61735

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