José Nunhez - Academia.edu (original) (raw)

Papers by José Nunhez

Research paper thumbnail of Bicos dispersores da industria do petroleo : analise bidimensional aplicando a fluido dinamica computacional

Os atomizadores de uma unidade petroquimica de craqueamento catalitico fluidizado (FCC), tem como... more Os atomizadores de uma unidade petroquimica de craqueamento catalitico fluidizado (FCC), tem como papel fundamental atomizar o gasoleo na entrada do reator catalitico (riser). Os atomizadores utilizados nas unidades da PETROBRAS, ate inicio da decada de noventa, apresentavam forte erosao, o que causa uma deficiencia na atomizacao, influenciando o rendimento do processo como um todo. Os metodos convencionais de analise proporcionam uma visao global do equipamento, de forma que nao se consegue avaliar comportamentos locais, principalmente dentro do equipamento. Utilizando-se uma modelagem ponto a ponto, atraves da fluido dinâmica computacional, mesmo com fortes simplificacoes, atraves de uma analise bidimensional associada ao conhecimento experimental, e possivel propor um mecanismo para o processo inicial de erosao, juntamente com a apresentacao dos perfis de velocidade, pressao e temperatura. O pacote fluido dinâmico CFX-4.3 da AEA Technology Inc. foi utilizado para obtencao dos res...

Research paper thumbnail of A Computational Model For The Prediction Of The Effect Of Multiple Effluent Discharges In A Large River Section

WIT Transactions on Ecology and the Environment

A future lack of water over the next decades has been observed by many studies. Much effort has b... more A future lack of water over the next decades has been observed by many studies. Much effort has been devoted to find strategies which will help to manage water resources properly. Theoretical studies have been used recently since the scope of computational fluid dynamics (CFD) has increased, allowing its use in the issue of water quality. In this scenario, it is important to develop new techniques to predict the environmental impact of emissions in rivers so that strategies can be devised to decrease the effects of pollution. This work presents an in-house three-dimensional CFD model to simulate the dispersion of substances along a river with multiple effluent discharges. The Cartesian coordinate system has been chosen to represent the river. The model also assumes the river has no curves. Although simple, this geometry is able to represent in a simple manner the behavior of most rivers. The finite volume method is used to approximate the momentum, mass and species conservation equations. Turbulence is taken into account by a zero-order equation model. The developed model considers the presence of multiple effluent discharges along the river. Some experimental validation is also presented in the work. Results show that the proposed methodology is a good tool for the evaluation of the environmental impact caused by pollutant emissions, mainly in rivers with multiple discharges from many industries. The software is very fast, especially when compared to other CFD packages.

Research paper thumbnail of Implementação De Um Modelo Com O Uso De CFD Para a Obtenção De Uma Correlação Do Número De Nusselt Em Tanques De Mistura Com Serpentinas Helicoidais

Anais do XX Congresso Brasileiro de Engenharia Química, 2015

RESUMO-Tanques de mistura com aquecimento são utilizados em diversos processos químicos. Quando r... more RESUMO-Tanques de mistura com aquecimento são utilizados em diversos processos químicos. Quando reações endotérmicas ou exotérmicas com uma alta liberação ou absorção de energia ocorrem nestes equipamentos, camisas e serpentinas helicoidais ou axiais são empregadas ao mesmo tempo para promover uma maior superfície de transferência de calor. O maior problema associado às serpentinas helicoidais é que estas podem limitar o fluxo no interior do reator, pois as serpentinas fornecem resistência à circulação do fluido. O objetivo deste trabalho foi desenvolver um modelo 3D com o uso da fluidodinâmica computacional para simular a troca térmica dentro destes equipamentos. Resultados iniciais indicam que o modelo em CFD reproduz a correlação de Nusselt obtida experimentalmente.

Research paper thumbnail of Impeller characterization and selection: Balancing efficient hydrodynamics with process mixing requirements

AIChE Journal, 2012

Current literature relies almost exclusively on the power number to compare and characterize impe... more Current literature relies almost exclusively on the power number to compare and characterize impellers. Industrial mixing requirements may rely on conditions far away from the impeller. A protocol is proposed to compare impellers designed for turbulent mixing on the basis of impeller hydrodynamic performance and mixing process objectives. A hydrofoil impeller (KPC), and a mixed-flow impeller (45 down-pumping PBT), each at two diameters, were used to test the protocol. Fourteen measures were considered. Five are recommended for full characterization: power number, momentum number, and peak rate of dissipation of turbulent kinetic energy to characterize conditions at the impeller; power at just-suspended speed to compare the efficiency of solids suspension at the bottom of the tank; and point of air entrainment as a measure of turbulence penetration to the free surface. These five measures provide complete information about mixing performance and good differentiation between the impellers and geometries. V V

Research paper thumbnail of A New Computational Fluid Dynamic (CFD) Model for the Estimation of Effluent Dispersion In Rivers Sections

The 2008 Annual …, 2008

186be. A New Computational Fluid Dynamic (CFD) Model for the Estimation of Effluent Dispersion In... more 186be. A New Computational Fluid Dynamic (CFD) Model for the Estimation of Effluent Dispersion In Rivers Sections. Jose Roberto Nunhez 1 , Marcio Bezerra Machado 2 , Mateus Lazzarini Furlan 3 , Luis Tadeu Furlan 4 , and E. Tomaz 2 . (1) UNICAMP, Fac. Eng. ...

Research paper thumbnail of Bicos dispersores da industria do petroleo : analise bidimensional aplicando a fluido dinamica computacional

Os atomizadores de uma unidade petroquimica de craqueamento catalitico fluidizado (FCC), tem como... more Os atomizadores de uma unidade petroquimica de craqueamento catalitico fluidizado (FCC), tem como papel fundamental atomizar o gasoleo na entrada do reator catalitico (riser). Os atomizadores utilizados nas unidades da PETROBRAS, ate inicio da decada de noventa, apresentavam forte erosao, o que causa uma deficiencia na atomizacao, influenciando o rendimento do processo como um todo. Os metodos convencionais de analise proporcionam uma visao global do equipamento, de forma que nao se consegue avaliar comportamentos locais, principalmente dentro do equipamento. Utilizando-se uma modelagem ponto a ponto, atraves da fluido dinâmica computacional, mesmo com fortes simplificacoes, atraves de uma analise bidimensional associada ao conhecimento experimental, e possivel propor um mecanismo para o processo inicial de erosao, juntamente com a apresentacao dos perfis de velocidade, pressao e temperatura. O pacote fluido dinâmico CFX-4.3 da AEA Technology Inc. foi utilizado para obtencao dos res...

Research paper thumbnail of A Computational Model For The Prediction Of The Effect Of Multiple Effluent Discharges In A Large River Section

WIT Transactions on Ecology and the Environment

A future lack of water over the next decades has been observed by many studies. Much effort has b... more A future lack of water over the next decades has been observed by many studies. Much effort has been devoted to find strategies which will help to manage water resources properly. Theoretical studies have been used recently since the scope of computational fluid dynamics (CFD) has increased, allowing its use in the issue of water quality. In this scenario, it is important to develop new techniques to predict the environmental impact of emissions in rivers so that strategies can be devised to decrease the effects of pollution. This work presents an in-house three-dimensional CFD model to simulate the dispersion of substances along a river with multiple effluent discharges. The Cartesian coordinate system has been chosen to represent the river. The model also assumes the river has no curves. Although simple, this geometry is able to represent in a simple manner the behavior of most rivers. The finite volume method is used to approximate the momentum, mass and species conservation equations. Turbulence is taken into account by a zero-order equation model. The developed model considers the presence of multiple effluent discharges along the river. Some experimental validation is also presented in the work. Results show that the proposed methodology is a good tool for the evaluation of the environmental impact caused by pollutant emissions, mainly in rivers with multiple discharges from many industries. The software is very fast, especially when compared to other CFD packages.

Research paper thumbnail of Implementação De Um Modelo Com O Uso De CFD Para a Obtenção De Uma Correlação Do Número De Nusselt Em Tanques De Mistura Com Serpentinas Helicoidais

Anais do XX Congresso Brasileiro de Engenharia Química, 2015

RESUMO-Tanques de mistura com aquecimento são utilizados em diversos processos químicos. Quando r... more RESUMO-Tanques de mistura com aquecimento são utilizados em diversos processos químicos. Quando reações endotérmicas ou exotérmicas com uma alta liberação ou absorção de energia ocorrem nestes equipamentos, camisas e serpentinas helicoidais ou axiais são empregadas ao mesmo tempo para promover uma maior superfície de transferência de calor. O maior problema associado às serpentinas helicoidais é que estas podem limitar o fluxo no interior do reator, pois as serpentinas fornecem resistência à circulação do fluido. O objetivo deste trabalho foi desenvolver um modelo 3D com o uso da fluidodinâmica computacional para simular a troca térmica dentro destes equipamentos. Resultados iniciais indicam que o modelo em CFD reproduz a correlação de Nusselt obtida experimentalmente.

Research paper thumbnail of Impeller characterization and selection: Balancing efficient hydrodynamics with process mixing requirements

AIChE Journal, 2012

Current literature relies almost exclusively on the power number to compare and characterize impe... more Current literature relies almost exclusively on the power number to compare and characterize impellers. Industrial mixing requirements may rely on conditions far away from the impeller. A protocol is proposed to compare impellers designed for turbulent mixing on the basis of impeller hydrodynamic performance and mixing process objectives. A hydrofoil impeller (KPC), and a mixed-flow impeller (45 down-pumping PBT), each at two diameters, were used to test the protocol. Fourteen measures were considered. Five are recommended for full characterization: power number, momentum number, and peak rate of dissipation of turbulent kinetic energy to characterize conditions at the impeller; power at just-suspended speed to compare the efficiency of solids suspension at the bottom of the tank; and point of air entrainment as a measure of turbulence penetration to the free surface. These five measures provide complete information about mixing performance and good differentiation between the impellers and geometries. V V

Research paper thumbnail of A New Computational Fluid Dynamic (CFD) Model for the Estimation of Effluent Dispersion In Rivers Sections

The 2008 Annual …, 2008

186be. A New Computational Fluid Dynamic (CFD) Model for the Estimation of Effluent Dispersion In... more 186be. A New Computational Fluid Dynamic (CFD) Model for the Estimation of Effluent Dispersion In Rivers Sections. Jose Roberto Nunhez 1 , Marcio Bezerra Machado 2 , Mateus Lazzarini Furlan 3 , Luis Tadeu Furlan 4 , and E. Tomaz 2 . (1) UNICAMP, Fac. Eng. ...