Luiz A. F. Coelho
Universidade do Estado de Santa Catarina
MiscibilityUltimate tensile strengthSupercritical fluidGlass transitionCuring (chemistry)CopolymerComposite materialEpoxyThermosetting polymerChemistrySelf-diffusionMaterials scienceDifferential scanning calorimetryChemical engineeringElastic modulusCrystallinityCarbon nanotubePolymerMolecular dynamicsNanocompositeThermodynamics
63Publications
17H-index
830Citations
Publications 61
Newest
#1Fabrício Da Costa Silva (UFRJ: Federal University of Rio de Janeiro)H-Index: 1
#2Luiz A. F. Coelho (UDESC: Universidade do Estado de Santa Catarina)H-Index: 17
Last. Marcio J. E. De M. Cardoso (UFRJ: Federal University of Rio de Janeiro)H-Index: 8
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In this work, we propose a new model to calculate viscosity of dense fluids based on the reference part of the Weeks–Chandler–Andersen perturbation theory. The reference fluid intermolecular interactions are given by a repulsive soft-sphere potential. The viscosity is calculated by means of a Chapman–Enskog equation corrected to high densities coupled with a density- and temperature-dependent effective diameter. The viscosity is also calculated by molecular dynamics simulations in a wide range o...
7 CitationsSource
#1Luiz A. F. CoelhoH-Index: 17
#2J. V. de OliveiraH-Index: 1
Last. Michael A. Matthews (USC: University of South Carolina)H-Index: 24
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Abstract Diffusion is an important practical consideration in the design of processes involving mass transfer. From a theoretical standpoint, it is a relevant information when developing an understanding of dense-phase fluid structure. Recently, due to increase in computational power, the molecular dynamics (MD) technique has been applied extensively to the study of thermodynamic and transport properties. Diffusion is the most studied transport coefficient since it is an individual property, not...
10 CitationsSource
#1Hong Fu (USC: University of South Carolina)H-Index: 4
#2Luiz A. F. Coelho (USC: University of South Carolina)H-Index: 17
Last. Michael A. Matthews (USC: University of South Carolina)H-Index: 24
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Dense CO2 extraction is an emerging technology in cleaning and remediation. The successful design and implementation of processes based on this technology require the accurate determination of solute diffusivities in the systems. In this work, a Taylor dispersion apparatus was constructed for measuring binary diffusion coefficients of benzoic acid, biphenyl, and p-dichlorobenzene in dense CO2 at temperatures of 293.15, 298.15, 308.15, 318.15, and 323.15 K and pressures from approximately 71 to 1...
28 CitationsSource
The Taylor−Aris dispersion technique was employed to measure the binary diffusion coefficients of five solid solutes (phenanthrene, biphenyl, benzoic acid, 1,4-dichlorobenzene, and phenol) in supercritical carbon dioxide within the pressure range from 75 to 170 bar at 308.2 K. Measurements were made at very dilute concentrations, in the vicinity of the pure CO2 critical point and also near the solid/supercritical fluid lower critical end point. At 308.2 K (4 K above the critical temperature of t...
21 CitationsSource
#1Luiz A. F. Coelho (UFRJ: Federal University of Rio de Janeiro)H-Index: 17
#2José Vladimir de Oliveira (UFRJ: Federal University of Rio de Janeiro)H-Index: 21
Last. Frederico W. Tavares (UFRJ: Federal University of Rio de Janeiro)H-Index: 24
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A procedure to correlate self-diffusion coefficients in dense fluids by using the perturbation theory (WCA) coupled with the smooth-hard-sphere theory is presented and tested against molecular simulations and experimental data. This simple algebraic expression correlates well the self-diffusion coefficients of carbon dioxide, ethane, propane, ethylene, and sulfur hexafluoride. We have also performed canonical ensemble molecular dynamics simulations by using the Hoover-Nose thermostat and the mea...
10 CitationsSource
#1Cláudio Dariva (UFRJ: Federal University of Rio de Janeiro)H-Index: 33
#2Luiz A. F. Coelho (UFRJ: Federal University of Rio de Janeiro)H-Index: 17
Last. J. Vladimir Oliveira (UFRJ: Federal University of Rio de Janeiro)H-Index: 50
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In this work the Enskog solution of the Boltzmann equation, as corrected by Speedy, together with the Weeks-Chandler-Andersen (WCA) perturbation theory of liquids is employed in correlating and predicting self-diffusivities of dense fluids. Afterwards this theory is used to estimate mutual diffusion coefficients of solutes at infinite dilution in sub and supercritical solvents. We have also investigated the behavior of Fick diffusion coefficients in the proximity of a binary vapor-liquid critica...
15 CitationsSource
#1Cláudio Dariva (UFRJ: Federal University of Rio de Janeiro)H-Index: 33
#2Luiz A. F. Coelho (UFRJ: Federal University of Rio de Janeiro)H-Index: 17
Last. J. Vladimir Oliveira (UFRJ: Federal University of Rio de Janeiro)H-Index: 50
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Abstract In this work, the Enskog solution of the Boltzmann equation coupled with the Weeks–Chandler–Andersen perturbation theory of liquids is shown to be an excellent approach for correlating and predicting self-diffusivities of dense fluids. Afterwards, this theory is used to estimate mutual-diffusion coefficients of solutes at infinite dilution in sub- and supercritical solvents. The approach presented here is based on the smooth hard-sphere theory, in which the coupling factor of the rough ...
28 CitationsSource
#1Luiz A. F. Coelho (UFRJ: Federal University of Rio de Janeiro)H-Index: 17
#2José Vladimir de Oliveira (UFRJ: Federal University of Rio de Janeiro)H-Index: 21
Last. José Carlos Pinto (UFRJ: Federal University of Rio de Janeiro)H-Index: 39
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This work intend to model supercritical fluid extraction of Rosemary essential oil (Rosmarinus officinallis l.) obtained at 310.15 and 320.15 K at 100, 120, 140 and 160 bar and to analyze the parameters and the objective function with statistic tools. We have been used the finite differences method to solve the model, the parameters were estimated using the maximum-likelihood method. The results have shown that the model can reproduce the experimental data of supercritical fluid extraction.
3 CitationsSource
A teoria das perturbacoes de Weeks-Chandler-anderson (WCA) juntamente com a solucao de Enskog da equacao de Boltzmann para fluidos densos de esferas rigidas e aplicada a correlacao e predicao de difusividades de misturas a elevadas pressoes. O denominado "efeito de densidade" na solucao original de Enskog para fluidos densos e analisado empregando-se a funcao de correlacao aos pares de Carnahan-Starling, e as correlacoes semi-empiircas de Speedy e Harris, correlacoes estas desenvolvidas atraves ...
1 CitationsSource
#1Luiz A. F. Coelho (UFRJ: Federal University of Rio de Janeiro)H-Index: 17
#2José Vladimir de Oliveira (UFRJ: Federal University of Rio de Janeiro)H-Index: 21
Last. Fernando Mauro LançasH-Index: 34
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The effects of temperature and solvent density on the characteristics of the extracts obtained from supercritical fluid extraction (SFE) of the volatile compounds from Brazilian rosemary (Rosamarinus officianalis L., Labiatae) using carbon dioxide (CO2) as solvent were investigated. The experiments were performed in a semi-batch laboratory scale home-made unit at two temperatures, viz. 310.15 and 320.15 K, over the pressure range of 100-160 bar. This study allowed to determine the crossover poin...
20 CitationsSource