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Mathematical simulation of radial heat transfer in packed beds by pseudohomogeneous modeling

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Particuology 2011年第2期9卷 107-113页

作者： Rodrigo Béttega Marcos Flávio Pinto Moreira Ronaldo Guimaraes Corrêa josé teixeira freire Federal University of Uberlandia/School of Chemical Engineering-Av.Jo o Naves ávila 2121 Uberlandia-MGCEP 38400-902Brazil Western Paraná State University-Rua da Faculdade 645 Jardim La SalleToledo-PRCEP 85903-000Brazil Federal University of S o Carlos/Department of Chemical Engineering-Rod.Washington Luiz km 235 S o Carlos-SPCEP 13565-905P.O.Box 676Brazil

Uniform flow regime and constant effective thermal conductivity inside packed beds are commonly accepted in the evaluation of the fluid dynamics and heat transfer in such systems. However, several authors have confirmed the presence of an oscillatory velocity profile caused by the effective contribu~ tion of porosity profile in the fluid dynamic behavior of packed beds, which directly influences the heat transfer inside the beds. This paper describes the application of a pseudo-homogeneous mathematical model for describing heat transfer in packed beds with oscillatory profiles of velocity and porosity, using a radius-dependent model for effective thermal conductivity kr. Several temperature profiles were obtained in a packed bed system with thermal source located on the wall. The simulated temperature and effective thermal conductivity obtained from simulations were compared with experimental data and calculation from a model based on uniform kr fitting. The results indicate that the proposed mathematical modeling was capable of better reDresenting the heat transfer in the packed bed.

关键词： Packed bedHeat transferPseudohomogeneous modeling

On the Influence of Particles Characteristics on Moisture Diffusivity during Drying of Granular Porous Media

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Advances in Chemical Engineering and Science 2014年第1期4卷 7-16页

作者： joséteixeira freire Fábio Bentes freire Hugo Perazzini Department of Chemical Engineering Federal University of Sao CarlosSao CarlosBrazil

The objective of this work was to study the diffusive mechanisms of mass transfer predominant in the drying of cylindrical unconsolidated granular porous media of different diameters of porous spherical particles. The experimental study was based on determining the drying kinetics of the porous media evaluated and on obtaining the physical properties regarding the particles that constitute them. Moisture data as a function of time were obtained by subjecting the porous media to an upward single-phase flow of heated air at a specific condition of temperature, velocity and absolute humidity of the drying air. The theoretical study regarded the determination of the overall effective diffusion coefficient based on mass transfer foundations. From the results obtained, it was verified that the drying kinetics, for a given operational condition applied, is influenced by particle diameter, and the effective superficial liquid diffusivity is the mechanism that limits the drying process.

关键词： Adsorption Desorption Diffusion Fick Knudsen Mass Transfer

Influence of Bed Geometry on the Drying of Skimmed Milk in a Spouted Bed

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Advances in Chemical Engineering and Science 2015年第4期5卷 447-460页

作者： Maisa Tonon Bitti Perazzini Fábio Bentes freire josé teixeira freire Department of Chemical Engineering Federal University of S&atildeo Carlos S&atildeo Carlos Brazil

In this present work, the fluidynamic and drying process of skimmed milk in conical and conical-cylindrical spouted bed was analyzed as a function of different bed geometry and operating conditions. It used three internal cone angles (45°, 60° and 75°), different loads of inert particles (1.50, 3.00 and 4.50 kg) and a fixed static bed height (20.50 cm). Polyethylene particles of 4.38 mm of diameter and 930.50 ± 0.3 kg/m3 of specific mass were used as inert particles. An artificial neural network model was trained to predict the peak pressure drop and the minimum spout velocity from an experimental data bank. The experimental results showed a significant effect of geometric characteristics of the bed on fluidynamics parameters. It was also observed for the operating conditions that conical spouted bed and cone angle of 45° were more suitable for drying skimmed milk. The neural network provided predictions in good agreement with experimental data.

关键词： Cone Angle Bed Geometry Bed Configuration Inert Particles Neural Network

Gas-Solid Flow Behavior in a Pneumatic Conveying System for Drying Applications: Coarse Particles Feeding with a Venturi Device

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Advances in Chemical Engineering and Science 2015年第3期5卷 225-238页

作者： Thiago Faggion de Pádua Rodrigo Béttega josé teixeira freire Department of Chemical Engineering Federal University of S&#227 o Carlos S&#227 o Carlos Brazil

The feeding of coarse particles (>0.5 mm diameter) directly into a riser operating at positive pressure is important for drying and pre-heating applications. The presence of the feeding device can lead to heterogeneity of drying and heating, and is the main factor responsible for pressure loss in short conveying systems. However, there is a lack of information concerning the axial and radial distributions of coarse particles in this type of configuration, despite the recent advances when dealing with fine particles (FCC catalyst). The present work therefore investigates a vertical venturi feeder with the conveying system operating in dilute-phase regime with 1 mm spherical glass particles. Experimental assays revealed the behavior of the mass flow rate of solids in the system, and pressure measurements were made along the riser in order to evaluate the accuracy of simulations. Euler-Euler simulations provided close estimation of the experimental pressure drop and the pressure drop according to distance in the linear region. Simulation of the fluid dynamics in the riser showed that solids clusters were formed at low concentrations near the feeding device, reflecting heterogeneity in the solid phase volume fraction.

关键词： Pneumatic Conveying Venturi Feeder Coarse Particles Drying CFD

Stochastic seismic inversion and Bayesian facies classification applied to porosity modeling and igneous rock identification

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Petroleum Science 2024年第2期21卷 918-935页

作者： Fábio Júnior Damasceno Fernandes Leonardo teixeira Antonio Fernando Menezes freire Wagner Moreira Lupinacci Exploratory Interpretation and Reservoir Characterization Group(GIECAR) Department of Geology and GeophysicsFederal Fluminense UniversityNiter oiRJ24210-346Brazil Petrobras Rio de JaneiroRJ20231-030Brazil National Institute of Science and Technology of Petroleum Geophysics(INCT-GP/CNPQ) Niter oiRJ24210-346Brazil

We apply stochastic seismic inversion and Bayesian facies classification for porosity modeling and igneous rock identification in the presalt interval of the Santos Basin. This integration of seismic and well-derived information enhances reservoir characterization. Stochastic inversion and Bayesian classification are powerful tools because they permit addressing the uncertainties in the model. We used the ES-MDA algorithm to achieve the realizations equivalent to the percentiles P10, P50, and P90 of acoustic impedance, a novel method for acoustic inversion in presalt. The facies were divided into five: reservoir 1,reservoir 2, tight carbonates, clayey rocks, and igneous rocks. To deal with the overlaps in acoustic impedance values of facies, we included geological information using a priori probability, indicating that structural highs are reservoir-dominated. To illustrate our approach, we conducted porosity modeling using facies-related rock-physics models for rock-physics inversion in an area with a well drilled in a coquina bank and evaluated the thickness and extension of an igneous intrusion near the carbonate-salt interface. The modeled porosity and the classified seismic facies are in good agreement with the ones observed in the wells. Notably, the coquinas bank presents an improvement in the porosity towards the top. The a priori probability model was crucial for limiting the clayey rocks to the structural lows. In Well B, the hit rate of the igneous rock in the three scenarios is higher than 60%, showing an excellent thickness-prediction capability.

关键词： Stochastic inversion Bayesian classification Porosity modeling Carbonate reservoirs Igneous rocks

Drying of pasty and granular materials in mechanically and conventional spouted beds

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Particuology 2019年第1期17卷 176-183页

作者： Robson C. Sousa Maria C. Ferreira Haritz Altzibar Fábio B. freire josé T. freire Rural and Chemical Engineering Department Federal University of Espirito SantoAlegreES. Brazil Chemical Engineering Department Federal University of Sao CarlosSao CarlosSPBrazil Chemical Engineering Department University of Basque CountryBilbaoSpain

A contactor vessel was built to operate as either a mechanically or a conventional spouted bed for the purpose of analyzing the drying of pasty and granular materials under comparable conditions in both configurations. A classical conical–cylindrical spouted bed with a 60° conical base and an air inlet central orifice was modified to enable the switch by introducing in the vessel’s center an open helicoidal conveyor screw placed above the air inlet orifice. This screw is removable and conveniently returns the bed to its conventional spouted configuration. Experiments on drying solutions (calcium carbonate suspensions and skimmed milk) and granular materials (porous alumina particles) were performed for various bed parameter settings. The spouting pressure drop, outlet air temperature, and relative humidity were measured over time under different conditions. Mechanical agitation is proved effective in drying diluted carbonate calcium liquid suspensions and coarse porous alumina particles at an air velocity approximately 50% lower in comparison to drying in a conventional spouted bed. The conventional spouted bed performed better at drying liquid skimmed milk as the mechanical agitation combined with the axial inlet air flow is not effective in mitigating sticking and powder agglomeration in the bed when handling pastes of complex composition. Introducing mechanical agitation in the designed setup broadens the operating range of a conventional spouted bed with axial air flow in the inlet.

关键词： Characteristic curve Drying kinetic Spouted-bed dynamics Mechanical agitation Alumina particles Paste drying

Leaf water potential and gas exchange of eucalypt clonal seedlings to leaf solar protectant

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Journal of Forestry Research 2019年第1期30卷 57-64页

作者： Talita Miranda teixeira Xavier josé Eduardo Macedo Pezzopane Ricardo Miguel Penchel josé Ricardo Macedo Pezzopane Departamento de Ciências Florestais e da Madeira Universidade Federal do Espírito Santo Fibria Celulose S.A Rodovia General Euryale Jesus Zerbini Embrapa Pecuária Sudeste

This experiment was carried out in acclimatized greenhouses with seedlings of two hybrid clones of Eucalyptus urophylla×Eucalyptus grandis. A sunscreen protector consisting of 62.5% calcium carbonate was sprayed on the seedlings at weekly intervals. Water stress was induced by suspending irrigation until the soil reached 30% available water and water was then replaced so that it returned to field capacity. Gas exchange and leaf water status were measured after 50 days. The experiment was set up in a 4×2 factorial randomized block design in four distinct environments:(1) temperatures less than 21.2℃ and vapor pressure deficit of 0.15 kPa;(2) intermediate temperatures of 24.2℃ and vapor pressure deficit of 0.69 kPa;(3) high temperatures of 27.0℃ and high vapor pressure deficit of 1.4 kPa; and,(4) high temperature of 27.0℃ and vapor pressure deficit below 1.10 kPa. Two leaf sun protector treatments were used, with five replications each. High atmospheric demand acted as a stress factor for the seedlings during the initial growth *** of leaf sunscreen protector provided beneficial effects in maintaining optimum water status and gas exchanges of the plants under water stress.

关键词： Eucalyptus urophylla×Eucalyptus grandis Calcium carbonate Water stress Atmospheric demand

Dealing with Multisource Information for Estuarine Flood Risk Appraisal in Two Western European Coastal Areas

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International Journal of Disaster Risk Science 2022年第2期13卷 199-213页

作者： Ana Rodrigues Rilo Alexandre Manuel de Oliveira Soares Tavares Paula Maria dos Santos freire josé Luis Zêzere Estuarine and Coastal Zones Unit LNEC-National Civil Engineering Laboratory.1700-075 LisbonPortugal Centre of Geographical Studies Institute of Geography and Spatial PlanningUniversidade de Lisboa1700-066 LisbonPortugal Centre for Social Studies and Earth Sciences Department Coimbra University3030-790 CoimbraPortugal

Estuaries are usually affected by compound flooding triggers that cause diverse territorial *** fluvial flood risk assessment frameworks are well established in the literature,integrated management instruments that deal with estuarine flood risk remain incomplete and often *** research presents a methodology to extract relevant information from multiple sources post-event and a database building process that is applied to two contrasting estuaries(the Tagus River estuary in Portugal,and the Shannon River estuary in Ireland)in the Western European coastal ***,a total of 274 documents were analyzed and the information was stored in two *** correspondence analysis was applied to extract the most informative and relevant estuarine flood *** integrated estuarine flood risk assessment framework is presented and discussed based on the extracted *** framework is driven by two distinct dimensions(oceanic and hydrographic)and revealed the transversal position of triggers of estuarine floods,reflecting the compounding effects usually present in these *** results also highlight two levels of flood risk mostly based on damage typology.

关键词： Estuarine floods Estuarine flood indicators Multiple correspondence analysis Post-hazard multisource information Western Europe

Application of data science in the prediction of solar energy for the Amazon basin:a study case

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Clean Energy 2023年第6期7卷 1344-1355页

作者： AndréLuis Ferreira Marques Márcio joséteixeira Felipe Valencia de Almeida Pedro Luiz Pizzigatti Corrêa Polytechnic School of the University of Sao Paulo Av.Prof.Luciano Gualberto380-ButantaSao Paulo-SP05508-010Brazil Institute of Physics of the University of Sao Paulo Brazil

The need for renewable energy sources has challenged most countries to comply with environmental protection actions and to handle climate *** energy figures as a natural option,despite its *** has a green energy matrix with significant expansion of solar form in recent *** preserve the Amazon basin,the use of solar energy can help communities and cities improve their living standards without new hydroelectric units or even to burn biomass,avoiding harsh environmental *** novelty of this work is using data science with machine-learning tools to predict the solar incidence(W.h/m^(2))in four cities in Amazonas state(north-west Brazil),using data from NASA satellites within the period of ***-tree-based models and vector autoregressive(time-series)models were used with three time aggregations:day,week and *** predictor model can aid in the economic assessment of solar energy in the Amazon basin and the use of satellite data was encouraged by the lack of data from ground *** mean absolute error was selected as the output indicator,with the lowest values obtained close to 0.20,from the adaptive boosting and light gradient boosting algorithms,in the same order of magnitude of similar references.

关键词： solar energy renewable energy Amazon basin machine learning time series data science decision-trees ensemble vector autoregression