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Registros recuperados: 9
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A computational fluid dynamics study of hydrogen bubbles in an electrochemical reactor BABT
Cavalcanti,Renata da Silva; Farias Neto,Severino Rodrigues de; Vilar,Eudésio Oliveira.
Most electrochemical reactors present reactions with the growth and departure of gas bubbles which influence on the reactor hydrodynamics and this study is usually complex, representing a vast field for research. The present paper had as objective to study a bi-phase (gas-liquid) system aiming to foresee the influence of departure of hydrogen bubbles generated on effective electrode surface situated on cathodic semi-cell. Nevertheless, it was idealized that the gas was injected into the semi cell, through the effective electrode surface With this hypothesis, it was possible to study, and numerically analyze, the hydrodynamic behavior of the hydrogen bubbles in the interior of the study domain, applying concepts of computational fluid dynamics by using the...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Hydrogen; Bubble; CFD; Finite volumes; Electrochemical reactor.
Ano: 2005 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132005000400027
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Airflow and microclimate patterns in a one-hectare Canary type greenhouse: an experimental and CFD assisted study Inra
Majdoubi, H.; Boulard, T.; Fatnassi, H.; Bouirden, L..
This study presents an analysis of air circulation and microclimate distribution during daytime in a 1-hectare Canary type tomato greenhouse in the coastal area of southern Morocco. The investigation of the climate inside the greenhouse is based on a numerical simulation using a finite volumes method to solve the mass, momentum and energy conservation equations. The main novelty of this simulation lies in the realism of the 3D modelling of this very large agricultural structure with (i) a coupling of convective and radiative exchanges at the surface of the plastic roof cover, (ii) simulation of the dynamic influence of the insect screens and tomato crop on airflow movement, using the concept of porous medium, (iii) simulation, in each grid cell of the crop...
Tipo: Journal Article Palavras-chave: MODELE TRIDIMENSIONNEL; FILET ANTI-INSECTES GREENHOUSE; CFD; MODELLING; AIRFLOW; CLIMATE DISTRIBUTION; INSECT SCREENS.
Ano: 2009 URL: http://www.prodinra.inra.fr/prodinra/pinra/doc.xsp?id=PROD2010e4485b5e&uri=/notices/prodinra1/2010/03/
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Application of computational fluid dynamics on a study in swine facilities with mechanical ventilation system Scientia Agricola
Sousa Junior,Vilmar Rodrigues de; Sabino,Luana Araújo; Moura,Daniella Jorge de; Nunhez,José Roberto; Sonoda,Lilia Thays; Silva,Alexandre Oliveira; Prada,Ronald Jaimes; Fontoura,Diener Volpin Ribeiro; Seber,Rogério Torres.
ABSTRACT: Ventilation systems used in swine facilities deserve to be studied because they directly affect productivity in the pig farming sector. Bearing this in mind the uniformity of air distribution and temperature is essential to animal welfare in this breeding environment. Thus, the purpose of this study was to identify whether changes in air entrances and exhaust fan positioning could influence air velocity and temperature distribution. The experimental data were collected in a commercial full-scale sow facility. Validation was carried out by comparing the simulated air temperatures and data measured in the field. These results showed agreement between data with a maximum relative error of approximately 3 %. The real settings showed a gradual...
Tipo: Info:eu-repo/semantics/article Palavras-chave: CFD; Airflow pattern; Temperature distribution.
Ano: 2018 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162018000300173
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Determinación de los gradientes térmicos nocturnos en un invernadero usando dinámica de fluidos computacional Agrociencia
Espinal-Montes,Verónica; López-Cruz,I. Lorenzo; Rojano-Aguilar,Abraham; Romantchik-Kriuchova,Eugenio; Ramírez-Arias,Armando.
En regiones con climas secos y templados, como los del centro y norte de México, los productores de cultivos en invernadero enfrentan temperaturas nocturnas bajas, que se agudizan en algunas temporadas del año. En un invernadero éstas pueden contrarrestarse con sistemas de calefacción; pero cuando no se tiene el recurso, el ingreso de aire frío se evita con el cierre de ventanas. El objetivo del presente estudio fue desarrollar un modelo basado en Dinámica de Fluidos Computacional (CFD) para evaluar las variaciones de temperatura y flujo de aire nocturno en un invernadero en dos escenarios: ventanas laterales cerradas y abiertas. Los datos usados en las simulaciones fueron recolectados durante el invierno de 2012, en un invernadero tipo sierra con cubierta...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Modelo numérico; Inversión térmica; CFD.
Ano: 2015 URL: http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S1405-31952015000300001
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Enhancement of the greenhouse air ventilation rate under climate conditions of central Mexico Agrociencia
Romero-Gómez,Pedro; Choi,Christopher Y.; Lopez-Cruz,Irineo L..
Mexican plastic-covered greenhouses use natural ventilation as the main method to control temperature and humidity. However, no studies on the dynamic behavior of airflow and ventilation rates are available. In the present study, air exchange rates were analyzed in a naturally-ventilated greenhouse in Mexico using Computational Fluid Dynamics (CFD). To enhance greenhouse cooling, roof vent areas and screen characteristics were examined undef various scenarios to quantify ventilation rates. The air exchange rates through the tight insect screen (model S) were about 50 % of those achieved with actual and loose insect screen (model SF) at the same outside wind speed. Enlargement of the roof vent size ftom 6 % (current) to 15 % of the greenhouse-floor area...
Tipo: Info:eu-repo/semantics/article Palavras-chave: CFD; Greenhouse; Natural ventilation; Rates.
Ano: 2010 URL: http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S1405-31952010000100001
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Numerical study of upstream disturbances on the performance of electromagnetic and ultrasonic flowmeters Scientia Agricola
Palau,Carmen Virginia; Bomfim,Guilherme Vieira do; Azevedo,Benito Moreira de; Peralta,Iban Balbastre.
ABSTRACT Electromagnetic and ultrasonic flowmeters are high precision devices that can measure the water flow in pressurized irrigation networks. In these networks, the inadequate installation distance of flow control valves generates upstream disturbances which will increase measurement errors and reduce the accuracy of the equipment. Therefore, estimating these errors is important to establishing the correct installation distance of the hydraulic accessories and to ensuring the metrological reliability of the flowmeters. This work proposes a numerical study using Computational Fluid Dynamics to evaluate water flow behavior in pipes and estimate measurement errors caused by gate and butterfly valves in installation configurations found at pressurized...
Tipo: Info:eu-repo/semantics/other Palavras-chave: CFD; Pressurized irrigation; Water flowmeter; Water supply network.
Ano: 2020 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162020000401602
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Numerical Study of Wake Characteristics in a Horizontal-Axis Hydrokinetic Turbine Anais da ABC (AABC)
SILVA,PAULO A.S.F.; OLIVEIRA,TAYGOARA F. DE; BRASIL JUNIOR,ANTONIO C.P.; VAZ,JERSON R.P..
ABSTRACT Over the years most studies on wake characteristics have been devoted to wind turbines, while few works are related to hydrokinetic turbines. Among studies applied to rivers, depth and width are important parameters for a suitable design. In this work, a numerical study of the wake in a horizontal-axis hydrokinetic turbine is performed, where the main objective is an investigation on the wake structure, which can be a constraining factor in rivers. The present paper uses the Reynolds Averaged Navier Stokes (RANS) flow simulation technique, in which the Shear-Stress Transport (SST) turbulent model is considered, in order to simulate a free hydrokinetic runner in a typical river flow. The NREL-PHASE VI wind turbine was used to validate the numerical...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Hydrokinetic turbines; Wake characteristics; CFD; Turbulence.
Ano: 2016 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652016000602441
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Redes bayesianas aplicadas a un modelo CFD del entorno de un cultivo en invernadero Agrociencia
de la Torre-Gea,Guillermo; Delfín-Santisteban,Oscar; Torres-Pacheco,Irineo; Soto-Zarazúa,Genaro; Guevara-González,Ramón; Rico-García,Enrique.
Los avances en sistemas y recursos informáticos permiten desarrollar modelos para simular el comportamiento de los fluidos en invernaderos. Sin embargo, la predicción de los gradientes de masa y energía, en los invernaderos con el cultivo y ventilación natural, es difícil por la naturaleza estocástica del viento y las relaciones de dependencia entre la temperatura, CO2 y humedad relativa. Existen técnicas heurísticas, como las Redes Bayesianas, que ayudan a conocer las relaciones entre las variables que no pueden determinarse con herramientas estadísticas. El objetivo del presente estudio fue determinar la temperatura, concentración de CO2 y humedad relativa con respecto a la altura del cultivo, en un invernadero con ventilación natural, mediante Redes...
Tipo: Info:eu-repo/semantics/article Palavras-chave: CFD; Flujo de aire; Invernadero; Solanum lycopersicum; Ventilación natural.
Ano: 2014 URL: http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S1405-31952014000300006
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氣流屏蔽式施藥系統之設計評估 Taiwan Agricultural Research Institute
蔡致榮; H. Erdal Ozkan; Jyh-Rong Tsay;H. Erdal Ozkan.
[[abstract]]噴霧飄移乃農藥使用者與施藥地區民眾關心噴藥作業之焦點,而噴霧屏蔽之使用已成為減低噴霧飄移推薦策略中之一項技術,儘管許多研究已顯示機械式屏蔽對噴霧飄移之減低有正面效果,然而仍少有氣流屏蔽使用之資料,本研究中使用電腦流體動力模擬軟體FLUENT,基於比較飄移減低效果而進行氣流屏蔽式噴藥系統之設計評估,為便於相對比較,使用噴頭之傳統噴霧、氣輔噴霧與擬氣流剪切噴霧也包括於此模擬研究中。本研究所得之主要結論如后,並非所有氣流屏蔽之模擬情形皆可提供良好之飄移控制,為確保較佳之飄移減低效果並減少氣流屏蔽所需之功率需求,主要變數之最適操作參數經多因子變方分析選定為氣流速度40m/s、單位長度氣流流量1.7m3/s/m 以及氣流角度15度,其與某些有關氣輔噴霧與氣流剪切噴霧之前人研究結果相當吻合。除了氣輔噴霧與擬氣流剪切噴霧外,具氣流速度大於40m/s、單位長度氣流流量大於1.7 m3/s/m,以及氣流角度為15度之氣流屏蔽噴霧頗有希望成為減低噴霧飄移之另類技術。
Palavras-chave: 氣流屏蔽 施藥系統 設計評估 CFD FLUENT Pneumatic shielded; Spraying system; Design evaluation; CFD; FLUENT [[classification]]8.
Ano: 1998
Registros recuperados: 9
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