Simulation and Control of Ventilation Rates in Greenhouses

Dayan, J.; Strassberg, Y.; Dayan, E.

doi:10.17660/actahortic.2001.566.6

Cited by 7 publications

(9 citation statements)

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“…A second approach to study natural ventilation in greenhouses, has been based on mass and energy balances of unsteady state (Fernández and Bailey, 1992;Teitel and Tanny, 1999;Dermati et al, 2001;Dayan et al, 2001;Dayan et al, 2002;Dayan et al, 2004;Majdoubi et al, 2007). In this case, ventilation rates appear in the Un segundo enfoque para estudiar la ventilación natural en invernaderos, se ha basado en balances de masa y energía en estado no estacionario (Fernandez y Bailey, 1992;Teitel y Tanny, 1999;Dermati et al, 2001;Dayan et al, 2001;Dayan et al, 2002;Dayan et al, 2004;Majdoubi et al, 2007). En este caso, las tasas de ventilación aparecen en las ecuaciones diferenciales que predicen el comportamiento tanto de la temperatura como la humedad dentro del invernadero.…”

Section: Introductionunclassified

Determinación de las tasas de ventilación natural en un invernadero mediante modelos teóricos y gases trazadores

Trujano

Cruz

2018

Remexca

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La mayoría de los invernaderos en México utilizan ventilación natural como mecanismo principal de controlar el clima. La cuantificación de las tasas de ventilación es difícil porque éstas dependen del efecto de la f luctuación de viento, resistencia de las ventanas al paso del aire y geometría del invernadero en el campo de presiones del viento sobre la estructura. El objetivo del presente trabajo fue determinar las tasas de ventilación natural de un invernadero, bajo tres configuraciones de ventilación: ventanas laterales, cenitales y laterales-cenitales, mediante el método dinámico de gases trazadores. Se compararon mediciones contra predicciones de modelos teóricos de ventilación natural y se analizó el efecto de velocidad del viento sobre las tasas de ventilación. El invernadero está ubicado en el campo experimental San Ignacio en la Universidad Autónoma Chapingo, Chapingo, México. El experimento se realizó en 2010 y el invernadero estuvo libre de cultivo. El gas trazador utilizado fue dióxido de carbono. Para la estimación de parámetros se usó el algoritmo de mínimos cuadrados no lineales. Los resultados mostraron que las tasas de ventilación son dependientes de la velocidad del viento y de la configuración de ventanas existente. Las tasas de ventilación más altas se observaron cuando ambas ventanas laterales y cenitales estuvieron abiertas. Los modelos teóricos predijeron de manera aceptable las tasas de ventilación tomando en cuenta los valores de los estadísticos coeficientes de determinación y cuadrado medio de error, así como el comportamiento de la línea 1:1 entre predicciones y mediciones.

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Section: Introductionunclassified

Determinación de las tasas de ventilación natural en un invernadero mediante modelos teóricos y gases trazadores

Trujano

Cruz

2018

Remexca

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“…There have been many studies to determine a kind of optimal geometric design of greenhouses that encourage improvements in weather conditions and the use of new technologies such as monitoring systems in real time, allowing improvements in automation using Web technology (Pontikakos, 2005). Other studies have focused on the evaluation of misting systems (Kim et al, 2007;Gázquez et al 2008), forced ventilation (Dayan et al, 2004, Baeza et al, 2008and Hughes and Abdul 2010) looking for energy savings. As simulation technology and computing power have improved, accuracy and realism in research based on CFD models, has increased as well, by defining more detailed models and by the use of textures that define the materials of the facilities.…”

Section: Main Results Of Cfd Models In Greenhousesmentioning

confidence: 99%

“…A numerical investigation by Rousseau (2008) on a prototype air-forced unit for crop growth chambers obtained simulations that show a nonlinear relationship between airflow rate and opening vents, showing the mixing zone. Dayan et al (2004) developed another simplified model to demonstrate the calculation of plant temperature when applying forced ventilation for climate control in greenhouses. The use of a device air flow deflector below the roof vents proved to increase air exchange in the area of cultivation effectively.…”

Section: Forced Ventilationmentioning

confidence: 99%

“…For instance; , based on studies by Nederhoff (1985) and Lee and Short (1998), assumed that a crop of 90 cm high and low density decreases between 12 and 15% greenhouse ventilation. Dayan et al (2004) built a representative model of a greenhouse for three vertical segments, horizontally oriented to the directions of energy and vapor transfer between the segments containing plants, considering the external weather. They concluded that Representative Plant Temperatures (RPTs) can be calculated instead of measured.…”

Section: Incorporation Crop Effects and Crop Modelingmentioning

confidence: 99%

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Advances in Computational Fluid Dynamics Applied to the Greenhouse Environment

Flores-Velázquez¹,

Torre-Gea²,

Rico-García³

et al. 2012

Applied Computational Fluid Dynamics

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“…Although it does not provide sufficient information on the geometric characteristics of the mesh, this term has been used in numerous scientific articles (e.g. Fatnassi et al, 2000;Linker et al, 2002;Dayan et al, 2004;Katsoulas et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Field analysis of the deterioration after some years of use of four insect-proof screens utilized in Mediterranean greenhouses

López-Martínez

Valera

Molina-Aiz

et al. 2013

Span. j. agric. res.

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The installation of insect-proof screens on greenhouse vents is one of the principal methods of protection against harmful insects for crops. Their main disadvantage lies on their negative effects on natural ventilation and greenhouse microclimate, which have been the focus of studies by several authors. However, few works have analysed the effect of accumulated dust and dirt on these screens. The present study has analysed four anti-insect screens, comparing their geometric characteristics before installation and after three to four years of use. Two negative effects have been observed and quantified: deterioration of the threads that make up the screen and reduction of porosity due to accumulated dirt in the pores. This deterioration over time gives leads to a mean increase in thread diameter of 3.1%, as well to a mean decrease in the pore size of 6.2% and 2.3% in the weft (Lpx) and the warp (Lpy), respectively. In fact, the insect-proof screen porosity (φ) decreased due to the deterioration of the threads by an average of 6.5%, in addition to an average 20.3% reduction due to the accumulation of dirt in the pores, making a total reduction in porosity of 26.8%. This decrease in porosity leads to lower greenhouse ventilation rates, and is therefore detrimental for the greenhouse microclimate. Consequently, it is recommended that insect-proof screens in arid areas such as Almería (Spain), with abundant dust suspended in the atmosphere, be washed monthly using water sprayed at high pressure.

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Simulation and Control of Ventilation Rates in Greenhouses

Cited by 7 publications

References 0 publications

Determinación de las tasas de ventilación natural en un invernadero mediante modelos teóricos y gases trazadores

Determinación de las tasas de ventilación natural en un invernadero mediante modelos teóricos y gases trazadores

Advances in Computational Fluid Dynamics Applied to the Greenhouse Environment

Field analysis of the deterioration after some years of use of four insect-proof screens utilized in Mediterranean greenhouses

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