Effect of greenhouse ventilation on humidity of inside air and in leaf boundary-layer

Boulard, Thierry; Fatnassi, H.; Roy, J.C.; Lagier, J.; Fargues, Jacques; Smits, Nathalie; Rougier, M.; Jeannequin, Benoit

doi:10.1016/j.agrformet.2004.04.005

Cited by 60 publications

(47 citation statements)

References 13 publications

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“…Similarly, one can expect that more air movement and consequently lower relative humidity occurred near the doors of the greenhouses, which were frequently opened during the growing season. This hypothesis is compatible with existing information on the heterogeneity of distribution of air movement and other physical parameters in different types of greenhouses (Boulard et al, 1997(Boulard et al, , 2004Wang and Boulard, 2000). Furthermore, comparisons of aeration regimes in tomato greenhouses in Portugal showed that enhanced aeration decreased the development of grey mould Meneses et al, 1994).…”

Section: Spatial Heterogeneity Of Disease Development and Plant Mortasupporting

confidence: 74%

Grey mould development in greenhouse tomatoes under drip and furrow irrigation

Aissat

Nicot²,

Guechi

et al. 2008

Agron. Sustain. Dev.

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Section: Spatial Heterogeneity Of Disease Development and Plant Mortasupporting

confidence: 74%

Grey mould development in greenhouse tomatoes under drip and furrow irrigation

Aissat

Nicot²,

Guechi

et al. 2008

Agron. Sustain. Dev.

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“…Studies relating to this parameter are quite limited. According to Boulard et al (2004) increase of greenhouse height causes a decrease in greenhouse temperature.…”

Section: Geometry Definitionmentioning

confidence: 99%

Evaluation of temperature distribution in different greenhouse models using computational fluid dynamics (CFD)

Cemek¹,

Atiş²,

Küçüktopcu³

2017

Anadolu Journal of Agricultural Sciences

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Areas of air inlet and outlet openings, orientation of openings, height difference between air inlet and outlet openings, wind direction, greenhouse geometry, and type of plant grown are among the many factors that should be taken into consideration in designing an effective ventilation system for greenhouses. In this study, five different model plastic greenhouses with different sidewall heights, air inlet and outlet opening areas and roof shapes were used to evaluate the ventilation efficiencies and they were compared with a conventional type of the region. A computational fluid dynamics (CFD) program was used to evaluate the behavior of the internal environment (internal flow rate and temperature distributions) and natural ventilation rates for all model greenhouses and a conventional greenhouse involved in the study. External wind speeds of 0.5, 1, and 2 ms -1 were used in the simulations for all conditions. The results of simulations and experimental studies were evaluated and used for recommendation of a better greenhouse model for this region. CFD software "FLUENT" was used to determine the effectiveness of greenhouse ventilation system and k-ɛ Renormalization Group (RNG) turbulence model was used in solutions.

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“…Portanto, nem mesmo a instabilidade atmosférica, oriunda da aproximação das frentes frias durante o período experimental, foi capaz de intensificar o movimento do ar no interior da casa de vegetação. Resultados semelhantes, relacionados a baixos valores de velocidade do ar em ambientes protegidos, também foram relatados por Wang et al (1999), Boulard et al (2004), Molina-Aiz et al (2004) e Bartzanas et al (2005).…”

Section: Resultsunclassified

“…ou valores extremamente baixos, como os observados em ambiente protegido (Wang et al, 1999;Boulard et al, 2004;Molina-Aiz et al, 2004;Bartzanas et al, 2005). Com a utilização do fator de desacoplamento, é importante observar que a velocidade do ar não é mais necessária para a estimativa do termo r a .…”

Section: Penman-monteith Modificado Para Ambientes Protegidos (Pmap)unclassified

Coeficiente de cultura da alface hidropônica baseado no conceito de graus-dia

et al. 2010

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Degree-day-based crop coefficient for hydroponic lettuceThe main objective in this work was to propose the adoption of a thermal crop coefficient by using accumulated degree-days after transplanting to estimate lettuce daily evapotranspiration (ET c ) for the cultivars Grand Rapids, Regina and Great Lakes in a NFT hydroponic system under protected environment. Subsequently, the adjusted model to the observed values of K c was used for estimating ET c during the growing period after transplanting with the following methods: Penman-Monteith parameterized by FAO in 1998 (PMF); Penman-Monteith modified for aerodynamic characteristics in protected environment (PMAP); simplified Penman-Monteith (PMAPS); Priestley-Taylor (PT); solar radiation (RS); and simplified solar radiation (RSS). It was verified that the sigmoid model with four parameters fitted well to observed values of K c ,giving adjusted coefficients of determination of 0,9874, 0,9784 and 0,9767 for cultivars Grand Rapids, Regina and Great Lakes, respectively. As far as daily ET c estimates are concerned, the methods PMF, PMAP and RS presented better statistical performance as compared to the methods PMAPS, PT and RSS, regardless of the evaluated cultivar. However, the method PMF systematically underestimated ET c in the lettuce initial growth period. Coeficiente de cultura da alface hidropônica baseado no conceito de graus-dia O objetivo principal deste trabalho foi propor a adoção de um coeficiente de cultura térmico, com a aplicação do conceito de graus-dia acumulados após o transplantio, para estimativa da evapotranspiração diária (ET c ) dos cultivares de alface Grand Rapids, Regina e Great Lakes em sistema hidropônico do tipo NFT ("nutrient film technique"), em ambiente protegido. Posteriormente, o modelo matemático ajustado aos valores observados de K c (coeficiente de cultura) foi utilizado para a estimativa de ET c no período pós-transplantio por meio dos métodos: Penman-Monteith parametrizado pela FAO, em 1998 (PMF); Penman-Monteith modificado para condições aerodinâmicas, características de ambientes protegidos (PMAP); Penman-Monteith para ambiente protegido simplificado (PMAPS); Priestley-Taylor (PT); Radiação solar (RS); e Radiação solar simplificado (RSS). Verificou-se que o modelo sigmoidal com quatro parâmetros ajustou-se bem aos valores observados de K c , proporcionando coeficientes de determinação ajustados de 0,99, 0,98 e 0,98 para os cultivares Grand Rapids, Regina e Great Lakes, respectivamente. No que se refere às estimativas diárias de ET c , os métodos PMF, PMAP e RS apresentaram melhor desempenho estatístico em relação aos métodos PMAPS, PT e RSS, independentemente do cultivar avaliado. No entanto, o método PMF subestimou sistematicamente a ET c no período inicial de crescimento da alface.Palavras chave: Cultivo protegido, tempo térmico, técnica de circulação laminar de nutrientes.

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Effect of greenhouse ventilation on humidity of inside air and in leaf boundary-layer

Cited by 60 publications

References 13 publications

Grey mould development in greenhouse tomatoes under drip and furrow irrigation

Grey mould development in greenhouse tomatoes under drip and furrow irrigation

Evaluation of temperature distribution in different greenhouse models using computational fluid dynamics (CFD)

Coeficiente de cultura da alface hidropônica baseado no conceito de graus-dia

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