A CFD Evaluation of Naturally Ventilated, Multi-Span, Sawtooth Greenhouses

Kaçıra, Murat; Short, T. H.; Stowell, Richard R.

doi:10.13031/2013.17222

Cited by 54 publications

(28 citation statements)

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“…This is in agreement with Kacira et al (1998) who identified the necessity of having a roof vent to maintain the natural airflow pattern. Montero and Anton (2000) and Kalsoulas et al (2006) have also shown a greater greenhouse ventilation capacity when combine ridge vents with side vents under tropical conditions.…”

Section: Discussionsupporting

confidence: 92%

Natural ventilation in insect screened single span greenhouses under warm weather

Weerakkody¹,

Amarathunga²,

Warnakulasooriya³

et al. 2010

International Journal of Biological and Chemical Sciences

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The ventilation rates of different types of ridge vents in combination with insect-screened side vents were assessed in single greenhouses in terms of the difference in temperature and humidity inside and outside under tropical conditions. The A-frame (slanted roof) was comparatively advantageous over the conventional arch frame (curved roof) for keeping daytime temperature lower in single span greenhouse with insect-screened side vents (mesh size: 1 by 1 mm) and without roof vents. The inclusion of ridge vents further reduced the internal temperature and relative humidity (RH) in the A-frame greenhouse during the daytime. The opening area of the ridge vent within the range between 9.3% and 14% (of the floor area) did not significantly change the ventilation based internal temperature and RH when operated under low wind speeds (0.5 ± 0.5 m s -1 ). Meanwhile the effect of ridge orientation, with respect to wind direction, on greenhouse ventilation was not obvious in terms of temperature or RH under inconsistent wind directions and low wind speeds. Greenhouse ventilation positively responded to low winds (0.25 m s -1 ) by reducing internal temperature as well as RH. However, the response to a further increase in wind speed from 0.25 to 0.5 m s -1 was not significant. Based on climate control characteristics an A-frame single-span greenhouse design with double sided alternate ridge vents and insect-screened side vents could be appropriate for tropical climates under low wind speeds and inconsistent wind directions as a cost effective and user-friendly greenhouse design. Particularly, it is highly applicable for the small-scale controlled environment vegetable production in mid and low elevations in the wet zone of Sri Lanka.

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Section: Discussionsupporting

confidence: 92%

Natural ventilation in insect screened single span greenhouses under warm weather

Weerakkody¹,

Amarathunga²,

Warnakulasooriya³

et al. 2010

International Journal of Biological and Chemical Sciences

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“…Kacira et al 5 studied the effect of side and roof vent configurations on air exchange rates of sawtooth greenhouse designs. Mistriotis et al 7,8 evaluated the efficiency of greenhouse ventilation with two-dimensional cases for Mediterranean-type greenhouses.…”

Section: Effects Of Side Vents and Span Numbers On Wind-induced Naturmentioning

confidence: 99%

Effects of Side Vents and Span Numbers on Wind-Induced Natural Ventilation of a Gothic Multi-Span Greenhouse

Kaçıra

Sase

Okushima

2004

JARQ

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In this paper, the effects of wind speed, side ventilators and span numbers on gothic type multi-span greenhouse natural ventilation were studied by numerical simulation using the Computational Fluid Dynamics (CFD) approach. The realizable k-ε model was used for the turbulence model in the simulations. The results showed that the maximum greenhouse ventilation rate was achieved when both side and roof vents were used for ventilation. Without the existence of buoyancy effect in the computations, it was found that the ventilation rate increased linearly with the external wind speed in all the cases studied. The ratio of the opening of the ventilator area to the greenhouse floor area, 9.6%, was found to be small compared to the recommended ratios of 15-25%. The results showed that a significant reduction in ventilation rate was determined as the number of spans was increased and an exponential decay explained the relationship between the ventilation rate and the number of spans.

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“…In the greenhouse engineering community, many researchers have employed CFD to study the effects of greenhouse design (Bartzanas, Boulard, & Kittas, 2004;, Bournet, Ould Khaoua, Boulard, Migeon, & Chassériaux, 2007Hong et al, 2008;Kacira, Sase, & Okushima, 2004;Kacira, Short, & Stowell, 1998;Kittas and Bartzanas, 2007;Lee, Short, Sase, Okushima, & Qiu, 2000;Ould Khaoua, Bournet, Migeon, Boulard, & Chassériaux, 2006), specific equipment (Baeza et al, 2009;Fatnassi, Boulard, & Bouirden, 2003;Fatnassi, Boulard, Poncet, & Chave, 2006;Montero et al, 2013;Tamimi, Kacira, Choi, & An, 2013) and external weather conditions (Hong et al, 2008;Nebbali, Roy, & Boulard, 2012; Ould 400 K. He et al Khaoua et al, 2006;Teitel, Ziskind, Liran, Dubovsky, & Letan, 2008;Tong et al, 2009) on greenhouse climates. Their results provide valuable guidance for ventilation system management; however, they are limited to specific greenhouse structures and local climate conditions.…”

Section: Introductionmentioning

confidence: 99%

“…Their results provide valuable guidance for ventilation system management; however, they are limited to specific greenhouse structures and local climate conditions. So far, most numerical studies of natural ventilation have focused on greenhouse climate and ventilation performance during the summer (Baeza et al, 2009;Bartzanas et al, 2004;Fatnassi et al, 2003Fatnassi et al, , 2006Hong et al, 2008;Kacira et al, 1998Kacira et al, , 2004Kichah, Bournet, Migeon, & Boulard, 2012;Nebbali et al, 2012;Ould Khaoua et al, 2006;Teitel et al, 2008). Few have examined the effect of vent opening on greenhouse climates during the different seasons of summer and winter when natural ventilation is respectively used for cooling and dehumidification.…”

Section: Introductionmentioning

confidence: 99%

The effect of vent openings on the microclimate inside multi-span greenhouses during summer and winter seasons

Chen

Sun

et al. 2015

Engineering Applications of Computational Fluid Mechanics

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In research literature, little attention has been applied to the effect of vent openings on greenhouse climates during cooling and dehumidification processes with natural ventilation, which would provide guidelines for greenhouse management. To address this problem, a 3D CFD model was successfully designed based on 11-span plastic greenhouses. The model was validated with the measured air temperature and relative humidity, and then used to investigate the effects of vent configuration and opening size on the greenhouse climate. The simulations show that the vent configuration affects greenhouse microclimate patterns and the spatial and temporal variations of the internal climate. Meanwhile, the vent opening size affects greenhouse dehumidification time, air temperature and relative humidity during the dehumidification process. Finally, the assessments of ventilation performance highlight that the roof plus side opening is most suitable for summer cooling, while the roof opening is most suitable for winter dehumidification.

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A CFD Evaluation of Naturally Ventilated, Multi-Span, Sawtooth Greenhouses

Cited by 54 publications

References 0 publications

Natural ventilation in insect screened single span greenhouses under warm weather

Natural ventilation in insect screened single span greenhouses under warm weather

Effects of Side Vents and Span Numbers on Wind-Induced Natural Ventilation of a Gothic Multi-Span Greenhouse

The effect of vent openings on the microclimate inside multi-span greenhouses during summer and winter seasons

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