Greenhouses ventilation has a key role in inside climate control, both in winter and in summer conditions. Vent openings design and ventilation schedule have a great influence in promoting air exchanges, preventing excessive heat losses or extreme temperature and humidity build-ups. Greenhouse manufacturers need nowadays to fully consider every environmental control component in order to fit their structures to each locality. The aim of this work is to give a first evaluation of a new asymmetric vent openings design by means of computational fluid dynamics (CFD). The roof pitch combinations and the position of the vent openings offered by this design, present a wide range of adaptations for different local situations, thus allowing an expected optimal air exchange control. The roof has two pitches oriented face by face in the middle of the span, while the vent openings are oriented on the sides of the greenhouse. The vent windows are opened inward the glasshouse. Two vent configurations are considered (0°; 30° and 10°; 20°), taking into account the combination effect of the leeward and windward openings; in fact the longitudinal axis of the greenhouses is normal to the imposed wind direction thus exposing differently the roof opening combination set-ups. The boundary conditions used for the simulation are representative of winter conditions in the Northern Italy. Two wind speeds (2 and 4 m s-1) and two outside temperatures (-2 and 7°C) were used considering a set point inside temperature of 16°C. The asymmetric design of the roof and the consequent positioning of the roof vents opened inward, seems to offer a sufficient range of combinations in order to obtain the best performance of air circulation for any outside climatic conditions. The CFD simulations confirm to be a fine test tool for manufacturers.

Investigation on airflow and temperature distribution in single-span greenhouses with new asymmetric vent openings using CFD

CHELI, FEDERICO;ROCCHI, DANIELE;SCHITO, PAOLO;
2011-01-01

Abstract

Greenhouses ventilation has a key role in inside climate control, both in winter and in summer conditions. Vent openings design and ventilation schedule have a great influence in promoting air exchanges, preventing excessive heat losses or extreme temperature and humidity build-ups. Greenhouse manufacturers need nowadays to fully consider every environmental control component in order to fit their structures to each locality. The aim of this work is to give a first evaluation of a new asymmetric vent openings design by means of computational fluid dynamics (CFD). The roof pitch combinations and the position of the vent openings offered by this design, present a wide range of adaptations for different local situations, thus allowing an expected optimal air exchange control. The roof has two pitches oriented face by face in the middle of the span, while the vent openings are oriented on the sides of the greenhouse. The vent windows are opened inward the glasshouse. Two vent configurations are considered (0°; 30° and 10°; 20°), taking into account the combination effect of the leeward and windward openings; in fact the longitudinal axis of the greenhouses is normal to the imposed wind direction thus exposing differently the roof opening combination set-ups. The boundary conditions used for the simulation are representative of winter conditions in the Northern Italy. Two wind speeds (2 and 4 m s-1) and two outside temperatures (-2 and 7°C) were used considering a set point inside temperature of 16°C. The asymmetric design of the roof and the consequent positioning of the roof vents opened inward, seems to offer a sufficient range of combinations in order to obtain the best performance of air circulation for any outside climatic conditions. The CFD simulations confirm to be a fine test tool for manufacturers.
2011
International Symposium on High Technology for Greenhouse Systems: GreenSys2009
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11311/667831
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