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ISHS Acta Horticulturae 491: International Symposium Greenhouse Management for Better Yield & Quality in Mild Winter Climates

VENTILATION INDUCED INTERIOR AIR MOVEMENT IN LARGE SCALE VENLO-TYPE GREENHOUSES

Authors:   J. Deltour, S. Wang
Keywords:   Natural ventilation, greenhouse climate, airflow pattern
Abstract:
Ventilation induced interior air movement was experimentally investigated in a 1700 m2 Venlo-type glasshouse. Air velocity measurements were performed by means of an automatized system using 12 two-dimensional sonic anemometers which simultaneously measured the horizontal air velocity components parallel and normal to the ridge at a 3 Hz frequency. The experiments showed that the horizontal and vertical profiles of the interior air velocity were successfully described by some simple (linear) regression functions of non-dimensional numbers expressing the local air velocity with respect to the wind speed above the greenhouse or the interior air velocity at 40 cm above the ground, respectively. Air streams through the ventilation openings were measured by means of 24 one-dimensional sonic anemometers. Based on the knowledge of the ventilation pattern inside the greenhouse for several values of the wind speed, a ventilation function could be established. The expression obtained in that way agreed well with that obtained by means of the dynamic heat balance method.
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