SE—Structures and Environment: Effect of Ventilator Configuration on Wind-driven Ventilation in a Crop Protection Structure for the Tropics
✍ Scribed by J.I. Montero; G.R. Hunt; R. Kamaruddin; A. Antón; B.J. Bailey
- Publisher
- Elsevier Science
- Year
- 2001
- Tongue
- English
- Weight
- 302 KB
- Volume
- 80
- Category
- Article
- ISSN
- 0021-8634
No coin nor oath required. For personal study only.
✦ Synopsis
A laboratory method for studying wind-driven natural ventilation was applied to a single-span greenhouse with side-wall and roof ventilation openings, a design common to crop protection structures used in tropical countries. A 1 : 15 scale model replica of the greenhouse, made from clear Perspex, was immersed in a #ume tank "lled with water. A steady mean #ow generated by the #ume simulated wind #ow past the model. The #ow inside the model greenhouse was examined for four di!erent ventilator con"gurations and ventilation #ow rates compared in each case. Neutrally-buoyant particles seeded in the #ow allowed for clear #ow visualization and these particles were tracked using a digital image analysis system from which detailed velocity measurements were obtained. Flow patterns observed in the scale model agree qualitatively well with full-scale observations. Predictions of the #ow at full scale inferred from measurements of pressure and #ow speed made at the side-wall openings of the model di!ered by less than 10% and 28%, respectively, from measurements made in the full-size greenhouse. For all ventilator con"gurations using side-wall openings an incoming jet-like #ow crossed the greenhouse and established a circulating #ow. The greenhouse with roof ventilation only had the lowest ventilation rate and the maximum rate was achieved with combined side-wall and roof openings. The results of these studies are detailed and design recommendations to improve the ventilation of tropical greenhouses are suggested.