ISHS Acta Horticulturae 534: International Conference and British-Israeli Workshop on Greenhouse Techniques towards the 3rd Millennium
DETERMINATION OF NATURAL VENTILATION RATE IN A DOUBLE SPAN ARCH TYPE GREENHOUSE |
| Authors: | N.N. Vassiliou, G.G. Martzopoulos, C. Nikita-Martzopoulou |
| Keywords: | Greenhouse, double span, natural ventilation, wind flow, temperature, side ventilators |
| Abstract:
Wind is an important factor influencing the greenhouse environment. It is normally the most significant parameter affecting natural air exchange in greenhouses, even at low speeds. The scope of this study is the experimental investigation of the wind eefect on the natural ventilation of a double arched greenhouse with a single plastic cover and vent openings only on the sides. This greenhouse was located at the University Farm of the School of Agriculture. This type of greenhouse is representative of those used in continental Greece as well as in most of the Mediterranean countries. The determination of the rate of air exchange (N) was based on measurements carried out with the use of CO2 as a tracer media. The wind speed (V10) measurements and the wind direction were taken by electronic sensors located at a height of 10 m above the ground level. The results of the experiments led to the determination of a relationship between ventilation rate, wind speed and direction. The mathematical expression of this relationship is:
The conclusion derived from the above relationships is that for a certain wind speed, the ventilation area required to provide a constant ventilation rate in a greenhouse with wind direction parallel to the side openings must be as much as twice of that required when the wind direction is normal to the opening. | |
Download Adobe Acrobat Reader (free software to read PDF files) | |
