ISHS Acta Horticulturae 691: International Conference on Sustainable Greenhouse Systems - Greensys2004
OPTIMISATION OF ALMERÍA-TYPE GREENHOUSE VENTILATION PERFORMANCE WITH COMPUTATIONAL FLUID DYNAMICS |
| Authors: | F.D. Molina-Aiz, D.L. Valera, A.A. Peña, J.A. Gil |
| Keywords: | Finite Elements Method, airflow, modelling, insect-proof screens, climatic control |
| Abstract:
The aim of the present study was to evaluate effects of different parameters that influence the greenhouses ventilation, and recommend to the growers and greenhouses manufacturer companies the optimal designs. The parameters studied in the different simulations were: greenhouse width and span number, vent area, location and type of vent openings, presence of insect-proof screen with different porosity and incidence of plants. The effect of these parameters on the natural ventilation of an Almería-type greenhouse is analysed by means of Computational Fluid Dynamics (CFD), using the commercial program ANSYS/FLOTRAN v8.0 based on the Finite Elements Method. Reduction of 88% in the ventilation rate were observed when the spans number increased from 1 to 5, as consequence of the increase of the greenhouse width (9 to 45 m). The use of insect proof screens decreased around 50% the speed in the next area to the lateral windows and ventilation rate. The presence of a crop inside the greenhouse causes an effect of airflow lamination and reduces the airflow at the ground level, while air speed is greater in areas above the crop. The CFD predicted results showed that an Almería greenhouse with five roof leeward flap openings and two side vents resulted in higher air exchange rates than with windward flap opening. However, temperature distribution is not as good as with the windward ventilation. | |
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