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ISHS Acta Horticulturae 654: International Workshop on Models for Plant Growth and Control of Product Quality in Horticultural Production

USING COMPUTATIONAL FLUID DYNAMICS TOOL TO MODEL THE INTERNAL CLIMATE OF AN ALMERíA-TYPE GREENHOUSE

Authors:   F.D. Molina, D.L. Valera, A.J. Alvares
Keywords:   natural ventilation, temperature, air velocity, climate heterogeneity, modelling, insect-proof screens
Abstract:
The aim of the present study is to use Computational Fluid Dynamics (CFD) to investigate the effect of wind speed on natural ventilation of an Almería-type greenhouse, situated in the south of Spain. The complete average air velocity vector field and temperature spatial distribution were numerically calculated in the case of transverse wind, using the commercial software ANSYS/FLOTRAN v 6.1 based in the Finite Element method. The experiments were carried out in a 42 m long, 3.2 m high and 45 m wide Almería-type greenhouse equipped with roof and side vents. Both momentum and energy equations were considered and the airflow’s in the crop cover together with the insect proof screens were described by means of a porous medium approach. Two-dimensional simulations were performed in stationary regime and the standard k-epsilon turbulence model described the turbulent transfers. Air comes in the greenhouse through both windward and the leeward sidewall windows. The temperature distribution showed a side wall-greenhouse centre gradient due to the hot air movement to the roof vent opening and a vertical gradient above the soil surface due to solar energy absorption at the soil level. Maximum air velocity values inside the greenhouse were observed near the openings, whereas air velocity was lowest in the middle of greenhouse. The computational results showed a good agreement with the experimental measurements (mean differences of 0.06 m/s for air velocities, and 0.6°C for air temperatures). CFD can be an optimum tool for developing improved designs with respect to ventilation efficiency.
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