Configuration by Evaluating Ventilation Efficiency Based on Computational Fluid Dynamics

The aim of the present study was to evaluate effects of different parameters that influence the greenhouses ventilation, and recommend to the growers and greenhouse manufacturers companies the optimal designs. The parameters studied in the different simulations were: greenhouse width and span number (1, 3 and 5), presence of insect-proof screens with different porosity, vent area and location and type of vent openings. We have analysed their effect on ventilation rates, airflow patterns and temperature distribution at the plant canopy zone in an Almeria type greenhouse under buoyancy and wind induced ventilation. The optimization of traditional vent configuration for an Almeria-type greenhouse for better air renewal, was attempted by two-dimensional numerical simulations using a Computational Fluid Dynamics (CFD) approach. For the different greenhouse configurations (11) we simulated 6 wind speed levels (0, 1, 2, 5, 7.5 and 10 m s(-1)), to study the effect of the wind speed, resulting in 66 CFD simulations. The simulations were carried out by means of a CFD software (ANSYS/FLOTRAN v11) that applies the Finite Elements method (FE) for the discretisation of the set of equations involved in the ventilation process. Reduction in the ventilation rate was observed when the spans number increased, with the use of screens and when side vents were partially closed. Closing partially the roof vents with fully opened side vents, we can obtain a better greenhouse cooling effect in an empty greenhouse.