Abstract

ROMERO-GOMEZ, Pedro; CHOI, Christopher Y.  and  LOPEZ-CRUZ, Irineo L.. Enhancement of the greenhouse air ventilation rate under climate conditions of central Mexico. Agrociencia [online]. 2010, vol.44, n.1, pp.1-15. ISSN 2521-9766.

Mexican plastic-covered greenhouses use natural ventilation as the main method to control temperature and humidity. However, no studies on the dynamic behavior of airflow and ventilation rates are available. In the present study, air exchange rates were analyzed in a naturally-ventilated greenhouse in Mexico using Computational Fluid Dynamics (CFD). To enhance greenhouse cooling, roof vent areas and screen characteristics were examined undef various scenarios to quantify ventilation rates. The air exchange rates through the tight insect screen (model S) were about 50 % of those achieved with actual and loose insect screen (model SF) at the same outside wind speed. Enlargement of the roof vent size ftom 6 % (current) to 15 % of the greenhouse-floor area increased the ventilation rate by 20-40 % at wind speeds ranging from 0 to 4 m s^-1. However, extensions of insect-proof screens area on side-walls did not produce any significant change in the ventilation rate. Greenhouse orientation was also considered to maximize cooling effects under the local climate condition, and the ventilation rate could be enhanced by positioning the roof vent area in a prescribed direction based on the average wind speed.

Keywords : CFD; greenhouse; natural ventilation; rates.