Effect of temperature on greenhouse natural ventilation under hot conditions: Computational fluid dynamics simulations

The aim of study was to investigate the effect of temperature on air patterns in two different greenhouse configuration using two-dimensional computational fluid dynamic models. The models were constructed on the basis of two major assumptions: first, the inside temperature is considered to have a vertical distribution while it is constant on horizontal planes; second, temperature is the main driven force that causes air movement. The computational results were validated with current literature data. The models were later used to study the air patterns inside two greenhouse configurations under zero and low wind, velocities. The ventilation efficiency was assessed on the basis of the ventilation rate and complemented with the study of the internal air velocities at a height of 1.5 m. Results indicate that applying temperatures as the main driven forces for the buoyaricy effect produced a positive correlation and agree with current literatum data, therefore, providing a simple way to study the ventilation and inner air patterns. Results also, show that the ventilation in greenhouses due to the temperature effect produces high air exchange rates. However, the study of the inner air patterns reveals that those air patterns occur near the openings causing almost no air exchange in the greenhouse central area due to a stagnant effect that reduces the wind effect throughout the greenhouse. © 2008 Asian Network for Scientific Information.