Experimental Evaluation by Sonic Anemometry of Airflow in a Mediterranean Greenhouse Equipped with a Pad-Fan Cooling System

Abstract

The aim of the present work is to study the airflow and distribution of temperature and humidity in a multi-span greenhouse equipped with a pad-fan cooling system operating both with a well-developed tomato crop and without a crop (simulating recently transplanted plants in the greenhouse). Maximum values of air velocity were recorded at the entrance of the pads. In the first few meters of air inside the greenhouse, high levels of turbulence intensity were recorded as the air dampened by the pads mixed with the hot, dry air inside and the airflow cross-section increased. The crop has a clear stabilizing effect on the airflow, producing lower energy levels and turbulence than when the greenhouse was empty. The maximum temperature gradient was recorded in the greenhouse that was empty, with an increase of 5.2C between the entrance of air through the pad and the exit through the extractor fans. This climate heterogeneity when young plants are transplanted in the greenhouse can produce over-consumption of irrigation water, which must be considered by growers to avoid plant damage by water stress. With a crop in the greenhouse, the maximum difference in temperature was reduced to 2.3C.