Effect of airflow control on temperature distributions in a greenhouse with a fan-and-pad evaporative cooling system

A numerical study of the microclimate in a greenhouse with a fan-and-pad evaporative cooling system was conducted using a computational fluid dynamics (CFD) model. In this study, we focused on the effect of an air circulator and an exhaust fan on temperature distribution in the greenhouse. The simulation model considered a plant canopy with a leaf area index (LAI) of 3.0, 1.8 m above the cultivation bed. Observed airflow, air temperature and solar radiation flux at the roof were used as boundary conditions. After validating the model's performance, the following simulations were conducted to investigate the effects of (a) different exhaust fan air speed and (b) different installation heights of air circulators on temperature distribution. Simulation results showed that (a) the temperature distribution in the plant canopy depends mainly on the operating state of air circulators, rather than the change of the air speed of the exhaust fans, and (b) the installation height of the air circulator strongly affects the mean temperature in the plant canopy and reducing non-homogeneity in temperature.