Transient CFD analysis of the natural ventilation of three types of greenhouses used for agricultural production in a tropical mountain climate

The microclimate of naturally ventilated greenhouses, which are extensively used in tropical regions to produce various food or commercial crops, is highly dependent on the efficiency of ventilation that varies according to the local climate and the main characteristics of the greenhouse. Numerical simulation facilitates the spatial analysis of air flows for different types of greenhouse and their effect on the internal microclimate. The objective of this work focused on the use of a transient CFD-2D model for the study of natural ventilation in three types of greenhouses, the traditional Colombian wood (TG) greenhouse and two alternative types of multi-span greenhouses (curved - DMG and gothic - GMG) that are characterised by having larger ventilation areas both on the sides and on the roof. The model was validated by experiments performed in the DMG greenhouse through the collection of temperature and air velocity data by means of anemometry techniques, developing an accurate relationship between the simulated and experimental data. The results of the simulations showed that both DMG and GMG have ventilation rates 3.4 times higher than those found in the TG. This is reflected in the more homogeneous thermal spatial distribution with the average temperatures which were reduced by 2.8 °C with respect to the TG.