Computational Fluid Dynamics-Based Simulation of Ventilation in a Zigzag Plastic Greenhouse

Zigzag plastic greenhouses are a type of greenhouse with a high natural ventilation capacity, and the number and quantities of their roof vents affect their ventilation and cooling effect. In this study, a CFD model of a greenhouse was constructed based on computational fluid dynamics (CFD) theory to simulate the temperature and airflow distribution of a zigzag plastic greenhouse and to investigate the effects that the number of zigzags and the construction orientation have on the cooling effect of this type of greenhouse. The results show that the average air temperature in a double zigzag plastic greenhouse (DZPG) was 0.58 °C lower than that in a single zigzag plastic greenhouse (SZPG) of the same size during the experiment. When the outdoor temperature is higher than 35 °C, the maximum temperature of the DZPG is significantly lower than that of the SZPG in a 1.5 m horizontal section; when the top vent is on the windward side, there is an obvious advantage of DZPG ventilation and the utilization efficiency of its top vent is higher, and when the top vent is on the leeward side, the distribution of the airflow in the DZPG is more intensive and more uniform. The maximum difference in the average temperature between the eight orientations of the DZPG was 0.17 °C. Therefore, the cooling effect in summer is not influenced by the construction orientation, but the airflow in the greenhouse is slightly worse when the direction of the roof vents is parallel to the prevailing wind direction.