Cooling Effect of Mechanical Ventilation in Grape Greenhouse Based on CFD Numerical Simulation

摘要

The effect of air volume supplied by top mechanical ventilation on multi-span greenhouse temperature field is studied with different ambient temperatures through CFD numerical simulation. The cooling effects of different mechanical ventilation volumes are compared in the same ambient temperature conditions such as summer calm and high illumination. Thus, the best supply air volume is found to provide a theoretical support for mounting ventilator at multi-span greenhouse top for cooling. Results show that a smaller mechanical ventilation volume can meet the cooling requirements when temperature is lower outside greenhouse. However, single mechanical ventilation has been unable to meet the cooling requirement when ambient temperature is too high outside greenhouse. Environmental control in greenhouse has been one of the most important challenges in agriculture facilities. Indoor temperature field distribution and variation are mastered through the simulation of greenhouse temperature environment. Thus, the indoor environmental factors can be timely adjusted by using intelligent control system, which is of great significance to promote crop growth. CFD (Computational Fluid Dynamics) has become a powerful tool for analyzing the heat environment inside greenhouse at present. Advantages of CFD include strong practicability, a wide range of application, time and money saving and big flexibility. Moreover, it is not subject to physical model and experimental model limitations and can use computer to do a variety of numerical simulation tests. A three-dimensional simulation model of greenhouse is established in the crop condition in this study, and the simulation calculation of indoor temperature and humidity field is performed.