Heat transfer in three-dimensional multi-span greenhouses containing ventilators

Abstract: The present study entails the investigation of the effect of number of spans on buoyancy-induced heat transfer in a cavity representing a greenhouse with a roof ventilator. Naturally ventilated greenhouses are used world-wide to cultivate crops and ornamental plants. This ventilation method uses less energy compared to mechanical ventilation, and is important to control the indoor greenhouse microclimate. Multi-span greenhouses are often used in industry. Initially, a two-dimensional numerical model using Computational Fluid Dynamics (CFD) representing a single span closed greenhouse was created and validated against experimental results found in the literature. The numerical model was extended to a three-dimensional CFD model, and once again validated against data found in the literature. After validating the models, these models were modified to represent multi-span greenhouses containing roof ventilators. A numerical model using Computational Fluid Dynamics was used to investigate the heat transfer in single and multi-span greenhouses. The results indicated a significant influence on the temperature and velocity distribution inside the greenhouses, but in general convective heat transfer improves when adding additional spans to the greenhouse