Modeling heat transfer and air circulation by convection in bottom-heated agricultural greenhouses

In agricultural greenhouses, effective heating systems are essential for maintaining proper temperature control and air circulation during the winter. This study delves into the analysis of heat exchange through natural convection within heated greenhouses, with a particular emphasis on the impact of bottom heating. Two distinct types: mono-chapel and bi-chapel, each featuring triangular or spherical roofs are examined. To capture the variable roof shapes, we employ a change-of-variable method, and the numerical solutions are obtained using the finite volume method. The results show that heat transfer is enhanced by increasing the Rayleigh number. This improvement differs according to the shape of the roof. Heat transfer decreases by about 5% for the spherical mono-chapel case compared to the triangular case for Ra = 10³. For Ra = 10⁵, the monospherical case favors heat transfer, with an increase of 0.35% compared to the triangular case. In the case of bi-chapel roof, heat transfer is greater with a triangular roof for Ra = 10³, showing an increase of 6.4% compared to the spherical case. This study not only sheds light on the fundamental aspects of heat transfer in greenhouses but also provides valuable insights for optimizing greenhouse design based on specific roof configurations and heating conditions.