Flow characteristics and temperature patterns in a fan ventilated greenhouse

Abstract

The effects of solar radiation distribution during fan ventilation in an arc type tunnel greenhouse in various hours of daylight were numerically investigated. Inside the greenhouse there was a tomato crop 1.5 m tall. For the simulation's needs a 3D mesh is used to render the geometry, and the finite volume method was adopted for the solution of the fully elliptic partial differential equations. Climatic data from experimental values were used in order to approach realistic conditions of typical summer day. Special items like the optical behaviour of covering material or the climatic behaviour of the rows of tomato crop are also considered. The results show the influence of the incidence angle of the incoming solar on the distribution of solar radiation inside the greenhouse. Although the dominance of the forced convection resulted from the mechanical assisted ventilation, flow recirculation are presented and buoyancy effects appear in areas where forced convection is limited via to the topology showing the influence of the temperature gradients in flow.