SOLAR RADIATION DISTRIBUTION IN SCREENHOUSES: A CFD APPROACH

In this paper the effect of solar radiation distribution in a typical screenhouse was numerically investigated, taking into account the thickness and aerodynamic properties of the screen and its spectral, optical and thermal properties. A two dimensional computational fluid dynamics (CFD) model was used to render the building’s geometry, and the Discrete Ordinates (DO) model to simulate the radiation transmission through the screen, taking into account its spectral distribution in three wavelength bands. The results show the influence of the properties of screen materials on the distribution of solar radiation, air velocity and air temperature inside the screenhouse. Decreasing screen porosity resulted in an increase of air temperature and in a decrease of air velocity under the screenhouse. In higher screen porosities, the flow was dominated by buoyancy effects, showing the importance of internal temperature gradients. Screening materials with high absorbance reduce internal solar radiation and air temperature and lead to the development of secondary recirculation where the air is trapped.