Abo Bibliothek: Guest

ISSN Online: 2377-424X

ISBN Print: 978-1-56700-421-2

International Heat Transfer Conference 15
August, 10-15, 2014, Kyoto, Japan

Effect of Boundary Conditions and Ventilator Size on the Natural Convection in a Naturally Ventilated Greenhouse

Get access (open in a dialog) DOI: 10.1615/IHTC15.ees.009294
pages 2189-2203

Abstrakt

In this paper, the effect of boundary conditions and ventilator size on the natural convection in a ventilated greenhouse is investigated using Computational Fluid Dynamics (CFD). The finite volume method using polyhedral cells is used to solve the governing equations for mass, momentum and energy. The two-dimensional CFD model is designed so as to simulate the climate above a plant canopy in an actual multi-span greenhouse heated by solar radiation. The objective of this paper is to numerically investigate the microclimate inside a cavity corresponding to a ventilated greenhouse. The effect of boundary conditions and ventilator size on the steady indoor velocity and temperature distribution will be studied. The CFD model is initially verified against experimental data found in the literature for a square cavity representing a single-span greenhouse with a zero-degree roof angle. As the flow inside greenhouses is usually in the turbulent regime, two turbulent models were investigated in the model, and the results compared. Relatively good agreement was found between the numerical and experimental results when the low Reynolds k-epsilon turbulence model was used. The boundary conditions were then adapted to represent classic Rayleigh-Benard convection and the cavity geometry modified to include a roof ventilator. The convective processes in a greenhouse are fairly complicated; therefore this paper will attempt further understanding of the convective cells forming above the plant canopy. Results showed that the convective heat transfer from the hot wall is significantly influenced by the roof opening size as well as the Rayleigh number.