ISHS Acta Horticulturae 633: XXVI International Horticultural Congress: Protected Cultivation 2002: In Search of Structures, Systems and Plant Materials for Sustainable Greenhouse Production
CFD PREDICTIONS OF NATURAL VENTILATION AND CLIMATE IN A TUNNEL-TYPE GREENHOUSE USING A TRANSPIRATION ACTIVE CROP MODEL |
| Authors: | J.C. Roy, T. Boulard |
| Keywords: | ventilation, porous media, energy balance, vapour balance, tomato crop, aerodynamics, modelling |
| Abstract:
A new model developed with the CFD2000® package is evaluated, which takes into account the crop like an active 3D region: the momentum transfer is considered (porous media) as well as the heat and humidity transfers between the crop and the inside airflow. The model consists in the determination for each node of the crop grid of the energy balance between radiation and the transpiration and sensible energy fluxes. The heat and humidity transfer coefficients are determined from the leaf laminar boundary layer characteristics which are calculated with the local characteristics of air in the crop (velocity, temperature, humidity). The active crop model is applied to a tunnel-type greenhouse with five vents on each side and a five rows mature tomato crop. A side wind perpendicular to the longitudinal axis of the greenhouse is considered and the boundary conditions for the velocity distribution in the vents are determined with a preliminary, purely mechanical, 3D simulation of the greenhouse and its environment. The results show clearly the 3D heterogeneity of the temperature and humidity fields both in the inner airflow and crop and their distribution, mainly in relation to the vents, and also their effects on the transpiration flux of the crop. | |
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