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Modélisation de l'aération naturelle et du microclimat des serres en verre de grande portée sous climat tempéré océanique

Abstract : The "climate" inside a greenhouse depends on its ventilation. The ventilation process is complex, it takes part in mass and heat transfers with the external environment, and its control makes it possible to manage the physical parameters such as the temperature, the moisture, and the gas concentration of CO2 for instance. This control is essential to maintain the plants under favourable metabolic conditions (breathing, photosynthesis, transpiration) and in a satisfactory health state.
Natural ventilation is the most economic system to control the internal microclimate of the greenhouse. Nevertheless, it only permits very limited control of the airflow inside the greenhouse and is difficult to manage.
This study aims at describing the microclimate which develops over the plants in a glasshouse equipped with shelves for ornamental horticultural crops. The investigation is based on the complementarity between experiment and mathematical modelling.
Two different types of measurements were conducted simultaneously in order to record input data for the model boundary conditions and to validate the simulations with respect to inside climate parameters. Thus, the climate parameters: outside wind velocity and direction, air temperature, walls surface temperature and the air exchange rate of the whole greenhouse were measured.
The CFD software solved the Navier-Stokes equations with the Boussinesq assumption and a closure. The virtual tracer gas technique was implemented to assess the ventilation rate. Solar and thermal (i.e. atmospheric) radiative fluxes were included in the model through the resolution of the radiative transfer equation.
The accuracy of this device was firstly validated against air exchange rate and temperature data collected in an experimental glasshouse. The model was then used to study the consequence of different opening configurations on the distributed climate. attention was paid to the analysis of the heat fluxes at roof level and also of the heterogeneity of the climatic parameters in the canopy vicinity.
Finally, the indicators of effectiveness of the natural ventilation of the greenhouse under summer conditions could be released for different opening configurations.
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Submitted on : Thursday, January 29, 2009 - 12:18:07 PM
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  • HAL Id : tel-00357023, version 1
  • PRODINRA : 250002

Citation

Sid-Ali Ould Khaoua. Modélisation de l'aération naturelle et du microclimat des serres en verre de grande portée sous climat tempéré océanique. Sciences de l'ingénieur [physics]. Université d'Angers, 2006. Français. ⟨tel-00357023⟩

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