ISHS Acta Horticulturae 458: International Symposium on Water Quality & Quantity-Greenhouse
A GREENHOUSE CLIMATE MODEL INCLUDING THE EFFECTS OF VENTILATION AND CROP TRANSPIRATION: VALIDATION FOR THE SOUTH TUNISIA CONDITIONS |
| Authors: | L. Sbita, T. Boulard, A. Baille, M. Annabi |
| Keywords: | greenhouse, ventilation, model, tracer gas |
| Abstract:
A greenhouse climate model incorporating the effects of natural ventilation is proposed. Crop transpiration is estimated using a simplified version of the Penman-Monteith approach. Air exchange rates are given by a ventilation model that estimates the ventilation flux as a function of the wind velocity and the surface of the opening. In order to validate this model in the case of plastic tunnels currently used in South Tunisia, measurements of air exchange rates were performed in situ in a reference plastic tunnel, using the decay rate method with N2O tracer gas. Linearization of the greenhouse heat and water balance equations leads to a simple system with two equations and two unknowns, the air temperature and the water vapor pressure, that can be solved analytically. Predictions of the climate model were validated against climatic data sets obtained in commercial plastic greenhouses of South Tunisia during the autumn of 1995. The results are satisfactory and it is now planned to implement a version of this model in a climate and irrigation control system. | |
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