ISHS Acta Horticulturae 174: Symposium Greenhouse Climate and its Control
A CONTROL ALGORITHM FOR NATURAL VENTILATION BASED ON WIND TUNNEL TESTING |
| Authors: | S. Sase, M. Nara |
| Abstract:
An effective control algorithm for natural ventilation of greenhouses equipped with side and ridge ventilators has been developed. The operation of ventilators is determined so that the desired average air temperature and minimum spatial distribution of air temperature can be established. According to weather conditions and desired temperature, suitable angles of ventilator openings are estimated from a computational model based on wind tunnel testing. In addition, the relationship between the patterns of temperature distribution and the arrangement of ventilators based on wind tunnel testing is included as a data base. To promote faster calculation for the estimation of the optimum angles of the ventilators, the arrangement of the open ventilators is determined in advance according to weather conditions as follow: 1) only ridge ventilators are opened when the external air temperature is cold, 2) all ridge ventilators are set at the same angle and all side ventilators are set at the same angle when the ventilation caused by stack effect is dominant to the ventilation caused by wind effect, and 3) each ventilator is set at a different angle when wind effect is dominant. The performance of the control algorithm has been tested with a twin-span glasshouse. | |
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