ISHS Acta Horticulturae 458: International Symposium on Water Quality & Quantity-Greenhouse
DESIGN AND PERFORMANCE ASPECTS OF A WATER PRODUCING GREENHOUSE COOLED BY SEAWATER |
| Authors: | B.J. Bailey, A. Raoueche |
| Abstract:
The purpose of this greenhouse is to produce normal greenhouse crops and also to provide a supply of water for irrigation; it is intended for use in hot arid coastal regions which have steady winds from a predominant direction. These promote the ventilation airflow which enters the house through an evaporative cooling pad and leaves through a second evaporation pad. The wind also creates an airflow through a seawater spray in the space between two roof layers and over seawater flowing on the lower roof surface. The humid air leaving the greenhouse and the roof passes through a seawater-cooled condenser which produces fresh water. The conditions inside the greenhouse, the water vapour produced by each element, and the water produced by the condenser were predicted with a greenhouse simulation model for a selected set of external conditions and system parameters. The simulations showed that the temperature of the condenser cooling water had a very strong influence on the water produced. The major sources of vapour were the water spray in the roof cavity (37%) and the inlet evaporation pad (35%), followed by the roof cavity (16%), the outlet pad (6%) and plant transpiration (6%). Simulations using meteorological data for the Cape Verde Islands and with cooling water 3°C below the temperature of the local surface seawater, showed that the complete system could have an annual net water output of 900 kg m-2 greenhouse, and that the conditions created inside the greenhouse would be suitable for protected crop production. | |
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