Articles
DESIGN AND PERFORMANCE ASPECTS OF A WATER PRODUCING GREENHOUSE COOLED BY SEAWATER
Article number
458_39
Pages
311 – 316
Language
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.
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.
Authors
B.J. Bailey, A. Raoueche
Keywords
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