Fogging Systems for Cooling Greenhouses

Abstract

This work focuses on development of the fogging system mathematical model, and theoperational characterization of the fogging system in combination with forced ventilation for coolinggreenhouses. The cooling system was installed and operated according to the following scheme:high-pressure spray nozzles with the highest possible uniformity of distribution, fans at both ends ofthe greenhouse (north & south) were placed at ground level, roof openings and two side openings(east & west). The results obtained revealed that inside the greenhouse air temperature and relativehumidity of 28oC and 80% respectively, were maintained during the summer at midday and generallyhigh uniformity of the climatic conditions (the same magnitude of temperature measurements error0.5C), within the greenhouse, in the lengthwise (north-south) and vertical directions. In contrast tothat, there was significant variation across the width of the greenhouse (east-west), which arose as aresult of wind action; however, under the conditions of a greenhouse with developed plants or withthe windward openings closed, uniform conditions were obtained. It must be concluded that in order to obtain completely uniform climatic conditions throughout the volume of the greenhouse, it isdesirable to install fans in all four sides. Such an arrangement may makes possible: uniform climaticconditions within the desired range, even in the summer months; good control over the climaticconditions through reduction of the influence of the wind; operation of the greenhouse by means of arelatively simple control system; the establishment of greenhouses in large units and, consequently,better exploitation of the land area and significant reduction in the cost per unit area of the structure.