Climate control inside a greenhouse by means of a solar cooling system

Microclimate control in the greenhouse is important to improve yield and obtain low environmental impacts. Ventilation, shading, evaporative cooling and refrigeration are methods of controlling air temperature inside the greenhouse; nevertheless, ventilation and shading are often not sufficient to remove the excess heat, refrigeration is generally expensive and evaporative cooling is based on the use of large quantities of water. In order to enhance the sustainability of the greenhouse sector, renewable energy sources can be exploited with the application of solar absorption systems for greenhouse cooling in areas with high outdoor temperatures and solar insolation. This paper describes the application of a solar cooling plant with absorption chiller for thermal control of a greenhouse. The experimental system consisted of a Mediterranean greenhouse, with a surface of 300 m2, and a single-effect LiBr-H2O absorption chiller fed by evacuated-tube solar collectors, located at the University of Bari, Italy. The distribution system provides the cooling power only for the volume surrounding the crop. The research demonstrated that solar cooling systems provide an opportunity for reducing the air temperature around the crop, allowing the reduction of primary energy consumption by exploiting the contemporaneity between the cooling requirements and solar energy availability.