Effects of the Rock-Bed Heat Storage System on the Solar Greenhouse Microclimate

The Mediterranean area is characterized by intense radiation generating high temperatures during the day in the greenhouse and low temperatures during the night. The temperature gap problem between the daytime and the nocturnal period which characterizes the region requires the use of greenhouses with a thermal storage system. A greenhouse equipped with a sensible heat storage system using a rock-bed, was compared to a witness one, under the same climatic conditions. Measurements were performed on the microclimate parameters of both greenhouses, such as temperature and relative humidity. Our work is based on an experimental analysis of greenhouse microclimate and evaluating the evolution of temperature and relative humidity prevailing inside the greenhouse. It has been found that the system efficiency is improved due to the storing of heat in excess during the daytime. This stored energy is used during night. The main obtained results showed that the heat storage system allowed an increase in the air temperature up to 0.9℃ and a decrease of the relative humidity about 3.4% during the night compared to the witness greenhouse. The improvement in the heated greenhouse microclimate during night has a very positive impact on the quality of fruit and yield.