The effect of nocturnal shutter on insulated greenhouse using a solar air heater with latent storage energy

Abstract

In order to reduce the energy consumption in agricultural greenhouses at night, two similar greenhouses with a nocturnal shutter are constructed and installed in the CRTEn (Research and Technologies Centre of Energy) in Tunisia. The first is equipped with a heating system. The solar heating system is a solar air heater collector with latent heat storage. At daytime, thermal solar energy is stored, however, at night it can be restored. Moreover, the shutter is used only at night. The analysis of the thermal energy is used to examine the repartition of the absorbed, the useful, the stored and the losses of energy in the greenhouse; with or without nocturnal shutter. The balances of the various components of the greenhouse are used to study the portions of the energy recovered, absorbed, stored and lost.The experimentally obtained results show that: the nocturnal variations of temperature inside the two greenhouses exceed 2°C between the first (with shutter) and the second one (without). Also, the nocturnal temperature inside the greenhouse equipped with solar heating system was maintained to 15°C while the outside temperature decreases to 8°C.