TEMPERATURE SMOOTHING IN GREENHOUSES USING A SYSTEM OF PHASE CHANGE MATERIALS

Experimental results are reported concerning the performance of an integrated storage system in a small prototype greenhouse. A dual storage system of suitable phase change materials (CaCl₂ · 6H₂O/CH₃COOH) was built in order to test its efficiency on the diurnal temperature smoothing. Both of these materials are rather cheap and available in large quantities. The melting points are about 29°C and 16°C, respectively, and the heat of fusion is satisfactory. The combination of these phase change materials allows us to construct storage systems which can control the maximum and minimum air temperature peaks in a greenhouse during the day. The storage system is integrated into the north wall of the greenhouse, while some other possibilities exist, depending on the nature of the plants inside. It was found that this system results in substantial energy savings as it stores part of the solar energy input for night use.