Storage of heat is seen as a major issue for the large-scale and long-term development of solar energy for house heating and cooling in all climates. Most of the storage systems available on the market use water as the storage medium. Enhancing storage performance is necessary in order to increase the performance of most systems. The idea studied here was to add a phase-change material (PCM) module at the top of a hot water storage tank with stratification. The advantages of the stratification still remain in this new system, but the addition of a PCM module would give higher density in the top layer. For this work, an experimental solar pilot plant was constructed to test the PCM behavior in real conditions, which could work continuously with the solar system or could also work with an electrical heater. The PCM module geometry adopted was to use several cylinders at the top of the water tank. Several experiments with two, four, and six PCM modules were carried out in the real installation. A granular PCMgraphite compound of about 90% sodium acetate trihydrate and 10% graphite was chosen as the PCM for the experiments presented here.

Units: SI