Combined short- and long-term heat storage with Sodium Acetate Trihydrate for solar heat supply in buildings

Because of its ability to preserve latent heat of fusion at room temperature in supercooled state, the phase change material (PCM) sodium acetate trihydrate (SAT) can be utilized for combined short and long-term heat storage in buildings. This was experimentally proved with a novel solar combisystem demonstrator including a segmented heat storage prototype, consisting of 4 flat units containing 200 kg of SAT composites each. A numerical model of the demonstrator was developed in TRNSYS environment. Ongoing system simulation indicates potential for more efficient domestic hot water and space heating supply. Further, based on experience with flat units, an inexpensive, cylindrical heat storage unit of the same PCM volume as one flat unit was designed and tested. Results showed that 27 kWh of heat can be stored. After cooling to room temperature, 11 kWh (long-term storage potential) were discharged during SAT composite solidification.