Monitoring results of heat pump application with PCM storage
In the “SunStore” project, a new heat storage based on phase change materials (PCM) is being installed, tested and evaluated under real conditions. The PCM is filled in capsules in the buffer storage tank. In particular, the project aims to investigate the advantages of PCM storage in terms of achieving high self-consumption of PV electricity with heat pumps. The pilot system is equipped with an air-to-water heat pump and PCM in capsules, which are filled into the existing heating buffer storage. The system is used to evaluate experiences in real operation over three heating periods. A reference period with a conventional water buffer storage and each one heating period with two generations of PCM capsules have been evaluated. Results show an increase in PV self-consumption and self-sufficiency in heating, which, however, cannot be exactly quantified due to changing boundary conditions in the heating periods, but verified by daily storage temperature evolution. The increase of the seasonal performance factor could not be verified due to limitation in the pilot plant but seems reachable with control improvements. In the meantime, the capsule technology is no longer being pursued, but a PCM-filled storage is being launched on the market as a successor product and further development. The new storage concept addresses the limitations found in the former capsule concept by the monitoring project. The charging and discharging capacity is considerably enhanced by the new concept. Moreover, since no PCM can be in contact with the water due to the separation by a heat exchanger, DHW heating is possible