Latent Heat Thermal Storage

The utilized Latent heat thermal storage (LHTS), based on phase change materials (PCMs) is a very promising solution in terms of compactness of the units, especially for building applications. However, PCMs typically suffer from poor conductivities and large response time of this thermal storage technology. Therefore, the project is performing a topological optimization of such technology, which, within the framework of additive manufacturing will allow for extremely effective design structures, able to dramatically enhance the heat transfer effectiveness.

In the RE-COGNITION project, a shell-and-tube geometry has been selected for the LHTES design. A large tank is filled by a PCM and it is crossed by a series of tubes containing the Heat Transfer Fluid (HTF), i.e. the water of the building heating system. In this application, the LHTES is used to store energy produced at the building level by the renewable technologies installed. When the hot water produced from renewable sources releases its energy to the PCM, this melts inside the tank; the storage is completely charged when the PCM is completely liquid. On the other hand, when the heat is required to the building the storage is discharged and the PCM solidifies.



  • ~150 MJ storage
  • Tubes with extensions (fins) to enhance heat exchange and reduce discharge/charge time
  • Simple (longitudinal) fins for easy manufacturing



  • Discharge during peak heat demand (~ 30 min)
  • Charge when surplus/cheap energy is locally produced (≥ 1 hour)
  • Working temperatures: 60-80 °C

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