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Thermal Energy Storage - Phase Change Materials based Spiral Heat Exchanger (PCM-SHE-TES)

Phase Change Materials (PCM) can store over six times the thermal energy of water for a given storage volume.  Phase change refers to the melting or solidification of a material such as wax.  When a PCM melts, heat is absorbed by the materials around its melting point changing the structure of the material from a solid to a liquid.  When the temperature of the liquid PCM drops below its melting temperature, the material releases its stored heat energy as its structure solidifies.

A Spiral Heat Exchanger consists of two isolated coils rolled in an Archimedean spiral coil.  The working fluids of the coils are totally separate allowing heat exchange between different heat transfer fluids in buildings.  The inter-space between the two coils is filled with PCM.  In the standard configuration, the primary coil is used to charge the PCM above its melting temperature.   The secondary coil is used to remove heat from PCM.  Both coils are identical allowing a range of plumbing combinations for multiple units run in series or parallel.  Each PCMHSHETES unit is 500 litres in volume (500mm high and diameter 1.2m), and holds the same heat as a water tank of 3250 litre tank.  The system is modular and multiple units can be stacked on top of each other or distributed around a building due to the small size and low weight.

The objective of this project was to build a full industrial demonstrator unit working in a live building. The storage unit was used to store the waste heat from a Combined Heat and Power (CHP) unit when operating at high electricity tariff intervals and use the stored thermal energy to pre-charge the building early the following morning during low tariffs when it is not economical to run the CHP. The deliverables of the project were to bring the technology from a Technology Readiness Level 4 (TLR4 lab scale) to a Technology Readiness Level 8 (TRL8 full scale demonstrator).


 The project delivered:  

  • A PCM thermal storage system with an energy density 6.5 times that of water
  • A modular design that allows a range of PCM materials to be used to suit a wide range of temperature ranges 
  • A modular design that allows the system to go into retrofit buildings due to its size, weight and ability to be distributed
  • A working industrial prototype demonstrator in a live building storing energy from a CHP using four 500 litre PCM units
  • A techno-economic analysis report on the technology applied to CHP applications.

Funded by the International Energy Research Centre (IERC) who are hosted in the Tyndall National Institute in UCC Cork.  The IERC is an industry led, world-leading, collaborative programme of research and innovation in integrated sustainable energy system technologies.  The project duration was a total of 30 months and was funded for €420,000. The three academic partners in the project were Dublin Institute of Technology (DIT), Cork Institute of Technology (CIT) and Warsaw University of Technology (WUT).  United Technologies Research Corporation (UTRC), Bord Gais Eireann, Alcatel Lucent Ltd, and Bilfinger Ltd are the four industrial companies involved in the project.


Project Contact: Dr. Mick Mc Keever

Project Website: