R. Cuypers1, A.J. de Jong1, J. Eversdijk2, H. van ‘t Spijker1, H. Oversloot1, B.L.J. Ingenhut2,
R.K.H. Cremers2, and N.E. Papen-Botterhuis2
1TNO Energy & Comfort Systems, Van Mourik Broekmanweg 6, 2628XE Delft, The Netherlands; 2TNO Responsive Materials & Coatings, de Rondom 1, 5612 AP Eindhoven, The Netherlands
Thermochemical storage is a new and emerging long-term thermal storage for residential use (cooling, heating & domestic hot water generation), offering high thermal storage density without the need for thermal insulation during storage. However, existing materials for thermochemical storage either suffer from practical issues like limited physical and mechanical stability and severe corrosivity (salt hydrates), or thermal storage capacities that are too low to substantially cover seasonal storage adequately (zeolites and silicagel).
To overcome the corrosion and stability problems with salt hydrate thermochemical materials and to make them more suitable for use in thermochemical reactor systems, microencapsulation is proposed. A suitable encapsulation material was assessed, having an open structure for good vapor transport, being capable of high loading fraction and therefore still a high storage density, and being flexible, stable and cheap. Initial experiments yield promising results on this material exhibiting high storage capacity, good reversibility and ease of use. Surprisingly, lower dehydration temperatures as compared to the non-encapsulated material were found, enabling the use of other salt hydrates with higher dehydration temperatures.