APPLICATION OF PHASE CHANGE MATERIALS (PCM) IN THERMAL STORAGE SYSTEMS FOR PRESSURISED LUKEWARM WATER

摘要

The majority of HVAC systems contain a (cylindrical) tank for small thermal buffer purposes. By sensible heat merits of water a thermal storage function is achieved. In spite of the high specific heat of water, tanks never tend to become large so that storage capacity is limited. Only Ice buffer systems have become popular for short term latent thermal storage, where storage (by phase change of water to ice vice verso) is created at 273 K. Phase Change Materials (PCM) have been under wide investigation in the last decades due to their excessive and extraordinary thermal storage capabilities. Nevertheless, application in closed water circuit systems has not yet been applied widely at all. This paper describes practical test work on a ready to use compound Phase Change Material storage product, intended for closed loop pressurized water storage systems at positive Celsius temperatures. The PCM is encapsulated in easy to install round tubes. Tests were carried out on small AT water inlet-to -PCM latent temperature differences in order to measure the behavior and to verify the applicability of PCM for short term thermal storage systems, both for very quick loading and unloading patterns. The PCM used is based on an eutectic salt hydrate, with additives for reassuring long term stability and increase of thermal conductivity.