Solar Heating Systems With Heat of Fusion Storage With 100% Solar Fraction for Solar Low Energy Builidngs

A storage concept based on the phase change material (PCM) sodium acetate trihydrate and active use of supercooling is theoretically investigated by means of TRNSYS simulations. The supercooling makes it possible to obtain a partly heat loss free storage when the melted salt due to heat loss supercools to the surrounding temperature and no further heat loss occur. The heat of fusion energy is preserved and can be released by activation of the solidification on demand. The investigations show that 100% solar fraction can be reached in a low energy house in a Danish climate with a solar collector area of 36 m2 and a PCM storage volume of 6 m3 combined with a 180 litres DHW tank. Experiments have proved that it is possible to melt large volumes of sodium acetate and an automatic controllable activation mechanism has been developed and tested.