One of the most studied types of encapsulation over the years is
the spherical capsules using water as PCM. Adref and Eames [62]
and Eames and Adref [63] studied the dynamic behavior of single
spherical thermal storage elements (capsule of a diameter of
7 cm). This study revealed that 90% of cold energy could be
extracted from the ice storage spherical element within 70% of
the time required to discharge it completely. The HTF temperature
and spherical capsules size have been found to influence the