Fraunhofer Energy AllianceFraunhofer ISE
The modularized encapsulation system for phase change material (PCM) allows larger storage units to be built quickly and easily. The module can be equipped with up to 75 capsules, providing a volume of up to 7.5 liters for PCM, for a total modul volume of 12.4 liters. The choice of capsules with a high surface-to-volume ratio results in heat transfer areas of up to about 1.7 m², allowing a charging and discharging capacity of between 5 and 20 kW/m³ to be achieved. Water, water-glycol or air can be used as heat transfer fluids. Even at maximum capsule loading, the differential pressure is in the range of a few mbar.
The capsule system has been tested using both salt hydrates and organic PCM (paraffins) and shows high stability against corrosion and leakage for both material groups.
By using capsules produced in large quantities from the food industry, the cost of the capsule system can be kept very low at less than 2 €/l. In addition, the system allows the use of existing highly automated filling and capping systems, which additionally reduces the costs compared to specially produced encapsulations for PCM.