Thermal energy storage in fluidized bed using microencapsulated phase change materials

Fluidized beds are widely used in effective heat and mass transfer applications for chemical processes. The beds can also used for storing thermal energy (TES) and offer a rapid and effective way to exploit solar energy especially for heating applications. Microencapsulated PCMs serve as the TES medium and the fluid phase in these applications. There exist few experimental studies that have investigated uses of fluidized beds for thermal storage. The works show that properties of microencapsulated PCMs have to be fine-tuned for them to become effective in fluidized beds. This paper investigates the performance of an experimental air-fluidized bed using microencapsulated PCM as the thermal storage system for two different storage temperatures of 55 degrees C and 65 degrees C. The results show that TES using microencapsulated PCM with mean particle size of 100 mu m that corresponds to A-type particle according to Geldart chart showing fluidization behavior of particles is possible. The fluidization process did not change the morphology of the microencapsulated PCM. Fast storage and recovery can easily be accomplished at efficiencies as high as 80%.