EXPERIMENTAL INVESTIGATION OF A PACKED-BED LATENT HEAT THERMAL STORAGE SYSTEM WITH ENCAPSULATED PHASE CHANGE MATERIAL

An experimental study on a laboratory scale prototype packed-bed latent heat thermal energy storage (TES) system is presented. Spherical capsules of sodium nitrate melting point of 306 degrees C were used as the PCM and air was used as the heat transfer fluid (HTF). The storage system was operated between 286 degrees C to 326 degrees C and the volumetric flow rate of the HTF was varied from 110 m(3)/hr to 151 m(3)/hr. Temperature distribution along the bed and inside the capsules was monitored continuously during charging and discharging of the system. The effect of mass flow rate of the HTF on the charging and discharging time and on the pressure drop across the bed was also evaluated.