Thermal performance of micro-encapsulated PCM with LMA thermal percolation in TES based heat sink application

Paraffin is one of preferred entrant phase change material (PCM) for the thermal energy storage (TES) based heat sink application. Encapsulation is one of the preferred methods to address the inherent issue with paraffin such as volume expansion, spillage and low bulk thermal conductivity. In this study, describes the synthesis, characterization and heat transfer performance of micro-encapsulated (ME) paraffin of average size similar to 64 mu m by insitu polymerization method. To conquer the adverse effect of reduced thermal diffusion in the bulk ME PCM, a thermal percolation by low melt alloy (LMA: Bi (32%), Sn (59%), Zn (4%) and In (5%)) of similar to 16% volume was incorporated. The characterization results show the form-stability and thermal degradation of PCM. The experiment with heat sink was conducted with fin and without finned heat sink for power levels of 1.57, 2.45, 3.61, 4.49 and 5.51 kW/m(2). The results reveal the promising role of ME PCM/LMA in keeping the heat sink without fin at a lower temperature for a prolonged duration. Obtained an enhancement ratio of 1.87-2.57 and 2.06-3.58 in time to reach set point temperatures of 55 and 65 degrees C with heat load of 1.57-5.51 kW/m(2) LMA percolation. The complete melting and more uniform temperature distribution in the PCM occurred within the operating temperature. Moreover, the recovery time of heat sink also diminished radically. Based on the results, the ME PCM can conquer the adverse effect due to the above mentioned drawback of conventional paraffin and the LMA percolation layer gives a prompt thermal response compared with fins of same volume fraction in the heat sink.