Heat transfer performance of graphene nano-platelets laden micro-encapsulated PCM with polymer shell for thermal energy storage based heat sink

Highlights: • Paraffin is microencapsulated with polymer shell by In-situ polymerization. • Graphene nano-platelets (GnP) of 0.5, 1 and 3 wt% added to enhance the heat transfer between the encapsulated PCM. • The thermal conductance the heat sink increased with GnP wt%. • The temperature rise rate (TRR) of heat sink reduced from 1.1 °C/min to 0.85 °C/min at the temperature range of 40–60 °C. • The GnP in the encapsulated PCM reduced the recovery time of heat sink. -- Abstract: Encapsulation of phase change material (PCM) prevents from leakage and can evade the adverse effect of bulk volume expansion. In this study, experimental results on the heat transfer performance of graphene nano-platelets laden microencapsulated PCM (ME/GnP PCM) in a finned thermal energy storage based heat sink are presented. In-situ polymerization method was used to prepare the capsules with paraffin/polyurethane as core/shell material. The samples were characterized by its morphology, capsule size, phase change properties, thermal and chemical stability. To enhance the heat transfer within the microcapsules, GnP of 0.5, 1 and 3 wt% were incorporated. The performance of PCM was compared with a finned heat sink under constant heat load condition of 10 W, 15 W and 20 W. The performance was evaluated based on the heat sink base temperature with time for set point temperatures and the temperature rise rate (TRR). The thermal conductivity increased from 0.192 to 0.379 W/m K and the TRR of the heat sink was delayed due to the enhanced the heat transfer within the ME/GnP PCM. Moreover, the recovery time of the heat sink also declined due to reduced thermal resistance and nucleation effect in the MEPCM by the GnP.