Graphene enhanced paraffin nanocomposite based hybrid cooling system for thermal management of electronics

Hybrid cooling systems combining forced convection with passive phase change material (PCM) based heat sink is an ideal solution for long-term cooling of high power electronics. The effectiveness of composite PCM with graphene nanofillers on transient performance of a hybrid thermal control system was investigated experimentally under uniform and periodic pulsed heat loads. Graphene was synthesized by liquid-phase exfoliation and paraffin/graphene composite was prepared for various concentrations. The thermo-physical properties of paraffin/graphene composite were measured. Transient thermal responses of heat sink with paraffin/graphene composite (HS-Gr/PCM) and paraffin (HS-PCM) were compared to heat sink without paraffin (HS) for passive and hybrid cooling mode configurations. The thermal performance of HS-Gr/PCM was far superior to HS and HSPCM in all thermal loading scenarios. In passive mode, maximum of 6 degrees C lower steady-state temperature was attained for HS-Gr/PCM relative to HS under uniform thermal load. In hybrid mode, time to reach fan onset temperature was enhanced by 109%, 122% and 110% for HS-Gr/PCM over HS, corresponding to periodic heat pulses with duty factors 0.5, 0.79 and 0.9 respectively. Experiments with hybrid cooling system showed 11-23% enhancement in fan energy savings for HS-Gr/PCM as compared to HS at different periodic heat pulses.