Experimental investigation of thermal performance for pulsating flow in a microchannel heat sink filled with PCM (paraffin/CNT composite)

A novel microchannel heat sink, which includes a heat exchange cavity with pyramid pin-fins and a PCM (phase change material) cavity with square pin-fins, is designed. The CNT (carbon nanotube) is added to paraffin to enhance thermal conductivity. GOPs (Graphene oxide particles) nanofluids pulsating flow driven by square wave are used to improve the thermal performance. The PCM cavity is filled with CNT/paraffin composite material to absorb and store the heat on the heating surfaces and to transfer the heat through the exchange chamber to achieve cooling. The results show that the microchannel heat sink?s thermal performance can be significantly improved using PCM composite and GOPs nanofluids. Under steady flow conditions, the total thermal resistance decreases significantly when the proportion of carbon nanotubes is approximately 20%; and, the maximum increase of Nusselt number reaches 34.9%. The thermal performance reaches the maximum enhancement under pulsating flow as the pulsating frequency is around 6 Hz. The total thermal resistance decreases by 19%, and the Nusselt number increases by 15.2%. The enhanced effects of pulsating flow and PCM composite on thermal performance are also affected by pump power and heating load. The higher heating power plays an active role in the enhancement effect, whereas the higher pump power has the opposite effect.