Abstract:

The relationships between the heat transfer behavior and the flow pattern, the temperature difference, the pressure droprin a Cu-base micro-channel heat sink with water coolant were investigated under low Reynolds number 34~191 with a developed micro-channel flow pattern visualization test system. It was found through visualized observation, the main flow pattern is an annular flow with the periodic oscillation appeares when higher heat flux density is supplied. The liquid flow rate decreases rapidly to zero when dry-up happens in the micro-channels. Under low entrance Reynolds number, it was revealed for the first time that the axial temperature distribution on the bottom of micro-channel heat sink presents lower temperature in the middle of sink substrate and higher in the both sides. It may be due to that the heat transfer coefficient is higher in the area where the flow pattern is the completely boiling annular flow. The pressure drop increases with the increase of Reynolds number and the heat flux density. Analysis shows that the flow pattern is the dominant factor affecting the heat transfer behavior of the Cu-water micro-channel heat sink.

Key words: pyrology, heat sink, micro-channel, Reynolds number, heat transfer, flow pattern