Numerical study of the flow boiling cooling performance of leaf vein manifold microchannels

The operational reliability of advanced semiconductor devices is contingent upon the effectiveness of heat dissipation methods. Extensive investigations have been conducted into the potential of manifold microchannels as a promising near-junction heat dissipation method. However, studies combining natural structures with manifold microchannels have been relatively scarce, particularly in the context of flow boiling. This paper proposed a leaf vein manifold microchannel heat sink. The thermal-hydraulic performance and flow distribution characteristics of symmetric and asymmetric arrangements are comparatively analyzed by VOF transient flow boiling simulations. In comparison to straight microchannels, the leaf vein microchannels exhibited an increase in the wetted area and a reduction in the skewness of the flow distribution by 18%. These improvements contributed to a 4K cooler heated surface at 100 W/cm². In addition, the asymmetric leaf vein microchannels reduced the thermal resistance by 5% in comparison to the symmetric structure, while the pressure drop remained unaltered. The enhancement of the asymmetric leaf vein structure on the thermal-hydraulic performance was found to be consistent across different heat fluxes and inlet velocities. Furthermore, it was observed that doubling the inlet flow rate resulted in a 29.7% reduction in thermal resistance of the heat sink, accompanied by a 130.6% increase in pressure drop. It is therefore recommended that a lower flow rate be employed to minimize the pumping power. The asymmetric leaf vein manifold microchannel proposed in this work demonstrated enhanced flow and heat transfer performance through structural adjustments, which has the potential to be applied to two-phase embedded cooling.