Flow thermohydraulic characterization of hierarchical-manifold microchannel heat sink with uniform flow distribution

•Flow uniformity of manifold microchannel (MMC) heat sink is analyzed.•Flow difference between adjacent microchannels is less than 7% in hierarchical-MMC.•Pressure drop of hierarchical-MMC is reduced by 28–32% compared to typical-MMC.•Heat dissipation of 450 W/cm2 is achieved under heated area of 9 cm2 in experiment.•Maximum value of cooling coefficient of performance (COP) is obtained to be 19,480. The manifold microchannel (MMC) heat sink has been used for thermal management of high heat flux electronics. Flow maldistribution among microchannels is one of the major hindrances that affect the proper functioning of the typical-MMC (i.e., a coplanar design of the manifolds and the inlet/outlet ports) cooling system, which is attributed to the Z-shaped flow of fluid between the microchannels and the manifolds. Herein, a novel hierarchical-MMC heat sink with stacked configuration is proposed, which mitigates flow maldistribution by optimizing the flow path. First, the fluid flow and heat transfer characteristics of the typical-MMC and the hierarchical-MMC are compared through single-phase conjugate simulation. Next, experimental tests are performed on the hierarchical-MMC heat sink fabricated by Selective Laser Melting (SLM) technology under single-phase and subcooled flow boiling conditions. The numerical results indicated that the hierarchical-MMC exhibits a uniform flow distribution, and the difference of percentage of volumetric flow rate in the section plane of the parallel microchannels is less than 5%. Compared with the typical-MMC, the total pressure drop and overall thermal resistance of the hierarchical-MMC are reduced by 28–32% and 7–13% at the volumetric flow rate of 0.12–1.17 L/min, respectively. Moreover, the experimental results verified the accuracy of the numerical simulation and the feasibility of fabricating the hierarchical-MMC through SLM technology. Under subcooled flow boiling condition, a heat dissipation of 450 W/cm2 is achieved under a footprint area of 30 × 30 mm at the volumetric flow rate of 1 L/min. The maximum value of cooling coefficient of performance (COP) for hierarchical-MMC heat sink is obtained to be 19,480 at the volumetric flow rate of 0.6 L/min and heat flux of 260 W/cm2.