Topologically optimized manifold microchannel heat sink with extreme cooling performance for high heat flux cooling of electronics

The manifold microchannel heat sink (MMCHS) has become one of the most promising cooling solutions for high heat flux electronics due to its lower pressure drop and higher temperature uniformity compared to the traditional microchannel heat sink (MCHS). However, the microchannel configurations in previous MMCHS are dominated by parallel, straight microchannels, which would limit their further enhancement in cooling performance. In this work, we designed the microchannel configuration in the MMCHS using a topology optimization method and proposed a manifold microchannel heat sink with a topologically optimized microchannel substrate (MMCHS-TOMS). The thermohydraulic performance of the MMCHS-TOMS was experimentally and numerically studied. The results showed that the microchannel configuration with optimal cooling performance is achieved at a width ratio of inlet to outlet (Win/Wout) = 0.5 and inlet pressure (Pin) = 10 Pa. The MMCHSTOMS demonstrates a uniform flow distribution in adjacent arrays, and the discrepancies of volumetric flow rate (Vd) among all inlets are less than 6 %. The MMCHS-TOMS is capable of removing 1570 W/cm2 heat flux under a footprint area of 42 x 10.5 mm2 with a pressure drop of 11.9 kPa, in which the volumetric flow rate and inlet temperature are 3 L/min and 293 K, respectively. With a volumetric flow rate of 1 L/min and a heat flux of 687 W/cm2, the MMCHS-TOMS achieved a maximum cooling coefficient of performance (COP) of 78273, which is the highest value reported up to date. Moreover, oscillations in temperature (mild) and pressure drop (large) are observed in the MMCHS-TOMS when violent boiling occurs; the system stability caused by those oscillations can be suppressed via increasing the volumetric flow rate, although the COP would thus be reduced.