Thermohydraulic performance of a double-layered microchannel heat sink with secondary channels and rectangular ribs

Microchannel heat sinks (MCHSs) are important micro-scale devices that play an essential role in managing the temperature and reliability of electronic components. In this study, the impact of implementing a double-layered structure on the functionality of the MCHS utilizing secondary oblique channels and rectangular ribs has been examined through numerical analysis employing the open-source OpenFOAM 11 software. To examine the thermal characteristics of the double-layered microchannel heat sink (DL-MCHS), three geometric variables, relative secondary channel width ( λ ), relative rib width ( β ) and angle of secondary channel ( θ ), have been introduced and investigated at Reynolds numbers ( Re ) of 100 to 500. The results indicate that the ribs enhance flow mixing and thermal distribution by redirecting the stream towards the secondary channels. Furthermore, the presence of secondary channels in a double-layered structure provides a significant amount of heat transfer area for heat dissipation and also lowers the pressure drop resulting from rib structures to an acceptable level. Also, for identical geometric parameters and Reynolds number, the thermal efficiency of the parallel flow double-layered structure is higher compared to the counterflow design due to the position of ribs, specifically at lower Reynolds numbers. Moreover, the parallel flow DL-MCHS at λ =0.666, β =0.6, θ =45° and Re =500 shows the best overall performance. Consequently, the highest overall performance factor of 1.224 is achieved with a 2.57 times rise in average Nusselt number compared to the straight double-layered design at an average temperature of 303.24 K and a maximum temperature of 304.9 K for the substrate of the model.