Interplay of wettability and confinement enhancing the performance of heat sinks

Abstract

• Tapered Double layer heat sink performance is enhanced by modifying surfaces (slip). • Value of slip length has been obtained using Molecular Dynamics simulation. • Analysis has been done based on both the first law and the second law of thermodynamics. • Entropy generation rate due to changes in kinetic energy has been introduced. • The optimal design of a double-layer microchannel heat sink has been obtained. Engineering microchannel heat sinks can help to develop compact and highly efficient cooling systems for electronic devices. In the present study, we demonstrate the coupled effect of surface modification and confinement on the performance of Double Layered Microchannel Heat Sink (DL-MCHS). The effect of wettability is incorporated using interfacial slip obtained from Molecular Dynamics (MD) simulations performed for various wettabilities, and the effect of confinement, through varying tapering degrees, is directly embodied in the geometry. The coupled transport equations are solved using the Finite Element Method (FEM) to depict the thermo-hydraulic characteristics of DL-MCHS. We quantified the enhancement in hydraulic performance and thermal performance of DL-MCHS with varying degrees of surface modification and varying tapering. For the first time, we demonstrate a regime where thermal and hydraulic performances can be enhanced simultaneously in tapered DL-MCHS thereby, making the configuration a viable heat sink system. Also, for the first time, we perform an entropy generation rate analysis in tapered DL-MCHS and demonstrated ways to reduce irreversibility making it a thermodynamically advantageous system, and following that perform an all parameter optimization study. We show that by tuning the tapering factor and interfacial characteristics, the performance of the heat sink can be adjusted for the best performance. The present study will provide helpful guidelines in designing viable heat sinks or exchangers with smart surfaces for electronics cooling and associated applications.