Thermo-hydraulic performance in modified double-layer microchannel heat sinks designs: Optimization of sinusoidal and rectangular fin configurations for enhanced fluid mixing and heat transfer efficiency

Abstract

A three-dimensional numerical analysis has been performed to investigate the thermo-hydraulic performance of innovative designs of double-layer microchannel heat sinks (DL-MCHS). The conventional DL-MCHS design has been altered by integrating intermediate fins with rectangular and sinusoidal shapes, the latter featuring varying amplitudes (A) and wave numbers (t). These fins are strategically placed along the flow paths within the channel. A comparative evaluation of heat transfer efficiency and pressure drop characteristics between the traditional and modified DL-MCHS designs has been conducted for Reynolds numbers ranging from 100 to 400, and heat flux levels between 500 and 2000 kW/m². Single-phase liquid water serves as the cooling medium. The results indicate that the modified designs can enhance heat dissipation by 50–70 % compared to the conventional DL-MCHS. But owing to higher obstructions encountered by coolant in the flow passage, pressure drop penalty also increases in such configurations. Among all the analyzed configurations, the modified DL-MCHS incorporating sinusoidal intermediate fins with an amplitude (A) of 10 μm and a wave number (t) of 5 mm⁻¹ demonstrated consistently better thermal performance, achieving approximately 5–10 % higher thermal performance factor compared to the conventional DL-MCHS. Flow visualization of the coolant indicates that the presence of sinusoidal fins promotes improved fluid mixing, which in turn enhances heat transfer. Furthermore, a time-efficient optimization study on DL-MCHS with sinusoidal intermediate fin discloses that heat sink with A = 10 μm, and t = 15.303 mm⁻¹ achieves average Nusselt number ($\overline{Nu}$) ≈ 60–70 % higher than the conventional DL-MCHS.