Thermal performance enhancement and optimization of double-layer microchannel heat sink with intermediate perforated rectangular fins

Abstract

In the present work, three-dimensional numerical investigation has been carried out to comprehend the thermohydraulic performance of novel design of double-layer microchannel heat sinks (DL MCHS). Conventional DL MCHS is modified by incorporating intermediate rectangular fin with holes of four distinct shapes namely triangular, rectangular, circular and square having equal perimeter. Series of numerical simulations have been performed for the Reynolds number (Re) ranging from 100 to 400, and uniform heat flux varied from 500 to 2000 kW/m2. Single-phase liquid water with varying thermophysical properties is used as cooling medium. Predicted numerical results confirm that compared to conventional configuration; modified DL MCHS has significantly augmented the heat transfer rate causing average Nusselt number to be increased by ≈ 45–60%. But they also encounter higher pressure drop due to massive flow restrictions prevailing in such configurations. Nevertheless, overall thermal performance of the modified DL MCHS is better than the conventional design. Among all the considered cases, heat sinks with circular and triangular holes consistently show superior thermal performance compared to square and rectangular holes, but it is very marginal of the order of ≈ 2–5%. Analysis of coolant flow behavior reveals that intermediate fins with holes facilitate better fluid mixing and provides staggered flow passages in addition to thinner boundary layer which keeps on re-evolving. All these favourable flow behaviors led to improve the heat transfer rate in modified DL MCHS. Furthermore, optimization study of the heat sink with circular holes identify that a configuration with hole radius (Rh) = 0.286 mm and number of holes (Nh) = 15 is superior which exhibits maximum heat transfer rate ≈51–64% higher than conventional DL MCHS.