CFD SIMULATION OF LAMINAR FLOWS IN A NOVEL PRINTED-CIRCUIT HEAT EXCHANGER

Abstract

To improve mixing quality and thermal homogeneity in small scale industrial applications involving viscous fluids, different microstructures have been designed. Split-and-Recombine (SAR) microstructures are one of the designs that have been extensively studied due to their compactness and efficiency.

The current work is a numerical study that describes the mixing, hydrodynamic and thermal performance of a new SAR geometry design used as a multifunctional heat exchanger. This new design utilizes double separation and recombination to achieve good mixing and heat transfer in a very compact structure. For this purpose, computational fluid dynamics tools were used to compute and assess mixing indices, pressure drop, friction factor, and thermal homogenization for a viscous fluid at different flow conditions. The findings were compared against two commonly used SAR mixers in the literature in the Reynolds range of 1 to 300. The results show that for Re<200, the new Double SAR design show mixing performance comparable to Chen SAR, but superior to Gray SAR design. Beyond Re=200 all the designs exhibited perfect mixing >99%. On the other hand, the thermal-hydraulic performance of the Double SAR was lower yet close to that of Gray SAR (with difference ranging between 19 % and 25%). Nonetheless, it was superior to the thermal- hydraulic performance of Chen SAR (with difference ranging between 70 % and 85%). Hence, the new Double SAR design has proved to offer a balance performance: achieving both good mixing quality and thermal homogenization at low energy expenditure.