Study of flow and heat transfer performance of nanofluids in curved microchannels with different curvatures

Abstract

This study focuses on investigating the flow and heat transfer characteristics of Copper-water nanofluids (Cu-H2O) and water in microchannels with varying curvatures. The results reveal that Cu-H2O nanofluids demonstrate superior heat transfer performance compared to pure water in all four microchannels. Moreover, curved microchannels exhibit higher heat transfer performance than straight microchannels, regardless of whether the flow is laminar or turbulent. The heat transfer performance improves with increasing channel curvature, volume fraction of nanoparticles, and decreasing particle size. During laminar flow, the impact of curvature on heat transfer performance is more significant. However, during turbulent flow, variations in volume fraction have a greater influence on heat transfer performance compared to changes in curvature and particle size reduction. While larger volume fractions and higher curvatures increase flow resistance, this relationship is less pronounced for turbulent flow as Reynolds number and volume fraction increase. It is worth noting that the comprehensive heat transfer performance index does not consistently improve with increasing curvature, and sometimes straight microchannels outperform curved microchannels with specific curvatures. Additionally, curved microchannels exhibit a smaller average field synergy angle (FSA) compared to straight microchannels, indicating better synergy between the flow field and temperature field. The FSA also shows a relatively uniform distribution of local field synergy angles throughout the flow region in curved microchannels. Furthermore, the FSA decreases as the curvature increases.