Entropy generation analysis of nanofluid heat transfer in dimpled heat exchangers

Abstract Enhancing thermal performance while minimizing thermodynamic losses in compact heat exchangers remains a critical challenge in modern energy systems, with limited understanding of synergistic effects between dimpled surfaces and nanofluids, particularly regarding entropy generation characteristics. This study investigates how shallow dimpled geometries (depth‐to‐diameter ratios δ / D = 0.1–0.3) combined with Al 2 O 3 –water and CuO–water nanofluids influence entropy generation patterns and identifies optimal configurations that minimize irreversibilities while maximizing heat transfer performance. Computational fluid dynamics simulations coupled with second‐law thermodynamic analysis were performed across Reynolds numbers 500–3000 and nanoparticle volume fractions 0%–4%, with comprehensive validation against published data (deviations <5%). Results demonstrate that shallow dimples with δ / D = 0.1–0.2 achieve 18%–25% reduction in total entropy generation compared to smooth channels, with optimal performance at Re = 1500–2500. Al 2 O 3 nanofluids at 2%–4% concentration exhibit superior thermodynamic performance (thermal conductivity ratios 1.12–1.18 vs. 1.08–1.14 for CuO). Bejan number analysis reveals transition from thermal‐dominated to viscous‐dominated irreversibility. This research establishes comprehensive design correlations and scaling laws enabling entropy‐optimized selection of geometric parameters and nanofluid specifications for thermodynamically superior compact thermal management systems.