Performance Analysis of Heat Transfer Enhancement Techniques in Compact Heat Exchangers

Abstract

Compact heat exchangers (CHEs) achieve high heat-duty-to-volume ratios that are essential in automotive, aerospace, HVAC, process, and electronics-cooling applications, but their air- and liquid-side thermal resistances remain the principal barrier to further volume reduction. This paper presents a comparative performance analysis of five widely studied heat transfer enhancement techniques for compact heat exchangers — offset strip fins, louvered fins, louvered fins combined with delta/rectangular-winglet vortex generators, microchannel/printed-circuit geometries, and single- and hybrid-nanofluid working fluids — evaluated through the Nusselt number (Nu), Fanning friction factor (f), and the Performance Evaluation Criterion (PEC). A CFD-based numerical framework using the ReynoldsAveraged Navier–Stokes (RANS) equations with the k–ω SST turbulence closure is described and validated against established Manglik– Bergles offset-strip-fin and louvered-fin correlations. Illustrative computational results, calibrated to the trends reported in the cited literature, show that combining louvered fins with delta-winglet vortex generators yields the highest PEC (up to 1.24 at Re = 1000), driven by longitudinal-vortex-induced thinning of the thermal boundary layer, while hybrid Al₂O₃–CuO/water nanofluids provide the largest singlephase Nusselt number enhancement (up to 63.5% at 2.0 vol.% at the cost of a near-50% friction penalty). The results are synthesized into a unified ranking that accounts jointly for thermal gain and hydraulic penalty, and design guidelines are proposed for selecting enhancement techniques according to application-specific pumping-power constraints.