Comparative performance of liquid cooled micro/mini channel heat exchangers and macro-scale shell and tube exchangers in phase turbulent flow: a systematic review

Abstract A systematic comparative hydraulic performance evaluation of liquid-cooled micro/minichannel heat exchangers and macro-scale shell-and-tube heat exchangers under unified constraints on Reynolds number, pumping power, thermal performance, and footprint over five different databases (Scopus, ScienceDirect, ASME, IEEE, and Web of Science databases from 2015 to 2025) was conducted in this study. Scale-dependent hydrodynamics are identified as the primary determinants of performance and design strategy. The systematic assessment of studies showed that liquid-cooled heat exchangers, with hydraulic diameters ranged 0.005–3 mm attained high heat-transfer coefficients and power density through micro-geometry and manifold control, but they incur steep elevated pressure losses unless flow uniformity and fabrication tolerances are tightly controlled. Shell-and-tube heat exchangers, with tube hydraulic diameters of 6–25 mm delivered robust, manufacturable gains mainly via shell-side flow management, optimizing baffle spacing/cut and controlling leakage/bypass, typically with only moderate increments in pressure drop. Coolant property effects were also scale-specific, with liquid-cooled heat exchangers being highly sensitive to viscosity-driven shifts in Reynolds number at the channel scale, whereas shell-and-tube heat exchangers respond primarily to temperature-dependent viscosity and macro-scale flow distribution. Methodologically, liquid-cooled heat exchangers predictions should bridge gaps between computational fluid dynamics and developed heat exchangers stemming from surface roughness, tolerance dispersion, and maldistribution; shell-and-tube heat exchangers use benefits from refining semi-empirical correlations with leakage-aware assessment. The resulting control is scale-tailored, to co-optimize liquid-cooled heat exchangers geometry and manifold configuration within pumping-power limits and manage shell-and-tube heat exchangers shell-side hydrodynamics and tube shaping to balance duty gains, maintainability, as well as allowable pressure drop. Overall, liquid-cooled heat exchangers suit compact, high-heat-flux applications when viscous losses are constrained, whereas shell-and-tube heat exchangers provide dependable, industrial-scale performance with broad coolant compatibility.