A Comprehensive Review of Printed Circuit Heat Exchangers: Fabrication, Thermal–Hydraulic Performance, and Reliability

Printed circuit heat exchangers (PCHEs) represent a critical technology for application in advanced energy systems due to their compact configuration, exceptional thermal efficiency, and robustness under extreme temperatures and pressures. This review systematically examines PCHE technology, covering key fabrication processes—including material selection, channel etching, and diffusion bonding—alongside the thermal–hydraulic performances of various channel geometries and optimization strategies. Although considerable progress has been made in geometric optimization—with reported heat transfer enhancements of up to 250% and flow resistance reductions of up to 84.7%—most of the available optimized designs remain confined to numerical analyses. A significant gap persists between these idealized models and real manufacturing constraints, where etching and inducing geometric deviations inherently affect both performance and mechanical integrity. Moreover, current Nusselt number and friction factor correlations lack universality, and mechanical integrity assessments often neglect long-term degradation mechanisms such as fouling. This review identifies these critical gaps and proposes that future research should prioritize integrating geometric optimization with fabrication feasibility and mechanical integrity. Also, there is a need to develop generalized correlations that incorporate both fluid property variations and geometric effects, and to systematically evaluate long-term performance via component-scale testing.