Impact of pin-fin profiles on high-effectiveness printed circuit heat exchangers

Recuperators are critical components in space reverse Brayton cryocoolers, where even slight effectiveness degradation directly causes significant cooling capacity loss. Printed circuit heat exchangers (PCHEs) offer a promising solution through their compact design and high performance, manufactured by chemical etching and diffusion bonding. However, etching effects directly influence flow passage geometry and consequently impact PCHE hydraulic-thermal performance, necessitating detailed investigation. This study quantifies etching impacts on high-effectiveness pin-fin PCHEs through the comprehensive analysis of 180 full-scale etched plates and systematic characterization of test samples with varying geometric parameters. Statistical models for channel depth and wall thickness distributions, along with descriptions for anisotropic etching-induced pin-fin tapering, are developed and validated. Results reveal that the etching process significantly deteriorates PCHE performance through channel-level dimensional deviations and pin-fin-level deviations. First, channel-level variations observed at etched channel geometries produce 4.5% reduced average etching depth and 8.5% increasing wall thickness, resulting in 0.34% effectiveness loss and 41%−45% pressure drop increase with 95% confidence. Second, pin-fin-level deviations prove more severe observed at etched pin-fin geometry, comprising height reduction, diameter oversizing, and sidewall tapering that collectively reduce effectiveness by 0.5% (corresponding to 57% system cooling capacity loss) and increase pressure drop by up to 193%. Meanwhile, the geometric sensitivity analysis reveals size-dependent responses to etching effects. Small-diameter pin-fin configurations suffer greater thermal degradation, while large-diameter designs experience more severe hydraulic penalties and compactness reduction. These findings provide essential design guidelines for high-effectiveness PCHEs that must account for etching-induced deviations, with applications extending to other etched pin-fin systems in thermal management.