Thermal-mechanical coupled stress prediction of printed circuit heat exchanger in the supercritical CO2 Brayton cycle

Printed circuit heat exchanger (PCHE) is widely recognized as the most promising heat exchanger for supercritical CO₂ (SCO₂) Brayton cycle. Stress assessment is critical to ensuring the safety and longevity of PCHE. This study addresses a critical gap in the thermal-mechanical stress assessment of PCHE for SCO₂ Brayton cycles by developing novel quantitative models to predict equivalent stresses at semicircular channel tips. Unlike conventional ASME codes, which overlook thermal stress, the pseudo-2D ANSYS Workbench model integrating both thermal and mechanical stresses, was used to offer a comprehensive evaluation. Key structural parameters (channel diameter, plate thickness, ridge thickness) and operational parameters (pressure, temperature difference) were analyzed. The results reveal that mechanical stress is most sensitive to cold-side pressure, while thermal stress correlates linearly with temperature gradients. Dimensional analysis yielded predictive formulas for thermal stress (±13.3 % error) and mechanical stress (±14.3 % error), validated against finite element method results. A backpropagation neural network further improved prediction accuracy (errors <10 %). The proposed models streamline PCHE design verification and dynamic control optimization, ensuring safer and more efficient SCO₂ cycle operation. This research advances sustainable energy systems by providing reliable tools for PCHE stress assessment, with potential applications in solar, nuclear, and waste heat recovery systems.