Influences of Circular Rib Geometries on the Heat Transfer Characteristics of Supercritical CO₂ in Annular Channels: A Numerical Study

To enhance cooling efficiency by supercritical CO₂ in annular structures, this study meticulously explores a rib-splitting strategy. Utilizing Shear Stress Transport (SST) k-ω within ANSYS Fluent, three-dimensional models are developed and simulated, with settings validated against existing experimental data. The investigation focuses on various structural parameters, including the height and position of circular ribs, and the spacing between semicircular ribs. Key findings reveal that a notable enhancement in heat transfer, measured by the comprehensive heat transfer factor, is observed when the rib’s dimensionless height reaches at least 0.25. Closer to the inlet, higher heat transfer performance is achieved, with a dimensionless position of 0.2 exhibiting the best performance across all instances about position effects. The rib-splitting approach has been proven effective in enhancing heat transfer performance, with the comprehensive heat transfer factor increasing progressively with the dimensionless distance and reaching its maximum at a value of 8. The heat transfer enhancement is characterized by an 8.2% increase in the comprehensive heat transfer factor, achieved with a rib’s dimensionless height of 0.5, a dimensionless position of 0.2, and a dimensionless distance of 8. The derived correlations for the Nusselt number (Nu) and friction factor (f) demonstrate the high accuracy of our computational models, as most cases fall within a ±10% deviation range. Crucially, the results advocate for the rib-splitting method’s efficacy in not only enhancing heat dissipation but also in mitigating pressure loss to a significant degree. The insights gained from this study hold considerable promise for thermal management in shafts, potentially elevating both their operational safety and efficiency. The rib-splitting strategy could be a valuable addition to the toolbox of thermal engineers seeking to optimize the performance of their systems.