An adequate CFD-calibrated 1D loss model applied for supercritical CO ₂ radial turbines

Supercritical carbon dioxide (sCO 2 ) represents a transformative technology for high-efficiency energy conversion, particularly in concentrated solar power plants. However, realizing its full potential is hindered by a critical design challenge related to the inaccuracy of preliminary performance prediction for the radial inflow turbine (RIT). In this context, the present work demonstrates that classical one-dimensional (1D) empirical loss models, calibrated for conventional working fluids such as air and water vapour, are profoundly inadequate for sCO 2 RITs. Indeed, it was confirmed that at both design and off-design conditions, these models exhibited excessive errors, exceeding 60% deviation from the reference sCO 2 turbine, in predicting efficiency. To address this gap, this study aims to develop and validate a novel 1D loss model specifically for sCO 2 RITs. Furthermore, a CFD campaign based on real-gas equations of state was first conducted across a wide specific speed range. Outcomes precisely quantified the dominant loss mechanisms, revealing an optimal efficiency zone localized for a specific speed between 0.51 and 0.65, with a peak total-to-static isentropic efficiency up to 82% at design point. On the other hand, the main novelty was the dynamic calibration of classical loss correlations using correction functions dependent on specific speed and mass flow rate (MFR) of the turbine. Subsequently, the proposed calibrated model demonstrates exceptional predictive performance compared to the reference CFD data, with a maximum deviation in terms of isentropic efficiency below 5%. Besides, the robustness of the newly calibrated model was rigorously validated through a multi-scale application on three distinct RITs with MFR ranging from 3 to 700 kg/s. This work successfully bridges the critical gap between the rapidity of preliminary 1D design and the accuracy of computationally expensive CFD, providing a reliable, fast and scalable framework for the design of high-performance sCO 2 radial turbines, directly supporting industrial innovation in sustainable energy systems.