Dynamic performance of supercritical CO2 Brayton cycle and its relationship to the correction of turbomachinery performance maps: A comparative analysis

Due to its numerous advantages, including the capability to achieve high thermal efficiencies and compactness, the supercritical carbon dioxide Brayton cycle (SCO2BC) has recently been considered as an attractive nextgeneration heat -to -power conversion cycle. Dynamic modelling of the SCO2BC is essential to simply grasp and analyze its performance in either design or off -design conditions. Turbomachines are key components in the SCO2BC, which are typically modelled by adopting their design-point performance map. However, during offdesign operations, the performance maps become inaccurate, and correction relations must be integrated into these models to enhance their validity. Despite the development of multiple performance map correction, reduction, and normalization methods, there is a scarce literature that implemented highly accurate correction relations in SCO2BC transient models, which impacts the validity of the obtained results. Therefore, there is a need to assess the accuracy of these results compared to the results of a SCO2BC model adopting an accurate correction method. However, some information needs to be provided first, which include how turbomachinery correction impacts the dynamic behavior of SCO2BC compared to using uncorrected turbomachinery models, and if the correction of one turbomachine (i.e., the compressor) is more significant than the other. This work aims to provide this data and more by developing dynamic SCO2BC models (CPP models), comprehensively evaluating their transient performance, and comparing them to SCO2BCs with uncorrected turbomachinery models (FPP models). This work possesses novelties of utilizing the most accurate turbomachinery correction model found for SCO2BC and building the model in Simcenter Amesim. It is found that FPP models may be viable when the dynamic responses of the components near the fluctuation source are desired. Otherwise, at least a compressor model correction is required to obtain reliable results. Moreover, all turbomachinery models should be corrected for accurate mass flow rate and power responses.