Abstract
Supercritical carbon dioxide (sCO2) cycles are gaining attention for their efficiency and low carbon footprint in power plants. This study focuses on optimizing the performance of a 5 MW simple recuperated sCO2 Brayton loop during inventory control, a recommended strategy for maximum part-load efficiencies. Variable speed operation of turbomachines is explored to enhance part-load efficiency across the operating range, contrasting with the baseline case of constant turbine and compressor speeds. The analysis, which is based on an analytical formulation and validated component models reveals that part-load efficiency can be improved by variable speed operation of the turbomachines. The decoupled shaft systems outperform coupled or single shaft systems. Further, part-load efficiency deterioration in case of constant speeds has been discussed in depth. A unique feature of this study is its modelling methodology. The compressor model is derived by modifying an ideal gas compressor model to account for the behavior of a real gas compressor. Component matching is performed systematically to estimate cycle conditions accurately. This work enhances our understanding of sCO2 cycle operation under part-load conditions, providing valuable insights on control strategy and inventory management system design for fast response and improved efficiency.
