Abstract
Supercritical Carbon Dioxide Brayton cycles can be used in conjunction with a host of heat sources associated with different magnitudes of net power generation. In this paper, the overall design features of the turbomachinery, namely the turbine and compressor are evaluated for kilowatt to Gigawatt range of net cycle power using a commercial design tool — AxSTREAM®. The thermodynamic cycle considered in all cases is a simple recuperated Brayton cycle with turbine and compressor inlet temperatures of 540 °C and 45 °C respectively. The highest and lowest pressures in the cycle are 210 bar and 85 bar respectively. The preliminary design is carried out using an inverse algorithm with a meanline solver that generates many geometries for the given boundary conditions using standard loss correlations to account for different losses in turbomachines. It, thus, provides the general design features of the compressor and turbine which include — machine size, shaft speed at design point, overall efficiency, number of blades, blade heights, blade angles and number of stages for axial turbines. The choice of axial or radial impeller and initial estimates of machine size and shaft speed are made based on standard specific speed-specific diameter charts and important loss parameters are presented for each case. This study serves as a first step towards in-depth blade profiling, 3-D analysis and design of the turbomachinery required to bring this technology to the practical realm.
