Research on design and optimization method for a supercritical CO2 centrifugal compressor for gas-cooled micro reactors

Abstract

The supercritical carbon dioxide(sCO₂) Brayton cycle shows significant advantages over the steam Rankine cycle due to its compact size, minimal space requirements, and high energy density. It has become a highly promising research direction in the field of fourth-generation nuclear reactors. The compressor, a core component of this cycle, plays a crucial role in ensuring system efficiency and stable operation. Among various typical compressors, the centrifugal compressor stands out as an excellent choice for the sCO₂ Brayton cycle due to its compact size, ease of manufacturing and installation, superior performance, and efficient operation. The conventional one-dimensional (1D) centrifugal compressor design does not accurately reflect the flow and compression process especially near the critical point, while the conventional three-dimensional (3D) design lacks boundary conditions and geometric parameter selection basis, therefore, this paper proposes an effective combination method of 1D and 3D design. First, this paper introduces the orthogonal test method to determine the primary parameters for the 1D design of sCO₂ centrifugal compressors, which shows an effective reduction in workload. Next, after validating the design method, the design and optimization of a 300 kW sCO₂ compressor in 3D has been carried out. Performance curves are obtained under different blade wrap angles and tip clearances. The optimal values of blade wrap angle and tip clearance of the compressor are identified using the sensitivity analysis. Finally, the performance of the optimized centrifugal compressor has been investigated through numerical simulation under several rotational speeds, inlet pressures, and inlet temperatures around the set operating conditions. This research holds significant implications for the design of sCO₂ centrifugal compressors in gas-cooled micro reactors.