Design and Analysis of Key Instruments of Supercritical Carbon Dioxide Brayton Cycle in Future Nuclear Power Field

The Brayton cycle with supercritical carbon (S-CO2) as working medium is one of the most promising new nuclear power systems. As the key device during the expansion and compression process in the Brayton power cycle, the turbine and compressor design and performance analysis is difficult for the strong nonlinear properties during the near critical region of S-CO2 medium. The design and analysis of the S-CO2 turbine and compressor is the key point for increasing the power device performance and operation security. As a result, this paper proposes a detail design and analysis method for turbine and compressor in the S-CO2 Brayton power cycle. The MW grade power cycle is used as the research project. The inlet and outlet parameters of the turbine and compressor are determined according to the power cycle scheme. Engineering thermodynamic principles combined with two-zone loss model are chosen to carry out the one-dimensional flow path design for the turbine and compressor respectively. Then the quasi-three dimension design of the flow path is accomplished by stream curvature method. The three dimensional geometry structure of the impeller is designed in detail. On this basis, numerical simulation models of the turbine and compressor are established to analysis the flow field and structural strength vibration in detail. Moreover, the simulation results show that the isentropic efficiency of the compressor impeller is 96.9%. The maximum total displacements of the compressor and turbine impeller are 0.12 mm and 0.106 mm respectively. The maximum von Mises equivalent stresses of the compressor and turbine impeller are 372 MPa and 320 MPa respectively. The impeller can meet the strength safty requiments for the maximum stress values are much less than the yield stress of the material.