To address the performance deviation of simplified component models for S-CO Brayton cycles under off-design conditions

this study establishes an integrated system simulation program based on one-dimensional predictive models incorporating variable efficiency for rotating machinery components. The program investigates the influence patterns of key parameters on the thermodynamic performance of both components and the system under off-design operation. Furthermore

it analyzes the deviation in overall system performance between the one-dimensional predictive models and traditional simplified constant-efficiency models. The research findings demonstrate that an increase in the main compressor inlet temperature results in reduced CO density

consequently leading to increased power consumption by the main compressor. However

under the combined effects of system pressure losses and turbine efficiency

the turbine output power exhibits an opposing trend. System efficiency decreases with rising main compressor inlet temperature

with a more pronounced reduction observed under lower inlet pressure conditions. The maximum efficiency reduction of 11.6% occurs at a suction pressure of 7.68 MPa. Higher system thermal efficiency is achieved when the main compressor inlet parameters approach the pseudo-critical point. Comparative analysis reveals that the maximum discrepancy in system efficiency between the simplified model and the one-dimensional predictive model reaches 6.6%.