The supercritical carbon dioxide (S-CO2) power generation system often operates under partial load conditions due to external disturbances and grid load requirements. When the system operates at low load

the equal flow model (EFM) faces risks of working fluid mixing losses and overtemperatures of the cooling wall. To address these issues

this paper innovatively proposes an equal temperature model (ETM)to adapt to the dynamic distribution of furnace thermal loads

which changes with varying loads

thereby mitigating mixing losses and cooling wall overtemperature problems. For a 300 MWe system

the EFM is more optimal when the load is above 45%. When the load falls below 45%

the ETM effectively reduces wall temperature (a maximum decrease of 19.1℃) and causes a maximum thermal efficiency drop of 0.2%

significantly improving the system’s security. The stability of efficiency results from the combined effects of increased boiler pressure drop (negative effect) and reduced mixing losses (positive effect). This study enriches the theoretical framework of the shunt mode for coal-fired S-CO2 power generation systems

enhances the system’s stability and reliability under low load conditions

and provides strong support for the operation optimization of S-CO2 power generation systems.