Conventional boiler combustion CFD models typically assume a constant waterwall temperature. In order to improve accuracy

some studies have adopted a heat flux coupling method to integrate combustion dynamics with heat transfer mechanisms of working fluid. To further enhance the precision of boiler combustion simulations

this paper proposes a novel model coupling method——radiation temperature coupling. This method employs the flame radiation temperature calculated by the combustion model instead of using heat flux to couple with the working fluid model. Through iterative refinement

an accurate waterwall temperature distribution under thermal equilibrium is obtained

leading to a more precise prediction of furnace flue gas temperature distribution. The model is validated by simulating the design thermodynamic calculation condition of a 300MW subcritical tangential combustion boiler. The results show that: the conventional model predicts a flue gas temperature of 1 574 K at furnace arch

corresponding to a -4.14% deviation from the thermodynamic reference value of 1 642 K. In contrast

the coupled model yields 1 660 K

improving accuracy with an error of 1.10%. Compared to the heat flux coupled model

the radiation temperature coupled model eliminates deviations caused by iterating with unbalanced waterwall temperature

thereby achieving more accurate predictions of flue gas temperature distribution. The radiation temperature coupled model delivers more accurate simulation results

thereby providing stronger support for systematic and precise optimization of boiler combustion and multi-stage heat exchanger performance under flexible operating conditions.