In view of the actual distribution of heat boundary conditions on the cooling wall of supercritical carbon dioxide(S-CO_2) coal-fired boiler

the heat transfer characteristics of supercritical CO_2 in a vertical circular tube under axial non-uniform heat flux were numerically studied by using SST k-ω low Reynolds number turbulence model. The influence of different heat flux distribution

mass flux on heat transfer performance and wall temperature distribution was analyzed. The results show that the axial non-uniform heat flux distribution has a significant effect on the heat transfer of S-CO_2. Compared with the uniform heat flux

the total heat transfer coefficient under the axial non-uniform heat flux increases by about 8%. The non-uniform distribution of axial heat flux can inhibit the heat transfer deterioration and effectively reduce the peak wall temperature. Under the condition of non-uniform heat flux

the heat transfer of S-CO_2 is mainly affected by the thickness of the gas-like film

the thermal conductivity of the gas-like film and the specific heat near the wall. The results provide theoretical guidance for the design of supercritical CO_2 boiler.