The impact of the pseudo-boiling on the thermal behaviors of supercritical CO2

Based on the comparative analysis of different turbulence models, the SST k - omega model is selected in the present study to simulate the flow of supercritical CO2(S - CO2) in horizontal straight tubes. First of all, the rationality and correctness of the numerical simulation is verified by experimental data. Secondly, to deeply investigate the effect of pseudo-boiling point on the convective heat transfer of S - CO2, the ideal gas model without peak specific heat and the actual model are established. The results show that the ideal gas model can increase the wall temperature at top generatrix for the outlet area of the heating section, reduce its heat transfer coefficient, and weaken the effect of S - CO2 absorbing heat from top generatrix. The pseudo-boiling point has a significant influence on density distribution but almost no effect on the velocity field. In addition, the pseudo-boiling point also affects buoyancy, which increases buoyancy near the outlet area of the heating section and reduces heat transfer effect. The research results can not only be used as a theoretical reference for heating device optimization and stability, but also provide new perspectives on the fundamental theories of research on various supercritical fluids.