Influence of Flow Inhomogeneity on Heat Transfer in Reheaters of Nuclear Power Units

Reheaters are key equipment in nuclear power units used to increase turbine power and reduce component corrosion, and the shell-stream steam axial flow inhomogeneity has a significant impact on efficiency and safety of the units. In this regard, a one-dimensional distribution numerical and simulation model of the reheater was firstly established to verify the steady state and the accuracy of the flow step dynamics under different operating conditions. Considering that the distribution of steam circulating in the reheater had a strong flow inhomogeneity along the tube length, the flow and heat transfer of steam inside and outside reheater tubes were simulated under different flow deviation coefficients. Results show that under the rated condition, the change of circulating steam outlet temperature is inversely proportional to the flow distribution, and as the flow deviation coefficient increases, the temperature distribution becomes more uneven; the outlet enthalpy and dryness of reheat steam in each tube section are less affected, but the probability of subcooling at the outlet of reheat bundle decreases with the increase of flow deviation coefficient. In addition, the low power operation of equipment makes the outlet of reheat bundle more susceptible to subcooling, and the influence of flow inhomogeneity increases.