CFD investigation of flow and heat transfer of supercritical CO2 in wire wrapped rod bundle

摘要

Computational fluid dynamics is increasingly applied to reactor safety analysis, and the applicability evaluation of turbulence model can effectively improve the calculation accuracy. In this paper, the applicability of six turbulence models and two near wall models is compared for simulation of flow and heat transfer of supercritical carbon dioxide in wire wrapped rod bundle. According to experimental data under various conditions, the applicability of turbulence models and near wall models is respectively evaluated from wall temperature and surface heat transfer coefficient. The results show that SST k-n model combined with low-Re model can simulate the change of wall temperature and surface heat transfer coefficient in critical state best, and the average relative error (Tw and h) is 6.88 and 13.17. When CO2 is heated into supercritical state in the latter 900 mm of wire wrapped rod bundle, the relative error (Tw and h) calculated by RNG k-n model is 5.94 and 18.02. The grids number of low Re method is nearly double of the grids number of wall function method. Therefore, the simulation results computed by wall function method at supercritical region are also acceptable due to the low computational consumption. This paper researches the applicability of turbulence model and near wall model to enhance the accuracy of simulation of flow and heat transfer in supercritical CO2 reactor rod bundle.