CFD Investigating Non-Uniform Circumferential Distribution in Heat Transfer Characteristics for a Single-Phase Helical-Coiled Tube

The helical-coiled tube (HCT) heat exchanger (HX) has been applied in the nuclear industry, especially HXs in the residual heat removal system for nuclear power plants (NPPs) and steam generators for small modular reactors. In this paper, a single-phase CFD model is developed to investigate the non-uniform circumferential distributions in the wall heat transfer characteristics for a vertically HCT since the localized information is needed for the safety of NPPs. As shown in comparison, predicted circumferential heat transfer characteristics agree well with data. Governed by the centrifugal/gravitational forces, these non-uniform distributions can be clearly seen in the present results, enhancing explanation of test data. Additional simulations are also performed using the conjugated heat transfer from the hot fluid of shell side to the cold fluid of tube side, confirming that the inhomogeneity of circumferential distributions for a HCT is essentially caused by assumption of constant-heat-flux boundary condition.