A Helical Coil Steam Generator (HCSG) is one type of heat exchangers used for the purpose of increasing the efficiency of heat transfer with low pressure drop in recent design of high temperature reactors (HTRs). To investigate the fluid phenomena around the coil bundle of HCSG, the experimental facility had been designed and computational fluid dynamics (CFD) simulations had been conducted to compare the results of experimental ones. In this study, various types of turbulent models in the commercial CFD code (STAR-CCM+) were tested with various grid sizes on the target Reynolds number, ReD = 163,000, to enhance the validity of the simulation result. The computational domain used to run the CFD simulation had the same geometry of the experimental test section which had the half-coil shaped ribs on each curved channel wall. The working fluid properties employed in the simulation was scaled to the target Reynolds number at room temperature. The averaged static pressure drop induced by coil bundle inside the test section was obtained between the inlet and outlet of the test section. In addition, flow structures inside the flow channel were examined going through the velocity field distribution around the coil and the effect of vortical structures in the flow channel.