Numerical simulation of the thermal-hydraulic characteristics of supercritical carbon dioxide in a wire-wrapped rod bundle

Abstract

A wire-wrapped spacer was considered in the fuel-assembly design of a supercritical carbon dioxide (SCO2) reactor to improve the heat transfer between the coolant and fuel elements. However, there is still a lack of understanding and detailed evaluation of the performance of the wrapped wire. In this study, the turbulent flow and heat transfer of SCO2 in a rod bundle were numerically investigated considering the fluid–solid conjugate interaction. Emphasis was placed on revealing the effects of wire shape, wire pitch and number of wire thread on the heat transfer and pressure drop. The performance evaluation criterion (PEC) was adopted to evaluate the performance of spacers. It was found that the heat transfer in the wire-wrapped rod bundle was enhanced compared to that in the bare rod bundle. The trapezoid-shaped wire shows a larger PEC than the circular- and rectangular-shaped wires. In addition, the PEC increased with the wire pitch first but declined subsequently, showing a peak with a wire pitch between 180 and 240 mm. The wire-wrapped spacer with two threads was recommended because of its high heat transfer efficiency and relatively low flow pressure drop.