Numerical Study of Thermo Hydraulic Effect of Wire Wrap Spacer with Different Pitch in Hexagonal Fuel Assembly

In this paper, thermo-hydraulic effects of the wire-wrap spacer in a hexagonal fuel assembly with seven fuel rods have been investigated. The effects of wire-wrap pitch and Reynolds number on fluid flow, pressure drop, and temperature distribution have been analyzed. Thermal and fluid analysis has been studied for 66, 100, 200, and 400 wire-wrap pitches. K-ε turbulence model is used to perform this numerical simulation. The results are compared with a no-wire-wrap state. The results show that by increasing the Reynolds number, the pressure drop of the assembly with and without wire-wrap increases (100% increase in Reynolds number of 100,000). At a constant Reynolds number, decreasing the pitch of wire-wrap increases the pressure drop (60% increase by reducing the pitch from 200 to 100 mm). Wire-wrap improves flow mixing and heat transfer, and by reducing the pitch of the wire-wrap, the results have a more uniform distribution of temperature in each section of the assembly.