Thermal hydraulic investigations with different fuel diameters of pebble bed water cooled reactor in CFD simulation

The thermal hydraulic characteristics of the pebble bed water cooled reactor (PBWR) have been studied by computational fluid dynamics (CFD). The “near-miss” model is applied considering the problem on the mesh quality. The standard κ–ε model is used as the turbulence model. The velocity and temperature fields of the coolant are obtained and analyzed in different fuel diameters (such as 3 and 6 mm). The effects of the diameters on the thermal hydraulic characteristics are also discussed. The distributions of the temperature, velocity, pressure and Nusselt number (Nu) of the coolant on the surface of the pellet are obtained and analyzed. This study can conduct the experimental and mechanism research of PBWR.

► Water is used as the coolant in the PBWR. ► The “near-miss” model is applied. ► The minimum temperature and maximum velocity are located at the neutral position of the four narrow gap regions. ► The high-temperature region and pressure drop of the coolant decreased with the increase of diameter.