Numerical study of single and two-phase models of water/Al2O3 nanofluid turbulent forced convection flow in VVER-1000 nuclear reactor

This is the second in a three-part series of papers on the behavior of nanofluid as a VVER-1000 nuclear reactor coolant, where heat transfer enhancement is studied through the use of homogeneous mixture of nanoparticles with water, so called nanofluid, as the reactor coolant. In the first paper we described the attribution of nanofluids to the neutronic properties of VVER-1000 reactor core. This paper investigates the thermal hydraulic attribution of nanofluid to a VVER-1000 nuclear reactor core. A fuel assembly coolant channel of a VVER-1000 core is modeled using a CFD code and heat transfer coefficient, pressure drop and temperature differences are calculated for water/Al2O3 nanofluid. Numerical predictions using single-phase and two-phase mixture model are presented in this paper. In the one phase model we use thermophysical properties of a homogenized mixture of water and nanofluid while for the two phase model we assume that the nanoparticles flow in separate phase and have their own properties different from water. The results indicate that the two phase model produces more realistic results due to inclusion of spacer grids which raises the turbulence and hence particle motions along the flow.