A strong non-uniformity of the circumferential distribution of the wall temperature, heat flux and heat transfer coefficient around the rod surface is observed by previous CFD investigations, especially in the tight lattice. This phenomenon is important for core design of some Generation IV reactors such as supercritical water-cooled reactors (SCWR) and liquid metal fast reactors (LMFR). In this paper important dimensionless numbers that affect the non-uniformity of heat transfer are summarized and CFD calculations are carried out to study the local heat transfer behavior of central, corner and wall sub-channels respectively. An empirical correlation is proposed based on CFD data.
Using this correlation, a three-dimensional fuel model is being developed in the sub channel code MATRA to incorporate some of this effect into the thermal-hydraulic analysis of SCWR.