A Heat Transfer Correlation for Flow Channels in a Prismatic Core VHTR

This paper presents the results of a coupled 3-D thermal-hydraulics and CFD analysis of helium flow in a coolant channel of a prismatic core, Very High Temperature Reactor (VHTR). Results are used to develop a turbulent convection heat transfer correlation that accounts for induced mixing in the entrance region as:

h = [0.10(k/D)Re_b^0.653Pr_b^0.4][1 + 0.57e^-(0.20z/D)]

The entrance effect (second term) increases the local turbulent heat transfer coefficient, but diminishes for z/D > 25. This correlation is within ± 2% of the numerical results.