HEAT TRANSFER WITH NONUNIFORM SURFACE HEAT FLUX AND THERMAL-HYDRAULIC DESIGN OF THE PLASMA-FACING COMPONENTS OF FUSION REACTORS

Convective heat transfer with circumferentially varying heat flux as encountered in plasma-facing components in fusion reactors is analyzed numerically. The flow is assumed non-MHD and fully-developed laminar and turbulent in a circular tube. A strong circumferential variation of Nusselt number with the possibility of negative values is observed. The Nusselt number is always lowered at the point of maximum heat flux. This reduction can be as much as 38%, 62% and 37% for the laminar Poiseuille, laminar slug and turbulent flows, respectively. Implications of this reduction in Nusselt number for the design of the plasma-facing components of a fusion reactor are shown by an example using the recently completed ARIES-I conceptual tokamak fusion reactor.