Study of New Core Design for Typical Nuclear Research Reactor to Enhance the Heat Transfer Rate

Abstract

Rough surfaces have been used as a tool to enhance heat transfer by increasing the level of turbulence mixing in the flow. In numerically simulating such flows. The main purpose of the present work is to increase the production of Mo-99 from a typical MTR nuclear research reactor by improving the thermal hydraulic properties in the reactor core. Ribs are known to enhance the heat transfer between the energy-carrying fluid and the heat transfer surfaces. A numerical investigation on the turbulent flow and heat transfer behavior in the rectangular channel with inclined broken ribs for six kinds of rib arrays has been conducted. In addition, the effects of rib thermal boundary condition and near-wall treatments are also investigated. All computations are undertaken using the commercial CFD code (ansys workbench 15.0). The computations, basedon the finite volume method with the SIMPLE algorithm, have been carried out with Reynolds numbers ranging from 8000 to 160000. Shear stress transport (SST) k – ω turbulence model was adopted. The studies of two-dimensional flow structure including vortex structure and turbulent mixing characterized by the turbulence kinetic energy were carried out. The numerical results show that the inline ribbed channel improved the heat transfer by about 160-230% compared with that of a smooth channel because co-rotating longitudinal vortices are generated on the cross section of the channel. In addition, the effects of geometric parameters for ribs on the heat transfer, such as rib height, rib pitch, were analyzed. Overall, the Stagg ribbed array shows the best thermal hydraulic performance factor. Modified flow channels doubles the production of Mo-99.