Optimization of heat transfer using V-shaped staggered ribs for BNCT Solid-State Li targets

As a crucial component of the accelerator device, the lithium (Li) target must withstand high-energy proton beam irradiation while effectively dissipating heat. Consequently, cooling the solid Li target for Boron Neutron Capture Therapy (BNCT) has become an urgent issue to address. In this study, V-shaped staggered ribs are incorporated into the top wall of the cooling channel designed for the BNCT neutron target substrate. The effects of rib height, rib angle, and flow direction on the flow field characteristics and heat transfer characteristics of the cooling channel were numerically investigated. The results indicate that the rib height, rib angle, and flow direction strongly affect the pressure drop, average Nusselt number, velocity distribution, and temperature distribution. Compared to smooth channels, the V-shaped rib channel with a rib angle of 60 degrees and a rib height of 2 mm reduced the maximum surface temperature by 48 %, decreasing it from 200 degrees C to 104 degrees C, and achieved a 26 % reduction compared to straight rib channels. Furthermore, the maximum surface temperature can be further minimized by employing backward flow at a specific rib height. While backward flow lowers the temperature, it slightly compromises thermal-hydraulic performance. By effectively reducing surface temperature and enhancing thermal management under high-energy proton beam irradiation, this design minimizes thermal stresses and improves the operational stability and lifespan of BNCT solid-state Li targets, providing a reliable solution for clinical applications.