Numerical analysis for heat transfer enhancement of a lithium flow under a transverse magnetic field

Related to the first wall and blanket cooling for magnetically confined fusion reactors, heat transfer characteristics of a lithium flow in a conducting rectangular channel in the presence of a transverse magnetic field was investigated numerically. Special attention was paid to the effect of convective heat transport by jets generated in sidelayers on heat transfer enhancement. The Navier–Stokes equations including the Lorentz force term, the equation for scalar potential and the energy equation were solved numerically to simulate the flow and heat transfer of the lithium flow with a heated wall parallel to the direction of the magnetic field. The jets appeared adjacent to side walls parallel to the applied magnetic field. The ratio of peak velocity in the jets to average velocity reached about six at the Hartmann number of 1900. Skin friction coefficient agreed well with the simple analytical model: Cf=kpM2/2Re, with kp=0.13. Temperature was lower in the center of a heating surface due to the cooling effect of the sidelayer jet. The Nusselt number increased by 42–50% at the Hartmann number of 1900 compared with hydrodynamic flow. It was confirmed that the jet in the sidelayer played an important role in the enhancement of heat transfer in a lithium flow in a rectangular channel.