Magnetic fin for heat transfer enhancement in liquid metal duct flow

Abstract

The use of fins in heat exchangers is one of the most common procedures to promote heat transfer enhancement. Here, we explore numerically the effect of a non-intrusive electromagnetic method, namely, a magnetic fin, to enhance heat transfer in a liquid metal duct flow. The idea is to place a small-size magnet externally to the duct but close to a heated wall so that the Lorentz force created in the fluid by the interaction of the induced electric currents and the localized magnetic field brakes the liquid metal flow creating vorticity and improving the convective heat transfer. Thus, the action of the localized Lorentz force (i.e. the magnetic fin) is analogous to the surface force created by a solid fin. Focusing the attention on how the laminar bulk flow affected by the presence of a magnetic fin influences the heat transfer on a heated sidewall in a wide interval of Hartmann numbers (0 ≤ Ha ≤ 550) for fixed Reynolds numbers (Re = 500,1000,1500), a two-dimensional numerical approximation is implemented. Optimal values for heat transfer enhancement of the interaction parameter N = Ha2/Re and magnet-wall separation are determined as well as the percentage increment of heat transfer due to the presence of the magnetic fin. Figs 6, Refs 9.