Convective heat transfer and entropy generation evaluation in the Taylor–Couette flow under the magnetic field

Abstract

An applied magnetic field could effectively regulate the fluid heat transmission after adding magnetic particles, and it has a wide application perspective in various fields. In the current research, the flow behavior and heat transfer characteristics of Iron (II, III) oxide (Fe3O4) microparticle suspension in a coaxial cylindrical annular gap with a magnetic field have been performed numerically. Lorentz force and Joule heat are evaluated to elucidate the mechanism of the flow and heat transfer properties regulated by a magnetic field. The entropy generation method is applied for analyzing energy loss inside the annular gap. The results demonstrate that enhancing the Reynolds number (Re) and Hartmann number (Ha) improves the heat transfer capability of the Taylor vortex flow. The maximum improvement in heat transfer performance compared with the case at no magnetic field is 8.09%, under the Re 2663∼4009 and Ha 0∼186. The applied magnetic field causes the velocity and temperature distributions to exhibit anisotropy, and it gets more prominent with the increase of Hartmann number. Lorentz force derived from the magnetic field promotes particle motion and facilitates the base fluids and particles to exchange momentum and energy, and the Joule heat effect also regulates heat transmission. When Re =2663, the SF increase by 21.72% but ST decrease by 17.15% as Ha increases from 0 to 186. It demonstrates the changes in frictional and thermal entropy generation (SF and ST) are positive and negative correlated with the enhancement of Ha. Additionally, the effect of volume fraction on entropy production is less than that of magnetic field intensity which indicates the advantage of a magnetic field in reducing irreversibility. The analysis presented herewith provides a new means to enhance heat transfer in Taylor-Couette flow for utilizing magnetic fields.