Investigation of external magnetic field effect on the performance of ferrofluid-based single-phase natural circulation loops

Abstract

The goal of this study is to investigate the performance of a Single-Phase Natural Circulation mini Loop (SPNCmL) operating under the influence of an external magnetic field (EMF).For this purpose, a numerical SPNCmL model working with Fe3O4 ferrofluids (1–3 vol%.) under the influence of an EMF is developed to reflect the effect of a NdFeB permanent magnet with a remanence of 1.22 T located at the outlet of the cooler-end for the magnetic field generation. System characteristics such as temperature difference at heater-end (ΔTheater) and maximum temperature (Tmax) and performance in terms of effectiveness (ε) are investigated. In addition, the effect of EMF on boundary layer energy transport along the cooler-end is evaluated in terms of the change in the local Nusselt number. Applying an EMF dramatically affects the system performance in terms of an increase in ΔTheater and ε, respectively up to 34% and 25% compared to those with water. Tmax values are obtained by up to 9% higher for Fe3O4 ferrofluids compared to water, while applying EMF results in an increment in Tmax by up to 5%. Improved heat transfer performance by employing EMF at the cooler-end outlet of the SPNCmLs emphasizes their potential in cooling applications.