Potential of enhancing a natural convection loop with a thermomagnetically pumped ferrofluid

Abstract

The feasibility of using a thermomagnetically pumped ferrofluid to enhance the performance of a natural convection cooling loop is investigated. First, a simplified analytical estimate for the thermomagnetic pumping action is derived, and then design rules for optimal solenoid and ferrofluid are presented. The design rules are used to set up a medium-scale (1 m, 10-1000 W) case study, which is modeled using a previously published and validated model (Aursand et al. [1]). The results show that the thermomagnetic driving force is significant compared to the natural convection driving force, and may in some cases greatly surpass it. The results also indicate that cooling performance can be increased by factors up to 4 and 2 in the single-phase and two-phase regimes, respectively, even when taking into the account the added heat from the solenoid. The performance increases can alternatively be used to obtain a reduction in heat-sink size by up to 75 %.

Numerical study of magnetic field effect on the ferrofluid forced convection and entropy generation in a curved pipe

“…For higher values of magnetic number, the variation of Nusselt number with circumferential angle of the magnetic source is non-monotonous. As can be seen, the maximum heat transfer enhancement occurs at ϕ = 60 ∘ and ϕ = 0 ∘ for Mn = 2 × 10 6 and Mn = 3 × 10 6 , respectively. According to Fig.…”

“…Despite other types of nanofluids, ferrofluids can be magnetized due to the existence of magnetic nanoparticles in the mixture. Because of this distinct feature, ferrofluids hydro-thermal behavior can be controlled by an external magnetic field, and therefore, they have widespread applications in various fields such as thermal engineering [2][3][4], microfluidics [5], FHD pumps and automatic cooling devices [6][7][8], flow manipulation [9], medicine [10,11] and other commercial applications such as lubrication [12], sealing [13] and magnetic dampers [14]. In the recent years, ferrofluids have received great attention and extensive research efforts have been devoted in order to develop new strategies for the preparation of magnetic nanofluids with improved thermal and magnetic properties.…”

Optimal ferrofluids for magnetic cooling devices

“…Most of the literature described the use of ferrite-based commercial ferrofluids. For enhanced heat load cooling, Aursand et al 52 numerically investigated cooling based on their optimization results for solenoid geometry, power consumption in the solenoid, thermomagnetic pumping, and MNP size.…”