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

TL;DR

This paper explores using thermomagnetically pumped ferrofluids to significantly enhance natural convection cooling loops, demonstrating potential performance improvements and size reductions through analytical estimates and validated modeling.

Contribution

It provides a simplified analytical estimate and design rules for thermomagnetic pumping, supported by a medium-scale case study showing substantial performance gains.

Findings

Cooling performance increased by up to 4 times in single-phase regimes

Performance gains of up to 2 times in two-phase regimes

Potential to reduce heat-sink size by up to 75%

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 %.