Effects of variable magnetic field on particle fouling properties of magnetic nanofluids in a novel thermal exchanger system

Abstract

Magnetic nanofluids, as a new type of heat transfer media, propose a possible way to achieve low energy consumption and carbon neutrality, which has attracted a lot of attention in the heat transfer field. To comprehensively discuss the feasibility of magnetic nanofluids application in heat exchange systems, this paper conducted an experimental study of the particle fouling properties based on Fe3O4–H2O-AG magnetic nanofluids. The effects of variables including Reynolds number, magnetic field form, and magnetic flux density B on the fouling properties were analyzed. The anti-fouling rate η was introduced to evaluate the anti-fouling properties. The results showed that high Reynolds number (Rf (Re = 9000) = 2.83 × 10−6 m2 W K−1), constant parallel magnetic field with high magnetic flux density (Rf (B = 18mT) = 3.86 × 10−6 m2 W K−1), and corrugated tube with twisted turbulator (Rf (with turbulator) = 3.74 × 10−6 m2 W K−1) demonstrated less fouling thermal resistance Rf. Meanwhile, constant parallel magnetic field with high magnetic flux density also exhibited better anti-fouling properties (η(B = 18mT) = 1.35), which indicated that the parallel magnetic field has a positive effect on preventing the deposition of magnetic nanoparticles.