Enhanced heat transfer in agitated vessels by alternating magnetic field stirring of aqueous Fe–Cu nanofluid

Abstract

In this work intrinsically magnetic quasi-crystalline Fe–Cu nanoparticles are used in an aqueous solution for heat transfer enhancement application. The experimental work commenced by synthesizing the Fe–Cu material via high energy ball milling in 1:1 ratio using 10 mm diameter stainless steel balls and crucibles, followed by cryogenic crushing to further reduce the particle size to the nanoscale. The results of grain size reduction are verified by transmission electron microscopy measurements that showed sizes down to 50 nm. Other measurements pertinent to the expected performance of these particles in solution are the determination of the zeta potential of the particles. To assess the enhancement of heat transfer characteristics within a closed vessel by the rotating magnetic agitation of the magnetic particles, the nano-powder is added to deionized water at different concentrations. The time required (Δt) to a reach a certain temperature difference (ΔT) is measured to construct the Wilson plot parameters for each of the fluids used. It is found that the addition of the Fe–Cu nanofluid has enhanced the transient heat transfer by up to 34.6%.