Experimental assessment on convection heat transfer characteristics of aqueous magnetite ferrofluid in a rifled tube under a rotating magnetic field

This work is devoted to the experimental evaluation of the impact of a rotating magnetic field (RMF) on the thermal-hydraulic characteristics of laminar forced convection of aqueous magnetite ferrofluid through a rifled tube. The RMF consists of two small permanent magnets that revolve around the rifled tube. Considering the clockwise and counterclockwise directions for the rotation of each magnets, four different arrangements were considered for the RMF. The results were determined for different values of Reynolds number (Re), nanoparticle concentration (phi) and rifling pitch (P). Nusselt number (Nu), friction factor and Performance Evaluation Criterion (PEC) were considered as performance parameters. The analysis of the PEC parameter showed that from an overall hydrothermal point of view, the use of rifled tube and RMF is desirable. In the absence of RMF, the highest PEC was equal to 1.813, which occurred in the case of Re=2000, phi=0% and P=5 mm. In addition, among the cases with RMF, the maximum PEC was equal to 1.601, which belonged to the case of Re=2000, phi=2% and P=5 mm.