THERMOMAGNETIC CHARACTERIZATION OF ORGANIC-BASED FERROFLUIDS PREPARED WITH Ni FERRITE NANOPARTICLES

P. G. BERCOFF; M. ARANA; S. E. JACOBO

Córdoba

Congreso; Congreso Internacional de Metalurgia y Materiales SAM-CONAMET 2016; 2016

The aim ofthis work is to study thethermal variables of ferrofluids (FFs) ?thermal conductivity and diffusivity,and heat capacity? under applied magnetic fields for possible industrialapplications, with focus in heat-transfer devices. For this purpose, FFs were prepared with kerosene and Ni-ferritenanoparticles (NPs). The NPs were synthesized by high-energy ball milling, asan alternative to the most commonly chosen NPs synthesis methods for FFs´ preparation[1]. The milling is an appropriate and low-costtechnique for large-scale NPs´ production since upto 5g of nanometric powder can be produced in short-time and one-stepprocedures. The thermal variables were determined with the transient hot-wiremethod. The application of a magnetic field on the FFs increases the thermalconductivity and diffusivity [2] due to cooperation between the NPs, as itagglomerates them favoring chain-like and clusters formations [3]. The obtainedenhancements in the thermal conductivity of prepared FFs, reach 48% in absenceof magnetic field with respect to the conductivityof pure kerosene and 173% for an applied field of 0.07T, which are in agreement with the obtained resultsfor other systems [4]. The thermal diffusivity relative to purekerosene was 3 at zero field and 127 under 0.07T. Also, the heat capacity relative to kerosene of the studiedferrofluids was calculated, and it was found that it decreases under theapplication of a magnetic field  in the range 0.3to 0.05. The thermal conductivity of FFs as a function of magnetic field was successfullyfitted by a gas-compressionmodel, considering NPs' agglomerates in the fluid.referencES1.     S. A. Angayarkanni and J. Philip. ?Review on thermalproperties of nanofluids: Recent developments?. Advances in Colloid InterfaceScience, (2015), http://dx.doi.org/10.1016/j.cis.2015.08.014Y.2.     J. Philip, P. D. Shima, and B. Raj. ?Evidence forenhanced thermal conduction through percolating structures in nanofluids?.Nanotechnology, Vol. 19 (2008), p. 305706.3.     I. Nkurikiyimfura, Y. Wang and Z. Pan. ?Effect ofchain-like magnetite nanoparticle aggregates on thermal conductivity ofmagnetic nanofluid in magnetic field?. Experimental Thermal and FluidScience, Vol. 44 (2013), p. 607-612.4.     J. Philip, P. D. Shima and B. Raj. ?Enhancement ofthermal conductivity in magnetite based nanofluid due to chainlike structures?.Applied Physical Letters, Vol. 91 (2007), p. 203108.