Browsing by Author "Turgut, Alpaslan"

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Citation - WoS: 4
Citation - Scopus: 5
3d Helmholtz Coil System Setup for Thermal Conductivity Measurements of Magnetic Nanofluids
(Pergamon-Elsevier Science Ltd, 2023) Alsangur, Rahime; Dog, Serkan; Ateş, Ismet; Turgut, Alpaslan; Çetin, Levent
This study aims to design a mechatronic system that involves a 3D Helmholtz coil system implemented with the 3 omega; method to measure the thermal conductivity of magnetic nanofluids under uniform and rotating magnetic fields. For this purpose, a 3D Helmholtz coil system was designed and manufactured to generate a uniform and rotating magnetic field up to 400 G. First, the uniformity and rotation abilities of the magnetic field generated by the system were investigated numerically and experimentally. The investigations pointed out that the 3D Helmholtz coil system can generate a uniform magnetic field in 1D, 2D, and 3D with a maximum non-uniformity factor of 0.0016. After that, the thermal conductivity of Fe3O4 - water magnetic nanofluid samples with 1, 2, 3, 4, and 4.8 vol.% were measured under 1D, 2D, and 3D uniform magnetic field application. The magnetic field was applied at different direction angles between X, Y, and Z axes in the Cartesian coordinate system. The results pointed out that the thermal conductivity of the samples increases as the magnetic field and particle concentration increase. The maximum thermal conductivity enhancement was observed as similar to 9.1% and the minimum thermal conductivity was observed as similar to 1.9% when the magnetic field is applied in parallel and perpendicular directions, respectively. The measurement results also pointed out that under the external uniform magnetic field application at 2D and 3D, thermal conductivity enhancement is less affected by the particle concentration increment.
Citation - WoS: 30
Citation - Scopus: 37
Experimental Study and Taguchi Analysis on Alumina-Water Nanofluid Viscosity
(Pergamon-Elsevier Science Ltd, 2018) Elcioglu, Elif Begum; Yazicioglu, Almila Guvenc; Turgut, Alpaslan; Anagun, Ahmet Sermet
Nanofluids as dispersions of fine particles within industrial fluids have potential in thermal applications due to their improved thermal characteristics. On the other hand, their viscosity may be a limitation for forced convective heat transfer, since increase in viscosity increases the pump power requirement. In this study we report experimental results for alumina-water nanofluid viscosity at different temperatures, for different nanoparticle fractions and diameters. Experimental data were collected based on a Taguchi experiment design (L8). Statistical analyses via Taguchi Method were done to determine the effects of experiment characteristics on nanofluid viscosity and relative viscosity. The viscosity of nanofluids decreased sharply with temperature (20-50 degrees C); increased with nanoparticle fraction (1-3 vol%), and increased slightly with nanoparticle diameter (10 +/- 5 nm, 30 +/- 10 nm). Taguchi Analysis revealed that the importance of the parameters on nanofluid viscosity can be sorted from lower to higher sequence as temperature, nanoparticle fraction, and nanoparticle diameter; and they were all statistically significant on nanofluid viscosity. One novel conclusion is that the interaction effect of temperature and nanoparticle volumetric fraction was significant on nanofluid viscosity at alpha = 5%, thus the effect of nanoparticle fraction was different at different temperatures, and vice versa. This interaction effect appeared in the developed nanofluid viscosity equation with a novel term, the product of temperature and nanoparticle fraction. This result may be beneficial for hydrodynamic applications, where the thermal aspects and flow characteristics need to be considered simultaneously. (C) 2017 Elsevier Ltd. All rights reserved.