Influence of size on anisotropic thermophysical properties of magnetic suspensions

• Published in: International journal of applied electromagnetics and mechanics Vol. 58; no. 3; pp. 371 - 385
• Main Authors: Iwamoto, Yuhiro, Kondoh, Syuhei, Ido, Yasushi, Yamamoto, Hisashi, Nishida, Hitoshi, Yamasaki, Haruhiko, Yamaguchi, Hiroshi, Jeyadevan, Balachandran
• Format: Journal Article
• Language: English
• Published: Amsterdam IOS Press BV 05.11.2018
• Subjects: Heat conductivity; Heat transfer; Magnetic fields; Magnetic levitation; Magnetic properties; Rheological properties; Rheology; Temperature gradients; Thermal conductivity; Thermophysical properties; Transient hot wire method; Viscosity
• ISSN: 1383-5416; 1875-8800
• DOI: 10.3233/JAE-180048

Thermophysical and rheological properties of magnetic suspensions, in which nm- and/or μm-sized magnetic particles disperse, are tunable by applying a magnetic field externally. In the present study, the influence of the size of magnetic particles on the thermophysical and rheological properties was investigated. Four types of the magnetic suspensions were prepared with varying the volume fractions of nm- and μm-sized magnetic particles. The total fraction of the magnetic particles in all samples was adjusted to be 6 vol.%. The thermal conductivity in the presence of homogeneous magnetic field was measured by the originally-designed transient hot-wire method (TPSY02, CLIMA-TEC). And the steady-state rheological behaviors were investigated by a magnetorheometer (MCR302, Anton-paar). As the obtained results, the thermal conductivity was enhanced when the magnetic field was applied parallel to the temperature gradient for all samples. On the other hand, the thermal conductivity decreased when the magnetic field was applied perpendicular to the temperature gradient in the case that both the nm- and μm-sized magnetic particles were dispersed. It was also found that the fluid only with the nm-sized magnetic particles showed a Newtonian-like behavior even in the presence of magnetic field. When the μm-sized magnetic particles were mixed and the fraction increased, the rheological behavior changed from Newtonian to viscoplastic fluid.