June 19, 2015
Journal of Applied Physics, 107 (2010) 104320
Authors: Mark Horton, Haiping Hong, Chen Li, Bo Shi, G. P. Peterson, and Sungho Jin
In this review, a relatively new paper on the use of magnetically stimulated nanofluids as heat transfer materials is explored.
Article Summary: Ni-coated single-walled carbon nanotubes (SWNTs) were dispersed in four fluids of varying viscosities to create magnetic nanofluids using sodium dodecylbenzene sulfonate as surfactant. Water, polyalphaolefin oil (PAO) and two types of polyol ether are used as carrier fluids for the coated nanotubes. Due to the magnetic properties of the Ni-coated SWNTs the researchers induced a magnetic field to hopefully increase the thermal conductivity of the nanofluids. It was determined experimentally that magnetic stimulation of the nanofluids increased the observed thermal conductivity of the nanofluids. The increase in thermal conductivity was caused by the alignment of the carbon nanotubes into chains and clusters due to the magnetic field. A Thermal Constants Analyzer was used to measure thermal conductivity of the different nanofluids. In addition to the thermal chracterization, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to observe physical properties before and after magnetic stimulation. Through the use of SEM it can easily be seen that the coated SWNTs are being aligned by the magnetic field. The greatest increase in thermal conductivity was seen with the use of water as a carrier fluid and its value increased from 0.63 W/mK to 1.10 W/mK during magnetic field stimulation. The other nanofluids showed increases in thermal conductivity, but not to the extent of the Ni-coated SWNT/water nanofluid. It was observed that the lower the viscosity of the carrier fluid used, the higher the thermal conductivity during magnetic stimulation. The thermal conductivity peaked after exposure to the magnetic field for 4 minutes and then subsequently decreased after the 4 minute mark.
Some interesting points to be taken from this article include:
To access a PDF of this journal article, click here.