Optical-fiber thermal-wave-cavity technique to study thermal properties of silver/clay nanofluids

Abstract

Thermal properties enhancement of nanofluids have varied strongly with synthesis technique, particle size and type, concentration and agglomeration with time. This study explores the possibility of changing the thermal wave signal of Ag/clay nanofluids into a thermal diffusivity measurement at well dispersion or aggregation of nanoparticles in the base fluid. Optical-Fiber Thermal-Wave-Cavity (OF-TWC) technique was achieved by using a small amount of nanofluid (only 0.2 mL) between fiber optic tip and the Pyroelectric detector and the cavity-length scan was performed. We established the accuracy and precision of this technique by comparing the thermal diffusivity of distilled water to values reported in the literature. Assuming a linear Pyroelectric signal response, the results show that adding clay reduced the thermal diffusivity of water, while increasing the Ag concentration from 1 to 5 wt.% increased the thermal diffusivity of the Ag nanofluid from 1.524×10 −3 to 1.789×10 −3 cm 2 /s. However, in particular, nanoparticles show the tendency to form aggregates over time that correlated with the performance change of thermal properties of nanofluid. Our results confirm the high sensitivity of OF-TWC technique raises the potential to be applied to measuring the optical and thermal properties of nanofluids. Furthermore, this technique allows the extraction of information not obtained using other traditional techniques.

Determination of the Thermal Diffusivity of Plasmonic Nanofluids Containing PVP-Coated Ag Nanoparticles Using Mode-Mismatched Dual-Beam Thermal Lens Technique

“…Besides the numerous studies employing techniques that allow direct access to the thermal conductivity and heat capacity of nanofluids, there are only a small number of studies that employ experimental techniques to directly obtain the thermal diffusivity of nanofluids. Some available methods and techniques are laser flash [7], hot-wire [8,9], photoacoustic [10][11][12], photopyroelectric [13], thermalwave resonator cavity [14], and the thermal lens technique [15]. The last one is based on the optical properties of a medium with optical absorption and has been employed previously to obtain the thermal diffusivity of colloids of superparamagnetic nanoparticles [16].…”