Analysis of the Dependence of the Sound Speed in a Nano-Particle Suspension on the Concentration of Nano-Paticles

Acoustic Method for Determination of the Thermal Properties of Nanofluids

“…The data of Kim et al 29 for water-based TiO 2 nanofluids shown in Figure 11 indicate that in the concentration range 0− 5 vol % the velocity decreases as the concentration increases. An important implication of this finding in the case of low particle concentrations is the wide interparticle distance, which was thought by Kim et al 29 to be the cause for the reduction of ultrasound wave propagation (due to scattering).…”

“…The data of Kim et al 29 for water-based TiO 2 nanofluids shown in Figure 11 indicate that in the concentration range 0− 5 vol % the velocity decreases as the concentration increases. An important implication of this finding in the case of low particle concentrations is the wide interparticle distance, which was thought by Kim et al 29 to be the cause for the reduction of ultrasound wave propagation (due to scattering). Kim et al 29 also showed that the sound velocity decreases until nanoparticle concentrations reach ∼30%, above which the sound velocity increases due to the small interparticle distance and rapid wave propagation through the particles.…”

“…The main observation from these results is the decrease in sound velocity with increasing particle concentration. To describe this phenomenon, the change in sound velocity measurements at room temperature is plotted against the concentration of d p = 50 nm alumina particles, together with the results obtained by Piotrowska 53 and Kim et al, 29 in Figure 11.…”

“…Kim et al 29 also showed that the sound velocity decreases until nanoparticle concentrations reach ~ 30%, above which the sound velocity increases due to the small interparticle distance and rapid wave propagation through the particles. Further details of this complex multiple scattering phenomena are given by Kim et al 29 It can also be observed that the nano-sized TiO2 used by Kim et al 29 decreased the speed of sound more than the micro-sized TiO2 particles used by Piotrowska 53 (i.e. by 30 ms -1 ), which is an important observation supporting the effect of particle size on the speed of sound measurements (Figure 11).…”

“…28 The focus of this study is on the use of an ultrasonic technique for the analysis and characterization of water-based nanosuspensions using the sound speed dependence on temperature and concentration. 29 This technique is promising for the characterization of multiphase systems because it is flexible, cost-effective, nondestructive, and noninvasive and can operate in dense and optically opaque nanosuspensions 30 with fewer restrictions than optical methods. The current study also demonstrates the potential of acoustic methods to determine the thermophysical properties of nanofluids.…”