Effect of clustering on the thermal conductivity of nanofluids

A Review of Thermal Conductivity Models for Nanofluids

“…According to the report of Wang et al [68] in 2003, these cluster structures act like local percolation structures and therefore add to the effective thermal conductivity enhancement of nanofluids [68] (this is contrary to the observation of Karthikeyan et al [66]). They proposed a method for modelling the effective thermal conductivity of nanofluids based on the effective medium approximation and the fractal theory for the description of nanoparticle clusters and its radial distributions.…”

“…These methods were used for preventing the nanoparticles to get agglomerated at the first step of nanofluid production because the nanoparticles as powder get agglomerated to each other very soon. When the nanofluid is treated by sonication (high frequency sound waves typically used to aid the dispersion of nanoparticles in a liquid) or other physical techniques, the cluster breaks into primary nanoparticles [66]. There have been some works on the effect of sonication time on the thermal conductivity of nanofluids [67].…”

“…Karthikeyan et al [66] studied effect of clustering on the thermal conductivity of CuO nanoparticles dispersed into water experimentally. They had shown that the cluster size has a significant effect on the thermal conductivity of CuO-Water nanofluids and the thermal conductivity of nanofluid decrease with elapsed time due to clustering of CuO nanoparticles.…”

Study of Swarm Behavior in Modeling and Simulation of Cluster Formation in Nanofluids

“…Brownian motion of the particles and cluster formation in nanofluids are the major issues in the studies of nanofluids according to the important effect of their size on the heat transfer rate. Cluster formation causes the viscosity of nano fluid and thermal conductivity to change [16][17][18][19]. Although there have been some efforts in modeling the behavior of nanoparticles in nanofluids, no special research has been done to describe the cohesion and cluster formations of these particles analytically, and most of these works were numerical or experimental approach to this point.…”

Evaluation of acoustical parameters and thermal conductivity of TiO2-ethylene glycol nanofluid using ultrasonic velocity measurements

“…A scan of the literature survey revealed that numerous works have enhanced the thermal conductivity of suspensions that contained the solid particles since Maxwell's theoretical work was published more than 100 years ago [9][10][11][12][13]. The metal oxide NPs are preferred for preparing nanofluids, though it possesses low heat transfer capacities than metals [14][15][16][17][18][19][20][21][22][23][24]. Metal nanoparticles increase the interfacial resistance due to the surface oxidation, and hence, its thermal conductivity decreases.…”