Influence of particle-matrix interface, temperature, and agglomeration on heat conduction in dispersions

Abstract

A combination of the effective medium and the phonon approaches is used to investigate heat conduction in heterogeneous media composed of a homogeneous matrix in which spherical particles of micro and nanosizes are dispersed. In particular, we explore the effect of different types of scattering on the particle-matrix interface, temperature dependence of the effective heat conduction coefficient, and the effect of various degrees of agglomeration of the particles. Predictions calculated explicitly for Si nanoparticles dispersed in Ge matrix agree with available Monte Carlo simulations. Our predictions show that the higher is the temperature the lower is the heat conductivity and the smaller is the influence of the details of the particle-matrix interactions. As for the influence of the agglomeration, we predict both decrease and increase of the heat conduction depending on the degree of the agglomeration.

Effect of volume-fraction dependent agglomeration of nanoparticles on the thermal conductivity of nanocomposites: Applications to epoxy resins, filled by SiO2, AlN and MgO nanoparticles

“…It follows also from our analysis that, at a fixed volume fraction, the effect of agglomeration is either to increase or to decrease the effective thermal conductivity: at loose agglomeration, tend to increase, while for more compact agglomerates, a decrease occurs. A similar behavior was noticed by Behrang et al [23] and Moreira et al [54].…”

“…This brings us to the conclusions that the most suitable fitting for the experimental results in Fig. 6 is the power law given by (23).…”

“…For comparison, the effective thermal conductivity, not taking into account the agglomeration effect, is given as well. represented by our model, stemming from expression (23). One important conclusion is that it is imperative to take into account the dependence of the agglomeration radius on the volume fraction in the study of agglomeration effects on the thermal conductivity of nanocomposites.…”

“…Many experiments have been performed on investigating the role of agglomeration [18][19][20][21][22], which will therefore be given a special attention. The majority of models taking into account nanoparticles' agglomeration introduce an agglomerate radius that is kept fixed [23] or consider a change in agglomerate's size due to aging [21], without examining the influence of volume fraction on the degree of agglomeration. This point will receive a particular attention in this work and a relation between the degree of agglomeration and the particle volume fraction will be established experimentally.…”

The role of several heat transfer mechanisms on the enhancement of thermal conductivity in nanofluids

“…However, this approach does not take into account the particles size effect. This has led some people to formulate renovated Maxwell's models by introducing explicitly the particle's dimensions [8][9][10][11][12].…”