Thermal properties of nanofluids- recent developments

Abstract

In this review, we highlight some of the most recent studies that have led to a better understanding of the mechanism of heat transport in nanofluids. Our studies show that the enhancement in thermal conductivity (k) in stable nanofluids is within the predictions of effective medium theory (EMT). On the contrary, in aggregating nanofluids the enhancement in k is beyond EMT. Further, our studies show the prominent role of agglomeration on thermal property enhancement and the importance of surface functionalization for improved stability and performance. The size dependent thermal conductivity studies in stable nanofluids containing nanoparticles of average diameters 3 – 10 nm showed an enhancement in k/k_f with increasing particle diameter. The temperaturedependent thermal conductivity measurements in aqueous and non-aqueous nanofluids showed that the k/k_f remains constant with increase in temperature. Our results show that the microconvection has a less dominant role on thermal conductivity enhancement in nanofluids.