Thermophoresis in Dispersed Nanoparticles

Abstract

This study explores the complex interplay of factors influencing thermal conductivity enhancement in nanofluids, which are sus-
pensions of nanoparticles in base fluids. Nanofluids have emerged as promising materials for improving thermal properties due to the high thermal conductivity of certain nanoparticles. The research delves into the phenomenon of thermophoresis, considering temperature-dependent properties of base fluids and nanofluids. It analyzes five particle materials (gold, alumina, titania, copper, and silver) and six types of base-fluids to understand particle migration potential. The study suggests that variations in scaled thermal diffusion factor with temperature and particle size indicate potential for more uniform particle distribution at higher temperatures and smaller sizes. Nanoparticle material and volume fraction also impact migration potential, with certain materials showing thermophoretic potential over wider temperature ranges. Additionally, the study investigates Kapitza resistance at the nanoparticle-fluid interface, which significantly affects effective thermal conductivity. Molecular dynamics simulations and experimental studies have calculated Kapitza resistance for various interfaces, highlighting its temperature-dependent nature. The study concludes by deriving a universal relationship between the Suratman number (Su) and the Scaled Thermal Diffusion Factor (φTST), providing insights into whether a system will develop a concentration gradient or remain uniformly distributed. This analysis serves as a valuable tool for predicting and designing nanofluid systems for enhanced thermal
conductivity in various engineering applications.