A molecular dynamics approach of the effect of thermal interfacial resistance and nanolayer on enhanced thermal conductivity of Al2O3-CO2 nanofluid

Nanofluids have a solid-fluid interface that affects their thermal properties during heat transfer processes. In this study, nanolayer and thermal interfacial resistance (TIR) at the solid-fluid interface are discussed to determine their role in the enhancement of thermal conductivity of Al<inf>2</inf>O<inf>3</inf>-CO<inf>2</inf> nanofluid. The current work focuses on molecular dynamics simulations to study the TIR and nanolayer formed of CO<inf>2</inf> molecules around the Al<inf>2</inf>O<inf>3</inf> nanoparticle (np) for supercritical and gaseous phases. The diameter of np (d<inf>NP</inf> ) used in this study is between 2 and 5 nm to determine the diameter effect on thermal conductivity of nanofluid and on TIR. The current research talks about the comparison in both phases. The results show the impact of TIR is greater with bigger diameters. Temperature and surface wettability (interaction strength) effect on TIR shows that TIR decreases with increase in temperature and wettability, but at elevated temperatures, TIR does not depend on temperature. The monolayer and nanolayer are studied using density distribution, and the results show that the monolayer is more uniform in the case of smaller diameters with low TIR. However, thermal conductivity is more extensive in the case of larger d<inf>NP</inf> due to a thick nanolayer formed around bigger np. Results show that the nanofluid with larger d<inf>NP</inf> are responsible for enhanced heat transfer due to thickened nanolayer, while TIR influence diminishes.