Nanofluids which containing nanometer-sized particles in a base fluid, have novel properties that made them potentially applicable in various industrial usages. Nanofluids showed enhanced thermal conductivity and the convective heat transfer coefficient compared to the base fluid which is applicable in many industrial applications such as engine cooling, thermal management of micro/nanoelectronic devices, heat exchanger, nuclear reactor coolant, grinding machining and smart intelligent cooling. These features made nanofluids as an interesting topic which has extensively been studied in last decade. In this way, a great challenge is to understand the underlying mechanisms responsible for the unique thermal behavior of nanofluids and to predict these properties. In this project, we attempt to understand the heat transfer mechanism in aqueous nanofluids containing two types of high conductive materials as silver nanoparticles and carbon nanotubes.
A classical molecular dynamics simulation is used to determine the microscopic behavior of the system and allowing insight into molecular motion of nanoparticles on an atomic scale. We simulate water as base fluid with different potential functions such as TIP4P, TIP3P and SPC and nanoparticles are simulated using REBO and Morse potential functions. This is in contrast to the previous studies which considered simple potential functions such as Lennard-Jones potential function. Molecular dynamics simulation is capable to investigate various parameters which are involved in thermal transport of nanofluids and can not been easily studied in the experiments. All simulations in this project are carried out using LAMMPS package which is an acronym for Large-scale Atomic/Molecular Massively Parallel Simulator.
We also experimentally measure the thermal conductivity enhancement of nanofluids using the transient hot-wire method. The effects of volume concentrations, nanoparticles size and temperature are investigated in the experiment. Results obtained from both the experiments and simulations are compared to understand the underlying mechanism