Multifunctional Nanofluids with 2D Nanosheets for Thermal Management and Tribological Applications
Taha Tijerina, Jaime
Ajayan, Pulickel M.
Doctor of Philosophy
Conventional heat-transfer fluids such as water, ethylene glycol, standard oils and other lubricants are typically low-efficiency heat-transfer fluids. Thermal management plays a critical factor in many applications where these fluids can be used, such as in motors/engines, solar cells, biopharmaceuticals, fuel cells, high voltage power transmission systems, micro/nanoelectronics mechanical systems (MEMS/NEMS), and nuclear cooling among others. These insulating fluids require superb filler dispersion, high thermal conduction, and for certain applications as in electrical/electronic devices also electrical insulation. The miniaturization and high efficiency of electrical/electronic devices in these fields demand successful heat management and energy-efficient fluid-based heat-transfer systems. Recent advances in layered materials enable large scale synthesis of various two-dimensional (2D) structures. Some of these 2D materials are good choices as nanofillers in heat transfer fluids; mainly due to their inherent high thermal conductivity (TC) and high surface area available for thermal energy transport. Among various 2D-nanostructures, hexagonal boron nitride (h-BN) and graphene (G) exhibit versatile properties such as outstanding TC, excellent mechanical stability, and remarkable chemical inertness. The following research, even though investigate various conventional fluids, will focus on dielectric insulating nanofluids (mineral oil - MO) with significant thermal performance. It is presented the plan for synthesis and characterization of stable high-thermal conductivity nanofluids using 2D-nanostructures of h-BN, which will be further incorporated at diverse filler concentrations to conventional fluids for cooling applications, without compromising its electrical insulating property. For comparison, properties of h-BN based fluids are compared with conductive fillers such as graphene; where graphene has similar crystal structure of h-BN and also has similar bulk thermal conductivity. Moreover, bot h-BN and graphene are exfoliated through the same method. In essence, this project, for the first time, unravels the behavior of the exfoliated h-BN effect on reinforced conventional fluids under the influence of atomistic scale structures (particularly, electrically insulating and lubricant/cutting fluids), thereby linking the physical, electrical and mechanical properties of these nanoscale materials. The innovative experimental approach is expected to result in de novo strategies for introducing these systems for new concepts and variables to engineer nanofluid properties suitable for very promising industrial applications.
Nanofluids; Hexagonal boron nitride (h-BN); 2D materials; Thermal management; Tribology