Session: 15-01-01: ASME International Undergraduate Research and Design Exposition

Paper Number: 100594

100594 - Experimental Study of the Nanofin Effect (Nfe) During Thin Film Evaporation From Nanopores in Anodic Aluminum Oxide (Aao) Membrane Substrates Integrated With Nano-Thermocouple/thin Film Thermocouple (Tft) Array 

Recent advances in micro/nano-fabrication has enabled the deployment of nanostructured surfaces, nanochannels, and nanoporous membranes for development of new generation thermal management devices with remarkable potential for heat transfer enhancement. Anomalous heat transfer has been reported in studies involving heaters with nanostructured surfaces. For example, nanofins with lower thermal conductivity values can cause higher levels of enhancement in heat flux values, especially during phase change (such as for boiling on heaters with nanostructured surfaces). In addition, confinement of fluid in nanopores can also result in anomalous properties. This is manifest in anomalous production curves during hydraulic fracturing operations in oil and gas applications. A transport model that resolves these conundrums is termed as the “nanoFin Effect (nFE)”. nFE is governed by interfacial phenomena, i.e., the formation of thermal impedances in parallel circuit configuration: (a) interfacial thermal resistance (also known as “Kapitza resistance”); (b) thermal capacitor; and (c) thermal diode (that form at the interface between each nanoparticle and the surface adsorbed thin-film of solvent molecules). nFE (i.e., primarily the interfacial thermal diode effect) also leads to preferential trapping of ions on the surface adsorbed thin film of solvent molecules leading to very high concentration gradients causing drastic reduction in corrosion.

The motivation of this study was to explore nFE during thin film evaporation from nanopores. The methods used in this study include mounting a nano-thermocouple array (also termed as Thin Film Thermocouples or “TFT”) on a hot plate and observing the transient response recorded by the TFT array when a small liquid droplet (of fixed mass or volume) is dispensed on to an isotropic AAO membrane containing nanopores. In this study, two different pore sizes were explored: 200 nm and 10 nm. The experiments were performed using acetone, isopropyl alcohol, and water droplets for four different temperature settings of the heated membrane (containing the nanopores).

As the experiment concluded, it was found that the size of the nanopore in the membrane had a definite effect on the behavior of the temperature of the system. This is important initial information about the need for further research into the phenomenon of naturally occurring nanopores for applications in natural gas for energy, as well as for the development of nanopore technologies to improve current heating and cooling technologies. At this scale, the confinement effect causes fluids to behave in ways that are not expected given classical formulations of behavior equations, which creates a need to study this effect more to better understand the behavior it creates.

Presenting Author: Juliet Shafer Texas A&M University

Presenting Author Biography: I am currently a graduate student at Texas A&M University pursuing a Master's degree in Mechanical Engineering, with a focus on heat transfer and fluid mechanics.

Authors:

Juliet Shafer Texas A&M University
Jonghyun Lee Texas A&M University
Ashok Thyagarajan Texas A&M University
Debjyoti Banerjee Texas A&M University