Proposal Number: CTS-0404174 Principal Investigator: Ranganathan Kumar, Jayanta S. Kapat, and Sudipta Seal Affiliation: University of Central Florida Proposal Title: NER: Nanofluid characteristics in Pool Boiling
This proposal was received in response to Nanoscale Science and Engineering initiative, NSF 03-043, category NER.
Nanoparticle suspensions have recently been discovered to enhance the heat transfer of fluids. Relative to micron-sized suspensions, the nano-sized suspensions are much more resistant to settling in stationary fluids, which is a significant concern when micron-sized suspensions are considered. In addition, the thermal conductivity of the nanofluid increases as the size of the nanoparticles decreases. With this added benefit, it is worth exploring nanoparticle suspension as potential coolants in a number of engineering applications. The heat transfer characteristics are significantly better in a nanofluid, which increases the power capability provided to a system prior to catastrophic failure. Nanofluids may also offer a potential back fit to existing cooling systems without a major overhaul in several industries. Because of this potential, fundamental understanding of the physical mechanisms in particle motion and how the particles affect the critical heat flux need to be studied. This research will focus on quantifying and understanding the source of the greater than expected thermal conductivity of nanofluids. As part of this study, the following tasks will be performed. - Different diameter ceria and silica particles will be suspended in water and other fluids at different concentrations, and pool-boiling experiments will be done. Different levels of enhancement of CHF will be measured with corresponding measurements of thermal conductivity. - For each experiment, the deposition of the particles on the wire will be measured. These deposited wires will be imaged using an SEM or TEM at different concentrations to understand the role of nanofins on the heat transfer. - For selected experiments, fluorescence imaging will be done using a fluorescence microscope to track the nanoparticles and to understand the particle preference, agglomeration characteristics and affinity to materials at different temperature. Since the silica particles do not fluoresce, quantum dots will be used to dope silica for imaging at least in one experiment for a specific diameter.
Since the boiling characteristics in pool boiling is similar to flow boiling, nanofluids have opened up exciting possibilities of raising chip power in electronic components, reducing fuel element surface temperature in pressurized water reactors, and reducing corrosion rates in cooling channels.
The research is being funded by the Thermal Transport and Thermal Processing Program of the Chemical and Transport Systems Division.
