Nanoparticle Research Points to Energy Savings
July 23rd, 2008
Nanoparticle additives to lubricants commonly combined with refrigerants used in chillers may encourage secondary nucleation-bubbles on top of bubbles. The double-bubble effect enhances boiling heat transfer and, ultimately, could help to boost the energy efficiency of industrial-sized cooling systems. Image: NIST
(PhysOrg.com) -- Adding just the right dash of nanoparticles to standard mixes of lubricants and refrigerants could yield the equivalent of an energy-saving chill pill for factories, hospitals, ships, and others with large cooling systems, suggest the latest results from National Institute of Standards and Technology research that is pursuing promising formulations.
NIST experiments with varying concentrations of nanoparticle additives indicate a major opportunity to improve the energy efficiency of large industrial, commercial, and institutional cooling systems known as chillers. These systems account for about 13 percent of the power consumed by the nation’s buildings, and about 9 percent of the overall demand for electric power, according to the Department of Energy.
NIST researcher Mark Kedzierski has found that dispersing “sufficient” amounts of copper oxide particles (30 nanometers in diameter) in a common polyester lubricant and combining it with an equally pedestrian refrigerant (R134a) improves heat transfer by between 50 percent and 275 percent. “We were astounded,” he says.
Results of this work have been presented at recent conferences and will be reported in an upcoming issue of the ASME Journal of Heat Transfer.
Just how nanomaterial additives to lubricants improve the dynamics of heat transfer in refrigerant/lubricant mixtures is not thoroughly understood. The NIST research effort aims to fill gaps in knowledge that impede efforts to determine and, ultimately, predict optimal combinations of the three types of substances.
“As with all good things, the process is far from foolproof,” Kedzierski explains. “In fact, an insufficient amount or the wrong type of particles might lead to degradation in performance.”
On the basis of work so far, the researcher speculates several factors likely account for nanoparticle-enabled improvements in heat-transfer performance. For one, nanoparticles of materials with high thermal conductivity improve heat transfer rates for the system. Preliminary results of the NIST research also indicate that, in sufficient concentrations, nanomaterials enhance heat transfer by encouraging more vigorous boiling of the mixture. The tiny particles stimulate, in effect, double bubbles—secondary bubbles that form atop bubbles initiated at the boiling site. Bubbles carry heat away from the surface, and the fact that they’re being formed more efficiently because of the nanoparticles means the heat gets transferred more readily.
Other interactions, Kedzierski says, also are likely to contribute to the dramatic performance improvements reported at NIST and elsewhere.
Success in optimizing recipes of refrigerants, lubricants and nanoparticle additives would pay immediate and long-term dividends. If they did not harm other aspects of equipment performance, high-performance mixtures could be swapped into existing chillers, resulting in immediate energy savings. And, because of improved energy efficiency, next-generation equipment would be smaller, requiring fewer raw materials in their manufacture.
Provided by NIST
Oct 02, 2008 |
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We should be very careful with anything that can render the blood-brain barrier irrelevant.
FUD will not make nanotechnology better or worse. concentrated "anything" - cigarette smoke, alcohol, heroin, etc... can cause serious problems. What are we doing about this? Oh, wait - money is too precious to consider the health risks of these "nano-particles" entering our bodies!
GMAFB...
You are wrong, we were exposed only to a tiny fraction of what we can make.
Certain kinds of carbon nanotubes were for example shown (reported on this site) to easily enter inside human cells including into the nucleus where our genetic material is stored. As long stiff molecules they are guaranteed to interfere with cell's molecular machinery. Due to their exotic structure not present in natural environment we have not evolved any defenses against them - no way to decompose or expel them from the cell and the body. This is a very serious situation and nanotubes should be banned from mass market until further research can better evaluate their impact on us and our environment.
I'm a big fan of nanotechnology, I believe it holds tremendous promise for humanity and I am doing some research in the area myself but I also see the risks very clearly and I'd really like others to show some caution too.
Not only human lives and our environment are at stake but there is also a potential for a huge setback in public acceptance and funding of this emerging field if the first wave of commercial products proves toxic and incites public hysteria.
HTTP://VULVOX.TRIPOD.COM
Don't believe we should ban nanotubes altogether. The longer nanotubes cause the same problems as long asbestos fibers. they get into the lungs and casue mesothelioma. Should we ban TVs with nanotubes in their screens? A lot of the things nanotubes do can be done with graphene nanoplatelts which are much less studied but they have shown no bad side effects to date. They do not have the huge aspect ratio (very long and thin) that nanotubes have. They might cut cells in half but their bigger surface area makes it likely the bloodstream will dislodge them from cells contacting the circulation. They would kill cells in the lungs if they were partly wedged into them, and that would cause localized necrosis. Granuloma might be damaged accordingly. If there is damage it wont be cancer but something else.