Tiny Particles Bring on a Big Chill

Sept. 11, 2008
Researchers at the National Institute of Science and Technology recently discovered that adding a dash of the right nanoparticle to a refrigerant can boost its heat-transfer capabilities.

For example, putting copper oxide particles, each about 30 nm in diameter, into a common polyester lubricant, then combining it with R134a refrigerant improved heat transfer by 50 to 275%. Though the phenomenon is not completely understood, scientists speculate that nanoparticle of materials with high thermal conductivities improve heat-transfer rates for some systems. NIST experiments do show that when in sufficient concentrations, nanoparticles enhance heat transfer by encouraging more vigorous boiling. The small particles seem to stimulate double bubbles — secondary bubbles forming atop bubbles initiated at the boiling site. Bubbles carry heat away from the surface. And because they form more readily due to the nanoparticles, heat is being transferred more efficiently.

National Institute of Science and Technology

www.nist.gov

If the researchers are successful, more-efficient refrigerants could be used in current chillers and HVAC equipment resulting in immediate energy savings. (Chillers consume about 9% of the nation’s electricity.) And future chillers could be made smaller and lighter.

Nanoparticles added to refrigerants create double bubbles like these when the mixture boils, a sign of higher heat transfer. It’s also a sign the modified refrigerant would be more efficient in industrial-sized cooling systems.

Sponsored Recommendations

Flexible Power and Energy Systems for the Evolving Factory

Aug. 29, 2024
Exploring industrial drives, power supplies, and energy solutions to reduce peak power usage and installation costs, & to promote overall system efficiency

Timber Recanting with SEW-EURODRIVE!

Aug. 29, 2024
SEW-EURODRIVE's VFDs and gearmotors enhance timber resawing by delivering precise, efficient cuts while reducing equipment stress. Upgrade your sawmill to improve safety, yield...

Advancing Automation with Linear Motors and Electric Cylinders

Aug. 28, 2024
With SEW‑EURODRIVE, you get first-class linear motors for applications that require direct translational movement.

Gear Up for the Toughest Jobs!

Aug. 28, 2024
Check out SEW-EURODRIVEs heavy-duty gear units, built to power through mining, cement, and steel challenges with ease!

Voice your opinion!

To join the conversation, and become an exclusive member of Machine Design, create an account today!