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 (NIST) 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 nations 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 th
|Contact: Mark Bello|
National Institute of Standards and Technology (NIST)