Nanoparticles Could Improve Energy Efficiency

How can nanoparticles save any energy at all? Well, if you think for a second about big ships, factories and large cooling systems, adding just the right mix of nanoparticles to lubricants and refrigerants can make all the difference in the world. Now, consider that about 13 percent of the electric power consumed in the US, or 9 percent of the energy produced by the country, goes into running large industrial cooling systems and you suddenly realize that even the smallest improvements can save millions.

Mark Kedzierski of the National Institute of Standards and Technology, discovered that by adding various amounts of copper oxide nanoparticles to a mix of polyester lubricant and refrigerant, the heat transfer of the newly created compound increased by up to 275 percent. "We were astounded," says Kedzierski.

Nonetheless, the way in which the presence of the nanoparticles affects the dynamics of the mix to enhance its heat transfer still needs to be studied. Perhaps, by understanding this key feature, researchers at NIST could eventually come up with the optimal combination between the three, so that the heat transfer is boosted to maximum. "As with all good things, the process is far from foolproof. In fact, an insufficient amount or the wrong type of particles might lead to degradation in performance," Kedzierski added.

One theory is that the nanoparticles transfer some of their properties to the material. First of all, copper oxides have much higher thermal conductivity than the lubricant-refrigerant mix alone. During experiments, the research team pointed out that certain concentrations of nanoparticles allowed the fluid to boil more vigorously by stimulating double bubbles, which form on top of the boiling site. This way, heat is carried out to the surface in a more efficient way. According to Kedzierski, NIST is not the only place where interactions essential to the increase in performance have been reported.

Furthermore, the introduction of nanoparticle additives to the mix did not impact any other aspects in the performance of the equipment, thus the existing heat transfer mixtures could be easily exchanged with the newly developed one, to enhance the energy efficiency.