Nanofluid heat transfers to industry

Michael Pollitt
The Guardian, Thursday 8 January 2009

Are you facing some hefty fuel bills this winter? Professor Richard Williams of the University of Leeds may have a possible answer to those rising costs. But the development of his innovative nanofluid technology (Tiny tubes could bring big savings on fuel bills, 13 April 2006) for improved heat transfer is taking longer than he originally hoped.
Add carbon nanotubes (an arrangement of carbon atoms more than 50,000 times thinner than a human hair) to liquid, and they'll disperse to form a "nanofluid". Williams's interest lies in the thermal conductivity properties of this mixture: the nanotubes could make a 10% difference to the efficiency of transferring heat from the boiler to your radiators.
The nanofluids transfer heat at a higher rate than ordinary fluids (for example, water) which allows for more efficient heating or cooling while reducing energy consumption. Over the past two years, Williams has carried out more scientific research into the phenomenon. "The most significant area that we have been exploring relates to how tiny clusters of particles cause heat to be transferred more effectively compared with fully dispersed nanodispersions. Many of these effects can be explained using conventional physics but a range of variables need to be accounted for."
Although domestic central heating remains of interest, Williams has since concentrated on industry as a quicker route to market. "We have been working with various partners to evaluate industrial applications including thermal transfer for transportation and computer cooling applications," he says.
Finding exactly the right nanofluids for car engines to computers is important as, even in flowing liquids, the particles can clump together, thanks to van der Waals forces - that is, attraction between molecules. In addition, carbon nanotubes cost thousands of pounds per kilogram, although you only need a tiny percentage by volume. "We have been developing fluid formulations that perform at low and high temperatures," says Williams.
This complex area is subject to patent applications, so he won't discuss specific details of the work. However, suitable nanofluids may be made from carbon nanotubes or metal oxides along with water, glycol (antifreeze), and mineral oil with other additives.
The practicalities of scaling up from the laboratory bench to 200-litre test batches have also slowed progress. But this hasn't deterred Williams and his colleague Professor Yulong Ding from establishing a spin-out company, Dispersia.
Backed by venture capital and a regional grant, they've managed to attract development collaborations in the automotive and power electronics fields. While all this looks promising, it'll be a while before your central heating system receives that energy-efficiency boost.