Tag Archives: individual cooling unit

Getting too hot? Strap on your personal cooling unit

Individual cooling units for firefighters, foundry workers, and others working in hot conditions are still in the future but if Pennsylvania State University (Penn State) researchers have their way that future is a lot closer than it was. From an April 29, 2016 news item on Nanotechnology Now,

Firefighters entering burning buildings, athletes competing in the broiling sun and workers in foundries may eventually be able to carry their own, lightweight cooling units with them, thanks to a nanowire array that cools, according to Penn State materials researchers.

An April 28, 2016 Penn State news release by A’ndrea Elyse Messer, which originated the news item, describes some of the concepts and details some of the technology,

“Most electrocaloric ceramic materials contain lead,” said Qing Wang, professor of materials science and engineering. “We try not to use lead. Conventional cooling systems use coolants that can be environmentally problematic as well. Our nanowire array can cool without these problems.”

Electrocaloric materials are nanostructured materials that show a reversible temperature change under an applied electric field. Previously available electrocaloric materials were single crystals, bulk ceramics or ceramic thin films that could cool, but are limited because they are rigid, fragile and have poor processability. Ferroelectric polymers also can cool, but the electric field needed to induce cooling is above the safety limit for humans.

Wang and his team looked at creating a nanowire material that was flexible, easily manufactured and environmentally friendly and could cool with an electric field safe for human use. Such a material might one day be incorporated into firefighting gear, athletic uniforms or other wearables. …

Their vertically aligned ferroelectric barium strontium titanate nanowire array can cool about 5.5 degrees Fahrenheit using 36 volts, an electric field level safe for humans. A 500 gram battery pack about the size of an IPad could power the material for about two hours.

The researchers grow the material in two stages. First, titanium dioxide nanowires are grown on fluorine doped tin oxide coated glass. The researchers use a template so all the nanowires grow perpendicular to the glass’ surface and to the same height. Then the researchers infuse barium and strontium ions into the titanium dioxide nanowires.

The researchers apply a nanosheet of silver to the array to serve as an electrode.

They can move this nanowire forest from the glass substrate to any substrate they want — including clothing fabric — using a sticky tape.

“This low voltage is good enough for modest exercise and the material is flexible,” said Wang. “Now we need to design a system that can cool a person and remove the heat generated in cooling from the immediate area.”

This solid state personal cooling system may one day become the norm because it does not require regeneration of coolants with ozone depletion and global warming potentials and could be lightweight and flexible.

Here’s a link to and a citation for the paper,

Toward Wearable Cooling Devices: Highly Flexible Electrocaloric Ba0.67Sr0.33TiO3 Nanowire Arrays by Guangzu Zhang, Xiaoshan Zhang, Houbing Huang, Jianjun Wang, Qi Li, Long-Qing Chen, and Qing Wang. Advanced Materials DOI: 10.1002/adma.201506118 Article first published online: 27 APR 2016

© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

One final comment, I’m trying to imagine a sport where an athlete would willingly wear any material that adds weight. Isn’t an athlete’s objective is to have lightweight clothing and footwear so nothing impedes performance?