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Environment

Conductive ink significiantly improves the efficiency of solar water heating

By Colin Jeffrey
October 30, 2015
Conductive ink significiantly improves the efficiency of solar water heating
The researchers claim that where the material has been applied in some houses, water flowing for just five meters (16 ft) through the ink-treated pipe reaches 68 °C (154 °F) almost instantly
The researchers claim that where the material has been applied in some houses, water flowing for just five meters (16 ft) through the ink-treated pipe reaches 68 °C (154 °F) almost instantly
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The researchers claim that where the material has been applied in some houses, water flowing for just five meters (16 ft) through the ink-treated pipe reaches 68 °C (154 °F) almost instantly
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The researchers claim that where the material has been applied in some houses, water flowing for just five meters (16 ft) through the ink-treated pipe reaches 68 °C (154 °F) almost instantly

Researchers at the Technological Institute of the Lagoon (ITL), Mexico, havecreated a nanoparticle-rich, superconducting ink that they have used to coatpipes of solar water heaters to increase their efficiency by up to 70 percent. The new coating was recently proven on the solar heating of a Mexicancity sports complex swimming pool, where 2 million cubic meters (70.6 million cubic feet) of water wereheated from 26 °C to 37 °C (79 °F to 98°F).

Classed as an ink because of its solvent-driven rapid drying time, the materialis really a fast-setting paint that is built up in several layers. The internallayer is one of magnetic titanium nanoparticles that trap the heat, the layerabove that consists of tungsten nano salt adhered with polyvinyl alcohol, andthe whole ensemble finishes with a layer of copper.

"A pipe exposed to the sun reaches a temperature of 40 °C (104 °F), if we add thesuperconducting ink the temperature increases 70 percent and reaches 68°C (154 °F)," says Sandra Casillas Bolaños, master at ITL, and head of the project.

To aid the heating, the outer layer of copper is also burnished to blackenit, so that it heats more rapidly and efficiently in order to trap and hold heatinside the inner particles. "Thus the center is heated more intensely:first the titanium, then tungsten and finally the copper," says Bolaños.

Thistechnique is so efficient, the researchers claim that where thematerial has been applied in some houses, water flowing for just five meters (16 ft) throughthe ink-treated pipe reaches 68 °C (154 °F) almost instantly. Even in overcastweather, the ink is also asserted to capture heat much more efficiently thanun-treated systems.

Currently being patented, the superconducting ink is slatedfor market at a price of around 600 pesos (about $US40) a liter.According to Bolaños, however, painting all of the solar water piping in astandard house should cost only around 150 pesos ($10) as the coatinggoes a long way using very little.

Bolaños says that the point of difference between her team’s material andother coatings coming to market, is that the others use much more expensivemetals than the tungsten the ITL team uses, meaning that theirs will come inaround 40 percent cheaper.

The final hurdle is to replace the current step-by-step process offine-tuning the nanoparticle layer and optimize its creation to allowproduction in greater volumes.

Source: Investigación y Desarrollo

Tags

EnvironmentNanoparticlesHeatingSolar ThermalCoatingTechnological Institute of the Lagoon
11 comments
Colin Jeffrey
Colin discovered technology at an early age, pulling apart clocks, radios, and the family TV. Despite his father's remonstrations that he never put anything back together, Colin went on to become an electronics engineer. Later he decided to get a degree in anthropology, and used that to do all manner of interesting things masquerading as work. Even later he took up sculpting, moved to the coast, and never learned to surf.

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11 comments
Bruce H. Anderson
This looks like quite the achievement. But I'll tell ya, 154F is mighty toasty. Normally water heaters are set to around 120F to prevent scalding. Setting it at 140F increases costs, but also helps eliminate bacterium (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2094925/) So some mixing valves would certainly be in order.
Jayna Sheats
Please just do one thing: remove the word "superconducting" from this article, or use a "sic" if it appears in source material. There are no superconductors listed, and if one had been discovered which works at 68C, I believe the world would have heard of it.
Thank you.
MikeW
If as advertised, this application would be a giant leap for solar water heaters in areas with limited hours of daylight where a simple, highly insulated, storage tank could hold a sufficient quantity of hot water.
Hopefully this will not just another in the endless stream of processes 5+ years out that gets forgotten when the next shinny object appears.
jerryd
Scam!! Sorry folks but not going to be more eff than a copper pipe. If they really wanted to increase eff an outside heat absorbing, non reflecting coating will be used. Nothing on the inside can help, only hurt, just a fact of physics.
quax
Superconducting means complete loss of electric resistance something that doesn't happen at normal temperature and is certainly not a property of the paint as this article claims.
Something got lost in translation, supposedly this paint has superb heat conductivity.
Captain Obvious
Either their technical explanation suffered in the translation, or it's total baloney. And going from 40 to 76 degrees is not a temperature increase of 70%.
Show us a side by side test versus a conventional selective surface.
notarichman
i wonder what the maximum temperature that the "ink" will withstand is? if it could withstand the inside of a cord wood or pellet stove; then the heat transfer would make them more efficient. i checked the approximate temp. at 1100 degrees F. silver melts at 1700 plus degrees and is very conductive as well. what if you could line the top inside of a stove with silver plates that connect through the iron/steel stove top to heat sinks made of aluminum? weld all 3 metals using the process that just came out on gizmag.com from ohio univ. blow air with fans across the heat sinks. more heat would be transmitted from the inside of the stove to outside. NOW, would the whole thing self-destruct from heat?
Yasha
How it is related to superconductivity ?
BeWalt
Superconducting is the wrong term here. What they are working on is called a selective coating. Selective because of its behavior with regards to wavelength from incoming solar radiation and outgoing infrared losses. These coatings have existed as galvanic coatings and also vapor coatings since the eighties and can lead to very high stagnation (absorber) temperatures, around 200 deg C. This comes from the coating absorbing in the high 90% range while only emitting, or loosing some 10% or less. A painted black body will lose far more. Brand names for this are Sunstrip, Maxorb or Tinox but they are so obscure that one needs to google "absorber" or "solar" alongside to find them. Paints doing the same have been worked on for just as long, and I know of at least one product coming out of the university of Ljubljana/Slovenia but they did only make it to market on a few products in the early 1990's. And the paint was not very durable. Not sure what became of them. Really good someone is working on this approach again. Would be great to be able to buy selective solar paint at your local hardware store.
ivan4
This article if full of contradictions and says very little.
Is this paint/ink applied as one coat or three? The article talks about three layers but implies it is in one application rather than three.
I assume it is applied to the outside of a copper pipe and then requires something else on top of it to darken the outermost surface which rather defeats the object of the paint in the first place.
I also question the temperatures - maybe they are correct for a particular place - It would have been better to give the full information including things like ambient temperature plotted over the time of the test, actual temperature of the outside surface of the pipe plotted over the time of the test and water temperature again plotted for the time of the test.
Without all the necessary data it is impossible to evaluate this product. The article reads like an over optimistic press release not a scientific discovery.
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