Conductive ink significiantly improves the efficiency of solar water heating
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