Pure Technology

esigned for air-purification systems, aphotocatalytic substrate combines thekey properties of low pressure drop, high

oxidation rates and W light transmission.

The Quartzel@ substrate, developed by Saint Gobain Quartz ofNemours, France, uses a process known as photocatalysis to destroyair pollutants while aiding in ozone reduction. Applications includeair purification systems such as stand-alone air purifiers, in-ductHVAC residential units and large building systems.

The key features of the substrate stem from the nature of thematerial and a photocatalysis chemical reaction. The substrate ismanufactured by impregnating TiO2 on ultra pure silica feit made upof fused quartz fibers. The quartz fibers have a l00-percent mineralcomposition and naturally conduct UV light, This purity is said tomake the material resistant to W light or chemical degradation andwill not poison the Ti02 catalyst, This is critical in order to maintainthe performance of an air-purification system, according to Jean-Marie Harry, sales and marketing director of Industrial Products. "lf

the material contained aikali, elements such as Na (sodium) and K(potassiun) would migrate from the fiber to the Ti02 coating, reduc-ing the photocatalytic efficiency of the system," Harry explains.

To destroy pollutants, photocatalysis uses the UV light and Ti02semiconductor on the substrate to create a hydroxyl radical from thewater present in the air. This hydroxyi is said to have twice the powerof chlorine in destroflng organic molecules and converts them intobasic molecules such as C02 and H20. Using the oxidizing power ofthe hydroxyl radical, air purification systems can destroy volatileorganic compounds (VOCs) such as halogenated organics, surfac-tants, herbicides, and pesticides.

The company says it also developed a patented technology for opti-mal Ti02 coverage and adhesion. With a large surface area of120 mz/g, the Ti02 is said to provide excellent pollutant/odor absorp-tion capability and bacteria trapping, and can help reduce mold.

Harry says the photocatalfiic substrate offers several advantagescompared to carbon-based systems. Whereas carbon systems onlyabsorb poliutants and need to be changed frequently, photocatalysisis a chemical reaction and can be continuously operated. In fact,Quartzel doesn't require a carbon layer at ail; it can absorb organicmolecules right on its surface. Poilutants that can be treated includeformaldehyde, aldehyde, ethylene, phenolic compounds, alcoholcompounds, alcene, alcyne, carbon family compounds, and sulfur.The substrate is also said to have an effect on ozone reduction.

With a low density of less than 10 kg/m3, the substrate enables apressure drop that is lower than G4 (MERV 10) and 50 Pa (0.2 inchesof water) in residential HVAC filters. "This pressure drop is key indesigning an HVAC system," Harry says. "The higher the pressuredrop, the bigger the fan has to be, resulting in more noise, moreener€5/ consumption and a more costly system.'

Although the material is currently used in HVAC applications,Harry notes that the technology may have potential in water purifi-cation systems. She also offers engineers some tips to get the most

Iunalier is usingQaartzel felt tronSaint Eohain fuuartzin its three-stage lA0-I air quality systen,

which can he installed

in nost 1.5-ton to i-tonair-handler and furnace units.

fhe Menphis, fennessee, U.S.-based OEM says that the felt enahles

the puritication systen to destruy volatile organic conpounds, including tobaccosnoke, pet snells, chenicals funes, and nost connon hoasehold odors.

out of the substrate: use UVA A or UV C lamps, and apply one layer ofQuartzel to each side of the UV lamps to increase efficiency.

Available in North America through Davidon Industries of Warwick,Rhode Island, U.S., Quartzel has an areal weight of 100 g/mz, a thick-ness of 10 mm and a surface area of 120 d^r. S

Circle t{0. 302

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Augttst 2006 @ Appliance 33