Scientists from China and the US have produced glass that responds to its environmental temperature, making it a promising material for energy efficient windows. On cold days, the windows would prevent heat escaping and on hot days, the windows would reflect infrared radiation, keeping the room inside cool.
Vanadium dioxide (VO2) has long been recognised as a potential candidate material for making 'smart windows' because it can change from a transparent semiconductive state at low temperatures, allowing infrared radiation through, to an opaque metallic state at high temperatures, while still allowing visible light to get through. VO2 has its drawbacks, however: it's not a very good insulator and can only be made at very high temperatures of 420-500°C.
A vanadium oxide layer combined with fluorine-doped tin oxide on glass is a promising material for energy efficient windows |
Zhong Lin Wang at the Georgia Institute of Technology, Atlanta, and co-workers at the Shanghai Institute of Ceramics Chinese Academy of Sciences and the Graduate University of Chinese Academy of Sciences in Beijing, have created a system with improved insulating ability by combining a layer of VO2 with a transparent fluorine-doped tin oxide (FTO) layer coated on glass. As an added benefit, the FTO layer enhances the crystallinity of the VO2 film - an important factor for improving the material's performance and reducing its cost - and lowers the synthesis temperature to 390°C.
'Buildings and maintaining man-made structures use 30-40 per cent of the primary energy supply, mainly for heating, cooling, ventilation and lighting. Effective control of the energy exchange between the interior and exterior of buildings through windowpanes is a key area in saving energy,' says Yanfeng Gao, one of the researchers. 'We conducted this research to create a film that can combine the functions of low emissivity and thermochromic coatings.'
Materials expert Seeram Ramakrishna, from the National University of Singapore, sees advantages to the group's approach. However, he also feels that improvements could be made to optimise the system. The work 'doesn't attempt to bring down the transition temperature of VO2 to room temperature, which would be desirable if it is to have practical technological applications,' he says.
Gao now hopes to realise his dream of seeing the smart windows go into mass production.
Heather Montgomery
ادامه مطلب
Batch Plant Process
The batch house is one of the most essential parts of a glass manufacturing site. Allowed down times are normally extremely short which implicates that the batch house operation has to be very reliable. Taking into account that such a batch house normally needs to supply several different recipes of raw material batches to multiple high pull rate furnaces it becomes clear that batch house design and automation asks for lot of “glass expertise”.
With up to 2.800 I/O points Batch House Automation systems are even more complex than furnace automation systems. Invensys Eurotherm delivers system conceptual design, detailed engineering, cabinet building, system programming, testing and installation and commissioning to actual silo and hopper filing, batch weighing, batch transport, mixing and cullet returns.
The batch process of the glass facility is normally divided into four sections. Each of the sections, or process cells, can be controlled either from the Distributed Control System (DCS) or from the Local Control System (LCS).
Silo feeding
It consists of feeding the raw matarial into one of multiple silos or hoppers. When unloaded from the trucks raw material is conveyed through a series of bucket elevators and conveyor belts to the silica, soda ash, limestone, feldspar or sodium sulphate silo. Each of these silos are fitted with level transmitters, pressure switches and over pressure flaps that are all mounted and controlled by the Eurotherm Foxboro PAC System. The silos will have a series of dedusting units that help in trapping the excess dust, which tends to rise as the silos get filled up. These dedusting units comprise of dust collectors and blower fans. At every stage magnetic separators will prevent iron impurities finding their way into silos.
Batch weighing and transport
This section deals with the weighing, dosing and transport issues of the batch plant. Dosing into the weigh scales is either through screw feeders, pneumatic feeders or vibrating feeders.
Both coarse and fine dosing from the feeders into the weigh scales is controlled by Eurotherm AC inverters. The time and sequenced dosing of the raw material is completely controlled by the Eurotherm Suite System. The conveyors are again controlled by Eurotherm AC inverters.
Mixers
Normally a plant is equipped with several mixers each driven by a 110kW motor that can be controlled with a Eurotherm flux vector AC drive. Raw material is fed to the mixer that has to be filled through a swivel pipe. The Invensys-Eurotherm Foxboro PAC also controls the elaborate water and oil feeding options that are used to ensure that the mix reaches the desired consistency before it is fed on to the main conveyor belt.
Cullet is added to the mix on the conveyor belt to get the final mixture that is ready to be loaded in the furnace. When the final mix is not of the desired quality it is rejected and fed to a waste hopper.
Single or multiple batch chargers takes the final mix form the furnace silos from where it is fed into the melting furnace.
Cullet and cullet return
As almost every glass producer is using cullet from external suppliers or cullet that is returned from its own production line. The cullet handling part of the control system deals with the loading of the cullet silo with material of the cullet yard as well as the cullet crushing and return from the float line. Invensys Eurotherm AC inverters control the operation of line crushers, water crushers finger drops and breakers as well as the conveyor belts that transport the cullet directly back into the batching process or to the cullet yard. Incoming cullet from external sources is loaded into a hopper that feeds the cullet to a series of crushers. On its way to the cullet silo the cullet passes magnetic detectors and magnetic separators that keep iron parts away from the silo and finally from the raw glass melt.
Safety
From a safety point of view the systems supplied are in compliance with all the relevant safety and machine directives. Emergency stop switches, pull cord switches zero speed detector units and belt sway detectors secure to bring the plant into a safe state when an emergency does arise.
ادامه مطلب
To enhance the glass melting process, increase throughput, improve glass quality and to reduce CO2 emissions electrical furnace boosting is often used. It also provides a useful control parameter for advanced glass temperature control strategies and pull rate fluctuation compensation
ادامه مطلب
Bath Roof Heating
The multiple zones of a tin bath roof require a huge electrical heating system that takes care of hundreds of silicon-carbide (SiC) heating elements. In order to guarantee the lifetime of those electrodes combined with the highest energy efficiency they have to be controlled in a special way.
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Annealing Lehr Heating
Annealing is a process of slowly cooling glass to relieve internal stresses after it was formed. The process is carried out in a temperature-controlled Lehr. Glass which has not been annealed is liable to crack or shatter when subjected to a relatively small temperature change or mechanical shock. Annealing glass is critical to its durability. If glass is not annealed, it will retain many of the thermal stresses caused by quenching and significantly decrease the overall strength of the glass.
In the annealing process the glass is heated until the temperature reaches a stress-relief point, that is, the annealing temperature (also called annealing point) at a viscosity, η, of 1013 Poise = 1012 Pa·s, at which the glass is still too hard to deform, but is soft enough for the stresses to relax. The piece is then allowed to heat-soak until its temperature is even throughout. The time necessary for this step varies depending on the type of glass and its maximum thickness. The glass is then slowly cooled at a predetermined rate until its temperature is below the strain point (η = 1014.5 Poise). Following this, the temperature can safely be dropped to room temperature at a rate limited by the heat capacity, thickness, thermal conductivity, and thermal expansion coefficient of the glass. After the annealing process the material can be cut to size, drilled or polished.
Next to necessarily well controlled annealing process, the control system also needs to take care for energy efficiency. In most of the cases the incoming glass containers will introduce enough heat to the annealing lehr by themselves and therefore a well designed temperature and draft control will result in best annealed glass as well as in low energy consumption.
ادامه مطلب
The bathroom is one of the most intimate places in your home.
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The market size of automotive glass approximates USD15 billion, with around USD13 billion from OE market and USD2 billion from AM market. In OE market, the five titans including AGC, NSG, Fuyao, PGW and Saint-Gobain occupy approximately 85% altogether in the global market, indicating a very high entry threshold.
As for the electronic display glass market, the market size is about USD16.5 billion, of which, large size TFT-LCD substrate registers around USD15.7 billion. As the production of glass substrate requires sophisticated technologies, only four companies, namely, US-based Corning, Japan-based AGC, Nippon Electric Glass and AvanStrate, can make the product. As the world’s largest glass substrate manufacturer jointly invested by Corning and Samsung, Samsung Corning realized revenue of USD4.856 billion in 2010, with the gross margin exceeding 75% as opposed to 5-8% of ordinary flat glass.
Low-E glass and solar glass are among the hottest investment topics at present, but their gross margin is far less than that of large size TFT-LCD substrate.
In Europe and the USA, the utilization rate of low-E glass is extremely high, but very few buildings are erected each year. In contrast, China inputs huge amounts of money to build public and commercial buildings each year, so it is the largest market of low-E glass. In China’s civil architecture field, the penetration rate of low-e glass is very low due to the exorbitant price, and the market size will see no considerable growth in the short run.
European and American enterprises are taking leading roles in low-e glass market. In particular, PPG, Guardian and Saint-Gobain take a lion’s share of the European and American market. However, due to high transportation cost, these enterprises can thrust into the Chinese market only through joint ventures. Thus far, the three have been very conservative about investments and rarely expanded capacities.
The market size of solar (PV) glass is relatively small. Solar glass is mainly classified into two categories: one is anti-reflective glass for silicon solar cell, and the other is TCO glass for thin film solar cell. The solar industry is facing unprecedented winter, witnessing grim price competition that causes sharp decline in gross margin. It is estimated that the market size of TCO glass in 2011 will approximate 57.092 million sq m valuing about USD1.3 billion. Due to very high industry admittance threshold, TCO glass market is largely monopolized by AGC and NSG of Japan.
The nosedive of polycrystalline silicon price has undermined the cost edge of thin film cell. In 2009, the silicon cell was priced at USD2.4/w with the cost around USD2.02/w; the thin film cell was priced at USD1.95/w with the cost around USD1.2/w. Presently, the cost of silicon cell is reduced to below USD1.18/w, while the cost of thin film cell cut down to USD0.92/w. As a result, the cost advantage of thin film cell manufacturers has been weakened significantly. The output of Chinese thin film cell manufacturers is relatively low. The major thin film cell manufacturers worldwide concentrate in the USA, Japan and Germany. Particularly, US-based First Solar occupies an overwhelming share of 50% or so.
ادامه مطلب
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ادامه مطلب
AR Glass/AZO coating glass/TCO Glass
Detailed Product Description
TCO glass is Transparent Conductive Oxide glass, which is produced by coated one transparent conductive oxide film with physical or chemical methods. It consists of In, Sn, Zn, CD oxide components or composite oxide film material
Damin Glass, imported international level TCO coating lines and automatic pattered surface treatment facilities, to supply stable AZO
Conductive thin-film glass. Annual capacity is around 1.5million SQM.
Main equipment: Multi-functional AZO coating line, patterned surface treatment automatic lines, testing facilities and other subsidiary equipment
Products characteristics
Szie and strcture
Glass size: 1100× 1400mm
Glass thickness: 3.2~8mm,
TCO film: Glass /SiO2
Average film thickness: 1000nm
Electrode property
Resistivityb: ≤ 10Ω/sqr
Uniformity of film thickness: ± 10%
Uniformity of resistivity: ± 7%
Sheet resistivity: 9.26
Uniformity of sheet resistance: ± 10%
Transmittance: ≥ 80%(at550 nm)
AR Glass, it's also called Anti-reflective glass, means high-transmittance coating glass, or low-reflective coating glass. It's based on nanometer porous inorganic SiO2 technology, coating one special chemical film on the glass surface, to lower the glass reflectance and enhance its transmittance. After AR coating, the normal low-iron transmittance rate can be rised from 91% to 97% roughly, meanwhile, the reflectance of glass can be reduced from 8% to 1%. The combinations of AR and TCO technology can enhance the PV solar modules converting and power efficiency extremely.
Comparison with AR coating and no-AR coating
AR characteristics
Enhance the transmittance, from 91% to 96%. Maximizes the conversion efficiency of solar modules
Treated by nano-technology, anti-reflective coating reduce diffuse reflection from 8% to 1%
Chemically-resistant, AR coating can withstand a range of pH in harsh outdoor environment)
Self-cleaning coating decomposes organic pollutants on the glass surface and reduce the
Maintenances time)
Anti-reflective coating has minimal amount of light absorption
Damin AR Glass:
Glass size: 1100× 1400mm
Glass thickness: 3.2~8mm,
Film: Nanometer porous inorganic layer
Average thickness of film(nm): 1000nm
ادامه مطلب
TCO for Photovoltaics
TCO coatings for thin film solar cells (a-Si, μc-Si and CdTe)
With the surge of photovoltaics (PV) in the world today, solar cell
manufacturers are looking for more economical coating solutions for
their production lines. Beneq, with its own nAERO®
aerosol-assisted pyrolytic deposition method, presents a technically
superior and economical coating method for in-line and off-line coated
products. nAERO is capable of producing low-haze and high-haze
transparent conductive oxide (TCO) coatings, which allows the cell
manufacturer to optimize the coating to suit his specific needs and
thus maximize the efficiency of the thin film cell.
Higher photon efficiency
A nAERO-produced TCO coating is a pyrolytic hard coating consisting of fluorine-doped tin oxide (SnO2:F). Coating parameters can easily be adjusted and optimized to yield best results for haze, conductivity or transmittance. Haze can be as low as < 1% or as high as 20%, including the range between the two extremes. nAERO TCO by Beneq is fully temperable and can be laser-scribed or wet-etched. In addition, the pyrolytic hard coating has very good adhesion to sealing materials.
Efficient raw material usage
nAERO deposition is based on sub-micron sized droplets that are directed to the glass substrate. This enables a high growth rate and good material economics, with a raw material (precursor) yield of 20% or better.
Underlayer
If needed, an underlayer consisting of SiOx, SiO2 or TiO2 can be added between the electrically active TCO layer and the glass substrate. This underlayer is produced in a process step prior to nAERO coating. The underlayer serves as a barrier layer against sodium diffusion and eliminates iridescence in reflected light.
Coating specifications1
| Type | transparent conductive oxide (TCO) | |
| Chemical composition | SnO2:F (FTO) | |
| Subgroup (based on haze) | low haze | high haze |
| Haze, D65/10% | 1 | 12 (example) |
| Transmittance2, average 400-1000 nm (%) | > 83 | > 83 |
| Sheet resistance3 (Ω/□) | 12 | 10 |
| Emittance | 0.15 | 0.15 |
| Thickness (nm) | 400 | 750 |
| Uniformity, sheet resistance (deviation) | < 2.0 (Ω/□) | |
| Uniformity, transmission (deviation) | < 1% | |
| Temperable | yes | |
1 All properties are nominal and solely applicable to
specimens under specific testing conditions. The information is not
intended to and does not create any warranties.
2 Transmission measured with index matching liquid CH3I (haze compensation) on 4 mm glass.
3 Measured by 4-point method.
More information
Download TCO for Photovoltaics brochure (pdf).
ادامه مطلب
For
more than 30 years Hubtex has been developing and producing glass
handling equipment. Their production of Four Directional Sideloaders as
well as special trucks has been used to offer customers in the float
glass industry a complete transport, storage and loading system of
glass piles. The well-proven technique, the component construction and
a high quality standard of our trucks guarantee a high grade of
availability.
