TECHNICAL LIBRARY AND HELP INFORMATION OF SHTIEVER LLC:  
 

    SMART GLASS
    TECHNOLOGY OF SMART GLASS PRODUCTION
    KOMFORT HEATABLE GLASS

     
  SMART GLASS  
 

Smart Glass, which is also known as “switchable” glass, belongs to a group of translucent products, or products which are able to change their features under the influence of electric current.

     There are three technologies of Smart Glass:

   • PDLC, Polymer Dispersed Liquid Crystals, LC Glass
   • SPD, Suspended Particle Devices
   • ECD, ElectroChromatic Devices, EC Glass

     Polymer Dispersed Liquid Crystals
   The point of PDLC technology is the formation of a special liquid crystal structure (layer) between two layers of electrically conductive polymer covering.

PDLC

   In absence of voltage liquid crystals have random positions and form non-transparent white structure. In this state the Smart Glass is optically impenetrable, which is why we can use it as a projection screen of frontal and reciprocal projection, as different kinds of partitions, and also to use it as part of protective windows for all manner of protections. When voltage is applied, the liquid crystal particles assume a position perpendicular to the surface of the electrically conductive layer and that makes the Smart Glass optically transparent with slight opalescence.

Principle of work a glass smart

 

   With use of up-to-date materials for producing Smart Glass Polyvision we can make wide-screen (more than 1,5 x 3 meters) panels, which are characterized by low-voltage power use and ultra-low energy consumption while providing both visibility, and protection when needed.

     Suspended Particle Devices

   The point of SPD technology is a solution between Smart Glass PDLC and ECD (see ECD).
   The structure of SPD layer glass is practically identical to the structure of PDLC; the difference is that in SPDs the particles have a rod-like structure. That is why Smart Glass SPD is optically transparent in any state.
   In the absence of voltage the suspended particles have random positions and the color of the glass is dark blue or, more rarely, black or gray. In 2-3 seconds after application of voltage the particles regularize their orientation and Smart Glass clarifies to light blue or gray color.

     ElectroChromatic Devices

   The principal difference of ECD technology is that, in contrast to Smart Glass PDLC and SPD, the coating is formed by multcoat sputtering of the layer or glass and is transparent when turned off.
   The change of state takes place when lithium ions migrate under direct current voltage.
   The control of darkening/ clarifying is executed by change of polarity and the rate of voltage (in the range of 3-5 volts).
   As with Smart Glass SPD, the tints of ElectroChromatic Glass vary from dark blue to light blue.

     Aside differing in their operating principles, all these types of materials used in production of Smart Glass are sensible to humidity, atmospheric conditions, and mechanical effects. Therefore, a procedure of lamination (triplexation) is obligatory.
   Triplex is produced with the use of modern technology; this technology helps to use prepared Smart Glass panels in different kinds of structures.

 
  TECHNOLOGY OF SMART GLASS PRODUCTION  
 

Smart Glass is produced by means of triplexation of 2 or more glass or polycarbonate sheets.
     The most widespread technologies of Smart Glass panels’ production are the following according to the type of used laminated films:

   • EVA — ethylene-vinyl-acetate film with good adhesion to plastics and glass.
     Major advantages — low cost of both film and equipment. You need only primitive furnaces with vacuum bags for production.
     Disadvantages — high rate of opalescence, especially after multicoat lamination. Furthermore, over time, yellowness appears.
     EVA has low shear strength, especially in low temperatures; it results in delamination (layering), and it is also sensitive to humidity.
     One of special features of Smart Glass produced with the help of EVA technology is the unpredictable appearance of tacks (layering).

 

  • PVB — polyvinyl butyral film with high rate of adhesion to glass and low rate — to plastics.
     Major advantages — low cost of mass production of triplex, insignificant rate of opalescence, high quality of product.
     Disadvantages — high initial cost of equipment, it is necessary to have an autoclave press for preliminary hot testing, a “clean” room, and qualified personnel. Besides that, triplex produced with the help of PVB technology can not be used in a wet environment.
     Concerning production of triplex, generally this technology gives better results than EVA.

   • TPU — thermoplastic polyurethane film with very high rate of adhesion to glass and plastics.
     Major advantages — insignificant rate of opalescence, insensible to humidity, mechanical effects and severe atmosphere; very high quality of the product.
     Disadvantages — high cost of film and equipment, it is necessary to have autoclave, “clean” room, and qualified personnel.
     When it comes to Smart Glass production this technology gives great results.
     Triplex, produced with the help of TPU technology, is used as the material for production of glazing for aerospace industry.

 
  KOMFORT GLASS  
 

Komfort Glass.

   Komfort Glass and windows are relatively new products, which help provide hi-tech solutions for more efficient, and more ecological design of buildings and vehicles.
   The idea of Komfort Glass is based on using energy-efficient low-emissive glass which is generally simple silicate glass with special metallic oxides covering it. Low-emissive covering decreases the loss of heat approximately by 30 %, a significant saving of energy. Komfort Glass can be used in all kinds of standard glazing systems, made of wood, plastic, aluminum or steel.
   Komfort Glass based on low-emissive coverings was first produced in high volume in the beginning of 1980s. Nowadays Komfort Glass is used in construction of many kinds of buildings and in production of serial vehicles.
   Komfort Glass does away with much of the discomfort and disadvantages induced by low heat-insulating features of silicate glass. The effect of “cold glass” disappear when the surface of the glass is heated, making it essential for cold climates.
   With Komfort Glass, there is no more condensation, no more ice crusts and snow covering, the window’s heat losses are compensated for, and that is why there is an atmosphere of comfort in the room or vehicle.
   Komfort Glass can be used as a principal system of heating and can combine with floor and ceiling heating to provide greater efficiency. This kind of combination helps to reduce the total rate of heat losses of the building thereby lowering costs expenses for heating. Besides, having Komfort Glass windows you can use the active area of the room more efficiently, because you do not have to install massive windowsill radiators.
   Initially Komfort Glass was produced by sputtering ordinary glass, and it therefore could not guarantee the quality or stability of the product. A technological breakthrough took place in 1989 when the mass production of low-emissive glass began. The glass was coated during the process of manufacturing and over time the quality of innovations to the product grew very high and this innovative product became the ideal component for Komfort Glass production.

     STANDARD WINDOWS

     Window construction

   Windows play a significant role in creation of comfort atmosphere in the room. That is why the area of glazing of buildings is constantly being increased.
   Window technologies are always in the process of further research and development, and it is common today to use low-emissive glass. In spite of progress in this field, the low temperature of glass surface is still a problem for constructive glazing. Komfort Glass helps to solve problems with low surface temperature and increase the level of comfort in the room significantly. Komfort Glass can be used in practically all kinds of glazing systems made of wood, plastic or aluminum.
   Komfort Glass and multiple glass panes can be used both in blind and openable constructions. Multiple glass panes made of Komfort Glass can have one or two chambers. The advantages of multiple glass panes are their hermiticity and ability to decrease heat transfer significantly.

     Optical transmission and heat losses of windows

   If the temperature in the building is higher than the temperature outside, then heat leaks through the elements of construction. Windows are usually the most vulnerable elements of the building in terms of heat losses. So the heat loss though window constructions are generally about 20-25% of total heat loss for a structure.
   Heat insulation of translucent constructions can be improved by increasing the number of glasses and chambers of multiple glass panes; but this will, however, increase construction costs while decreasing visibility and the rate of optical transmission. The reasonable alternative is the usage of low-emissive glass, which is practically the same as ordinary glass in terms of optical transmission, even as it it also reflects the heat radiation back into the room.
   The major indicator which characterizes the ability of glass to reflect heat radiation is its emissivity (E) or the “emission factor”. The lower emission factor is, the more effectively the material reflects heat, and the more heat will accumulate inside the structure. The emission factor of ordinary glass is 0.83; the E factor of low-emissive glass can reach 0.03, so more than 90% of accumulated heat will be reflected back into the room. To compare, the emission factor of multiple glass pane with two chambers made of ordinary glass is the same as the emission factor of just one multiple glass pane with one chamber produced with low-emissive glass.
   Besides energy-efficient functions in cold seasons of the year, low-emissive glass also possesses the ability to reflect the excess of outside heat energy in summer seasons, thereby acting as a coolant in summer.
   Visibility or the optical transmission coefficient is however not affected by this in any significant way.

   The key additional factor in lowering the heat transfer of multiple glass panes is the production of panes using low thermal conductivity gases – argon or krypton – to fill the chambers. Generally in multiple glass pane production argon is more often used, which helps to reduce heat losses by 20%, though the cost of multiple glass pane is hardly increased at all.

     Influence of window surface temperature on comfort

   There are two reasons why people feel discomfort when they are close to cold window surfaces. First, cold windows are a reason for an outflow of heat, which is produced by the cutaneous covering of individual surfaces. Second, cold windows provoke the circulation of air, which is felt like a draft.
   In order to reduce these factors, heating radiators are always places under window sills. As far as people can feel cold and heat, the actual temperature of environment is not the only factor which defines the total level of comfort. In reality, the heat radiation of surrounding surfaces has a greater influence than air temperature. If the window surface is cold then to maintain the comfort atmosphere it is necessary to increase the heating temperature, but it will also significantly increase energy consumption.
   The problem of cold windows can be solved effectively with the help of Komfort Glass. These windows allow one to maintain the optimal comfort level and temperature of the room. The air temperature can be decreased at least by 1 degree if the temperature of surrounding surfaces has the same protection. You also do not have to install heating radiators and free the additional space for this. Besides, even when turned off, the multiple glass panes made of Komfort Glass act like ordinary low-emissive glass.

 

     Komfort Glass and multiple glass panes made of Komfort Glass.

     Structure of Komfort Glass.

   The idea of Komfort Glass is based on using energy-efficient low-emissive glass, where the coating plays the role of a heating element. Komfort Glass can be used both in the production of multiple glass panes and as a part of a triplex, which has also has a function of protective glazing.
   The technological process of production of multiple glass panes made of Komfort Glass is practically the same as the process of ordinary multiple glass panes production. The main difference is the presence of power supply and, if necessary, temperature sensor.
   The temperature sensor allows us to track the temperature of Komfort Glass and eliminates the possibility of overheating of the product.
   In order to prevent shocks, the conductive coating is always placed inside the multiple glass pane or triplex.
   Only secure hardened glass, the strength of which is a lot higher than the strength of ordinary glass, is used in production of Komfort Glass. When the hardened glass is broken there are safe splittings. Also the current-carrying coating loses its integrity and an automatic fuse, which turns off the power supply of the glass, is activated. The electrodes are placed inside triplex and no one can reach them without destroyion of the product.

     Usage of Komfort Glass.

   Komfort Glass is mostly used for heating of windows. Komfort Glass is especially useful for rooms where people spend much time by their windows, either at home or at work. The most common usage of Komfort Glass — windows of country homes, office buildings, display areas and other big areas involve leaded panes, translucent roofing, garret windows, canopies and so on.
   Komfort Glass is also used for defogging and prevention of frosting of windows of pools, saunas and other buildings of such kind.
   Also, because Komfort Glass has current-carrying coating it can be used as the sensor in alarm systems. When the glass is broken, the system of protection is activated and which automatically also results in activation of the alarm system.
   These kinds of products are increasingly widely used on objects of tightened security standards in need of greater protection: nuclear power plants, stations of air traffic and aviation navigation control, museums, governmental institutions, special storehouses, etc.
   Komfort Glass is also used in production of windows for different kinds of vehicles: electric and diesel locomotives, vessels and boats, different kinds of aircraft and automobiles.
   One of well-known examples of application of Komfort Glass is armored windows, because the protective glazing is very thick and yet adaptable to switchable visibility needs. The usage of Komfort Glass is especially urgent in terms of being the part of armored multiple glass of Smart Glass of switchable transparency, because the heating significantly decreases the period of reaction of liquid crystals’ structure.
   The power consumed by Komfort Glass products depends on their type of use. Power of about 50-100 watt for 1 square meter of the window is generally enough for maintenance of comfort temperature in the room and for maintenance of glass surface temperature at the rate from +20 degrees to +30 degrees.
   When the Komfort Glass is used as the only resource of heat it is necessary to maintain the glass surface temperature at a rate from +30 degrees to -45 degrees and provide the power of 100 to 300 watts for 1 square meter of the window.
   The power needed for vehicle windows reaches 1,5 kilowatts for one square meter or more, that is why there are such tight standards in terms of sputtering of current-carrying components.
   Heat power of about 500-700 watts for one square meter of glazing is necessary for snow unloading and taking ice-covering off the outside protective translucent constructions in low temperatures and windy environment.

     Technology of production

   Komfort Glass is produced by lamination of two or more sheets of silicate glass. The most widespread technologies are the following technologies of panels’ production according to the type of used materials:

  • EVA — ethylene-vinyl-acetate film with good adhesion to glass.
   Major advantages — low cost of both film and equipment. You need only a primitive furnace with vacuum bags for production.
   Disadvantages — high rate of opalescence, especially after multcoat lamination, with the lapse of time appears yellowness.
   EVA has low shear strength, especially in low temperatures; it results in delamination (layering), sensitive to humidity.

  • PVB — polyvinyl butyral film with high rate of adhesion to glass.
   Major advantages — low cost of mass production of triplex, insignificant rate of opalescence, high quality of product.
   Disadvantages — high initial cost of equipment, it is necessary to have autoclave, press for preliminary hot testing, “clean” room, and qualified personnel.
   Another disadvantage is that, triplex made with the help of PVB technology can not be use in wet environment.

  • TPU — thermoplastic polyurethane film with very high rate of adhesion to glass.
   Major advantages — insignificant rate of opalescence, insensible to humidity, mechanical effects and severe atmosphere; very high quality of the product.
   Disadvantages — high cost of film and equipment, it is necessary to have autoclave, “clean” room, and qualified personnel.

  • Photocurable polymers (resins) — so-called “filling technology”.
   Major advantages — low cost of both polymers and equipment. You only require an ultraviolet furnace and a minimum of additional equipment to produce triplex.
   Disadvantages — it is necessary to have highly qualified personnel for work.
   However eating triplex that is produced with the help of this technology is insensible to humidity and temperature influence, and has high shear strength.

Article in WIKI

 
 
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