FR2609285A1 - MULTI-GLASS INSULATING GLASS FOR COLD OR SIMILAR CHAMBERS - Google Patents

Abstract

THE INVENTION CONCERNS A MULTI-GLAZED INSULATING GLASS FOR WINDOWS OR THE LIKE OF A REFRIGERATED SHOWCASE FOR PRESENTATION OF PRODUCTS. THE INSULATED GLASS INCLUDES AN EXTERNAL GLASS 10 DIRECTED TOWARDS THE ENVIRONMENT, AN INTERMEDIATE GLASS 12 AND AN INTERNAL GLASS 14; WHEN THE COLD CHAMBER IS SUBJECT TO A FORCED AIR CIRCULATION AND WHEN THE HEAT TRANSMISSION COEFFICIENT OF THE MULTI-GLASS GLASS IS LESS THAN 2 WMK, PREFERRED TO 1.6 WMK, THE OUTER SURFACE OF THE INTERIOR GLASS 14 IS PROVIDED 'A 24 INFRARED REFLECTION LAYER WITH HEAT REFLECTING POWER IN A WAVELENGTH RANGE GREATER THAN APPROXIMATELY 4 MM, IS MORE THAN 50.

Description

The present invention relates to a multi-glazed insulating glass for

  patio doors or the like used for the isolation of a cold room subjected to a relatively low air temperature compared to an environment with air at a higher temperature,

  with an outer ice directed towards the environment

  and an inner glass facing the chamber

  cold, separated from the outer ice by an inter-

  ice cream, possibly divided into

  mediated by one or more intermediate ices, and

  whose outer surface directed towards the

  ice cream is subject to the atmosphere of the cold room.

  Multi-glazed insulating glass of the definite type

  nor above are advantageously used for French windows, which serve for the isolation of rooms

  cold. This is the case, for example, of refrigerated windows.

  where it is desirable to obtain a large viewing surface of the products stored in the cold room and for which the French windows can be opened for a short period of time

  collection of refrigerated products.

  Such refrigerated display cases have, depending on the application envisaged, internal temperatures of between approximately 10 ° C. and -30 ° C. Because of the low

  internal volume, it is necessary to use

  glazing which exerts a good thermal insulation effect

  only to keep the necessary cooling work as low as possible. For this reason, it is generally used in such applications as glazing a multi-glazed insulating glass. In practice, for example, a three-glass pane with two volumes has been used.

  of intermediate air each having a width of 6 mm.

  In this respect, an important point of view is to give the total thickness of the multi-glazing insulating pane a

  value as small as possible so that the doors

  corresponding windows are not too expensive. A problem with such windows of cooling windows results from the formation of condensation water on the side of the outer ice which is turned towards the surrounding atmosphere, as this hinders vision through the window. For the low internal temperatures of such cooling windows, the temperature of the outer ice is still about 20 to 25 ° C below the temperatures usually present in the product presentation spaces, so that, because of the Because of the relatively high humidity in such spaces, the dew point temperature is about 50-70% by default and moisture is deposited on the outer ice. To prevent such condensate from forming, the outer ice of the above-mentioned three-ice pane is additionally heated and accordingly its temperature is maintained at values above

  the critical temperature of dew point.

  Heating is done by means of a coating

  transparent and electrically conductive which is disposed on the side of the outer ice which is directed towards the intermediate air volume. This heating results in a significant additional expense resulting from the coating, the necessary arrivals of current and

  the power supply. In addition to this, it consumes

energy for this heating.

  For this reason, it would in principle be

  it is desirable to have for the above-mentioned application a multi-glazed insulating pane for which the thermal insulation is sufficiently large so that the critical temperature of the dew point is not exceeded by default and so that the heating can be dispensed with completely. outside ice or at least that the

  temperature of the outer ice is increased sufficiently

  to significantly reduce the heating power required. In addition, with such a highly insulating glazing, the work necessary for the cooling of the showcase

  refrigerant would also be significantly reduced.

  There are different means or combinations of means for improving the thermal insulation of a multi-glazed insulating glass. The first way is to increase the number of insulating intermediate volumes. This means, however, is not generally applicable to refrigerated display windows having a structure comprising more than three windows because the total thickness of windows of such French windows must be as small as possible

  for reasons of weight construction. Other possibilities

  improvements in thermal insulation are

  obtained by filling the volume or volumes between

  with a gas having a thermal conductivity smaller than that of air, or if necessary by means of a vacuum and by means of transparent but infrared reflective coatings which are arranged on ice surfaces which are directed to the intermediate volume (s). Such means have been proposed for example in the German patent application DE-OS 24 43 390 to improve the thermal insulation of

  window panes in the field of construction.

  Also for glazing used to insulate cold rooms, means of this kind are already known (for example those described in the German patent applications DE-OS 26 44 523 and DE-OS 28 42 045 or in the European patent O 036 657). By the combination of the two last mentioned means, it is possible to improve the thermal insulation of a glazing in significant proportions without the total ice thickness substantially exceed that of the aforementioned three-ice structure having two volumes of glass. intermediate air with a width of 6 mm and for which a heat transfer coefficient k (k-value) of about 2.4 W / m2K is obtained. A comparable k value of 2.2 W / m2K is indicated for a two-ice structure having an intermediate air volume of 12 mm and in which the outer ice has, on the side facing the volume

  intermediate, a transparent gold coating and reflective

  infrared, which simultaneously serves as a heating layer to prevent the formation of condensate on

  the outer side of this ice.

  By the expression "heat transfer coefficient k" is meant in this respect the flux density

  of heat, relative to the difference between the temperatures

  volumes adjacent to both sides of the glazing. For the heat transfer coefficient, three influences must be taken into account: the influence of the glazing proper and the influences of the air layers respectively adjacent to the hot side and the cold side of the glazing, in correspondence with the relation : k = 1 / i + 1 / a + R o: R = glazing resistance to heat transfer, a 'i = heat transfer coefficients to

outside and inside.

  When the values of k are given, the values relating to the heat transfer coefficients are defined in correspondence with the average conditions for a vertical glazing of the construction field by λ = 23 W / m K and λ. = 8 W / m K. a 1 In the following, all the indications of

  values of k will be related to the limiting conditions

  indicated above. In this respect, it is obvious that in practice, for refrigerated display cases, the values

  actual values may differ slightly from the above values.

  Thus, the coefficient of heat transfer between the glazing and the surrounding volume is a function, inter alia, of the presentation conditions and the air currents existing in the presentation space. The same consideration applies to the transmission coefficient of

  heat i to the internal volume of the refrigerated display case

  pacity. It also depends, among other things, on the dimensions of the corresponding refrigerated showcase and also on the degree of forced circulation of the air, which still exists in such refrigerated display cases in order to standardize the temperature of the internal volume. In this respect, it must be taken into account that, in the range, interesting here, low values of k below 2 W / m2K, the influence of the air layers limits

  The value of k is already relatively low.

  The insulation effect is determined in this range essentially by the high resistance of the glazing to the heat transfer and, for this reason, the choice of the value of k below the above-mentioned normal conditions

  already represents a sufficient characterization.

  As has been stated initially, the value of k refrigerating display windows can, in particular through the use of a filling gas having a low thermal conductivity in combination with an infrared reflective coating, be

  significantly reduced compared to the higher values

  at 2 W / m K, which were obtained with the above arrangements. Thus, for example for a double-glazed pane, a value of k of 1.5 W / m2K is obtained when the intermediate volume of a width of 12 mm is filled with argon and when, on the side of the outer ice that is directed to the intermediate volume, a clear coating with an infrared reflectance of 92%. These experiments have further shown that with a three-ice structure, it is possible to obtain a value of k of interest of 1 W / m 2K. With this structure, the two intermediate volumes with a width of 6 mm are

  filled with krypton and a transparent coating is

  They have an infrared reflectance of 92% respectively on the side of the outer ice and the side of the inner ice that are directed towards

the adjacent intermediate volume.

  With glazing having such small values of k, it is possible to considerably reduce the cooling work required for a refrigerated showcase. In addition to this, the temperature of the outer glazing of such a large insulation glazing

  thermal system is already located in most applications.

  above the dew point temperature so that expensive heating of the outer ice can be dispensed with. This naturally depends on the relative humidity of the existing air in the presentation space as well as on the temperature inside the showcase

  refrigeration. When an increase in the relative humidity

  the air and the temperature inside the refrigerated windows, it is necessary to adopt smaller values of k for glazing.

  when the heating of the outer ice

  re. For conventional applications, the aforementioned values of k are already sufficient. Thus with the above-mentioned three-ice structure, it would be possible, for a value of k of 1 W / m2K and for an internal cold storefront temperature of 20 C and an ambient temperature of 25 C, to dispense with the coating of ice outer

  up to a relative humidity of 80%.

  Tests carried out with such glazings

  very insulators for refrigerated display cabinets

  in these applications, a significant and unexpected disadvantage compared to conventional glazings having

  values of k greater than 2 W / m2K. When the door

  window of such a refrigerated showcase is opened for a sampling of products, it is formed in a known manner, on the side, directed to the cold room, the inner glass of the glazing and under the effect of contact with the ambient air, an ice film or a

  water film for superficial temperatures above

  to OC. This occurs in the same manner for the aforementioned conventional glazings having K values slightly greater than 2 W / m2K and for glazings with very high thermal insulation which have been subject to

  aforementioned tests. Differences in the quantities

  could not be defined because, in both cases, the dew point temperature of ambient air was

  considerably exceeded by default for the ice

  higher in the case of conventional relative humidities

air.

  After closure of the French window, the deposit significantly disturbing the vision through the window is again removed. This is achieved with conventional glazings for values of k greater than 2 W / m2K for an opening time of 10 seconds approximately in less than one minute when the humidity of the air is about 65% . For highly insulating glazing, this fogging time is increased in significant proportions. The extension of the fogging time corresponds

  about a factor of 2.5 when using a vitreous

  ge having a value of k of 1 W / m2K.

  The observed prolongation of the fogging time is a significant disadvantage of the highly insulating glazings which are used in practice because, during this period of time, it is no longer possible to obtain a correct vision of the exposed products. In principle, this time should be reduced as much as possible and fogging times greater than about 1 minute are not generally accepted in practice.

for such applications.

  The object of the invention is to create a multi-glazed insulating window with high thermal insulation of the aforementioned type which, after the opening and closing at the end

  as short as possible of the corresponding door.

  cold room or similar, guarantees the

  again a correct vision through the glass.

  According to the invention, this problem is solved in that, when used for a cold room with forced circulation of air and a heat transfer coefficient of the multi-glazing insulating pane of less than 2 W / m2K, preferably less than 1.6 W / m2K, the outer surface of the inner ice is provided with an infrared reflection layer whose heat reflecting power in a wavelength range

  greater than about 4 μm, amounts to more than 50%.

  In this respect, it can be ensured that the heat reflection power of the

  Infrared reflection amounts to over 70%.

  In addition, the invention provides in this respect where appropriate that the infrared reflection layer is composed of doped tin oxide and / or doped indium oxide. In addition, another embodiment of the invention is characterized in that the infrared reflection layer is a metal layer of silver, copper or gold, which comprises, at least on the opposite side to the inner ice, a dielectric layer

Exception of reflection.

  In this respect, it is possible for the reflection-free dielectric layer to be formed of a

metal oxide.

  The reduction of fogging time that can be obtained with such a coating of the outer surface, directed towards the cold room, of the inner ice of the multi-glazing insulating glass is a surprising result for highly insulating glazings for cold rooms with forced circulation. of air, after a

  opening and reclosing windows doors vitri-

refrigerators of this kind.

  Obviously, glazings are known which separate

  cold volumes of hot volumes and which

  on the ice surface directed towards the cold room, an infrared reflection layer. Thus according to the German patent application DE OS 28 33 234, the formation of ice during cold nights on the

  outer surfaces of single windows of motor vehicles

  biles is reduced by means of such a layer. As already stated above and as confirmed by the tests described below, on the contrary the arrangement according to the invention of an infrared reflection layer on the outer surface of the inner ice of a highly insulating glass in a cold room produces precisely no reduction in ice formation. The abovementioned patent application, which is foreign to the aforementioned subject, is therefore of no significance for the resolution of the problem which

is the basis of the invention.

  According to the German patent application DE-OS 28 42 045, it is possible, by the provision of a

  infrared reflection layer on the outer surface

  re of the inner ice of a refrigerated showcase glazing, to improve only in a specific application its thermal insulation, especially when the refrigerated showcase comprises a horizontal glazing

  and o there is no forced circulation of air.

  On the other hand, for refrigerated display cases with circula-

  force of air, to which the present invention relates exclusively, it is expressly stated that the

  aforementioned provision of the infra-red reflection layer.

  red brings disadvantages compared to multi-glazed insulating windows in which the infrared reflection layers are disposed only on the ice surface directed towards the interglacial volume. German patent application DE-OS 28 42 045 therefore defines a principle which is precisely opposite to that of the invention; this applies in the same way to the European patent EP-0 036 657, which also recommends

  expressly to have the reflection layers of infra-

  in a way which does not make it possible to solve the problem which is at the basis of the invention, in particular on

  ice surfaces directed to the inter-

  ice cream or towards one of the inter-ice volumes.

  For the transparent infrared reflection layer, deposited on the outer surface, directed towards the cold room, that is to say the interior volume of the refrigerated display case, the inner glazing glass, different materials can be used. In particular, doped tin oxide and indium oxide layers, which are characterized by a high light transmission in relation with a strong infrared reflection, which are mechanically

  very stable. In addition, it is also appropriate to use

  for example, thin layers of metals such as gold, copper and silver, in particular multiple layers, in which these metal layers are embedded in

  two sides in interference layers in order to increase

  the light transmission capacity and the improvement of

  also the strength and chemical resistance. Other features and advantages of the invention will be highlighted later in the

  description, given by way of non-limiting example, in

  relationship with the attached single drawing which represents an embodiment of a multi-glazed insulating pane according to the invention, in sectional view perpendicular to the

ice plan.

  As the drawing shows, the insulating glass

  multi-lens includes, in the exemplary embodiment

  here, an outer ice cream 10, an intermediate ice cream

  12 and an inner ice 14, all of which are made of a silicate glass and each having a thickness of 4 mm. Between the outer ice 10 and the intermediate ice 12 on the one hand and between the intermediate ice 12 and the inner ice 14 on the other hand, there is provided respectively an outer inter-ice volume 16 filled with gas and an interstitial volume. -glaces inside 18 filled with gas. The two inter-ice volumes 16, 18 each have a width of 6 mm and are filled with krypton. On the surfaces of the outer ice 10 and the inner ice 14 which are directed towards the corresponding inter-ice volume 16 or 18, transparent and infrared reflecting layers are provided.

  20, 22, which have a heat reflectance of 92%.

  On the outer surface of the inner ice 14 which is directed to the cold room after installation,

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  another transparent and reflective layer is provided

  infrared 24, which has a heat reflection capacity of about 92%, the infrared reflection layers 20, 22, 24 being composed, in the embodiment shown, of silver embedded in layers

free from SnO2 reflection.

  The value of k of the multi-layer insulating glass

  ice described above and shown schematically in the drawing amounts to 1 W / m K. To confirm the effectiveness of the

  infrared reflection 24 provided in accordance with the invention.

  On the outer surface, directed towards the cold room, of the inner ice 14, a comparative test was carried out on a refrigerated display case provided with a front glazing unit. The refrigerated showcase had two windows of the same dimensions, which were provided on the one hand with a multi-glazed insulating glass of the type described above, that is to say according to the invention, and having dimensions of 71 cm x 127 cm and secondly a multi-glass insulating pane of the same dimensions but of a different structure, in which in particular the infrared reflection layer 24 on the outer surface, directed towards the cold room, has been removed, of the

  14. In addition, the glazing of

  it presented a structure identical to that of the

  embodiment of the invention described above.

  For a refrigerated showcase interior temperature of -21 ° C. and for an ambient temperature of 25 ° C. and a relative humidity of 75%, no condensation of water condensate on the side was observed, directed to the environment, the outer ice of the two windows. The two French windows were then opened simultaneously for 10 seconds. This was done for a relative humidity of ambient air of 60%. It was then formed on the side, directed towards the interior volume of the refrigerated showcase, the inner ice 14 of the two glazings an ice layer which has

  greatly hampered vision through the windows.

  This discomfort was the same for both windows.

  After the simultaneous closing of the two doors

  windows, it has been determined, for the glazing provided with the additional infrared reflection layer 24 provided

  according to the invention, a fogging time of 60 seconds

  while this fogging time was 110 sec-

  For the comparison glazing which does not have an infrared reflection layer 24, it has been confirmed that the fogging time could be reduced by a factor of approximately 2 by the means provided according to the invention. and which could be found, with respect to the principle defined in patent application DE OS 28 42 045,

  simply by eliminating a prejudice.

  The particularities of the invention defined

  in the description above, on the drawings

  as well as in the claims may be essential-

  both individually and in any combination for the implementation of the invention in its

  different embodiments.

Claims (5)

  1. Multi-glazed insulating glass for doors   windows or the like for isolating a cold chamber subjected to a relatively low air temperature compared to an environment with higher temperature air, having an outer ice directed towards the environment and a directed inner ice to the cold room, separated from the ice   outside by an inter-ice volume divided   in several intermediate volumes by one or more   intermediate ice, and the outer surface of which   directed towards the inter-ice volume is subjected to the atmosphere of the cold chamber, characterized by the fact that   when used for a cold room with   Forced air filtration and a heat transfer coefficient of the multi-glazing insulating pane of less than 2 W / m2K, preferably less than 1.6 W / m K, the outer surface of the inner ice (14) is provided with an infrared reflection layer (24) whose heat reflection power in a wavelength range   greater than about 4 pm, amounts to more than 50%.   2. Multi-glazed insulating glass according to the claim   1, characterized in that the heat-reflecting power of the infrared reflection layer (24) is greater than 70%.   3. Multi-glass insulating glass according to one of the   1 or 2, characterized in that the layer   Infrared Reflection (24) consists of tin oxide doped and / or doped indium oxide.   4. Multi-glass insulating glass according to one of the   1 or 2, characterized in that the layer   infrared reflector (24) is a metal layer of silver, copper or gold, which comprises, at least on the   opposite side to the inner ice (14), a dielectric trench trique free of reflection.   5. Multi-glazing insulating glass according to the claim   4, characterized in that the dielectric layer   Reflection free consists of a metal oxide.