FR2483564A1 - Double-skinned panels for glazing or storage systems - has the inner space maintained under vacuum - Google Patents

Abstract

The panel consists of two skins held in a plastic framework which has an interior reflecting surface. The two skins are braced throughout with struts made from reflecting plastic. One inner surface of the panel is coated in tin-oxide. The inner space is evacuated by a vacuum pump connected to the outlet. The panels can be constructed with transparent skins for glazing units or opaque skins for the construction of enclosures or they can be utilised as solar collecting panels.

Description

The present invention relates to the production of vacuum panels
large area with very low heat losses: intended, in the
transparent variant, make insulating "glazing" of very high per
training for the use of residential greenhouses and solar collectors
intended, in the opaque variant, to produce insulation panels of very
high porformhncee for the use of storage volumes, or any other anplica-
tion requiring excellent insulation; and, also intended for a
another variant, the production of very high perfor mancies solar collectors.

In known devices of this kind, glazing 'or so-called cators
large areas, the separation between the interior and the mid
outdoor place is done with one or more transparent partitions, having
or not a reflective treatment for far infrared, with, between the
partitions, either air or an appropriate gas These devices all sense the drawback of still having far too great heat losses
to rationally use solar energy.

Calculations of thermal losses by conduction, by convection,
and by radiation, relating to these known devices, give us the following estimates
- for a single window, the total losses are between 9 and I5 W / m2 / degrees c
- for a double window, between 4 and 6 W / m2 / degrees c
- for a double window with infrared reflective treatment
far, between 2.5 and 4 W / m2 / degrees c
- for a single pane solar collector with selective absorber
(a IRL P 0.05), between 3.5 and 4 W / m2 / degrees c
- for a double pane solar collector with selective absorber
(a IRL = 0.05), between 2 and 2.5 W / m2 / degrees c
(calculations made for temperatures from + 5 to + 30 degrees c)
The device according to the invention makes it possible to produce panels under vacuum or under low pressure, of small thickness, of large surface area,
having heat losses 10 to 50 times lower than the various devices
known.

Calculations of heat losses, by conduction, by convection
and by radiation, relating to these panels, object of the invention, give us
for the various variants the following estimates
- for insulating glass, the total losses are included in
be 0.25 and 0.75 W / m2 / degrees c
- for solar collectors, between 0.2 and 0.5 W / m2 / degrees c
- for opaque insulation panels, between 0.02 and 0.08 W / m2 /
degrees c (calculations made for temperatures from + 5 to + 30 degrees c and for several
technologies).

Thus, with such perneaax, by means of a storage capacity re
laterally low, we can guarantee full solar heating of greenhouses and
dwellings on the entire French territory, except the altitudes
too high.

The device which is the subject of the invention comprises at least two transparent or opaque partitions, depending on the variants, flat or of any shape,
rigid or flexible, identical or not, placed one opposite the other, at
a generally small distance becomes the dimensions of these partitions. A sys
joint or sealing plate, preferably placed over the entire perimeter of the
partitions, seals, vis-à-vis the outside, the interior volume thus de
limit. A resistant structure, placed inside between the two partitions
and distributed over the entire surface, allows these two partitions to support the
atmospheric pressure when the interior volume is subjected to vacuum or low pressure. The geometry and materials of this resistant structure are
such as athermal conduction losses caused by this structure
remain very weak between the two partitions. On the other hand, the surface of all
the elements constituting this resistant structure a, with respect to radiation
visible and infrared ultraviolet, the lowest possible absorption eoefficient, this in order to avoid any unnecessary loss of energy and any rise in time
untimely temperature of this structure.

The interior face of at least one partition, and sometimes both, has a
factor of reflection the the largest possible in the far infrared. These pro
physical pieties are either inherent in the materials chosen to make the
partitions, either obtained by an appropriate surface treatment of the internal haulm
of these partitions.

By way of nonlimiting examples, these surface treatments are
for glass, either an indium oxide layer (In2 03) or an oxide layer
of tin (Sn 02) be '1st column' titanium oxide (Ti 02) (doped oxides) ciu au
treks, deposited by various processes, such as pyrolysis, evaporation under
vacuum, high frequency spraying, etc ... For opaque partitions or
absorbers, these surface treatments are by eY- ^ aple: special peiatures, electrolytic deposits, oxidations, ithemics, etc ...

The exterior faces of these two partitions are either smooth or
of texture and geometry studied to solve at least partially
certain problems of optics, mechanical resistance, or technology.

Depending on the case, these devices are either static vacuum, sealed panels, or. vacuum maintained, panels connected to a pom system
page. The vacuum panels maintained are of less complex technology. On the other hand, the temperature can be regulated by "playing" on the internal pressure of the
panels, that is to say on its convective losses.

In addition, these panels have good mechanical performance at ni
shock calf, and in particular hail, this thanks to the resistant structure
support distributed over the entire surface between the two partitions, this set
strongly tightened by atmospheric pressure behaves like a composite beam of great inertia.

To summarize, it is clear that these panels, according to the inventionp have
excellent performance, by the fact that the three main causes of thermal losses have been reduced simultaneously by various appropriate means the losses by conduction, by a judicious choice of materials and their geom
sorts; radiation losses, by the fact that at least one of the two faces
interior of the partitions as well as the elements of the support structure, have a large reflection coefficient in far infrared or a low emissivity also in far infrared; and convection losses, by maintaining a vacuum or a very low pressure between the two partitions. The vacuum between the two partitions is possible thanks to the presence
that of the resistant support structure.

The accompanying drawings illustrate, by way of non-limiting example, more
several variants and several embodiments of the device in accordance with the present invention.

- Figure nQ I is a perspective view of an insulating glazing,
Figure 2 is a sectional view of the same glazing. The transparent partitions
annuities (I) are made of window glass, they rest on a frame made of plastic
tick (2) whose inner face (8) is reflective, the seal being
provided by a cast joint (7) having a slight flexibility; the structure
resistant ()) consists of a network of plastic balusters
reflective 3 to 4 ne in diameter spaced 25 to 30 mm; the treatment
surface area of at least one of the partitions (5)> far infrared reflector
tin, is a layer of tin oxide Sn 2 or doped indium oxide In2 03 deposited by pyrolysis, the orifice (4) is used to maintain the vacuum (6) between the two partitions1 the dimensions are for example : length 2 meters, width I meter, thickness 5 centimeters.

 - Figure ni 3 is a sectional and perspective view of an insulating glazing consisting of flexible transparent partitions in the form of a bracelet of great length which is put on like a glove on a resistant support structure represented symbolically by (2), the vacuum maintained inside the panel (3) imposes on the whole of the partition .souple the shape represented by the drawing (I); this shape is explained by the fact that the flexible transparent partition works under tension, while the support structure (2) works under compression. This mechanical design for given materials allows us to obtain the lowest possible weight per square meter of panel, therefore a reduced material price. In (4), inside the panel, there is a reflective treatment for far infrared.

 - Figure n2 4 is a sectional and perspective view of an opaque or transparent insulating panel obtained by extruding a material having the lowest possible thermal conductivity. The partitions (I) have a shape which allows them to work as much as possible in traction, the closest internal space between these two partitions is relatively small so as to have the lowest possible lateral thrust, the resistant structure of support (2) works on compression, the inner face (3) of at least one partition has a very high reflection coefficient in the far infrared, the tube (4) maintains the vacuum between the two partitions (5 ).

 - Figure 2 is a sectional view of an opaque insulating panel, the partitions (I) are made of plastic for example, the frame (2) is also made of plastic, the mile and female shapes of these frames allow assembly, sealing is obtained by welding (3), the support structure is shown diagrammatically by (4), the internal faces of the two partitions preferably (5) have large coefficients of reflection in the far infrared, the tube (6) maintains the vacuum between the two partitions (7).

- Figure n2 6 is a perspective view of a molded strip section, intended to produce resistant support structures working under compression and which can cover any surface. The grooves (2) allow them to be embedded "head to tail", perpendicularly to each other. Seen from above, such an assembly forms squares over the entire desired surface, the two opposing partitions to be supported thus rest on the feet (I) of these strips.

The material for making these strips has a high thermal resistance to
conduction. The surface of these strips has a low absorption coefficient
for visible and infrared ultraviolet radiation. Shapes and
dimensions of these strips can vary infinitely.

FIG. 7 is a perspective view and FIG. 8 is a top view of the same element of resistant support structure, obtained by slack
age for example. The balusters (I) work on compression and support.
the partitions of any panel, the crosspieces (2) secure the columns
your between them, the eyelets (3) allow to assemble several elements so
to cover the desired area. Mechanical, thermal and optical properties
of these elements are the same as for the strips in Figure 6.

- Figure n 9 is the sectional view of a solar collector according to the invention. The partition (I) is transparent, the partition (2) pst is transparent,
either opaque, these partitions rest on a frame (3) made of plastic by
example, the seal is obtained by a cast joint (4), the absorber (5) is
"pinched between two support structures (7), the tubes (6) convey the fluid
coolant, the tube (8) allows to maintain the vacuum inside (9) .The surface of .absorbPur has a very good absorption coefficient vis-à-vis the rayon
solar and a very low coefficient of expansion in the far infrared
if this coefficient is sufficiently low, the interior face of the partition (I)
may not have infrared reflective treatment, ideas for the partition
sound (2). Note that if the two partitions (I) and (2) are transparent, the panel will capture solar energy by its two sides, and this feature
can become interesting treks in many cases: sensors placed near
tee of a reflective area; sensors placed -rs- ticålement, lne facing south and
the other to the north; collectors placed vertically above clear ground, sand, snow, etc. It should be noted that if the thermal losses of the collector are
important, c1 is the case with known devices, this peculiarity becomes
overall uninteresting.

- Figure 10 is the sectional view of a solar collector, one of which
partitions (2) is the absorber itself, the partition (I) is transparent, the
frame (3) supports the two partitions, sealing is ensured by a joint
formable (4) immobilized by a stirrup (5) having a clamping system shown diagrammatically by a cross (6), the whole of this panel being removable. We find
the tubes (8! for the heat transfer fluid, the tube (9) for the vacuum, and the support structure (7). The absorber will have the same characteristics as those described
your for figure (9) and it can come in various forms, refrnidi by liquid, by gas, or be only a simple "sheet", this type of solar collector has its interest in certain applications.

- Figure n2 II shows in section a composite panel, comprising an insulating glazing according to the invention, identical to that described by the figures
I and 2, with regard to the references tI) (5) (6) (7) (II) and (I2) of figure ng II, the system of removable seals is identical to that described by the
figure no IO, with regard to the references (2) (3) (4) and (13) of figure nQ II. In addition, this panel has an additional volume (9) delimited
by the partitions (5) and (8) and the frame (2).
serve to regulate either the heat flow through the glazing or the flow
luminous, or both, thanks to mechanisms which will be the subject of a description
subsequent tion.

The applications of these panels are numerous and important. in
effect, when insulating glass or solar collectors have losses
overall thermal about 0.3 W / m2 / degree, it can easily be shown that the energy balance, between solar gain and total losses, is very largely positive, even in December and throughout France. The heat
full solar fage all year round is therefore possible for greenhouses and homes; on the other hand, given the high efficiency of these panels, the necessary storage capacity will remain low and not restrictive. In addition, these panels also make it possible to collect energy at a fairly high temperature while having good yields; the advantages are numerous: optimization of storage capacities, direct industrial use of very hot water, better efficiency of the various "solar motors",
etc ... in the case of insulating glazing, their characteristics would allow the realization of greenhouses whose interior temperature
would be maintained throughout the year between + 25 and + 30 degrees centigrade only by solar energy; inside such greenhouses one could pra
tick crops of equatorial plants at high speed of development therefore of great profitability. These insulating glazing will also allow the reac
building greenhouses for fully "solar"dwellings; in addition, the utility
sation of composite panels, see figure II, would allow regulation
thermal and light of these greenhouses, an electric control would vary the opacity of these panels and even obscure them
completely. A project to use these insulating glazing is currently being developed. It involves associating a methane digester with an equatorial greenhouse in which we would cultivate plants
aquatic, like water hyacinth for example. The digester will provide the necessary photosynthesis and the liquid effluents will serve as fertilizer for these plants. The water needed for aquatic culture will also serve as energy storage. For an equal area, such crops could produce between 50 and 150 times more protein than a corn field.

Claims (9)

CLAIMS I. Device allowing the production of large area panels with very low thermal losses, intended for the production of: insulating glazing, solar collectors and thermal insulation panels, - characterized by the fact that it simultaneously comprises - Means for having very low heat losses by conduction between their two partitions. - Means for having very low heat losses by radiation between their two partitions. - Means for having very low thermal by convection between their two partitions.  2. Device according to claim I, characterized in that one of the means for reducing the heat losses by convection between the two partitions consists of establishing a vacuum, or a low pressure between these two  partitions despite their large areas.  3. Device according to claim 2, characterized in that 1 ' one of the means for establishing the vacuum between the two partitions, consists in place a resistant, distributed support structure between these two partitions  over the entire surface, in the form of small pillars fairly close loved one another and working on compression to support the pres atmospheric ion exerted on the two partitions.  4. Device according to claim 3, characterized by the fact that the  resistant support structure consists of an assembly of molded elements, provided for this purpose, with adequate physical characteristics: good resistance compressive strength, low thermal conduction and absorption coefficient  weak for ultraviolet, visible and infrared radiation.  5. Device according to claim I, characterized in that 1 '  one of the ways to reduce heat losses by radiation between the two partitions consists in ensuring that: either the cold interior face, or both have a high reflection coefficient in the far infrared.  6. Device according to claim I, characterized in that one  ways to reduce radiation heat loss between the two walls  sounds, is to make the warm inner side have a low  emitting power in the far infrared.  7. Device according to claim I, characterized in that the  one of the ways to reduce heat losses by radiation between the two  partitions consists in ensuring that the hot interior face has a low emissivity in far infrared and that the cold face has a large reflection coefficient also in far infrared.  8. Device according to claims I, 2, 3, and 4 taken together, plus any one of claims 5, 6 or 7, characterized in that the two partitions are transparent to most of the solar radiation, and that the panel thus formed is insulating glazing. 9. Device according to claims I, 2, 3 and 4 taken together, plus any one of claims 5, 6 or 7, characterized in that the two partitions are opaque and that the panel thus formed is a "partition" 'thermal insulation. IO. Device according to claims I, 2, 3, 4, and 8, taken together, plus any one of claims 5, 6 or 7, characterized in that an absorber cooled by a heat transfer fluid is placed between the two transparent partitions and that the panel thus formed is a double-sided solar collector.  11. Device according to claims I and 8, taken together, characterized in that the transparent partitions are flexible, and withstand atmospheric pressure like a membrane working under tension.  I2. Device according to claims I and 8 taken together, or I and 9 taken together, characterized in that the entire panel is obtained by extruding a suitable material.