U.S. patent application number 14/762518 was filed with the patent office on 2015-12-17 for construction element having a controllable heat-transfer coefficient u.
This patent application is currently assigned to BASF SE. The applicant listed for this patent is BASF SE, FRAUNHOFER-GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG E.V.. Invention is credited to Andreas DAI, Andre GLUCK, Klaus HAHN, Elena KHAZOVA, Tilmann KUHN, Achim LOFFLER, Christoph MAURER, Nikolaus NESTLE, Ralf NORENBERG, Thibault PFLUG, Johann Martin SZEIFERT, Jan WIENOLD.
Application Number | 20150361654 14/762518 |
Document ID | / |
Family ID | 47681681 |
Filed Date | 2015-12-17 |
United States Patent
Application |
20150361654 |
Kind Code |
A1 |
NESTLE; Nikolaus ; et
al. |
December 17, 2015 |
CONSTRUCTION ELEMENT HAVING A CONTROLLABLE HEAT-TRANSFER
COEFFICIENT U
Abstract
A structural element with a controllable heat transfer
coefficient comprises a frame. A first sheet and a second sheet
opposite one another are arranged in the frame. The sheets and the
frame have the effect of defining a closed-off volume which is
filled with at least one gas. At least one two-dimensional element
is arranged between the sheets. An upper intermediate space is
formed between the two-dimensional element and the frame vertically
upwardly and a lower intermediate space is formed between the
two-dimensional element in the frame vertically downwardly. A first
cavity is between the first sheet and the two-dimensional element.
A second cavity is between the two-dimensional element and the
second sheet. The cavities are connected via the upper intermediate
space and the lower intermediate space such that a convection flows
between the cavities via the intermediate spaces. At least one
means arranged in the intermediate spaces controls the convection
flow.
Inventors: |
NESTLE; Nikolaus;
(Heidelberg, DE) ; DAI ; Andreas; (Ludwigshafen,
DE) ; HAHN; Klaus; (Kirchheim, DE) ;
NORENBERG; Ralf; (Heidelberg, DE) ; SZEIFERT; Johann
Martin; (Mannheim, DE) ; KHAZOVA; Elena;
(Mannheim, DE) ; LOFFLER; Achim; (Speyer, DE)
; KUHN; Tilmann; (Hinterzarten, DE) ; MAURER;
Christoph; (Freiburg, DE) ; PFLUG; Thibault;
(Freiburg, DE) ; WIENOLD; Jan; (Freiburg, DE)
; GLUCK; Andre; (Mannheim, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BASF SE
FRAUNHOFER-GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG
E.V. |
Ludwigshafen
Munchen |
|
DE
DE |
|
|
Assignee: |
BASF SE
Ludwigshafen
DE
Fraunhofer-Institut (ISE) fur Solare Energiesystem
Freibury
DE
|
Family ID: |
47681681 |
Appl. No.: |
14/762518 |
Filed: |
January 17, 2014 |
PCT Filed: |
January 17, 2014 |
PCT NO: |
PCT/EP2014/050892 |
371 Date: |
July 22, 2015 |
Current U.S.
Class: |
52/220.1 ;
52/741.1 |
Current CPC
Class: |
F24S 50/80 20180501;
F24S 80/60 20180501; F24S 20/66 20180501; E04B 1/74 20130101; Y02B
10/20 20130101; Y02E 10/44 20130101; Y02E 10/40 20130101; F24S
20/61 20180501 |
International
Class: |
E04B 1/76 20060101
E04B001/76; E04C 2/52 20060101 E04C002/52; E04B 2/56 20060101
E04B002/56 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 22, 2013 |
EP |
13152267.4 |
Claims
1.-15. (canceled)
16. A structural element (1) with a controllable heat transfer
coefficient U, comprising a frame (7), a first sheet (3) and a
second sheet (5), which are opposite one another and which are
arranged at a distance A from one another in the frame (7), the
first sheet (3), the second sheet (5) and the frame (7) having the
effect of defining a closed-off volume V, which is filled with at
least one gas, at least one two-dimensional element (9), the width
of which corresponds to the vertical clear width W of the frame (7)
and the height of which is less than the clear height H of the
frame (7), the two-dimensional element (9) being arranged between
the first sheet (3) and the second sheet (5) such that it finishes
laterally with the inner sides of the frame (7), and an upper
intermediate space (11) being formed between the two-dimensional
element (9) and the frame (7) in the vertically upward direction
and a lower intermediate space (13) being formed between the
two-dimensional element (9) and the frame (7) in the vertically
downward direction, a first cavity (15), which is formed between
the first sheet (3) and the two-dimensional element (9) with a
spacing X, a second cavity (17), which is formed between the
two-dimensional element (9) and the second sheet (5) with a spacing
Y, the first cavity (15) and the second cavity (17) being in
connection via the upper intermediate space (11) and the lower
intermediate space (13) such that a convection flow can flow
between the first cavity (15) and the second cavity (17) via the
upper intermediate space (11) and the lower intermediate space
(13), at least one means for controlling the convection flow, which
is arranged for the upper intermediate space (11) or for the lower
intermediate space (13), the at least one means consisting in the
vertical displacement or tilting about a horizontal axis of the at
least one two-dimensional element (9), so that the upper
intermediate space (11) or the lower intermediate space (13) is
closed by the two-dimensional element (9) and the convection flow
is thereby completely or partially prevented, or the at least one
means comprising the changing of the vertical extent of the at
least one two-dimensional element (9), so that the upper
intermediate space (11) or the lower intermediate space (13) is
closed by the two-dimensional element (9) and the convection flow
is thereby completely or partially prevented, or the at least one
means comprising a closure device for the upper intermediate space
(11) or for the lower intermediate space (13), which is preferably
chosen from flaps, inflatable tubes or bellows, closures in the
form of cylinder cocks or displaceable or rotatable wedges.
17. The structural element (1) according to claim 16, the first
sheet (3) or the second sheet (5) being at least partially
transparent or translucent.
18. The structural element (1) according to claim 16, the at least
one means also comprising a device (19) for displacing the at least
one two-dimensional element (9), preferably chosen from
servomotors, pneumatic, magnetic or piezoelectric systems,
mechanical levers, cables or bimetallic structures.
19. The structural element (1) according to claim 16, the first
sheet (3) or the second sheet (5) being transparent and the
material of the first sheet (3) or of the second sheet (5)
comprising glasses or polymers.
20. The structural element (1) according to claim 19, the glasses
being chosen from silicate glasses, borosilicate glasses,
lead-silicate glasses or the polymers being chosen from PET, PVB,
EVA, polyolefins, styrenic polymers, polycarbonates, PMMA,
polyurethanes, PVC or mixtures or multilayer systems thereof, the
polymers being formed as sheets or extruded, blown or cast
films.
21. The structural element (1) according to claim 16, the at least
one two-dimensional element (9) being formed from a translucent
material, chosen from organic, inorganic or hybrid closed-cell or
open-cell foams or coated or uncoated textiles.
22. The structural element (1) according to claim 16, the at least
one two-dimensional element (9) being formed from a mineral,
metallic, polymeric or bio-organic material.
23. The structural element (1) according to claim 16, the material
of the frame (7) being chosen from concrete, gypsum, clays,
glasses, natural stones, ceramics, polyamide, polyesters, wood,
metals, PVC, polycarbonate, PMMA, styrenic polymers, polyurethanes
and fiber composite materials and composite materials of two or
more of these materials and also from open-cell or closed-cell
foams and fiber boards of synthetic or renewable raw materials.
24. The structural element (1) according to claim 16, the first
sheet (3) or the second sheet (5) or the at least one
two-dimensional element (9) being three-dimensionally structured on
the surface.
25. The structural element (1) according to claim 16, comprising a
first two-dimensional element (9a) and a second two-dimensional
element (9b), the width of which respectively corresponds to the
vertical clear width W of the frame (7) and the height of which is
respectively less than the clear height H of the frame (7), the
first two-dimensional element (9a) and the second two-dimensional
element (9b) being arranged between the first sheet (3) and the
second sheet (5) such that they each finish laterally with the
inner sides of the frame (7), and a first upper intermediate space
(11a) and a second upper intermediate space (11b) being
respectively formed between the first two-dimensional element (9a)
and the second two-dimensional element (9b) and the frame (7) in
the vertically upward direction and a first lower intermediate
space (13a) and a second lower intermediate space (13b) being
respectively formed between the first two-dimensional element (9a)
and the second two-dimensional element (9b) and the frame (7) in
the vertically downward direction, a first cavity (15), which is
formed between the first sheet (3) and the first two-dimensional
element (9a) with a spacing X, a second cavity (17), which is
formed between the second two-dimensional element (9b) and the
second sheet (5) with a spacing Y, a third cavity (23), which is
formed between the first two-dimensional element (9a) and the
second two-dimensional element with a spacing Z, at least the first
cavity (15) and the second cavity (17) being in connection via the
first upper intermediate space (11a) and the second upper
intermediate space (11b) and the first lower intermediate space
(13a) and the second lower intermediate space (13b) such that a
convection flow can flow at least between the first cavity (15) and
the second cavity (17) via the first upper intermediate space (11a)
and the second upper intermediate space (11b) and the first lower
intermediate space (13a) and the second lower intermediate space
(13b).
26. The use of the structural element (1) according to claim 16 as
a wall or roof element in buildings or vehicles.
27. A method for controlling the heat transfer coefficient U in a
structural element (1) according to claim 16, comprising the steps
of providing a structural element (1), absorbing thermal energy by
a first sheet (3) or a second sheet (5) on a first side of the
structural element (1), whereby the gas filling the volume V is
heated in a first cavity (15) or in a second cavity (17) and rises
vertically upward, opening a vertically upper intermediate space
(11) or a vertically lower intermediate space (13), whereby a
convection flow from one of the cavities (15, 17) through the
intermediate space (11) into the other of the cavities (15, 17) is
made possible, giving off thermal energy by the gas filling the
volume V to the first sheet (3) or the second sheet (5) on a second
side of the structural element (1), whereby the gas filling the
volume V in the other of the cavities (15, 17) cools down and falls
vertically downward, so that the convection flow flows from this
cavity (15, 17) through the lower intermediate space (13) into one
of the cavities (15, 17), the intensity of the convection flow
being set by the opening or closing of the lower intermediate space
(11) or of the upper intermediate space (13).
Description
[0001] The present invention relates to a structural element with a
controllable heat transfer coefficient U and the use thereof as a
wall and/or roof element in buildings or vehicles and to a method
for controlling the heat transfer coefficient U in such a
structural element.
[0002] In construction, the heat transfer coefficient U is a
specific characteristic value of a compound unit or building
material which in principle indicates the heat insulating
properties thereof. The higher the heat transfer coefficient U is,
the poorer the heat insulating property of the compound unit or
building material.
[0003] The heat transfer coefficient U became particularly
significant, if not before, when the amended energy-saving order
[Energieeinsparverordnung (EnEV)] came into force in Germany in the
year 2009, providing that the annual primary energy requirement and
the specific transmission heat loss of a building to be erected
must be kept within specific limit values. The heat transfer
coefficient U is thereby included in the calculation of the
transmission heat loss and this in turn is included in the
calculation of the primary energy requirement. Furthermore, the
energy-saving order prescribes limit values for the heat transfer
coefficient U for specific compound units, when they are being
replaced in existing buildings or are included in a newly built
structure.
[0004] A large number of insulating elements that are used for the
heat insulating of buildings are known from the prior art. They
generally consist of one or more insulating layers of an insulating
material (for example foams, expanded polymer materials). Depending
on the nature of the insulating material, a protective layer is
applied on the outer side of such insulating elements. These
insulating elements serve in particular for preventing an outflow
of heat from the interior of a building to the outside. At the same
time, a heat flow into a building can likewise be reduced.
According to the prior art, most insulating elements have fixed
insulating properties, that is to say the insulating property can
only be controlled by varying the thickness and/or number of
insulating elements. However, it is not possible in this way to
react flexibly to prevailing temperatures at a given time inside
and outside a building.
[0005] The use of highly insulating materials has, however, in the
meantime led to situations in which the natural outside temperature
variation can no longer be used to dissipate the heat introduced
into the building during the day by solar irradiation again at
night. The energy requirement for active cooling devices is
increased by the heat accumulation produced hereby.
[0006] There is therefore a need for an insulating element of which
the insulating properties are variable. In the prior art, there are
a whole host of initial approaches to satisfying this need.
[0007] For instance, DE 10 2006 024 067 A1 describes an insulating
element which is suitable in particular for the inside and/or
outside insulation of buildings. The insulating properties of the
insulating element described there can be changed according to the
desired inside temperature of the building or according to the
outside temperature and/or solar irradiation, in particular by
changing the heat transfer coefficient U and/or the reflection
properties of the insulating element itself. As a technical
solution, the insulating element is in this case provided with an
insulating material which can be changed in its position, so that
the insulating material used contributes completely, partially or
scarcely at all to the insulation of the building. For this
purpose, for example, the insulating material may be completely or
partially compressed, in order to completely or partially release
the heat flow through the insulating element. A major disadvantage
of all embodiments of the prior art is that great amounts of
material have to be moved or compressed, since the surface area of
the element must be substantially filled with or freed from
insulating material.
[0008] Furthermore, in U.S. Pat. No. 4,058,109 a device for
insulating and/or solar heating is disclosed. This device is
applied to the facade of an existing building and consists of a
transparent panel which is set in front of a wall and thereby
encloses a defined space with the wall. Within the defined space, a
heat absorber of a closed-cell insulating material is arranged.
This heat absorber has openings, so that, depending on the
temperature conditions, a convection flow can form within the
device described. This is intended on the one hand to achieve a
heat insulation of the building by the presence of the insulating
material, while on the other hand solar irradiation of the heat
absorber is used for heating the volume of gas enclosed in the
device and for giving off this heat to a certain extent to the
existing wall of the building by way of the convection flow.
[0009] A further approach taken in the prior art is described in DE
196 47 567 A1. There, a switchable vacuum insulation, in particular
for use for solar energy utilization, is realized, a coarsely
porous or coarsely structured insulating material being enclosed in
a gastight manner and evacuated. As and when required, this element
may be flooded with hydrogen gas, whereby there is within the
enclosure an electrically heatable getter material, which is
suitable for the adsorption and deadsorption of hydrogen and is
enclosed by a heat insulating material, the thermal conductivity of
which does not depend, or only a little, on the gas pressure in
this structural element.
[0010] Furthermore, US 2003/0061776 A1 discloses an insulating
system with a variable heat transfer coefficient, which is based on
an inflatable structure and thus reacts to a change in the ambient
temperature by changing its volume. This allows the rate of heat
transfer therethrough to be controlled.
[0011] AT 380 946 B1 discloses what is referred to as a heat
exchange wall, which substantially consists of an insulating sheet
which is surrounded by a system of tubes and in which a gaseous
heat transfer medium can circulate, the circulation of which can be
automatically shut off as a result of the special design of the
system of tubes. An automatic shut-off is not necessarily advisable
for an insulating element with switchable insulating behavior,
since, depending on the weather situation, the same temperature
differences may make strong insulation or else reduced insulation
appear advisable. Furthermore, the insulating element described in
AT 380 946 B1 is of a comparatively complicated construction, and
accordingly can only be produced poorly.
[0012] In addition, there are a series of multi-shell wall, window
and roof elements, as described for example in EP 0 317 425 A2, FR
2 478 800 A1, EP 2 366 845 B1 and DE 10 2006 037 741 A1. In these
elements, a change of the heat flow is achieved by the flow of
outside air through an intermediate space between the various
shells either being allowed or prevented. The exchange of air
through the element also partially takes place with the interior
room. All of these approaches share the disadvantage that, when
outside air flows through, dust from the air gets into the
intermediate space and can lead to undesired contaminants there,
which particularly in the case of translucent and transparent
elements impair their optical function. When there is an additional
exchange of air with the interior room, this hygiene-related
problem is additionally exacerbated, since undesired germs or pests
can also be entrained by the stream of air.
[0013] Finally, FR 2 798 991 A1 presents an element in the case of
which the wall is divided into rhomboidal cells, in which it is
possible by inclination of an insulating element fitted in them to
allow a convection stream to flow around the element or prevent it.
On account of the numerous segments and the non-cuboidal outer
shape of the individual cells, this element is in turn
comparatively complicated to produce.
[0014] Although the insulating elements described in the prior art
with heat transfer coefficients U that can be controlled within
certain limits have advantages over conventional insulating
materials, they all entail significant disadvantages with respect
to their usability in the building industry and are in some cases
extremely complex to manufacture.
[0015] It is therefore an object of the invention to provide a
novel structural element that minimizes the energy requirement of a
building by contributing to controlling the heat balance
thereof.
[0016] This object is achieved in the case of a structural element
of the type mentioned at the beginning by it having a controllable
heat transfer coefficient U and being designed as follows:
a structural element (1) with a controllable heat transfer
coefficient U comprising [0017] a frame (7), [0018] two opposing
sheets (3, 5), which are arranged at a distance A from one another
in the frame (7), the sheets (3, 5) and the frame (7) having the
effect of defining a closed-off volume V, which is filled with at
least one gas, [0019] at least one two-dimensional element (9), the
width of which corresponds to the vertical clear width W of the
frame (7) and the height of which is less than the clear height H
of the frame (7), the two-dimensional element (9) being arranged
between the sheets (3, 5) such that it finishes laterally with the
inner sides of the frame (7), and an intermediate space (11) being
formed between the two-dimensional element (9) and the frame (7) in
the vertically upward direction and an intermediate space (13)
being formed between the two-dimensional element (9) and the frame
(7) in the vertically downward direction, [0020] a first cavity
(15), which is formed between the sheet (3) and the two-dimensional
element (9) with a spacing X, [0021] a second cavity (17), which is
formed between the two-dimensional element (9) and the sheet (5)
with a spacing Y, the first cavity (15) and the second cavity (17)
being in connection via the intermediate space (11) and the
intermediate space (13) such that a convection flow can flow
between the first cavity (15) and the second cavity (17) via the
intermediate space (11) and the intermediate space (13), [0022] at
least one means for controlling the convection flow, which is
arranged at least for one of the intermediate spaces (11, 13).
[0023] In a first aspect of the present invention, the object of
the invention is achieved by a structural element (1) with a
controllable heat transfer coefficient U that comprises [0024] a
frame (7), [0025] a first sheet (3) and a second sheet (5), which
are opposite one another and which are arranged at a distance A
from one another in the frame (7), [0026] the first sheet (3), the
second sheet (5) and the frame (7) having the effect of defining a
closed-off volume V, which is filled with at least one gas, [0027]
at least one two-dimensional element (9), the width of which
corresponds to the vertical clear width W of the frame (7) and the
height of which is less than the clear height H of the frame (7),
[0028] the two-dimensional element (9) being arranged between the
first sheet (3) and the second sheet (5) such that it finishes
laterally with the inner sides of the frame (7), and [0029] an
upper intermediate space (11) being formed between the
two-dimensional element (9) and the frame (7) in the vertically
upward direction and a lower intermediate space (13) being formed
between the two-dimensional element (9) and the frame (7) in the
vertically downward direction, [0030] a first cavity (15), which is
formed between the first sheet (3) and the two-dimensional element
(9) with a spacing X, [0031] a second cavity (17), which is formed
between the two-dimensional element (9) and the second sheet (5)
with a spacing Y, [0032] the first cavity (15) and the second
cavity (17) being in connection via the upper intermediate space
(11) and the lower intermediate space (13) such that a convection
flow can flow between the first cavity (15) and the second cavity
(17) via the upper intermediate space (11) and the lower
intermediate space 13), [0033] at least one means for controlling
the convection flow, which is arranged for the upper intermediate
space (11) and/or for the lower intermediate space (13).
[0034] In a second aspect, the aforementioned object is achieved by
the use of the structural element (1) according to the invention as
a wall and/or roof element in buildings or vehicles.
[0035] The third aspect of the present invention achieves the
underlying object by a method for controlling the heat transfer
coefficient U in a structural element (1) according to the
invention, comprising the steps of [0036] providing a structural
element (1), [0037] absorbing thermal energy by a first sheet (3)
or a second sheet (5) on a first side of the structural element
(1), whereby the gas filling the volume V is heated in a first
cavity (15) or in a second cavity (17) and rises vertically upward,
[0038] opening a vertically upper intermediate space (11) and/or a
vertically lower intermediate space (13), whereby a convection flow
from one of the cavities (15, 17) through the intermediate space
(11) into the other of the cavities (15, 17) is made possible,
[0039] giving off thermal energy by the gas filling the volume V to
the first sheet (3) or the second sheet (5) on a second side of the
structural element (1), whereby the gas filling the volume V in the
other of the cavities (15, 17) cools down and falls vertically
downward, so that the convection flow flows from this cavity (15,
17) through the lower intermediate space (13) into one of the
cavities (15, 17), the intensity of the convection flow being set
by the opening and/or closing of the lower intermediate space (11)
and/or of the upper intermediate space (13).
[0040] The present invention is based on the realization that the
heat transfer through a structural element (1) of the type
described can be controlled by forming and regulating an internal
convection flow.
[0041] It has surprisingly been found that it is possible with the
structural element (1) according to the invention to minimize
significantly the energy requirement of a building and thus to
utilize optimally the prevailing temperatures inside and outside a
building and even to do so in a technically simple manner. It is of
advantage that, according to the present invention, the heat
transfer coefficient U can be controlled according to requirements
and independently of the prevailing inside/outside
temperatures.
[0042] It can thus be achieved by the design according to the
invention of the structural element (1) that an intensified
discharge of heat from the building is made possible during the
cooler nighttime hours, while an insulating effect that conforms to
the specifications for adequate heat insulation can be ensured when
there are high outside temperatures during the daytime in summer
and when there are low outside temperatures in winter.
[0043] The present invention is specified more precisely below.
[0044] In a first aspect, the present invention relates to a
structural element (1) with a controllable heat transfer
coefficient U, comprising [0045] a frame (7), [0046] a first sheet
(3) and a second sheet (5), which are opposite one another and
which are arranged at a distance A from one another in the frame
(7), the first sheet (3), the second sheet (5) and the frame (7)
having the effect of defining a closed-off volume V, which is
filled with at least one gas, [0047] at least one two-dimensional
element (9), the width of which corresponds to the vertical clear
width W of the frame (7) and the height of which is less than the
clear height H of the frame (7), [0048] the two-dimensional element
(9) being arranged between the first sheet (3) and the second sheet
(5) such that it finishes laterally with the inner sides of the
frame (7), and an upper intermediate space (11) being formed
between the two-dimensional element (9) and the frame (7) in the
vertically upward direction and a lower intermediate space (13)
being formed between the two-dimensional element (9) and the frame
(7) in the vertically downward direction, [0049] a first cavity
(15), which is formed between the first sheet (3) and the
two-dimensional element (9) with a spacing X, [0050] a second
cavity (17), which is formed between the two-dimensional element
(9) and the second sheet (5) with a spacing Y, [0051] the first
cavity (15) and the second cavity (17) being in connection via the
upper intermediate space (11) and the lower intermediate space (13)
such that a convection flow can flow between the first cavity (15)
and the second cavity (17) via the upper intermediate space (11)
and the lower intermediate space (13), [0052] at least one means
for controlling the convection flow, which is arranged for the
upper intermediate space (11) and/or for the lower intermediate
space (13).
[0053] In this case, the frame (7) and the opposing sheets (3, 5),
i.e. the first sheet (3) and the second sheet (5), form a
three-dimensional body, which defines a closed-off volume V. The
frame (7) of the structural element (1) according to the invention
serves in particular for enclosing and mechanically stabilizing the
structural element (1) and for receiving the first and second
sheets (3, 5). The design of the first and second sheets (3, 5) is
described in more detail below.
[0054] The form of the structural element (1) can be freely chosen
and adapted to the requirements for its installation position
and/or use within wide limits. A preferred embodiment is an
approximately cuboid element. But other geometrical forms can also
be realized with the structural element (1) according to the
invention, depending on the installation situation, for example the
basic form of a triangle, a pentagon or the like. Further designs
of the frame are defined below.
[0055] The structural element (1) comprises at least one
two-dimensional element (9), which is arranged substantially
centrally such that the internal convection flow around the
two-dimensional element (9) is possible, the convection flow being
conducted from the side of the structural element (1) on which heat
is supplied, through the upper intermediate space (11) to the other
side of the two-dimensional element (9), where the convection flow
can give off heat to the opposite side, and subsequently flows back
through the lower intermediate space (13) to the side of the heat
supply. The two-dimensional element (9) consists in particular of
an insulating material.
[0056] For regulating the internal convection flow, the structural
element (1) according to the invention comprises at least one means
by which opening and/or closing of one of the intermediate spaces
(11, 13) is performed, whereby in turn the convection flow is
controlled.
[0057] The term "means", as it is used in the present case,
describes on the one hand measures and on the other hand devices by
which the convection flow can be controlled. Preferred designs are
defined below. If the means are devices, they may be arranged both
on and/or in the frame (7) and on and/or in the two-dimensional
element (9), in order to control the convection flow in the way
according to the invention. Furthermore, the means also include
auxiliary structures for achieving the control according to the
invention of the convection flow.
[0058] The term "structural element", as it is used here, should be
understood for the purposes of the present invention as meaning
that the structural element (1) is suitable both for wall surfaces
and for roof surfaces. The structural element (1) is
self-supporting and can therefore be fitted on its own into a shell
of a building as a wall and/or roof element.
[0059] The heat transfer coefficient U (formerly also "k value")
describes a heat equalization as a result of a temperature
difference between different energy systems. The heat transfer
coefficient U is consequently a measure of the rate of heat
transfer. The power (amount of energy per unit time) that flows
through a surface area of one square meter when the difference in
temperature between the air on the two sides of a wall is one
Kelvin is given as the heat transfer coefficient U. The heat
transfer coefficient U is defined internationally in the standard
EN ISO 6946. Its unit of measure is W/(m.sup.2K).
[0060] The determination of exact heat transfer coefficients U of
different materials is known to a person skilled in the art. It is
calculated from the mean value of the heat transfer resistance
R.sub.T:
U = 1 R T . ##EQU00001##
[0061] The required dimensioning values for the heat transfer
coefficient U are stipulated in the standards EN 12524 and DIN
4108-4.
[0062] It is determined substantially by the thermal conductivity
and the thickness of the materials used, but in addition also by
heat radiation and convection at the surfaces of the compound unit.
The heat transfer coefficient U consequently indicates the rate of
heat transfer through a single- or multi-ply layer of material when
there are different temperatures on the two sides. In the case of
the structural element (1) according to the invention, the heat
transfer coefficient U can be varied between a value determined by
the insulating materials in the layers contained in the structural
element (1) and a value determined by the convection around
these.
[0063] The term "cavity" is understood as meaning the space that is
substantially invariable in its dimensions between a sheet (3, 5),
i.e. between the first sheet (3) or the second sheet (5), and a
two-dimensional element (9), while "intermediate space" refers to a
space between a two-dimensional element (9) and a frame (7) that
can be closed in a suitable way.
[0064] The references to "vertically upward" and "vertically
downward" are to be understood in the context of the present
invention as though they relate not only to perpendicularly aligned
structural elements (1) but also to structural elements (1) that
are arranged at a certain angle with respect to the perpendicular.
The reference to "vertically upward" then means that the upper
intermediate space (11) is arranged substantially above the lower
intermediate space (13), in particular obliquely above it.
[0065] It is preferred if the gas filling the volume V is chosen
from argon, krypton, xenon, carbon dioxide, hydrocarbons, partially
halogenated hydrocarbons, halides of chalcogens and/or pycnogens
and mixtures thereof, in order to achieve additional improvements
in the insulating effect of the structural element or in the order
of magnitude of the heat transfer. The use of polyatomic gases is
particularly preferred because of the higher convective thermal
conductivity.
[0066] In a development of the structural element (1) according to
the invention, at least one of the sheets (3, 5), i.e. the first
sheet (3) and/or the second sheet (5), is at least partially
transparent or translucent.
[0067] The design according to the invention of the structural
element (1) in which the opposing sheets (3, 5), i.e. the first
sheet (3) and/or the second sheet (5), are transparent or at least
translucent, and furthermore the two-dimensional element (9) is
likewise transparent or at least translucent, allows the structural
element (1) also to be used in the form of a partially transparent
or at least translucent window element. In particular, the
structural element (1) according to the invention of this design is
suitable for the replacement of conventionally used glass blocks,
as were frequently used in the past for example for stairwells.
Here, the structural element (1) according to the invention has the
great advantage over conventional glass blocks of good heat
insulation with at the same time sufficient light transmittance for
the illumination of a stairwell for example.
[0068] In a further design of the invention, the structural element
(1) may be formed as what is known as an insulating glass unit
(IGU). Such an insulating glass unit can be installed in a
corresponding modified, conventional window frame structure. Of
interest here in particular is the installation of the elements
according to the invention in the region of the skylight and the
parapet, which can be combined with customary insulating glazing
units at eye level. The installation of a structural element (1)
according to the invention with translucent two-dimensional
elements (9, 9a, 9b) in the region of the skylight is accompanied
in particular by the advantage that, as a result of the
isotropization of the incident radiation in the translucent
two-dimensional element (9, 9a, 9b), the light that is incident in
the region of the skylight can partially reach areas further back
in the room than is possible in the case of light incidence through
transparent skylight elements.
[0069] One design according to the invention of the means mentioned
above comprises the vertical displacement or tilting about a
horizontal axis of the at least one two-dimensional element (9), so
that at least one of the intermediate spaces (11, 13), i.e. the
upper intermediate space (11) and/or the lower intermediate space
(13), is closed by the two-dimensional element (9) and the
convection flow is thereby completely or partially prevented. In
this way it is possible to control the convection flow in a simple
way just by moving the at least one two-dimensional element
(9).
[0070] In this case, the means mentioned may also comprise a device
for displacing the at least one two-dimensional element (9) that is
preferably chosen from servomotors, pneumatic, magnetic or
piezoelectric systems, mechanical levers, cables or bimetallic
structures. The choice can consequently be made to suit the
external conditions of the structural element.
[0071] Another design according to the invention of the means
mentioned above comprises the changing of the vertical extent of
the at least one two-dimensional element (9), so that at least one
of the intermediate spaces (11, 13), i.e. the upper intermediate
space (11) and/or the lower intermediate space (13), is closed by
the two-dimensional element (9) and the convection flow is thereby
completely or partially prevented. This design also has the
advantage of controlling the convection flow in a simple way just
by moving the at least one two-dimensional element (9).
[0072] In a further design according to the invention, the means
mentioned above may also comprise a closure device for at least one
of the upper and lower intermediate spaces (11, 13), which is
preferably chosen from flaps, inflatable tubes or bellows, closures
in the form of cylinder cocks or displaceable or rotatable wedges.
Depending on the dimensional design of the structural element (1)
and the materials used for the at least one two-dimensional element
(9), it may be advantageous to provide these additional closure
devices to allow the convection flow to be effectively controlled.
Inflatable bellows of a suitable configuration may also be used for
switching the structural element (1) according to the invention
automatically into the insulating state when there are very low
outside temperatures, as a result of the negative pressure then
prevailing in the interior space of the structural element (1).
This is of advantage to ensure that there is always adequate
insulation even in the event of failure of some other control of
the convection at the cold time of year.
[0073] If the sheets (3, 5), i.e. the first sheet (3) and/or the
second sheet (5), are transparent and the material of these sheets
comprises glasses and/or polymers, and also the two-dimensional
element or elements (9, 9a, 9b) consist(s) of a translucent
material, daylight can additionally enter the building through the
structural element (1) according to the invention.
[0074] In this case, the glasses are preferably chosen from
silicate glasses, borosilicate glasses, lead-silicate glasses
and/or the polymers are preferably chosen from PET (polyethylene
terephthalate), PVB (polyvinyl butyral), EVA (ethylene vinyl
acetate), polyolefins, styrenic polymers, polycarbonates, PMMA
(polymethyl methacrylate), polyurethanes, PVC (polyvinyl chloride)
or mixtures or multilayer systems thereof. In particular, the
polymers may be formed as sheets or extruded, blown or cast films
or panels. Depending on the application area of the structural
element (1) according to the invention, the suitable material is
thus available, for example polymers for lightweight applications
or special glasses for applications with greater chemical exposure.
Furthermore, it is possible to provide one or more layers with
specific functions, for example heat protection layers or
chromotropic layers.
[0075] To allow the structural element (1) also to be used as a
light-transmissive window element, apart from using the
aforementioned glasses it has proven to be appropriate also to form
the at least one two-dimensional element (9) from a translucent
material that is preferably chosen from organic, inorganic or
hybrid closed-cell or open-cell foams or coated or uncoated
textiles.
[0076] As an alternative to the aforementioned embodiment, the at
least one two-dimensional element (9) may be formed from a mineral,
metallic, polymeric and/or bio-organic material.
[0077] This is of advantage if the structural element (1) is not
intended to be used as a light-transmissive compound unit but is
for example exposed to greater mechanical loads (metallic material,
fiber-reinforced polymer) or is intended to serve solely for heat
insulation (mineral and/or polymeric material). Furthermore, it is
possible with this embodiment also to create structural elements
(1) that are ecologically particularly compatible (bio-organic
materials). In this case, the material used may be open-cell or
closed-cell. If in addition the outer first or second sheet (3, 5)
of the structural element (1) has been coated or otherwise modified
in a suitable way such that it can reflect the incident solar
irradiation directly or diffusely, the structural element (1) is
responsible for particularly little heating up being caused by the
solar irradiation during the day.
[0078] To be able to react flexibly to a wide variety of
requirements for the structural element (1) according to the
invention, it has proven to be advantageous to choose the material
of the frame (7) from concrete, gypsum, clays, glasses, natural
stones, ceramics, polyamide, polyesters, wood, metals, in
particular steel and aluminum and alloys thereof, PVC,
polycarbonate, PMMA, styrenic polymers, polyurethanes and fiber
composite materials and composite materials of two or more of these
materials and also from open-cell or closed-cell foams and fiber
boards of synthetic or renewable raw materials. It is particularly
preferred if the material of the frame (7) is made so as to be
impermeable to gas and/or moisture.
[0079] In particular in the case of embodiments of the structural
element (1) according to the invention that do not have to be
light-transmissive, the aforementioned materials may also be used
for one or both sheets (3, 5), i.e. the first sheet (3) and/or the
second sheet (5). Materials with a low thermal conductivity should
preferably be used. Furthermore, in a further embodiment, the frame
(7) may be constructed from photovoltaic elements or solar-thermal
elements. Such elements are known to a person skilled in the art
and may be made either as opaque elements or as partially
translucent structures. They can also be used in such a way that
only part of the surface area of the frame is taken up by them.
[0080] In a development of the invention, at least the first sheet
(3) and/or the second sheet (5) and/or the at least one
two-dimensional element (9) may be three-dimensionally structured
on the surface. This allows the achievement of optical effects,
which for example bring about protection from the glare of directly
incident light by modifying the angular distribution of the light
radiated and/or by changing the intensity thereof. If a number of
two-dimensional elements (9, 9a, 9b) are contained in the
structural element (1) according to the invention, the light
directing effect can be additionally intensified by suitable
combinations of two-dimensional elements (9, 9a, 9b) with differing
angular behavior of the translucence. For example, it has proven to
be particularly advantageous to combine a two-dimensional element
(9, 9a, 9b) with strongly isotropizing translucence on the outer
side and a two-dimensional element (9, 9a, 9b) with preferred
radiation perpendicularly to the element surface with one another
in order to intensify the effect of further dividing the light
further back into the room. A similar effect as in the case of a
three-dimensionally structured surface can be achieved by a
combination of two-dimensional elements (9, 9a, 9b) with different
translucence properties.
[0081] In addition, in the non-technical area, a three-dimensional
structuring allows creative effects to be achieved. As an
alternative to this, the first and/or the second sheets (3, 5)
and/or the at least one two-dimensional element (9) may be printed
on or coated to achieve the same or similar effects.
[0082] In a particularly preferred embodiment, the structural
element (1) according to the invention comprises [0083] a first
two-dimensional element (9a) and a second two-dimensional element
(9b), the width of which respectively corresponds to the vertical
clear width W of the frame (7) and the height of which is
respectively less than the clear height H of the frame (7), [0084]
the first two-dimensional element (9a) and the second
two-dimensional element (9b) being arranged between the first sheet
(3) and the second sheet (5) such that they each finish laterally
with the inner sides of the frame (7), and [0085] a first upper
intermediate space (11a) and a second upper intermediate space
(11b) being respectively formed between the first two-dimensional
element (9a) and the second two-dimensional element (9b) and the
frame (7) in the vertically upward direction and a first lower
intermediate space (13a) and a second lower intermediate space
(13b) being respectively formed between the first two-dimensional
element (9a) and the second two-dimensional element (9b) and the
frame (7) in the vertically downward direction, [0086] a first
cavity (15), which is formed between the first sheet (3) and the
first two-dimensional element (9a) with a spacing X, [0087] a
second cavity (17), which is formed between the second
two-dimensional element (9b) and the second sheet (5) with a
spacing Y, [0088] a third cavity (23), which is formed between the
first two-dimensional element (9a) and the second two-dimensional
element with a spacing Z, [0089] at least the first cavity (15) and
the second cavity (17) being in connection via the first upper
intermediate space (11a) and the second upper intermediate space
(11b) and the first lower intermediate space (13a) and the second
lower intermediate space (13b) such that a convection flow can flow
at least between the first cavity (15) and the second cavity (17)
via the first upper intermediate space (11a) and the second upper
intermediate space (11b) and the first lower intermediate space
(13a) and the second lower intermediate space (13b).
[0090] The convection flow forming thereby flows substantially
through the first cavity (15), the first and second upper
intermediate spaces (11a, 11b), the second cavity (17) and the
first and second lower intermediate spaces (13a, 13b). A convection
flow through the third cavity (23) does not form, or only to a
negligible extent.
[0091] In a second aspect, the present invention relates to the use
of the structural element (1) described above as a wall and/or roof
element in buildings or vehicles, in particular in rail vehicles or
watercraft. Particularly in rail vehicles with the large ratio
thereof between wall surface and volume and long stationary times
at locations with high solar irradiation, the need for active
cooling can be reduced here.
[0092] The third aspect of the present invention that achieves the
aforementioned object relates to a method for controlling the heat
transfer coefficient U in a structural element (1) described above
that comprises the steps of [0093] providing a structural element
(1), [0094] absorbing thermal energy by a first sheet (3) or a
second sheet (5) on a first side of the structural element (1),
whereby the gas filling the volume V is heated in a first cavity
(15) or in a second cavity (17) and rises vertically upward, [0095]
opening a vertically upper intermediate space (11) and/or a
vertically lower intermediate space (13), whereby a convection flow
from one of the cavities (15, 17) through the intermediate space
(11) into the other of the cavities (15, 17) is made possible,
[0096] giving off thermal energy by the gas filling the volume V to
the first sheet (3) or the second sheet (5) on a second side of the
structural element (1), whereby the gas filling the volume V in the
other of the cavities (15, 17) cools down and falls vertically
downward, so that the convection flow flows from this cavity (15,
17) through the lower intermediate space (13) into one of the
cavities (15, 17), [0097] the intensity of the convection flow
being set by the opening and/or closing of the lower intermediate
space (11) and/or of the upper intermediate space (13).
[0098] Further features, advantages and application possibilities
emerge from the following description of the preferred exemplary
embodiments, which do not however restrict the invention, and the
figures. All of the features described here form the subject matter
of the invention by themselves or in any desired combination, even
independently of how they appear together in the claims or how the
claims refer back to preceding claims. In the drawing:
[0099] FIG. 1 shows a schematic representation of a structural
element in a first embodiment of the invention,
[0100] FIG. 2 shows a schematic representation of a structural
element in a second embodiment of the invention,
[0101] FIG. 2a shows a view of a detail of the region marked in
FIG. 2,
[0102] FIG. 3a shows a simplified depiction of the structural
element represented in FIG. 1 with a schematically represented
convention flow,
[0103] FIG. 3b shows a simplified depiction of the structural
element represented in FIG. 2 with a schematically represented
convention flow,
[0104] FIG. 4a shows a simplified depiction of the structural
element represented in FIG. 1 with a schematically represented
prevented convention flow,
[0105] FIG. 4b shows a simplified depiction of the structural
element represented in FIG. 2 with a schematically represented
prevented convention flow,
[0106] FIG. 5 shows a schematic perspective representation of the
structural element represented in FIG. 1,
[0107] FIG. 6 shows a schematic representation of a structural
element in an embodiment of the invention with reduced flow
resistance.
[0108] FIG. 1 shows the basic form of a structural element 1
according to the invention. The structural element 1 is constructed
by a frame 7, which forms four sides of the element, to be specific
the upper side and underside and the side faces. Arranged opposite
one another in the frame 7 are two sheets 3, 5, i.e. a first sheet
3 and a second sheet 5, which together with the frame 7 define a
closed-off volume. In the interior of the defined volume, a
two-dimensional element 9 is arranged such that it respectively
finishes laterally with the frame 7 and at the top leaves an upper
intermediate space 11 and at the bottom leaves a lower intermediate
space 13 with respect to the frame. Furthermore, the
two-dimensional element 9 is arranged with a spacing X in relation
to the first sheet 3 and with a spacing Y in relation to the second
sheet 5.
[0109] As represented in the simplified representation of FIG. 3a,
a convection flow can form around the two-dimensional element 9. In
the representation of FIG. 3a, heat is transferred from the second
sheet 5 by free convection to the first sheet 3, the free
convection being established because the temperature T.sub.2 on the
left side of the figure is greater than the temperature T.sub.1 on
the right side of the figure. As a result, the temperature of the
gas in the second cavity 17 is higher on average than in the first
cavity 15 and the density is correspondingly lower. This produces a
pressure difference upstream and downstream of the lower
intermediate space 13, which finally sets the convection movement
in motion, so that the warmer gas flows out from the second cavity
17 via the upper intermediate space 11 into the first cavity 15,
while the colder gas flows via the lower intermediate space 13 into
the second cavity 17. Overall, an energy flow from right to left
thus takes place.
[0110] A preferred embodiment of the invention is schematically
represented in FIG. 2. This embodiment has two two-dimensional
elements 9a, 9b, i.e. a first two-dimensional element 9a and a
second two-dimensional element 9b, arranged in the defined volume.
These elements are arranged in principle in the same way as the
two-dimensional element 9 in FIG. 1, but with the difference that
they form between them a third cavity 23 with the spacing Z from
one another. As is shown in FIG. 3b, the formation of the internal
convection flow is substantially the same as the embodiment
represented in FIG. 3a.
[0111] In order to control or prevent the convection flow in one
embodiment the two-dimensional element 9 can be moved by suitable
means, for example upward, so that it closes the upper intermediate
space 11, as is represented in FIG. 4a. Although the gas volume in
the first cavity 15 that has been heated by the heat W1 can rise
upward, the formation of a convection flow is not possible due to
the closed upper intermediate space 11.
[0112] The particular embodiment that is represented in FIG. 2 acts
in a similar way when the first and/or second two-dimensional
element or elements 9, 9a, 9b are displaced such that one of the
intermediate spaces 11a, 11b, 13a, 13b, i.e. the first upper
intermediate space 11a, the second upper intermediate space 11b,
the first lower intermediate space 13a, the second lower
intermediate space 13b, is closed. One possible configuration is
represented in FIG. 4b, a configuration in which the first
two-dimensional element 9a has been displaced upward, in order to
close the first upper intermediate space 11a, while the second
two-dimensional element 9b has been displaced downward, in order to
close the second lower intermediate space 13b. No convection flow
can form in this embodiment either.
[0113] Generally, the configurations in FIGS. 3a and 3b represent
the state in which the structural element 1 has a maximum heat
transfer coefficient U, that is to say it makes a maximum heat
transfer possible. On the other hand, the configurations in FIGS.
4a and 4b represent a state in which the structural element 1 has
its minimum heat transfer coefficient U, that is to say offers
maximum heat insulation.
[0114] FIG. 5 is a perspective representation of the structural
element 1 shown in FIG. 1, from which it is clear in particular how
the two-dimensional element 9 finishes laterally with the frame
7.
[0115] FIG. 6 shows an embodiment of the structural element
according to the invention with reduced flow resistance, the
reduction in the flow resistance occurring as a result of the
rounding 25 of the edges of the two-dimensional element 9 and as a
result of the round shaping 27 of the corners of the first and/or
second sheets 3, 5. The advantage of such an embodiment is that,
with the same temperature difference, a greater convection flow
results, and more energy can thereby be transferred, while in the
closed case (FIGS. 4a, 4b) there is no deterioration of the
insulating effect.
[0116] Depending on the installation situation of the structural
element 1, it is also possible for more than two two-dimensional
elements 9, 9a, 9b to be provided in the defined volume V.
Moreover, it may be of advantage to reduce the third cavity 23
formed between two first and second two-dimensional elements 9a, 9b
to a minimum, to the extent of the embodiment where the first and
second two-dimensional elements 9a, 9b are touching.
[0117] According to a further embodiment, active convection
elements may be integrated into the first cavity 15 and/or into the
second cavity 17. "Active convection elements" are understood as
meaning for example small rotors that promote the formation of the
convection flow and maintain it. As a result, in particular the
shift stroke between the side with the higher temperature T.sub.2
and the side with the lower temperature T.sub.1 is increased.
[0118] As becomes clear from the figures, in a reverse of the
effect known from the prior art, the structural element 1 according
to the invention can in particular be used for the purpose of
removing heat from buildings. This may be advantageous for example
at the warm time of year. Application of the structural element 1
according to the invention for heat dissipation from industrial
constructions is also conceivable.
[0119] Depending on the installation situation of the structural
element 1 according to the invention, the first and/or second
sheets 3, 5 may be provided either in a perpendicular or an
inclined configuration. In this way, both wall surfaces and sloping
roof surfaces can be formed. The angle of the sloping roof surfaces
in relation to the perpendicular is substantially between 0.degree.
and 90.degree., preferably between 5.degree. and 60.degree.. In
spite of the sloping position of the structural element 1 according
to the invention, the principle of the controllable heat transfer
coefficient U, i.e. control obtained by specifically controlling
the internal convection flow, is retained.
[0120] For use of the structural element 1 according to the
invention for flat roof surfaces, only small structural
modifications have to be performed, so that the internal convection
flow continues to be ensured. Imperative for use in flat roof
surfaces is the use of inflatable bellows, slides, flaps and wedges
instead of the displacement of the two-dimensional elements 9, 9a,
9b, since they would involve a high amount of friction and
resulting damage to the two-dimensional elements 9, 9a, 9b.
Depending on the conditions in which it is used, slightly different
dimensioning of the structural elements 1 is possibly
necessary.
[0121] The structural element 1 according to the invention can
accordingly be used as a wall and/or roof element in a shell,
without further wall elements or roof elements having to be
provided. Of course, the structural element 1 according to the
invention can also be used as a classic insulating element for
mounting on a facade.
[0122] In a further embodiment, the at least one two-dimensional
element 9 is formed from a flexible, open-cell foam on a melamine
resin basis, which is commercially available under the designation
Basotect.RTM. (BASF SE). Basotect.RTM. displays the same physical
properties over a wide temperature range, with at the same time low
weight, good heat insulating properties and high sound absorption
characteristics. Moreover, Basotect.RTM. is flame resistant
(without the addition of flame retardants), which makes a
structural element 1 according to the invention comprising this
material particularly suitable for wall and/or roof elements.
[0123] In a specific embodiment, the frame 7 may be provided with
light sources (for example LEDs), in order also to use the
structural element 1 according to the invention in darkness for
interior/exterior lighting. Furthermore, optical and creative
effects can be achieved by a diffuser effect of structured sheets
3, 5 and/or structured two-dimensional elements 9, 9a, 9b.
[0124] The preferred dimensions of the structural element 1 and
parts thereof are specified below.
[0125] The distance A between the first sheet 3 and the second
sheet 5 is <50 cm, preferably <35 cm, particularly preferably
between 5 cm and 12 cm. It generally applies that, the higher the
structural element 1 is, the wider the first and second cavities
15, 17 have to be chosen in order to bring about a spontaneous
convection even when there are small differences in temperature.
This ratio of the height of the structural element 1 to the width
of the first and second cavities 15, 17 is very sensitive and needs
to be set precisely.
[0126] In principle, the structural elements 1 according to the
invention are not subject to any size limitation. From a practical
viewpoint, a height of up to 1.5 m has been found to be
appropriate. The width of the elements is substantially limited by
the stability of the materials used and is appropriately up to 5 m.
For reasons of thermally induced pressure changes, the gas volume
enclosed in the structural element 1 should be kept as small as
possible.
[0127] Dimensions for the structural element 1 according to the
invention that have been determined by computer-aided optimization
are specified below.
Value ranges (relative) for a first embodiment of the structural
element 1: X/H: relative thickness of the gap between sheet 3 and
two-dimensional element 9: 0.001.ltoreq.X/H.ltoreq.0.05;
preferably: 0.005.ltoreq.X/H.ltoreq.0.04 Y/H: relative thickness of
the gap between two-dimensional element 9 and sheet 5:
0.001.ltoreq.Y/H.ltoreq.0.05; preferably:
0.005.ltoreq.Y/H.ltoreq.0.04
if Y<X:
[0128] s.sub.O/Y: relative thickness of the gap between the
two-dimensional element 9 and the upper frame 7 in the state with a
high heat transfer coefficient: 0.3.ltoreq.s.sub.O/Y.ltoreq.5;
preferably: 0.5.ltoreq.s.sub.O/Y.ltoreq.4; particularly preferably:
1.ltoreq.s.sub.O/Y.ltoreq.3 s.sub.U/Y: relative thickness of the
gap between the two-dimensional element 9 and the lower frame 7 in
the state with a high heat transfer coefficient:
0.3.ltoreq.s.sub.U/Y.ltoreq.5; preferably:
0.5.ltoreq.s.sub.U/Y.ltoreq.4; particularly preferably:
1.ltoreq.s.sub.U/Y.ltoreq.3
if Y.gtoreq.X:
[0129] s.sub.O/X: relative thickness of the gap between the
two-dimensional element 9 and the upper frame 7 in the state with a
high heat transfer coefficient; 0.3.ltoreq.s.sub.O/X.ltoreq.5;
preferably: 0.5.ltoreq.s.sub.O/X.ltoreq.4; particularly preferably:
1.ltoreq.s.sub.O/X.ltoreq.3 s.sub.U/X: relative thickness of the
gap between the two-dimensional element 9 and the lower frame 7 in
the state with a high heat transfer coefficient:
0.3.ltoreq.s.sub.U/X.ltoreq.5; preferably:
0.5.ltoreq.s.sub.U/X.ltoreq.4; particularly preferably:
1.ltoreq.s.sub.U/X.ltoreq.3 H: height of the structural element 1:
0.25 m.ltoreq.H.ltoreq.6 m; preferably: 0.5 m.ltoreq.H.ltoreq.4 m;
particularly preferably: 0.7 m.ltoreq.H.ltoreq.3 m
[0130] Value ranges (relative) for a second embodiment of the
structural element 1:
X/H: relative thickness of the gap between sheet 3 and
two-dimensional element 9a: 0.001.ltoreq.X/H.ltoreq.0.05;
preferably: 0.005.ltoreq.X/H.ltoreq.0.04 Y/H: relative thickness of
the gap between two-dimensional element 9b and sheet 5:
0.001.ltoreq.Y/H.ltoreq.0.05, preferably:
0.005.ltoreq.Y/H.ltoreq.0.04
if Y<X:
[0131] s.sub.O/Y: relative thickness of the gap between the
two-dimensional elements 9a, 9b and the upper frame 7 in the state
with a high heat transfer coefficient:
0.3.ltoreq.s.sub.O/Y.ltoreq.5; preferably:
0.5.ltoreq.s.sub.O/Y.ltoreq.4; particularly preferably:
1.ltoreq.s.sub.O/Y.ltoreq.3 s.sub.U/Y: relative thickness of the
gap between the two-dimensional elements 9a, 9b and the lower frame
7 in the state with a high heat transfer coefficient:
0.3.ltoreq.s.sub.U/Y.ltoreq.5; preferably:
0.5.ltoreq.s.sub.U/Y.ltoreq.4; particularly preferably:
1.ltoreq.s.sub.U/Y.ltoreq.3
if Y.gtoreq.X:
[0132] s.sub.O/X: relative thickness of the gap between the
two-dimensional elements 9a, 9b and the upper frame 7 in the state
with a high heat transfer coefficient:
0.3.ltoreq.s.sub.O/X.ltoreq.5; preferably:
0.5.ltoreq.s.sub.O/X.ltoreq.4; particularly preferably:
1.ltoreq.s.sub.O/X.ltoreq.3 s.sub.U/X: relative thickness of the
gap between the two-dimensional elements 9a, 9b and the lower frame
7 in the state with a high heat transfer coefficient:
0.3.ltoreq.s.sub.U/X.ltoreq.5; preferably:
0.5.ltoreq.s.sub.U/X.ltoreq.4; particularly preferably:
1.ltoreq.s.sub.U/X.ltoreq.3 H: height of the structural element 1:
0.25 m.ltoreq.H.ltoreq.6 m; preferably: 0.5 m.ltoreq.H.ltoreq.4 m;
particularly preferably: 0.7 m.ltoreq.H.ltoreq.3 m
[0133] Value ranges (relative) for a first embodiment with reduced
flow resistance:
r/(A-X-Y): relative rounding radius of the two-dimensional element
9: 0.ltoreq.r/(A-X-Y).ltoreq.0.5; preferably:
0.1.ltoreq.r/(A-X-Y).ltoreq.0.5; particularly preferably:
0.25.ltoreq.r/(A-X-Y).ltoreq.0.5 R/A: relative rounding radius of
the outer corners: 0.ltoreq.R/A.ltoreq.0.5; preferably:
0.1.ltoreq.R/A.ltoreq.0.5; particularly preferably:
0.25.ltoreq.R/A.ltoreq.0.5
[0134] For the distance between the two-dimensional elements 9a, 9b
which defines the intermediate space 23, a width of 0.003 m to 0.05
m, preferably 0.005 m to 0.04 m, particularly preferably 0.007 m to
0.03 m, has proven expedient.
EXAMPLES
[0135] In an experimental setup, the properties of structural
element prototypes according to the invention were determined. For
the sheets 3, 5, Plexiglass panels with a size of 800.times.800 mm
were used, while the two-dimensional element consisted of a
translucent insulating material (non-colored Basotect.RTM.). The
frame 7 was made out of PVC sheets. The thickness of the prototype
was 96 mm. The cavities 15, 17 respectively had a size X, Y of 30
mm.
[0136] The test setup was chosen such that a heatable element was
pushed in between two identical prototypes of the type described
above, while coolable elements were provided on the opposing sides.
The heat flow from the heatable element to the coolable elements
was measured electrically. The heat flow passing through one of the
prototypes is consequently half the heat flow measured as a whole.
In this way, the thermal conductivity .lamda. and the heat transfer
coefficient U were measured.
[0137] In a first measuring setup (I), the size of the upper
intermediate space 11 was 60 mm and the size of the lower
intermediate space 13 was 0 mm; in a second measuring setup (II),
both sizes of the upper and lower intermediate spaces 11, 13 were
respectively 30 mm. In a further pair of measuring setups (III) and
(IV), the two switching states of a structural element 1 according
to the invention have been realized in the configuration with two
two-dimensional elements 9a, 9b. In the measuring setups, two
two-dimensional elements 9a, 9b from Basotect.RTM. with a thickness
of in each case 15 mm have been used. The sizes of the cavities 15
and 17 were in each case 15 mm, the size of the intermediate space
23 was 10 mm. In setup (III), the sizes of the intermediate spaces
11a and 13b were 30 mm, the sizes of the intermediate spaces 11b
and 13a were 0 mm. In setup (IV), the sizes of the intermediate
spaces 11a, 11b, 13a and 13b were in each case 15 mm. The setups
(III) and (IV) were additionally measured with CO.sub.2 as the
filling gas instead of air. These measurements are denoted in the
table by IIIb and IVb.
[0138] For each measuring setup, two measurements were respectively
carried out with a low difference in temperature between the
heatable element and the coolable element (measurements 1 and 3)
and one measurement was carried out with a high difference in
temperature between the heatable element and the coolable element
(measurements 2 and 4). The results of the measurements are
represented in the table below.
TABLE-US-00001 Temperature difference between Measuring both sides
of the prototype U setup [K] [W*m.sup.-2*K.sup.-1] 1 I 12.8 1.046 2
I 34.7 1.317 3 II 13.7 2.417 4 II 32.7 2.775 5 III 15 0.71 6 III 29
0.8 7 IV 14 1.44 8 IV 28 1.6 9 IIIb 15 0.65 10 IIIb 29 0.74 11 IVb
14 1.45 12 IVb 28 1.67
[0139] Measurements 1 and 3 show that the heat transfer coefficient
U is more than doubled if the position of the two-dimensional
element 9 is changed while there is substantially the same
difference in temperature at the prototypes.
[0140] Measurements 2 and 4 confirm that the convection, and
consequently also the heat transfer coefficient U, rise with the
difference in temperature.
[0141] It has been shown with the experimental setup and the
measurements that the heat transfer coefficient U in the structural
element according to the invention can be controlled.
LIST OF DESIGNATIONS
[0142] 1 structural element [0143] 3 first sheet [0144] 5 second
sheet [0145] 7 frame [0146] 9 two-dimensional element [0147] 9a
first two-dimensional element [0148] 9b second two-dimensional
element [0149] 11, 11a, 11b upper intermediate space [0150] 13,
13a, 13b lower intermediate space [0151] 15 first cavity [0152] 17
second cavity [0153] 23 third cavity [0154] 25 rounded outer corner
[0155] rounded inner corner [0156] H clear height of the frame 7
[0157] W clear width of the frame 7 [0158] A distance between first
sheet 3 and second sheet 5 [0159] X spacing of first sheet 3 in
relation to two-dimensional element 9, 9a, 9b [0160] Y spacing of
second sheet 5 in relation to two-dimensional element 9, 9a, 9b
[0161] S.sub.1 thickness of the first sheet 3 [0162] S.sub.2,
S.sub.2a, S.sub.2b thickness of the two-dimensional element 9, 9a,
9b [0163] S.sub.3 thickness of the second sheet 5 [0164] S.sub.o
width of upper intermediate space 11, 11a, 11b [0165] S.sub.u width
of lower intermediate space 13, 13a, 13b [0166] r radius of inner
corner [0167] R radius of outer corner
* * * * *