EP2948600A1

EP2948600A1 - Construction element having a controllable heat-transfer coefficient u

Info

Publication number: EP2948600A1
Application number: EP14701321.3A
Authority: EP
Inventors: Nikolaus Nestle; Andreas Daiss; Klaus Hahn; Ralf NÖRENBERG; Johann Martin SZEIFERT; Elena Khazova; Achim LÖFFLER; Tilmann Kuhn; Christoph Maurer; Thibault PFLUG; Jan Wienold; Andre GLÜCK
Original assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV; BASF SE
Current assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV; BASF SE
Priority date: 2013-01-22
Filing date: 2014-01-17
Publication date: 2015-12-02
Also published as: WO2014114563A1; US20150361654A1; CN105008630B; KR20150109452A; CN105008630A

Abstract

The present invention relates to a construction element (1) having a controllable heat-transfer coefficient U, comprising - a frame (7), - a first panel (3) and a second panel (5), which are opposite each other and which are arranged at a distance A from each other in the frame (7), wherein a closed volume V that is filled with at least one gas is defined by the first panel (3), the second panel (5), and the frame (7), - at least one planar 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), wherein the planar element (9) is arranged between the first panel (3) and the second panel (5) in such a manner that the planar element ends laterally at the insides of the frame (7), and wherein an upper intermediate space (11) is formed between the planar element (9) and the frame (7) vertically upward and a lower intermediate space (13) is formed between the planar element (9) and the frame (7) vertically downward, - a first cavity (15), which is formed between the first panel (3) and the planar element (9) having a distance X, - a second cavity (17), which is formed between the planar element (9) and the second panel (5) having a distance Y, wherein the first cavity (15) and the second cavity (17) are connected by means of the upper intermediate space (11) and the lower intermediate space (13) in such a manner 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, said means being arranged for the upper intermediate space (11) and/or for the lower intermediate space (13). The present invention further relates to the use of the construction element (1) according to the invention as a wall element and/or roof element in buildings and to a method for controlling the heat-transfer coefficient U in a construction element (1) according to the invention.

Description

Construction element with adjustable heat transfer coefficient U

The present invention relates to a structural element with controllable heat transfer coefficient U and its use as a wall and / or roof element in buildings or vehicles and a method for controlling the heat transfer coefficient U in such a structural element.

The heat transfer coefficient U in construction is a specific characteristic value of a component or building material, which in principle indicates its thermal insulation properties. The higher the heat transfer coefficient U, the worse the heat-insulating property of the component or building material.

The heat transfer coefficient U has become particularly important at the latest since the amended Energy Saving Ordinance (EnEV), which came into force in Germany in 2009, according to which the annual primary energy demand and the specific transmission heat loss of a building to be constructed must comply with certain limit values. The heat transfer coefficient U is included in the calculation of the transmission heat loss, which in turn is used in the calculation of the primary energy demand. Furthermore, the Energy Saving Ordinance prescribes limits for the heat transfer coefficient U for certain components when they are replaced or newly installed in existing buildings.

From the prior art, a variety of insulation elements is known, which are used for thermal insulation of buildings. These typically consist of one or more insulating layers of insulating material (e.g., foams, foamed polymeric materials). Depending on the nature of the insulating material, a protective layer is applied on the outside of such insulation elements. These insulating elements are used in particular to prevent heat leakage from the interior of a building to the outside. At the same time, a heat flow into a building can also be reduced. According to the state of the art, most of the insulating elements have fixed insulating properties, that is, the insulating property can only be regulated by varying the thickness and / or the number of insulating elements. However, this does not make it possible to react flexibly to current temperatures inside and outside a building.

Due to the use of high-insulating materials, however, it is now possible that the natural outside temperature fluctuation can no longer be used to dissipate the heat introduced by the sun during the day into the building again at night. The resulting heat accumulation increases the energy requirement for active cooling devices. There is therefore a need for an insulating element whose insulating properties are variable. In the prior art, there are first approaches to meeting this need. Thus, DE 10 2006 024 067 A1 describes an insulating element which is particularly suitable for internal and / or external insulation of buildings. The insulating properties of the insulating element described there can be changed depending on the desired internal temperature of the building or depending on the outside temperature and / or sunlight, in particular by changing the heat transfer coefficient U and / or the reflection properties of Dämmements themselves. For technical solution, the insulating element is provided with an insulating material , which can be changed in its position, so that the insulation used wholly, partially or substantially does not contribute to the insulation of the building. For this purpose, for example, the insulating material can be completely or partially compressed in order to release the heat flow through the insulating element completely or partially. A major disadvantage of all embodiments of the prior art is that large amounts of material must be moved or compressed, since the surface of the element must be substantially met or free of insulating material.

Further, in US 4,058,109 a device for insulating and / or solar heating is disclosed. This is applied to the façade of an existing building and consists of a transparent panel, which is placed in front of a wall and thus 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. In this way, on the one hand by the presence of the insulating material thermal insulation of the building can be achieved, while on the other hand solar radiation is used by the heat absorber to heat the trapped gas volume in the device and deliver this heat on the convection flow to a certain extent on the existing building wall. Another approach in the prior art is described in DE 196 47 567 A1. There, a switchable vacuum insulation, in particular for use for the solar energy use, realized, with a coarse porous or coarsely structured insulation material is gas-tight enveloped and evacuated. This element can be flooded with hydrogen gas as needed, whereby within the enclosure there is an electrically heatable getter material, which is enclosed by a heat insulation material, for the adsorption and adsorption of hydrogen. whose thermal conductivity does not or only slightly depends on the gas pressure in this component.

Further, US 2003/0061776 A1 discloses a variable heat transfer coefficient insulating system based on an inflatable structure which responds by changing the volume to changes in the atmospheric temperature. As a result, the heat flow can be controlled.

AT 380 946 B1 discloses a so-called heat exchange wall, which consists essentially of a surrounded by a tube system insulation board in which a gaseous heat transfer medium can circulate, the circulation can be automatically locked by the special design of the tube system. For an insulating element with switchable insulation behavior is an automatic lock is not necessarily useful because the same temperature differences depending on the weather either a strong insulation or a reduced insulation make sense sense. In addition, the insulation element described in AT 380 946 B1 is constructed comparatively complicated and accordingly only bad to manufacture.

In addition, there are a number 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 in the heat flow is achieved by either permitting or suppressing the flow of a space between the various shells with outside air. In part, the air exchange also takes place through the element with the interior. All of these approaches have the common drawback that when air flows in with outside air, dust from the air gets into the intermediate space and can lead to undesirable contamination there, which impair their optical function, in particular in the case of translucent and transparent elements. With an additional exchange of air to the interior, this hygienic problem is exacerbated in addition, as unwanted germs or pests can be carried off by the air flow.

In FR 2 798 991 A1, finally, an element is presented in which the wall is subdivided into diamond-shaped cells in which, by inclining an insulating body fitted into it, either its flow around it through a convection current is enabled or suppressed. This element is again comparatively complicated to manufacture due to the numerous segments and the non-cuboid outer shape of the individual cells. Although the insulation elements described in the prior art with, within certain limits, controllable heat transfer coefficient U advantages over conventional insulation materials, they all bring significant disadvantages in terms their building technical applicability with them and are sometimes extremely expensive to produce.

The invention is therefore an object of the invention to provide a novel construction element that minimizes the energy consumption of a building by helping to control its heat balance.

This object is achieved in a design element of the type mentioned in that it has a controllable heat transfer coefficient U and is configured as follows:

Construction element (1) with controllable heat transfer coefficient U, comprising

a frame (7),

- Two opposite plates (3, 5), which are arranged at a distance A from each other in the frame (7), wherein by the plates (3, 5) and the frame (7) a closed volume V is defined, which with at least a gas is filled,

- At least one planar element (9) whose width of the vertical clear width W of the frame (7) and whose height is less than the clear height H of the frame (7), wherein the sheet-like element (9) so between the plates ( 3, 5) is arranged such that it terminates laterally with the inner sides of the frame (7), and wherein between the planar element (9) and the frame (7) vertically upwards a gap (1 1) and between the planar element ( 9) and the frame (7) vertically downwards a gap (13) is formed,

a first cavity (15) which is formed between the plate (3) and the planar element (9) with a distance X,

- A second cavity (17) which is formed between the sheet-like element (9) and the plate (5) with a distance Y, wherein the first cavity (15) and the second cavity (17) via the intermediate space (1 1) and the intermediate space (13) in such a way that between the first cavity (15) and the second cavity (17) via the intermediate space (1 1) and the intermediate space (13) can flow a convection flow,

- At least one means for controlling the convection flow, which is arranged at least for one of the intermediate spaces (1 1, 13).

The object of the invention is achieved in a first aspect of the present invention by a construction element (1) with controllable heat transfer coefficient U, which comprises

a frame (7),

a first plate (3) and a second plate (5) facing each other and spaced apart from each other in the frame (7), wherein a closed volume V defined by the first plate (3), the second plate (5) and the frame (7) is filled with at least one gas,

at least one planar element (9) whose width corresponds to the vertical clear width W of the frame (7) and whose height is less than the clear height H of the frame (7),

the planar element (9) being arranged between the first plate (3) and the second plate (5) such that it terminates laterally with the inner sides of the frame (7), and

wherein between the planar element (9) and the frame (7) vertically upwards an upper intermediate space (1 1) and between the planar element (9) and the frame (7) vertically down a lower gap (13) is formed,

a first cavity (15) which is formed between the first plate (3) and the planar element (9) with a distance X,

a second cavity (17) which is formed between the planar element (9) and the second plate (5) with a distance Y,

wherein the first cavity (15) and the second cavity (17) communicate via the upper space (11) and the lower space (13) so as to communicate between the first cavity (15) and the second cavity (17) the upper intermediate space (11) and the lower intermediate space (13) can flow a convection flow,

- At least one means for controlling the convection flow, which is arranged for the upper intermediate space (1 1) and / or for the lower intermediate space (13).

In a second aspect, the above object is achieved by the use of the construction element (1) according to the invention as a wall and / or roof element in buildings or vehicles.

The third aspect of the present invention solves the underlying object by a method for controlling the heat transfer coefficient U in a construction element (1) according to the invention, comprising the steps

Providing a construction element (1),

Absorbing heat energy through a first plate (3) or a second plate (5) on a first side of the construction element (1), whereby the gas filling the volume V in a first cavity (15) or in a second cavity (17) is heated and rises vertically,

- Opening a vertically upper intermediate space (1 1) and / or a vertically lower intermediate space (13), whereby a Konvektionsströmung of the one of the cavities (15, 17) through the intermediate space (1 1) in the other of the cavities (15, 17 ),

- Delivery of heat energy through the volume V filling gas to the first plate (3) or the second plate (5) on a second side of the structural element (1), whereby the gas filling the volume V in the another of the cavities (15, 17) cools and falls vertically downwards, so that the convection flow from this cavity (15, 17) flows through the lower space (13) into one of the cavities (15, 17),

wherein the intensity of the convection flow is adjusted by opening and / or closing the lower intermediate space (11) and / or the upper intermediate space (13).

The present invention is based on the finding that the heat transfer through a construction element (1) of the type described can be regulated by forming and controlling an internal convection flow.

It has surprisingly been found that with the construction element (1) according to the invention it is also possible in a technically simple manner to significantly minimize the energy consumption of a building and thus optimally exploit the prevailing temperatures inside and outside a building. It is advantageous that, according to the present invention, the heat transfer coefficient U can be regulated as required and independently of the prevailing indoor / outdoor temperatures. Thus it can be achieved by the inventive design of the construction element (1) that during the cooler night hours increased discharge of heat from the building is enabled, while at high outdoor temperatures during the daytime and at low outdoor temperatures in winter one of the regulations for adequate thermal insulation appropriate insulation effect can be ensured.

Hereinafter, the present invention will be further clarified.

In a first aspect, the present invention relates to a structural element (1) with controllable heat transfer coefficient U, comprising

a frame (7),

- a first plate (3) and a second plate (5) which are opposite to each other and which are arranged at a distance A from each other in the frame (7), wherein by the first plate (3), the second plate (5) and the frame (7) is defined as a closed volume V filled with at least one gas,

the planar element (9) being arranged between the first plate (3) and the second plate (5) such that it terminates laterally with the inner sides of the frame (7), and wherein between the planar element (9) and the frame (7) vertically upwards an upper intermediate space (1 1) and between the planar element (9) and the frame (7) vertically down a lower gap (13) is formed,

In this case, the frame (7) and the opposite plates (3, 5), i. the first plate (3) and the second plate (5), a three-dimensional body defining a closed volume V. The frame (7) of the construction element (1) according to the invention is primarily used for enclosure and mechanical stabilization of the construction element (1) and for receiving the first and second plates (3, 5). The configuration of the first and second plates (3, 5) will be described in more detail below.

The shape of the construction element (1) can be chosen freely within wide limits and adapted to the requirements of its installation situation and / or use. A preferred embodiment is an approximately cuboidal element. But other geometric shapes are, depending on the installation situation, realized with the construction element (1) according to the invention, for example, the basic shape of a triangle, a pentagon or the like. Further embodiments of the framework are defined below.

The structural element (1) comprises at least one planar element (9) which is arranged substantially centrally so that the inner convection flow around the planar element (9) is possible, the convection flow from the side of the structural element (1) the heat is supplied through the upper space (1 1) on the other side of the sheet-like element (9) is passed, where the convection flow heat to the opposite side and then through the lower space (13) back to the side of the Heat supply flows. The planar element (9) consists in particular of an insulating material. To control the internal convection flow, the construction element (1) according to the invention comprises at least one means with which an opening and / or closing of one of the intermediate spaces (11, 13) is carried out, which in turn regulates the convection flow.

The term "agent", as used herein, describes on the one hand measures and, on the other hand, devices with which the convection flow can be regulated Preferred embodiments are defined below: If the means are devices, they can be both on and / or in the frame (7) as well as on and / or in the planar element (9) in order to regulate the convection flow according to the invention.Furthermore, the means also include auxiliary constructions for achieving the control of the convection flow according to the invention is used herein is to be understood in the context of the present invention, that the construction element (1) is suitable for both wall and roof surfaces. The construction element (1) is self-supporting and can therefore be used independently in a shell of a building as a wall and / or roof element.

The heat transfer coefficient U (formerly also "k-value") describes a heat balance due to a temperature difference between different energy systems, thus the heat transfer coefficient U is a measure of the heat flow passage. if the temperature difference between the air on both sides of a wall is one kelvin, then the heat transfer coefficient is U. The heat transfer coefficient U is defined internationally in the standard EN ISO 6946. Its unit of measurement is W / (m ² · K) The determination of exact heat transfer coefficients U of various materials is known to the person skilled in the art and is calculated from the mean value of the heat transfer resistance R _T :

i

υ = -. The required design values for the heat transfer coefficient U are specified in the standards EN 12524 and DI N 4108-4.

It is essentially determined by the thermal conductivity and the thickness of the materials used, but also by heat radiation and convection at the surfaces of the component. The heat transfer coefficient U thus gives the Heat flow passage through a single or multilayer material layer, when different temperatures abut on both sides. In the construction element (1) according to the invention, the heat transfer coefficient U can be varied between a value determined by the layers of insulating materials contained in the construction element (1) and a value determined by the convection around it.

The term "cavity" is understood to mean the essentially unchanging space between a plate (3, 5), ie between the first plate (3) or the second plate (5) and a planar element (9), while "Space" is a space between the flat element (9) and frame (7) is called, which can be suitably closed.

The terms "vertically upwards" and "vertically downwards" in the sense of the present invention should be understood to refer not only to vertically oriented structural elements (1) but also to structural elements (1) that have a certain angle are arranged opposite the vertical. The term "vertically upwards" then means that the upper intermediate space (11) is arranged essentially above the lower intermediate space (13), in particular obliquely above it.

It is preferred if the gas filling the volume V is selected from argon, krypton, xenon, carbon dioxide, hydrocarbons, partially halogenated hydrocarbons, halides of the chalcogenes and / or pyknogens and mixtures thereof to provide additional improvements in the insulating effect of the structural element To achieve magnitude of the heat transfer. The use of polyatomic gases is particularly preferred because of the higher convective thermal conductivity. In a development of the construction element (1) according to the invention, at least one of the plates (3, 5), i. the first plate (3) and / or the second plate (5), at least partially transparent or translucent.

The inventive design of the construction element (1), in which the opposite plates (3, 5), that is, the first plate (3) and / or the second plate (5), are transparent or at least translucent and further also the planar element ( 9) is transparent or at least translucent, the construction element (1) can also be used in the form of a partially transparent or at least translucent window element. In particular, the construction element (1) according to the invention in this embodiment offers itself for the replacement of conventionally used glass blocks, as they were often used previously, for example, for staircases. Here has the inventive Design element (1) over conventional glass blocks the great advantage of good thermal insulation while sufficient light transmission for lighting, for example, a staircase. In a further embodiment of the invention, the construction element (1) can be formed as a so-called insulating glass unit (IGU). Such insulating glass unit can be installed in a correspondingly modified, conventional window frame construction. Here, in particular, the installation of the elements according to the invention in the area of the skylight and the parapet of interest, which can be combined with conventional glazing at the sight. The incorporation of a construction element (1) according to the invention with translucent planar elements (9, 9a, 9b) in the area of the skylight brings with it the advantage that the light incident in the skylight area due to the isotropization of the incident radiation in the translucent planar element (9, FIG. 9a, 9b) can partially reach into deeper areas of the room than is possible in the case of light through transparent skylight elements.

An inventive embodiment of the aforementioned means comprises the vertical displacement or tilting about a horizontal axis of the at least one planar element (9), so that at least one of the intermediate spaces (1 1, 13), i. the upper intermediate space (1 1) and / or the lower intermediate space (13), closed by the sheet-like element (9) and the Konvektionsstromung is thereby completely or partially prevented. In this way it is possible to regulate the convection current in a simple manner only by moving the at least one flat element (9).

In this case, said means may further comprise a device for displacing the at least one planar element (9), which is preferably selected from servomotors, pneumatic, magnetic or piezoelectric systems, mechanical levers, cables or bimetallic constructions. The selection can thus be made adapted to the external conditions of the construction element.

Another embodiment of the abovementioned means according to the invention comprises changing the vertical extent of the at least one planar element (9), so that at least one of the intermediate spaces (1 1, 13), ie the upper intermediate space (11) and / or the lower intermediate space (13), closed by the sheet-like element (9) and the convection current is thereby completely or partially prevented. This embodiment also has the advantage that the convection current can be regulated simply by moving the at least one flat element (9) in a simple manner. The above-mentioned means may further comprise, in a further embodiment according to the invention, a closure device for at least one of the upper and lower intermediate spaces (11, 13), which is preferably selected from flaps, inflatable tubes or bellows, cylinder-shaped closures or sliding or rotatable wedges. Depending on the dimensional design of the structural element (1) and the materials used for the at least one planar element (9), it may be advantageous to provide these additional closure devices in order to effectively control the convection flow. Suitable designed inflatable bellows can also be used so that the construction element (1) according to the invention automatically switches to the insulating state at very low outside temperatures as a result of the negative pressure then prevailing in the interior of the construction element (1). This is advantageous to always ensure adequate insulation even in the event of failure of another control of convection in the cold season.

As far as the plates (3, 5), i. the first plate (3) and / or the second plate (5) are transparent and the material of this plate comprises glasses and / or polymers and also the one or more planar elements (9, 9a, 9b) consist of a translucent material by the construction element (1) according to the invention additionally receive daylight into the building.

The glasses are preferably made of silicate glasses, borosilicate glasses, lead silicate glasses and / or the polymers of PET (polyethylene terephthalate), PVB (polyvinyl butyral), EVA (ethylene vinyl acetate), polyolefins, styrenics, polycarbonates, PMMA (polymethyl methacrylate), polyurethanes, PVC (polyvinyl chloride) or Mixtures or multilayer systems selected therefrom. In particular, the polymers may be formed as sheets or extruded, blown or cast sheets or disks. Depending on the field of application of the construction element (1) according to the invention, the suitable material is thus available, for example polymers for lightweight applications or special glasses for applications with increased chemical stress. Furthermore, it is possible to provide one or more layers with specific functionalities, for example heat protection layers or chromotropic layers. In order to use the construction element (1) as a translucent window element, it has proven useful in addition to the use of glasses mentioned above to form the at least one planar element (9) of a translucent material, preferably of organic, inorganic or hybrid closed-cell or open-cell foams or coated or uncoated textiles. As an alternative to the above-mentioned embodiment, the at least one planar element (9) may be formed from a mineral, metallic, polymeric and / or bioorganic material. This is advantageous if the construction element (1) should not be used as a translucent component, but is exposed to increased mechanical stresses (metallic material, fiber-reinforced polymer) or purely for thermal insulation (mineral and / or polymeric material). Furthermore, it is possible with this embodiment, also ecologically particularly compatible design elements (1) to create (bio-organic materials). The material used may be open-pored or closed-cell. In addition, as far as the outer first or second plate (3, 5) of the structural element (1) has been suitably coated or otherwise modified so as to reflect the incident solar radiation directly or diffusely, the structural element (1) will find a particular one during the daytime low heating due to the sunlight instead.

In order to be able to react flexibly to a wide variety of requirements for the construction element (1) according to the invention, it has proven to be advantageous to use the material of the frame (7) made of concrete, gypsum, clays, glasses, natural stones, ceramics, polyamide, polyesters, wood, metals in particular steel and aluminum and its alloys, PVC, polycarbonate, PMMA, styrenics, polyurethanes and fiber composites and composite materials of two or more of these materials and of open-cell or closed-cell foams and fibreboards of synthetic or renewable raw materials. It is particularly preferred if the material of the frame (7) is made gas- and / or moisture-proof.

In particular, in embodiments of the construction element (1) according to the invention, which need not be translucent, the abovementioned materials can also be used for one or both plates (3, 5), i. the first plate (3) and / or the second plate (5) are used. Preferably, materials with low thermal conductivity should be used. Furthermore, in another embodiment, the frame (7) may be constructed of photovoltaic elements or solar thermal elements. Such elements are known to the person skilled in the art and can be embodied either as opaque elements or as partially translucent constructions. They can also be used so that only a part of the frame surface is claimed by them.

In one development of the invention, at least the first plate (3) and / or the second plate (5) and / or the at least one planar element (9) can be structured three-dimensionally on the surface. As a result, optical effects can be achieved, for example, a glare protection in direct incident light by modifying the Angle distribution of the emitted light and / or by changing its intensity effect. As far as a plurality of planar elements (9, 9a, 9b) are included in the construction element (1) according to the invention, the light-directing effect can be further enhanced by suitable combinations of planar elements (9, 9a, 9b) with different angular behavior of the translucency. For example, it has proved particularly advantageous to combine a planar element (9, 9a, 9b) with strongly isotropic translucence on the outside and a planar element (9, 9a, 9b) with a preferred ablation perpendicular to the element surface to increase the effect of light distribution in the depth of the room. A similar effect as in a three-dimensionally structured surface can be achieved by a combination of flat elements (9, 9a, 9b) with different translucency properties.

In addition, design effects can be achieved in the non-technical field by means of three-dimensional structuring. Alternatively, the first and / or second plates (3, 5) and / or the at least one planar element (9) may be printed or coated to achieve the same or similar effects.

In a particularly preferred embodiment, the construction element (1) according to the invention comprises

a first planar element (9a) and a second planar element (9b) whose width corresponds in each case to the vertical clear width W of the frame (7) and whose height is in each case smaller than the clear height H of the frame (7),

wherein the first sheet member (9a) and the second sheet member (9b) are disposed between the first plate (3) and the second plate (5) so as to end laterally with the inner sides of the frame (7), respectively

wherein between the first sheet-like element (9a) and the second sheet-like element (9b) and the frame (7) vertically upwards respectively a first upper gap (1 1 a) and a second upper gap (1 1 b) and between the first planar element (9a) and the second planar element (9b) and the frame (7) is formed vertically downwards in each case a first lower intermediate space (13a) and a second lower intermediate space (13b),

a first cavity (15) formed between the first plate (3) and the first planar element (9a) at a distance X,

a second cavity (17) formed between the second planar element (9b) and the second plate (5) at a distance Y,

a third cavity (23) which is formed between the first planar element (9a) and the second planar element with a distance Z,

wherein at least the first cavity (15) and the second cavity (17) over the first upper space (1 1 a) and the second upper space (1 1 b) and the first lower gap (13 a) and the second lower gap (13 b ) so that at least between the first Cavity (15) and the second cavity (17) via the first upper space (1 1 a) and the second upper space (1 1 b) and the first lower gap (13 a) and the second lower gap (13 b) flow a convection flow can.

The convection flow which forms thereby flows essentially 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.

In a second aspect, the present invention relates to the use of the above-described structural element (1) as a wall and / or roof element in buildings or vehicles, in particular in rail vehicles or watercraft. Especially in rail vehicles with their large ratio between wall surface and volume and long idle times in places with high solar radiation here the need for active cooling can be reduced.

The third aspect of the present invention, which achieves the above object, relates to a method of controlling the heat transfer coefficient U in a structural element (1) described above comprising the steps

Providing a construction element (1),

Delivery of heat energy through the gas filling the volume V to the first plate (3) or the second plate (5) on a second side of the constructional element (1), whereby the gas filling the volume V in the other of the cavities (15 17) cools and falls vertically downwards, so that the convection flow from this cavity (15, 17) flows through the lower intermediate space (13) into one of the cavities (15, 17),

Other features, advantages and applications will become apparent from the following description of the preferred, but not the invention restricting embodiments and the figures. All the described features alone or in any combination form the subject matter of the invention, also independent of their summary in the claims or their relations. Show it:

Fig. 1 is a schematic representation of a construction element in a first

Embodiment of the invention, a schematic representation of a construction element in a second embodiment of the invention, a detailed view of the area marked in FIG. 2, a simplified representation of the construction element shown schematically in FIG.

FIG. 3b is a simplified representation of that shown in FIG

Structural element with schematically shown Konventionsströmung, Fig. 4a is a simplified representation of the illustrated in Fig. 1

Construction element with schematically shown prevented conventional flow,

4b shows a simplified representation of that shown in FIG

Construction element with schematically shown prevented conventional flow,

Fig. 5 is a schematic perspective view of that shown in Fig. 1

Design element

Fig. 6 is a schematic representation of a construction element in a

Embodiment of the invention with reduced flow resistance.

FIG. 1 shows the basic form of a construction element 1 according to the invention. The structural element 1 is constructed by a frame 7 which forms four sides of the element, namely top and bottom and the side surfaces. In the frame 7 opposite two plates 3, 5, that is, a first plate 3 and a second plate 5, are arranged, which define together with the frame 7 a closed volume. Inside the defined volume, a planar element 9 is arranged such that it terminates laterally in each case with the frame 7 and above an upper intermediate space 1 1 and below a lower gap 13 to the frame leaves free. Furthermore, the sheet-like element 9 is arranged at a distance X from the first plate 3 and at a distance Y from the second plate 5.

As shown in the simplified illustration of FIG. 3 a, a convection flow can form around the flat element 9. In the illustration of Figure 3a, heat from the second plate 5 is transferred by free convection to the first plate 3, wherein the free convection is adjusted by the temperature T ₂ on the left side of the figure being greater than the temperature Ti on the right Side of the figure is. 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 results in a pressure difference before and after the lower gap 13, which finally sets the convection in motion, so that the warmer gas from the second cavity 17 flows through the upper space 1 1 in the first cavity 15, while the colder gas over the lower Interspace 13 flows into the second cavity 17. Overall, this is an energy flow from right to left.

FIG. 2 schematically shows a preferred embodiment of the invention. This has two arranged in the defined volume surface elements 9a, 9b, i. a first planar element 9a and a second planar element 9b. These are arranged in principle like the flat element 9 in Figure 1, but with the difference that they form a third cavity 23 with the distance Z from each other. As shown in Figure 3b, the formation of the internal convection flow is substantially the same as the embodiment shown in Figure 3a.

In order to regulate or prevent the convection flow, in one embodiment, the planar element 9 can be moved by a suitable means, for example upwards, so that it closes the upper intermediate space 11, as shown in FIG. 4a. Although the volume of gas heated by the heat W1 in the first cavity 15 can rise to the top, the formation of a convection flow is not possible due to the closed upper intermediate space 11.

Similarly, the particular embodiment shown in FIG. 2 acts when the one or more first and / or second planar elements 9, 9a, 9b are displaced such that one of the interspaces 11a, 11b, 13a, 13b that is, the first upper clearance 1 1 a, the second upper clearance 1 1 b, the first lower upper clearance 13 a, the second lower clearance 13 b, is closed. One possible configuration is illustrated in FIG. 4b, in which the first planar element 9a has been displaced upwards in order to close the first upper intermediate space 11a, while the second planar element 9b has been displaced downwards to close the second lower gap 13b. Also in this embodiment, no convection flow can form.

In general, the configurations in Figures 3a and 3b represent the state in which the structural element 1 has a maximum heat transfer coefficient U, that is, it allows maximum heat transfer. On the other hand, the configurations in FIGS. 4a and 4b represent a state in which the construction element 1 has its minimum heat transfer coefficient U, ie offers maximum thermal insulation.

FIG. 5 is a perspective view of the construction element 1 shown in FIG. 1, from which it is particularly clear how the planar element 9 terminates laterally with the frame 7. Figure 6 shows an embodiment of the construction element according to the invention with reduced flow resistance, wherein the reduction of the flow resistance by the rounding 25 of the edges of the sheet member 9 and by round molding 27 of the corners of the first and / or second plates 3, 5 takes place. The advantage of such an embodiment is that, with the same temperature difference, a larger convection current results and thereby more energy can be transmitted, whereas in the closed case (FIGS. 4a, 4b) there is no deterioration of the insulating effect.

Depending on the installation situation of the construction element 1, more than two planar elements 9, 9a, 9b may also be provided in the defined volume V. In addition, it may be advantageous to reduce the third cavity 23 formed between two first and second planar elements 9a, 9b to a minimum, up to the embodiment that the first and second planar elements 9a, 9b touch.

According to a further embodiment, active convection elements can be integrated into the first cavity 15 and / or into the second cavity 17. By "active convection elements" is meant, for example, small rotors which assist in the formation of the convection flow and maintain it, which in particular increases the switching stroke between the higher temperature side T ₂ and the lower temperature side Ti.

As is clear from the figures, in contrast to the effect known from the prior art, the construction element 1 according to the invention can in particular be used to dissipate heat from buildings. This can be advantageous, for example, in the warm season. Furthermore, the Application of the construction element 1 according to the invention for heat dissipation from industrial buildings conceivable.

Depending on the installation situation of the construction element 1 according to the invention, the first and / or second plates 3, 5 can be designed to be either vertical or inclined. In this way, both wall surfaces and sloping roof surfaces can be formed. The angle of the sloping roof surfaces to the vertical is substantially between 0 ° and 90 °, preferably between 5 ° and 60 °. Despite the oblique position of the construction element 1 according to the invention, the principle of the controllable heat transfer coefficient U is maintained, i. the control by targeted control of the internal convection current.

For the use of the construction element 1 according to the invention for flat roof surfaces, only slight structural changes have to be made, so that the inner convection current is still ensured. Mandatory for use in flat roof surfaces is the use of inflatable bellows, sliders, flaps or wedges instead of the displacement of the sheet-like elements 9, 9a, 9b, since these with too high friction and a resulting damage to the sheet-like elements 9, 9a, 9b would be connected. Depending on the circumstances, a slightly different dimension of the construction element 1 may be necessary.

The construction element 1 according to the invention can therefore be used as a wall and / or roof element in a shell, without having to provide further wall elements or roof elements. Of course, the construction element 1 according to the invention can also be used as a classic insulating element for placement on a facade.

In a further embodiment, the at least one flat element 9 formed of a flexible, open-cell foam based on melamine resin, commercially available under the name of Basotect ^® (BASF SE) is available. Basotect ^® displays consistent physical properties over a wide temperature range, with low weight, good thermal insulation properties and high sound absorption capacity. In addition, Basotect ^® (without the addition of flame retardants) is flame retardant, making an inventive construction element 1 with this material particularly suitable for wall and / or roof elements.

In a special embodiment, the frame 7 can be provided with lighting means (for example LEDs) in order to use the construction element 1 according to the invention also for interior / exterior lighting in the dark. Further By a diffuser effect of structured plates 3, 5 and / or structured sheet-like elements 9, 9a, 9b optical and design effects can be achieved.

The preferred dimensions of the structural element 1 and its parts are given below.

The distance A between the first plate 3 and the second plate 5 is <50 cm, preferably <35 cm, particularly preferably between 5 cm and 12 cm. Generally, the higher the structural element 1 is, the wider the first and second cavities 15, 17 must be chosen to effect spontaneous convection even at small temperature differences. This ratio of height of the structural element 1 to the width of the first and second cavities 15, 17 is very sensitive and requires a precise vote. The construction elements 1 according to the invention are in principle subject to no size limitation. From a practical point of view, a height of up to 1, 5 m has been found to be useful. The width of the elements is essentially limited by the stability of the materials used and is usefully up to 5 m. For reasons of thermally induced pressure changes, the volume of gas enclosed in the construction element 1 should be kept as small as possible

The following gives dimensions for the construction element 1 according to the invention, which were determined by computer-aided optimization.

Range of values (relative) for a first embodiment of the construction element 1:

X / H: Relative thickness of the gap between plate 3 and sheet member 9:

0.001 <X / H <0.05; preferred: 0.005 <X / H <0.04

Y / H: Relative thickness of gap between sheet 9 and plate 5:

0.001 <Y / H <0.05; preferably: 0.005 <Y / H <0.04 if Y <X:

s ₀ / Y: Relative thickness of the gap between the sheet member 9 and the upper frame 7 in the high heat transfer coefficient state:

0.3 <s ₀ / Y i 5; preferably: 0.5 <s ₀ / Y ^ 4; particularly preferred: 1 <s ₀ / Y ^ 3

Su / Y: Relative thickness of the gap between the sheet member 9 and the lower one

Frame 7 in the high heat transfer coefficient condition:

0.3 <Su / Y i 5; preferably: 0.5 <Su / Y ^ 4; particularly preferred: 1 <Su / Y ^ 3 if Y> X: s ₀ / X: Relative thickness of the gap between the sheet member 9 and the upper frame 7 in the high heat transfer coefficient state;

0.3 <s ₀ / X i 5; preferred: 0.5 <s ₀ / X ^ 4; particularly preferred: 1 <s ₀ / X ^ 3

Su / X: Relative thickness of the gap between the sheet member 9 and the lower frame 7 in the high heat transfer coefficient state:

0.3 <Su / X i 5; preferably: 0.5 <Su / X ^ 4; particularly preferred: 1 <Su / X ^ 3

H: height of construction element 1:

0.25 m <H <6 m; preferred: 0.5 m <H <4 m; particularly preferred: 0.7 m <H <3 m

Range of values (relative) for a second embodiment of the construction element 1:

X / H: Relative thickness of the gap between plate 3 and planar element 9a:

0.001 <X / H <0.05; preferably: 0.005 <X / H <0.04

Y / H: Relative thickness of gap between sheet 9b and plate 5:

0.001 <Y / H <0.05, preferably: 0.005 <Y / H <0.04 if Y <X:

s ₀ / Y: relative thickness of the gap between the sheet members 9a, 9b and the upper frame 7 in the high heat transfer coefficient state:

Su / Y: Relative thickness of the gap between the sheet members 9a, 9b and the lower frame 7 in the high heat transfer coefficient state:

0.3 <Su / Y i 5; preferably: 0.5 <Su / Y ^ 4; particularly preferred: 1 <Su / Y ^ 3 if Y> X:

s ₀ / X: relative thickness of the gap between the sheet members 9a, 9b and the upper frame 7 in the high heat transfer coefficient state:

Su / X: Relative thickness of the gap between the sheet members 9a, 9b and the lower frame 7 in the high heat transfer coefficient state:

0.3 <Su / X i 5; preferably: 0.5 <Su / X ^ 4; particularly preferred: 1 <Su / X ^ 3 H: height of the construction element 1:

0.25 m <H <6 m; preferred: 0.5 m <H <4 m; particularly preferred: 0.7 m <H <3 m

Range of values (relative) for a first embodiment with reduced flow resistance: r / (AXY): Relative radius of curvature of the planar element 9: 0 <ι7 (Α-Χ-Υ) <0.5; preferably: 0, 1 <r / (AXY) <0.5; particularly preferred: 0.25 <r / (A-XY) <0.5

R / A: Relative rounding radius of the outer corners:

0 <R / A <0.5; preferably: 0, 1 <R / A <0.5; particularly preferred: 0.25 <R / A <0.5

For the spacing 23 of the planar elements 9a, 9b, which defines the gap 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

In an experimental setup, the properties of design element prototypes according to the invention were determined. For the plates 3, 5, plexiglass discs with a size of 800 × 800 mm were used, while the flat element consisted of a translucent insulating material (non-colored Basotect®). The frame 7 was made of PVC plates. The strength of the prototype was 96 mm. The cavities 15, 17 each had a dimension X, Y of 30 mm. The experimental setup was chosen so that between two identical prototypes of the type described above, a heatable element was inserted, while on the opposite sides of coolable elements were provided. The heat flow from the heatable element to the coolable elements was measured electrically. The heat flow through one of the prototypes is thus half of the total measured heat flow. In this way, the thermal conductivity λ and the heat transfer coefficient U were measured.

In a first measuring setup (I), the dimension of the upper space 1 1 was 60 mm and the dimension of the lower space 13 0 mm, in a second measurement setup (II) were both dimensions of the upper and lower spaces 1 1, 13 each 30 mm. In a further pair of measurement setups (II I) and (IV), the two switching states of a construction element 1 according to the invention in the configuration with two planar elements 9a, 9b have been realized. Two flat elements 9a, 9b of Basotect® with a thickness of 15 mm each were used in the measurement setups. The dimensions of the cavities 15 and 17 were each 15 mm, the dimension of the gap 23 10 mm. In structure (III), the dimensions of the spaces 1 1 a and 13b were 30 mm, the dimensions of the spaces 1 1 b and 13a 0 mm. In structure (IV), the dimensions of the spaces 1 1 a, 1 1 b, 13a and 13b were each 15 mm. The structures (III) and (IV) were additionally measured with C0 ₂ as filling gas instead of air. These measurements are indicated in the table with ll lb and IVb. For each measurement setup, two measurements with a low temperature difference between the heatable element and the coolable element (measurements 1 and 3) and a measurement with a high temperature difference between the heatable element and the coolable element (measurements 2 and 4) were carried out. The measurement results are shown in the table below.

Measurements 1 and 3 show that the heat transfer coefficient U is more than doubled when the position of the sheet 9 is changed while substantially the same temperature difference is applied to the prototype.

Measurements 2 and 4 confirm that the convection and thus also the heat transfer coefficient U increase with the temperature difference. With the experimental setup and the measurements it was shown that the heat transfer coefficient U can be regulated in the construction element according to the invention. LIST OF REFERENCE NUMBERS

1 construction element

3 first plate

5 second plate

7 frames

9 flat element

9a first planar element

9b second planar element

1 1, 1 1 a, 1 1 b upper space

13, 13a, 13b lower space

15 first cavity

17 second cavity

23 third cavity

25 rounded outside corner

27 rounded inside corner

H clear height of the frame. 7

W clear width of the frame 7

A distance first plate 3 to second plate. 5

X distance first plate 3 to planar element 9, 9a, 9b

Y distance second plate 5 to planar element 9, 9a, 9b

S-i thickness of the first plate 3

S ₂ , S _2a , S _2b thickness of the sheet-like element 9, 9a, 9b

S ₃ thickness of the second plate 5

S ₀ width upper intermediate space 1 1, 1 1 a, 1 1 b

S _u width lower gap 13, 13 a, 13 b

r radius inside corner

R radius outside corner

Claims

claims

1 . Construction element (1) with controllable heat transfer coefficient U, comprising

a frame (7),

a first plate (3) and a second plate (5) facing each other and spaced apart from each other in the frame (7),

wherein a closed volume V defined by the first plate (3), the second plate (5) and the frame (7) is filled with at least one gas,

Second construction element (1) according to claim 1, wherein the first plate (3) and / or the second plate (5) is at least partially transparent or translucent.

3. Construction element (1) according to claim 1 or 2, wherein the at least one means in the vertical displacement or tilting about a horizontal axis of the at least one planar element (9), so that the upper intermediate space (1 1) and / or the Lower intermediate space (13) through the flat element (9)

[Characters] closed and the convection flow is thereby completely or partially prevented.

4. Construction element (1) according to claim 3, wherein the at least one means further comprises a device (19) for displacing the at least one planar element (9), preferably selected from servomotors, pneumatic, magnetic or piezoelectric systems, mechanical levers, cables or bimetallic structures.

5. construction element (1) according to claim 1 or 2, wherein the at least one means comprises the change of the vertical extent of the at least one planar element (9), so that the upper intermediate space (1 1) and / or the lower intermediate space (13) closed by the sheet-like element (9) and the convection flow is thereby completely or partially prevented.

6. Construction element (1) according to claim 1 or 2, wherein the at least one means comprises a closure means for the upper intermediate space (1 1) and / or for the lower gap (13), preferably selected from flaps, inflatable tubes or bellows, cylinderhahnformigen Closures or sliding or rotating wedges.

7. Construction element (1) according to one of the preceding claims, wherein the first plate (3) and / or the second plate (5) is transparent and the material of the first plate (3) and / or the second plate (5) glasses and / or polymers.

8. The structural element (1) according to claim 7, wherein the glasses are selected from silicate glasses, borosilicate glasses, lead silicate glasses and / or the polymers are selected from PET, PVB, EVA, polyolefins, styrenics, polycarbonates, PMMA, polyurethanes, PVC or mixtures or Multi-layer systems thereof, wherein the polymers are formed as plates or extruded, blown or cast films.

9. Construction element (1) according to one of the preceding claims, wherein the at least one planar element (9) is formed from a translucent material selected from organic, inorganic or hybrid closed-cell or open-cell foams or coated or uncoated textiles.

10. Construction element (1) according to one of claims 1 to 8, wherein the at least one planar element (9) is formed from a mineral, metallic, polymeric and / or bioorganic material.

1 1. Construction element (1) according to one of the preceding claims, wherein the material of the frame (7) is selected from concrete, gypsum, clays, glasses, natural stones, ceramics, polyamide, polyesters, wood, metals, PVC, polycarbonate, PMMA, styrenics, polyurethanes and fiber composites and composites of two or more of these materials, as well as open cell or closed cell foams and fiberboards of synthetic or renewable resources.

12. Construction element (1) according to one of the preceding claims, wherein the first plate (3) and / or the second plate (5) and / or the at least one planar element (9) is structured three-dimensionally on the surface.

13. Construction element (1) according to one of the preceding claims, comprising

a first planar element (9a) and a second planar element (9b) whose width correspond to the vertical clear width W of the frame (7) and whose height is less than the clear height H of the frame (7) the first sheet-like element (9a) and the second sheet-like element (9b) are disposed between the first plate (3) and the second plate (5) so as to terminate laterally with the inner sides of the frame (7), respectively

a third cavity (23) formed between the first planar element (9a) and the second planar element at a distance Z, wherein at least the first cavity (15) and the second cavity (17) extend beyond the first upper space (FIG. 1 a) and the second upper intermediate space (1 1 b) and the first lower intermediate space (13 a) and the second lower intermediate space (13 b) are connected in such a way that at least between the first cavity (15) and the second cavity (17 ) above the first upper one Space (1 1 a) and the second upper space (1 1 b) and the first lower space (13 a) and the second lower space (13 b) can flow a convection flow.

14. Use of the construction element (1) according to one of claims 1 to 13 as a wall and / or roof element in buildings or vehicles.

15. A method for controlling the heat transfer coefficient U in a structural element (1) according to one of claims 1 to 13, comprising the steps

Providing a construction element (1),

Delivery of heat energy through the gas filling the volume V to the first plate (3) or the second plate (5) on a second side of the constructional element (1), whereby the gas filling the volume V in the other of the cavities (15 , 17) cools down and falls vertically downwards, so that the convection flow from this cavity (15, 17) flows through the lower intermediate space (13) into one of the cavities (15, 17), wherein the opening and / or closing of the lower space (1 1) and / or the upper intermediate space (13), the intensity of the convection flow is adjusted.