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(11) | EP 4 429 405 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | A HEATING DEVICE |
| (57) The current invention concerns a heating device comprising a glass substrate whereby
an array of discrete IR radiation zones each comprising an Li2O-based conductive layer provided on said glass substrate.
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Field of the Invention
[0001] The present invention concerns a heating device, in particular an infrared heating device comprising a glass substrate whereon an IR radiation zones is provided.
Background to the Invention
[0002] Electrical heating devices generating infrared radiation are known in the art. Some of such heating devices comprise a flat glass substrate whereon a coating is applied comprising a mixture of a matrix material and nanoparticles or nanosheet, whereby the matrix material comprises a glass frit comprising one or more oxides selected from a group with amongst others, Li2O.
[0003] The heating devices of the prior art however are not designed for efficiently and effectively heating a living or outer space that has a relatively large volume in view of the heating surface provided by the heating device. With increasing awareness of electric consumption and increasing demand for in time heating of living spaces, there remains a market need for relatively small heating devices having a high heating capacity and consume relatively little power.
Summary of the Invention
[0004] The present invention addresses the above market need and provides a heating device comprising a glass substrate characterized by an array of discrete IR radiation zones each comprising an Li2O-based conductive layer provided on said glass substrate.
[0005] Said glass substrate is preferably a flat glass panel and may comprise a pattern of surface increasing elements such as nubs, preferably at its surface opposed to the surface whereon the discrete irradiation zones are provided. The glass substrate is preferably a ceramic glass substrate designed to withstand high temperatures of 400°C or more. More preferably, the glass substrate is a micro-crystalline ceramic with a Li2O-Al2O-SiO2 based structure.
[0006] The heating device comprises a layered structure of consecutively, the glass substrate, the array of discrete IR radiation zones, and an insulative, anti-oxidant layer.
[0007] The IR radiation zones comprising sintered layer comprising a mixture of a ceramic or metal material and a matrix material, said matrix material comprising Li2O. The IR radiation zones have an operating temperature of between 150 and 400°C, preferably between 200 and 350°C.
[0008] The IR radiation zones comprising an IR motivating layer comprising tourmaline and nanoparticles or nanosheets of carbon.
[0009] The present invention also concerns the use of such heating device for heating an indoor living space or an outdoor space, whereby the heating device may be configured to be fixed to a wall or fixed stand or can be configured as a portable design.
Brief Description of the Appended Figures
[0010]
Fig. 1 schematically illustrates the main parts of a heating device according to the present invention;
Fig. 2 schematically illustrates the heating device of Fig. 1 in assembled state;
Fig. 3 illustrates a glass substrate that can be used in a heating device according to the present invention;
Fig. 4a and 4b comparatively illustrate respectively a heating device having an array of IR radiation zones in accordance with the present invention and a heating device with a single IR radiation zone, when in operation;
Fig. 5 schematically illustrates a cross-sectional layer buildup of a preferred embodiment of the heating device according to the present invention.
Detailed Description
[0011] A heating device according to the present invention includes a glass substrate, an array of discrete IR radiation zones applied to a surface of the glass substrate and an insulative layer applied over the IR radiation zones (or patches) such that these zones are sandwiched between the glass substrate and the insulative layer. Further, electrodes are provided at two opposed edges of each of the conductive coating patches.
[0012] In the illustrated embodiment, the glass substrate is made of ceramic glass or any other suitable material. It is understood by one skilled in the art that ceramic glass can survive high temperature and thermal shock, and is often selected over other glass substrates in providing consistent and reliable high temperature heating functions. An example of such ceramic glass is Nextrema® by Schott®. The ceramic glass is preferably a micro-crystalline ceramic with a Li2O-Al2O-SiO2 based structure that is transparent for longwave infrared (LWIR) radiation with wavelengths ranging from 6 to 14 micrometers, preferably 8 to 14 micrometers.
[0013] The glass substrate preferably comprises surface increasing elements such as nubs, preferably on a surface of the glass facing away the IR radiation zones. Such nubs provide a more even and dispersed radiation through the glass substrate and may have a semicircular form such as to create convex lenses.
[0014] In accordance with the present invention, the array of discrete IR radiation zones are applied on the glass surface. At least one zone hereby comprises (i) IR motivating layer applied to the glass substrate and (ii) a conductive coating applied on the IR motivating layer. The conductive coating comprises Li2O. According to a preferred embodiment, the conductive coating comprises a mixture of a matrix material and nanoparticles or nanosheets. The nanoparticles or nanosheets can comprise carbon as a main element such as carbon nanotubes, carbon black, graphite, graphene, etc. and/ or can include conductive ceramic elements including at least one of an oxide, a boride, a carbide, and a chalcogenide.
[0015] Examples of oxides are: RuO2, MnO2, ReOz, VO2, OsO2, TaO2, IrO2, NbO2, WO2, GaO2, MoO2, InO2, CrO2 and RgO2. Examples of boride comprise: Ta3B4, Nb3B4, V3B4, TaB, NbB, VB. Examples of carbide are: Dy2C, Ho2C. Examples of chalcogenide comprise: AuTe2, PdTe2, PtTe2, YTe3, CuTe2, NiTe2, IrTe2, PrTe3, NdTe3, SmTe3, GdTe3, TbTe3, DyTe3, HoTe3, ErTe3, CeTe3, LaTe3, ZrTe2, HfTe2, TaTe2, TiSe2, TiTe2, Hf3Te2, VTe2, NbTe2 and CeTe2, TaSe2, VSe2, TiS2, NbS2, TaS2.
[0016] The IR motivating layer preferably comprises tourmaline and nanoparticles or nanosheets comprising carbon as a main element such as carbon nanotubes, carbon black, graphite, graphene, etc.
[0017] At least one, and preferably all of the IR zones are configured to generate LWIR radiation when applied to a alternating current of between 50 to 60HZ at 220 to 380V.
[0018] The discrete patches are preferably provided at a distance of one another. Maintaining a distance between adjacent patches allows for thermal radiation to cover a larger area of a space while allowing heat energy to be distributed more evenly in space.
[0019] The insulative layer protects the conductive layer patches from oxidation, provides electrical insulation and preferably reflects heat and infrared radiation emitted by the conductive layer when the heating device is turned on. The insulative layer can be a monolayer material or a stack of layers of different materials.
[0020] The heating device further preferably comprises a housing, defining an opening, wherein the glass substrate is provided such that the surface thereof facing away the conductive patches is situated at the outside of the housing, whereas the patches of conductive layer and the insulative layer are situated inside the housing. Outside of the housing, in this case means that the concerned surface is in direct contact with a space outside the housing. The housing preferably also accommodates electronic components for controlling the power supply to the conductive patches and a connector for an external power supply such as a power cord. The housing is preferably sealed according to IP44 standard or higher, such that the heating device is suitable for use in bathrooms or outdoors.
[0021] Fig. 1 schematically illustrates a heating device 1 according to the present invention, comprising a single glass substrate 2 with two arrays of seven discrete patches 3a, 3b of conductive coating applied thereon. Each of said patches defines a IR radiation zone. Each array is electrically connected to two electrodes 4a and 4b. Both arrays and the electrodes are covered with in this case one insulative layer 5. The glass substrate with the conductive patches provided thereon can be housed in a housing 6 such that the surface of the glass substrate opposite to the surface thereon on which the conductive patches are applied is situated outside of the housing.
[0022] The number of conductive patches is however not limited to two arrays of seven patches but can be of any number of 3 to 10 or more patches per array and with a single or a plurality of arrays applied on a single glass substrate. Clearly a heating device according to the present invention may comprise more than one glass substrate whereon one or more arrays of conductive patches are applied.
[0023] The glass substrate, as shown in more detail in Fig. 3, is in this case a flat ceramic glass substrate comprising nubs 7 on its surface opposite to the surface whereon the conductive patches are applied. The nubs increase the glass area surface and increase heat transfer through the glass from the glass surface contacting the conductive patches to the opposed glass surface where heat is transferred to the ambient air. Additionally, the nubs disperse the radiation generated in the conductive patches and as such improve the heating efficiency of the heating device for heating a space such as a living space (bathroom, kitchen, sleeping room, conference room or such) or an outdoor space such as a terrace.
[0024] The conductive patches in this case comprise a mixture of an electronic paste comprising carbon powder and Li2O, coating on the glass substrate and subsequently sintered at a temperature of between 400°C and 1000°C or even more in accordance with the exact composition requirements. When current is applied to the patches, these patches heat up and generate IR radiation, in particular, in the LWIR spectrum with wavelengths predominantly between 6 and 14 micrometers, preferably predominantly between 8 and 14 micrometers. The conductive patches are designed to heat up to between 150 and 400°C, preferably between 200 and 350°C when in operation.
[0025] The housing is preferably made in metal or in a high temperature resistant polymeric material such as PEEK, and is preferably adequately sealed to achieve at least the IP44 standard for water ingress and solids ingress. Inside the housing, the electrodes are coupled to a power supply cord 8 that, as depicted in Fig. 2 exits the housing for coupling to an external power supply, preferably power of 220-380V at 50-60Hz such as grid power.
[0026] According to a preferred embodiment, a controller (not shown) may be applied in the housing for controlling the electrical power supply to each of the arrays of patches and as such control the heat output of the heating device. The controller may be coupled to an operation module 9 that can be manipulated by a user or can communicate wireless with an external control unit that can be manipulated by a user.
[0027] Fig. 4a & 4b show pictures of a heating device according to the present invention (4a) and a heating device comprising only a single conductive patch on a glass substrate (4b) when in operation. Although the total surface area of the patches in the devices of both pictures is equal and the electrical power supplied in both devices is the same, clearly the heating device according to the present invention provides are larger effective heating surface than the heating device with a single conductive patch and this at a higher temperature. Without being bound to any theory, it is believed that the heating device according to the present invention provides a higher heating efficiency and effectiveness than heating devices with a single conductive patch.
[0028] Fig. 5 schematically illustrates a crosse section of the heating device through a single IR radiation zone, showing all consecutive layers in the heating device. Said consecutive layers comprising: the glass substrate (2), the IR motivating layer (10), the conductive layer (11), the insulative layer (12) that itself comprises a stack of layers, namely, an electrical insulation and anti-oxidative layer (12a), a LWIR ray reflecting layer (12b) and a heat insulation layer (12c) such as an insulative foam layer.
[0029] A heating device according to the present invention can be used for heating indoor living spaces and/or outdoor spaces, can be fixed to a wall or stand, or can be provided on a movable stand as a portable design.
[0030] The dimensions of a heating device according to the present invention preferably range from devices having a total surface of IR radiation zones ranging from 0,010 to 0,025 m2, allowing effectively heating living spaces ranging from approximately 10 up to 50 m2. For these dimensions the rated power of the heating device preferably ranges between 1400 and 2800W.
1. A heating device comprising a glass substrate characterized by an array of discrete IR radiation zones each comprising an Li2O-based conductive layer provided on said glass substrate.
2. The heating device according to claim 1, said glass substrate is a flat glass panel.
3. The heating device according to claim 1 or 2, said glass substrate comprising a pattern
of surface increasing elements.
4. The heating device according to any of the preceding claims, said glass substrate
is a ceramic glass substrate.
5. The heating device according to claim 4, wherein said ceramic glass substrate is a
micro-crystalline ceramic with a Li2O-Al2O-SiO2 based structure.
6. The heating device according to any of the preceding claims, having a layered structure
of consecutively, the glass substrate, the array of discrete IR radiation zones, and
an insulative, anti-oxidant layer.
7. The heating device according to any of the preceding claims, said IR radiation zones
comprising an IR motivating layer comprising tourmaline and nanoparticles or nanosheets
of carbon.
8. The heating device according to any of the preceding claims, the IR radiation zones
comprising sintered layer comprising a mixture of a ceramic or metal material and
a matrix material, said matrix material comprising Li2O.
9. The heating device according to any of the preceding claims, wherein the IR radiation
zones have an operating temperature of between 150 and 400°C, preferably between 200
and 350°C.
10. Use of a heating device according to any of the preceding claims for heating an indoor
living space.
11. Use of a heating device according to any of the preceding claims for outdoor heating.
12. Use of a heating device according to claim 9 or 10, as a portable heating device.