DE102004025033A1 - Radiant heaters with heating elements made of graphite foils or graphite laminate boards - Google Patents

Abstract

The invention relates to radiant heaters made of marble, granite, marbled limestone or other natural stones, metal, ceramic, glass or their combinations with heating elements of graphite or graphite laminate. The provision of such heating elements results in improved energy efficiency, longer service life, reduced manufacturing costs, increased heating rate and limited electromagnetic radiation emissions.

Description

The The invention relates to radiant heaters of marble, granite, marbled Limestone or other natural stones, ceramics, glass or their combinations with heating elements made of graphite foils or graphite laminate plates. The equipment with such heating elements results in improved Energy efficiency, higher Lifetime, reduced production costs, increased heating rate and reduced electromagnetic radiation emissions.

Radiant heating, especially made of natural stone, have been known for a long time. These show the back an electric heating arrangement, which heats the radiator, which has a high Heat storage capacity features. Compared to conventional Wall heaters omitted Mostly a convective upheaval the air, creating a pleasant and healthy indoor climate with optimal Humidity arises. When using natural stones as a jet body possess These heaters also have an aesthetic Value and fulfill in the house at the same time decorative purposes. In addition, radiation heaters can be used format and require arbitrary just a power connection, so they also work as mobile units or about in caravans and in many other areas outside a permanent accommodation for applications. Another popular Application of radiant heaters is the preparation of food, such as when grilling or for the pizza baking.

by virtue of various new provisions by the legislature are the Requirements for the efficiency of heating systems in the recent past increased sharply. This development mainly affects the electricity-driven radiant heaters, which are no longer installed as full heaters in new buildings allowed to.

EP 1 182 406 describes a radiant heater made of natural stone with meandering or spirally inserted and glued heating conductors on the back in channels. For this purpose, however, must first be milled into the relatively expensive and brittle natural stone material channels into which the heating conductors are laid. Then the channels are filled with marble cement.

In US 6,087,630 is a method for heating surface radiators set forth, wherein a laminated heating element is sandwiched between the radiant bodies to be heated embedded. For this purpose, several steps and the introduction of various other functional layers are necessary.

To DE 200 15 750 For example, a natural stone radiant heater may also be made to apply a laminated heater mat to the back of the radiant body. In order to meet the different coefficients of thermal expansion (CTE), several adhesive layers are used here.

In all cases, already in the basic approach, the energy balance of the radiant heater is degraded by using heating mats, which consist of a combination of mostly metallic wires or thin sheets with one or more plastic films and other insulating materials. The term heating mat is to be understood in the sense of the description of the invention quite generally a flexible planar structure which acts as an electrical resistance heating. The insulation of the heating element creates an extremely high heat transfer resistance, which leads to high losses in the heat transfer to the radiation body. In addition, these losses are further increased by the poor contact of the heating mats with the surface of the radiation body. One tries, among other things, to remedy this blemish by smoothly polishing the surface of the radiation bodies ( EP 0 445 253 ), whereby, however, the result obtained partially perverts the target, since with a smoothly polished surface, the geometric contact surface is again significantly reduced in comparison with a surface with natural roughness, for example in the case of natural stones.

Besides the energy losses increase with increasing useful life, since it due to the partially highest different CTEs of the materials used, such as copper wire, Plastic films, adhesives or natural stone, to Delaminationserscheinungen through material fatigue due to cyclic thermal stress.

Around the heat generated in the heating mat as possible only to the front, that is to say in the direction of the radiator body, is to act it is also common thermal insulating Layers in the form of sheets or foils on the back of the To install heating mat. This requires further labor and material costs.

The outstanding advantage of radiant heaters, in particular made of natural stone, their high heat storage capacity, can also be perceived as a disadvantage. The resulting inertia in heating is a flaw that can not be remedied with conventional heating mats in situations or applications where the user desires rapid heating, such as when entering a cold apartment or when preparing food. The heat losses at the interface between conventional heating mats and the radiation body are so high that it takes more than a day to heat radiation by 30 heat up mm thick marble slab. In addition, due to the heat losses, the temperature of the heater can hardly exceed 60 ° C.

These Heating mats use engineering plastics, which at temperatures up to 150 ° C can be used, but then partially soften at the same time the delamination described above is greatly accelerated. It is so not possible in practice, with these heating mats accelerated heating of the jet body by short-term Heating the mats to temperatures well above 200 ° C, without thereby clearly the heating mat itself and the composite to the jet body damaged would.

This irreversible adverse result is also obtained when the conventional Heating mats are overheated due to technical malfunction.

One meanwhile important quality aspect for the Purchase and use of radiant heaters, which are in the house area mainly because of the positive health aspects as well as in terms of legal guidelines, the quantity is that of such heaters emitted electromagnetic radiation, too referred to as electrosmog. Since almost always mats with braided copper wires There is a high risk of being emitted electromagnetic radiation to undesirable load on users leads and that legal standards for electrosmog are no longer complied with can.

It So the task was to use radiant heaters with improved energy efficiency, higher life, reduced production costs, increased heating speed and limited electromagnetic radiation emissions.

The The object is achieved in that one for one Radiant heaters an electrically conductive heating element made of graphite foils or graphite laminate plates used to heat the jet body.

At various embodiments will below, the inventive element described. The accompanying drawings will be explained below.

1 : Radiant heating in the side profile

2 : View of a graphite heating element

The 1 shows a side sectional view of a radiant heater, the erfindungsmäßige execution will be described below. In 1 becomes a radiation body 1 made of natural stone, which is at least 0.5 cm and at most 10 cm thick. It can be marble, granite or marbled limestone. The essential characteristics of this natural stone heating result from the fact that this high-quality and carefully selected natural stones are used. This makes every natural stone heater a stylish unique. The term marble is defined differently. In geological science marble is a metamorphic rock transformed from limestone. In the construction industry, in commerce and in the vernacular every solid and therefore polishable limestone is called marble. The "real", that is, the metamorphic marble is formed by contact or regional metamorphosis of limestone, it is coarsely crystalline and like limestone monominerally composed of calcite.Some crystals are coarsened at the expense of others, so that the whole aggregate shows a sugar-like appearance. Foreign components change the originally snow-white rock into a striped, flamed, speckled, grained, veined, colorful marble with two major differences: Crystalline marble is mostly coarse-crystalline, sugar-granular, translucent in plates, more fossil, and has no voids. the marbled limestone being finely crystalline and not translucent, occasionally containing voids and often fossils.

On the back of the radiation body 1 meandering graphite heating elements are located 2 consisting of graphite foils or graphite laminate boards, which are made of natural graphite. This is converted by the incorporation of foreign ions into so-called storage or intercalation compounds. The thermal decomposition of the intercalation compounds produces expanded, voluminous graphite flakes, which are rolled into flexible films without the addition of a binder or pressed into sheets and molds. This material, which is marketed by the SGL Carbon Group under the brand name ^® SIGRAFLEX, has extraordinary properties. Particularly important are the anisotropy of the electrical and thermal conductivity, the temperature resistance and the reflection of heat radiation. Graphite sheets or graphite laminate sheets can be used as standard in air up to 400 ° C and under protective gas atmosphere up to more than 3000 ° C, are exceptionally temperature resistant, have smooth reflecting surfaces, have excellent chemical resistance, are very light and have a low heat storage capacity. When used as Heizleiterermaterial their small thickness allows extremely short heating and cooling cycles. In particular, the graphite foils can be very easily processed by cutting, punching, embossing or similar methods.

These advantages make them an ideal construction material for high-temperature furnaces where they serve for heat insulation or as a heating element ( DE 2646890 , Brochure "SIGRAFLEX graphite foils and graphite laminate panels for thermal insulation and electrical heating elements", 2001) However, the most important application of this material is in gaskets where the graphite material is used because of its plastic deformability Various graphite materials are able to absorb high frequency electromagnetic radiation For example, in mobile phones or computers.The particular suitability for the absorption of electromagnetic radiation results from the special energetic structure of the chemical graphite structures.

Graphite laminate panels are made of 2 graphite foil layers with a core of sheet metal or Wire mesh made for mechanical reinforcement.

graphite foils and many graphite laminate plate types are very easy to machine. For cutting or punching, similar tools and devices can be used use as for processing cardboard boxes.

in the The purposes of this invention are graphite sheets and graphite laminate sheets collectively referred to as graphite heating elements.

graphite heating elements are very thin, because they have a very high conductivity due to the high anisotropy within the layer plane, and unlike heating elements from a metal-plastic laminate the complete material cross-section for the transmission of electrical power and at the same time to Distribution of heat is being used. The thickness of the graphite sheets used is only 0.15 mm to 0.5 mm and the graphite laminate plates 0.5 mm to 2 mm.

By resulting extremely short heating and cooling cycles let yourself very quickly a perfectly adjustable temperature-steady state to reach.

The Heating time is determined primarily by the thermal conductivity of the material of the radiation body. It is about for a temperature difference of 70 ° C (20 ° C - 90 ° C) at a Marble plate of 30 mm thickness at about 30 min.

In addition, by a very rapid heating to temperatures of 250 ° C up to 400 ° C and a correspondingly tuned, easy-to-regulate, sequential cooling of the Graphitheizelemente also a rapid heating of the radiation body 1 be effected to required operating temperatures. In the 1 graphite heating elements shown 2 are made meander-shaped for optimal use of heating power with little use of heating conductor material. In addition, the geometric design of the Graphitheizelemente can be made very diverse due to the ease of processing. The graphite heating elements can be produced, for example, with relief, mesh, slot, serpentine or hole structures.

there can Hole structures are incorporated, which holes or Wells for later attachment from auxiliary equipment, panels or wall brackets.

These geometric structures can through different processing methods are generated. graphite foils and graphite laminate plates due to their small thickness and relatively soft consistency cut easily, milled, punched or stamped become. This can already be done during the production of the graphite foils and graphite laminate plates take place, so no trimmings attack. Even if the desired Geometries in the finished graphite sheets or graphite laminate sheets mainly graphite foil waste is produced, which can be 100% recycled.

As a rule, the graphite heating element is used for a more efficient assembly 2 in one piece to make this on the inside of the back cover 5 but, of course, smaller segments can be made if necessary.

A heating unit is made, such that a graphite foil is applied to a custom-cut Fermacell plate 5 is glued. As adhesive Weican RK 1500 can be used. The adhesive has an approved temperature range of -40 ° C to + 180 ° C. After curing, the graphite heating element 2 the meander structure introduced by CNC milling technology. The power contacts 3 are realized by applied with conductive adhesive Cu films. On the back of the Fermacell plate 5 becomes a 230 V junction box 4 mounted, in which the thermal switch, the security element and the connections are located. After cleaning the graphite heating element 2 the conductive side is covered with an up to 6 kV voltage resistant Isalierlack. The radiation heating thus produced is then by means of wall plugs 7 , Special anchor 8th , Wall bracket 9 and spacers 10 on a wall 6 appropriate.

The heating power depends on the size of the radiation body 1 and after the operation of the surface heating element. A typical value is a heating power of 500 W for a panel radiator of dimensions 1 m × 0.5 m at 230V input voltage.

2 shows a view of a Graphitheizelements 2 on a back cover 5 with the external dimensions of the junction box 4 and the power contacts 3 ,

The above-described combination of missing insulation layers and the direct and very close contact between graphite heating element 2 and radiation body 1 enables the reduction of heat transfer losses across this interface by more than 50%.

The through the flow of current in the graphite heating element 2 generated electromagnetic radiation is absorbed in situ due to the special electronic structure of the graphite, so it is generated very little electrosmog. In addition, the graphite heating element 2 Intercept electromagnetic radiation that may be generated by other sources, such as running in the wall power lines.

The Equipment of radiant heaters with Graphitheizelementen results in significantly improved energy efficiency, longer life, reduced Production costs, significantly increased Heating rate and limited electromagnetic radiation emissions. By this invention, the use of radiant heaters as primary heating in buildings despite strict energy efficiency standards. Radiant heaters according to the invention let because of the fast and accurate temperature control also a more user-friendly preparation of food when used as a grill or Baking plate too. The simple, flat and inexpensive construction of the radiant heaters according to the invention allows another use of these in applications such as gazebos or in the camping area.

1

radiant body

2

graphite heating elements

3

current contacts

4

junction box

5

back cover

6

wall

7

wall plugs

8th

special anchors

9

spacer

10

wall mount

Claims (11)

Radiant heating with radiation bodies of marble, granite, marbled limestone or other natural stones, metal, ceramic, glass or their combinations with heating elements, characterized in that heating elements made of graphite or graphite laminate boards are used. Radiant heating with radiant marble, granite, marbled Limestone or other natural stones, metal, ceramics, glass or their combinations with heating elements, characterized in that It can be heated briefly to 400 ° C until it heats up. Graphite heating elements according to claim 1, characterized in that that they are made of a graphite foil thickness of 0.15 mm to 0.5 mm or a graphite laminate plate of thickness 0.5 mm to 2 mm. Graphite heating elements according to claim 3, characterized in that that they meander, Have relief, mesh, slot, serpentine or hole structures. Graphite heating elements according to claims 3 to 4, characterized that they are during or after production of the graphite sheets or graphite laminate sheets cut, milled, punched or stamped become. Graphite heating elements according to claims 3 to 5, characterized that their outer dimensions are those of the radiation body correspond. Graphite heating elements according to claims 3 to 5, characterized that their external dimensions so procure are that several segments cover the radiation body. Production of radiant heaters according to claims 1 and 2, characterized in that graphite heating elements according to claims 3 to 7 by means of adhesive under pressure on the rear, preferably rough, surface of a radiation body is glued on. Production of radiant heaters according to claim 8, characterized in that the graphite foil according to claim 3 contacted with glued copper foil. Production of radiant heaters according to claim 8, characterized in that the graphite laminate plate according to claim 3 is contacted directly on the metallic inlet. Use of radiant heaters according to claims 1 to 10 as primary heating in buildings, for preparing food as a grill or baking plate as well as for others Applications in the leisure and camping area.