DE202022100876U1 - Device for the controlled heating of shaped bodies - Google Patents

Abstract

Having a device for the controlled heating of shaped bodies (7).
a) a high-frequency voltage source (1), the high-frequency voltage source (1) providing an electromagnetic field with at least one frequency in the range from 100 kHz to 300 MHz,
b) at least two electrodes (5, 6), the shaped body (7) to be heated being arranged in an area of influence of the at least two electrodes (5, 6),
c) a control unit (10) for controlling the high-frequency voltage source (1), the control unit (10) being connected to the high-frequency voltage source (1).

Description

The invention relates to a device for the controlled heating of building material shaped bodies such as asphalt or concrete slabs and shaped bodies of other materials by means of electromagnetic waves, preferably in the frequency range of radio waves, containing at least two electrodes, which are matched in terms of their field distribution, for introducing the high-frequency energy into their area of influence the material to be treated is located, which in turn are preferably connected to a high-frequency voltage source via an electronic matching network. In preferred variants, the device is supplemented by a control unit, as a result of which largely automated operation can take place. Furthermore, it is advantageous to provide the device with a device for feeding in the material to be heated and a device for removing the heated material, which can optionally be the same or different from the feed. In a particularly preferred variant, the device contains a means for measuring the temperature of the material to be heated.

Asphalt is a mixture of one or more rock components with an organic component as a binder, for which bitumen obtained mostly from mineral oil fractions is used. In dielectric heating, energy absorption usually occurs through the rock phase, even when its moisture content is low. This advantageously leads to passive heating of the organic bitumen phase, which minimizes the risk of unwanted thermal damage to this phase. This also applies to special asphalts that contain other material components to modify the usage properties. For this reason, high-frequency dielectric heating is predestined for heating asphalt in a controlled manner up to the processing temperature, which is usually above 100°C. Due to the low humidity and the higher penetration depths, heating with frequencies in the range between 100 kHz and 300 MHz, preferably between 1 and 50 MHz, has advantages compared to microwave heating, in which frequencies above 500 MHz are typically used. Within these ranges, frequencies that are released for industrial, medical and scientific work (ISM frequencies) are particularly preferred.

The damage to the bitumen phase initiated or accelerated by temperature is usually correlated with oxidative processes. Naturally, the access of atmospheric oxygen is primarily relevant in the outer areas, while damage is less likely to occur inside. For this reason, the exact control of the temperature of the surface areas is of particular importance. While in conventional heating methods the heating takes place via thermal conduction from the outside to the inside, i.e. the surface region has the highest temperature, dielectric heating offers the possibility of using the device according to the invention to control the temperature distribution between the outside and inside in a targeted manner. In one embodiment, the device according to the invention also implements the option of compensating for or excluding overheating in the event of overheating of the surface caused by the water content by selecting the electrode design.

Another aspect that is influenced by the temperature control of the surface region is the mechanical stability of shaped bodies made of asphalt, for example. At higher temperatures, the rock-bitumen mixture breaks down into a pourable and therefore workable granulate. With conventional heating, i.e. heating carried out via thermal conduction, this process increases the surface and thus also the area of oxidative damage, even before the target temperature is reached inside, which usually leads to a reduction in the overall quality of the substance to be heated.

Asphalt roads and paths form an essential element of the transport infrastructure. Damage through cracking to the appearance of "potholes" occurs continuously as a result of aging, with freeze-thaw cycles, seasonal and daily temperature fluctuations, overloading and UV radiation playing a major role. This leads to the need to repair road damage in the form of potholes or other damage, since a complete new construction is generally not ecologically sensible and economically impracticable. For the repair, hot asphalt offers several advantages over alternative methods such as the use of cold asphalt due to sustainability and cost aspects. Especially in winter, when asphalt plants are closed or when repairs have to be planned at night during off-peak periods, the use of hot asphalt preferably requires on-site heating for reasons of flexibility. Using the device according to the invention, radio wave technology, in which high-frequency electromagnetic waves are used, makes it possible to heat prefabricated asphalt slabs on site to the desired temperature, so that they can be filled into the pothole in the hot state immediately afterwards.

Likewise, a thermal treatment of concrete allows to influence its hardening process and to increase the properties in the desired way determine (cf. curing of fresh concrete, DE 102013217864 B4 "Method for curing hydraulically setting building material mixtures and treatment device"). Here, too, high-frequency energy can be used to heat the concrete with different levels of free water, ie also in different phases of the hardening process, for which the device according to the invention can be used.

Another possible application of the device according to the invention is the heating of building material bodies for the purpose of removing pore water in order to be able to subsequently introduce additives such as organic polymers into the material. Another application option is the killing of potentially harmful insects or fungi after procurement or in the course of a restoration.

In principle, there are a number of established heating methods in which the energy input takes place via the outer surfaces of the shaped body and in which the heat propagation inside is based on heat conduction processes. This is naturally associated with internal temperature gradients and thus temperature differences. The greater the overheating of the outer surfaces, the faster the warming up occurs on the inside. However, there are limits to this, which are correlated with the temperature sensitivity of the materials and the internal dielectric strength. For this reason, processes based on heat conduction such as heating plates, radiators or burners have considerable disadvantages, especially for types of rock that are prone to thermal fracture, such as marble, or sensitive materials with low heat conduction, such as wood, wax or asphalt materials.

Dielectric heating, on the other hand, has the advantage of introducing energy directly into the volume of the building material, which leads to significantly lower internal temperature differences and thus damage to the material. In turn, dielectric heating in the high-frequency range is advantageous over the use of microwaves, since the flexibility is greater, especially with dry materials, the heating is often more homogeneous and the penetration depths are greater.

With regard to the prior art, the use of different variants of high-frequency heating with frequencies in the range between 100 kHz and 300 MHz, preferably between 1 and 50 MHz, is described, which differ in terms of the geometry and the coupling of the electrodes used. In the simplest case, parallel plate or mesh electrodes are used to homogeneously heat a material between these electrodes [ EP 2354349 A2 "Device for drying and decontamination of masonry, concrete, wood and other solids"]. A typical example of this is the heating of masonry. If access to the body of material to be heated is only possible from one side, a superficially arranged binary electrode array can be used, whereby the effect of the penetration depth given for high-frequency radiation for material heating is also used on the inside [ DE 102016107550 A1 and EP3236710B8 "Method and device for the thermal treatment of solids"]. The use of this option is preferable, for example, for chemical-free wood protection for parquet or wall paneling. In addition, a capacitive coupling can be used if an electrode arrangement cannot be contacted on both sides, as is the case, for example, with a damp cellar wall or a cellar floor. Here, a working electrode is arranged on one side, which is surrounded by a grounded shield. On the other side of the structure to be heated there is a conductive structure that forms a capacitor arrangement with the aforementioned electrodes and that mediates the energy input into the volume [ EN 102016107547 B3 and EP 3236711 B1 "Method and apparatus for non-invasive dielectric heating of solids"]. The device according to the invention basically uses the first principle, but due to the special and adapted design according to the invention, which is explained in more detail below, ensures the homogeneous heating of the building material body under different conditions.

In particular, the device can be used to heat thermally sensitive materials, in which undesirable processes increasingly occur from a certain temperature as the temperature rises, with sufficient homogeneity to temperatures that enable further processing but largely rule out damage. In a focused field of application, the heating of shaped asphalt bodies, for example, damage to the organic bitumen phase and emission of pollutants can be significantly reduced. The adjustment according to the invention of the electrode properties to the material with possibly varying humidity and in particular surface humidity enables a sufficiently homogeneous increase in temperature. In addition, based on a correlation of surface and volume temperatures, it is possible to use the temperature measurement on the surface to control the process. Here, the frequency range used offers an advantage over, for example, microwaves in the frequency range above 500 MHz, since the material there can practically not be heated dielectrically without sufficient moisture or on the other hand, in the case of increased moisture in the surface area, overheating of which cannot be avoided.

The relationship between internal and surface temperature is therefore of process engineering (homogeneity to avoid thermal damage) and metrological significance. From a metrological point of view, heat losses into the environment, either via the electrodes or via the surrounding medium, also play a role in this relationship. It should be noted that the internal temperature of many shaped bodies can hardly be measured directly, since damage to the material is to be avoided, the material consistency makes it difficult to drill holes for sensors, or other reasons make direct temperature detection in the volume difficult.

Since the target temperatures are usually well above the ambient temperature, the surface areas would be heated at a lower heating rate due to heat losses with homogeneous primary energy input, which also leads to lower end temperatures in the corresponding area. To prevent this, the configuration of the heating device according to the invention using radio waves is used, whereby preferred heating of the areas particularly affected by the heat losses, such as corners and edges, can be made possible and the temperature profile is thus homogenized.

Moisture plays a major role in energy absorption in the material. For this reason, water films on the outer surface or particularly moist surface areas can also have a strong influence on heating by radio waves. Here even preferential heating of the surface areas would be possible, which could lead to higher temperatures remaining on the surface despite the heat losses. An electrode design according to the invention could also be used for such cases in order to achieve homogeneous heating rates.

The requirement of a sufficiently homogeneous heating to achieve the material-technical effects, the processability and the avoidance of thermally induced damage requires a special arrangement of the individual components for high-frequency heating, which is tailored to the dielectric material properties and which also takes into account the geometric boundary conditions and the roughness of the material Shaped body considered. In addition, process control components such as feeders should preferably be included in the design. In many cases, the roughness and the need to remove the treated material from the device mean that a gap remains between the surface of the plate or the surface of the shaped body and one, preferably the upper, electrode. This air gap significantly changes the distribution of the electrical field in the body of the building material and thus the dielectric heating in the material volume. Another boundary condition is the possible presence of an inhomogeneous moisture distribution in the material body, with increased moisture in the edge areas, for example due to outdoor storage, being typical. Due to the significant influence on the dielectric properties, these areas of increased humidity also determine the heating in its spatial characteristics.

Although the device according to the invention is used in most cases to heat the shaped body as homogeneously as possible, overheating or undercooling of the surface can also be advantageous in certain applications. This is the case, for example, when a surface coating requires temperatures for structure formation that are higher than those that are to be achieved in the interior according to the method. In another case, it may be necessary to keep the surface temperature lower than the temperature inside, for example, since air ingress at the surface would lead to greater damage at the same temperature. In this case, a cooling device can be effective, for example, via a directed air flow.

A device according to the invention offers particular flexibility in which two parallel plate electrodes are supplemented by a working electrode constructed as a cage at a defined distance from individual surfaces of the shaped body. In a preferred variant, this working electrode can be inserted into the device automatically. In a particularly preferred variant of the device according to the invention, the working electrode is at the electrical potential of the outer shielding and/or one of the two parallel plate electrodes.

In order to solve the specific tasks of the device according to the invention, various defined device options were developed which enable the homogeneous heating of differently shaped and differently moist material bodies. The corresponding developments also included the presence of a gap (preferably an air gap) and, in preferred implementations, feed components for the shaped body. Various implementation options of the device according to the invention are shown as examples in the exemplary embodiments.

The invention is explained below by way of example using exemplary embodiments with reference to the drawings. The different features of the embodiments can be combined independently of one another, as has already been explained for the individual advantageous configurations.

• 1 eine schematische Gesamtdarstellung der Anlage zur Radiowellen-Erwärmung von Formkörpern,
• 2 eine Ausführung der Radiowellen-Erwärmungseinheit mit möglichen peripheren Komponenten,
• 3 eine Ausführung der Radiowellen-Erwärmungseinheit mit weiteren möglichen peripheren Komponenten,
• 4 eine exemplarische Detaildarstellung einer technischen Realisierung der erfindungsgemäßen Vorrichtung,
• 5a eine Darstellung der homogenen Erwärmung eines formstabilen isotropen Formkörpers zu moderaten Temperaturen,
• 5b eine Leistungseintragsdichteverteilung des in 5a gepunktet dargestellten Ausschnitts,
• 6a eine Darstellung der homogenen Erwärmung eines formstabilen isotropen Formkörpers mit rauer oder klebriger Oberfläche,
• 6b eine Leistungseintragsdichteverteilung des in 6a gepunktet dargestellten Ausschnitts,
• 7a eine Darstellung der selektiven Erwärmung bestimmter Bereiche eines formstabilen isotropen Formkörpers mit rauer oder klebriger Oberfläche: Seite (oben) und obere Kante (unten) als exemplarische Ausgestaltungen,
• 7b ein selektiver Energieeintrag in die kurze Seite (oben) bzw. die obere Kante (unten) des zu erwärmenden Körpers in Form der Leistungseintragsdichteverteilung des in 7a gepunktet dargestellten Ausschnitts,
• 8a eine Darstellung der Realisierung von verschiedenen Erwärmungsmustern für eine selektive Erwärmung bestimmter Bereiche bzw. eine homogene Erwärmung unter Verwendung einer zusätzlichen Elektrode: selektive Erwärmung der oberen Kante (oben), homogene Erwärmung (Mitte) oder selektive Erwärmung der unteren Kante (unten) als exemplarische Ausgestaltungen,
• 8b Leistungseintragsdichteverteilungen der in 8a jeweils schwarz gepunktet dargestellten Ausschnitte für eine selektive Erwärmung der oberen Kante (oben), eine homogene Erwärmung (Mitte) sowie eine selektive Erwärmung der unteren Kante (unten),
• 9a eine Darstellung einer Anordnung eines Formkörpers mit erhöhter Feuchte im Oberflächenbereich,
• 9b Temperaturverteilung der Anordnung aus 9a direkt nach einer Radiowellen-Leistungs-anwendung von 6 kW für 20 min mit einer Starttemperatur von 20°C (293 K),
• 10a eine Darstellung einer Anordnung eines Formkörpers mit erhöhter Feuchte im Bereich der horizontalen Begrenzungsflächen,
• 10b Temperaturverteilung der Anordnung aus 10a direkt nach einer Radiowellen-Leistungs-anwendung von 6 kW für 20 min mit einer Starttemperatur von 20°C (293 K),
• 11a eine Darstellung einer Anordnung eines Formkörpers mit erhöhter Feuchte im Bereich der vertikalen Begrenzungsflächen,
• 11b Temperaturverteilung der Anordnung aus 11a direkt nach einer Radiowellen-Leistungsanwendung von 6 kW für 20 min mit einer Starttemperatur von 20°C (293 K),
• 12a eine Darstellung einer Anordnung eines kontrolliert zu erwärmenden Formkörpers mit sensibler Oberfläche,
• 12b Temperaturverteilung der Anordnung aus 12a direkt nach einer Radiowellen-Leistungsanwendung von 24 kW für 20 min mit einer Starttemperatur von 20°C (293 K),
• 13 Prinzipskizze für den Einsatz der erfindungsgemäßen Vorrichtung bei der Reparatur eines lokalen Straßenschadens (Schlagloch) und
• 14 eine Zusammenfassende Darstellung der technischen Realisierung einer modular aufgebauten, mobilen Anlage zur Radiowellen-Erwärmung von vorkonfektionierten Asphalt-Formkörpern.

Show it:

• 1 a schematic overall view of the system for radio wave heating of shaped bodies,
• 2 an embodiment of the radio wave heating unit with possible peripheral components,
• 3 an embodiment of the radio wave heating unit with further possible peripheral components,
• 4 an exemplary detailed representation of a technical realization of the device according to the invention,
• 5a a representation of the homogeneous heating of a dimensionally stable isotropic molded body at moderate temperatures,
• 5b a power input density distribution of the in 5a dotted excerpt,
• 6a a representation of the homogeneous heating of a dimensionally stable isotropic shaped body with a rough or sticky surface,
• 6b a power input density distribution of the in 6a dotted excerpt,
• 7a a representation of the selective heating of certain areas of a dimensionally stable isotropic molded body with a rough or sticky surface: side (top) and upper edge (bottom) as exemplary configurations,
• 7b a selective energy input into the short side (top) or the upper edge (bottom) of the body to be heated in the form of the power input density distribution of the in 7a dotted excerpt,
• 8a a representation of the realization of different heating patterns for selective heating of certain areas or homogeneous heating using an additional electrode: selective heating of the upper edge (top), homogeneous heating (middle) or selective heating of the lower edge (bottom) as exemplary configurations ,
• 8b Power input density distributions of the in 8a excerpts shown with black dots for selective heating of the upper edge (top), homogeneous heating (middle) and selective heating of the lower edge (bottom),
• 9a a representation of an arrangement of a shaped body with increased moisture in the surface area,
• 9b Temperature distribution of the arrangement 9a directly after a radio wave power application of 6 kW for 20 min with a starting temperature of 20°C (293 K),
• 10a a representation of an arrangement of a shaped body with increased moisture in the area of the horizontal boundary surfaces,
• 10b Temperature distribution of the arrangement 10a directly after a radio wave power application of 6 kW for 20 min with a starting temperature of 20°C (293 K),
• 11a a representation of an arrangement of a shaped body with increased moisture in the area of the vertical boundary surfaces,
• 11b Temperature distribution of the arrangement 11a immediately after a radio wave power application of 6 kW for 20 min with a starting temperature of 20°C (293 K),
• 12a a representation of an arrangement of a shaped body to be heated in a controlled manner with a sensitive surface,
• 12b Temperature distribution of the arrangement 12a immediately after a radio wave power application of 24 kW for 20 min with a starting temperature of 20°C (293 K),
• 13 Schematic diagram for the use of the device according to the invention in the repair of a local road damage (pothole) and
• 14 a summary of the technical realization of a modular, mobile system for radio wave heating of pre-made asphalt moldings.

• - eine erfindungsgemäße Vorrichtung zur kontrollierten und vorzugsweise homogenen Erwärmung von Formkörpern mit isotropen dielektrischen Eigenschaften,
• - eine erfindungsgemäße Vorrichtung zur kontrollierten und vorzugsweise homogenen Erwärmung von Formkörpern mit rauer Oberfläche mit der Notwendigkeit eines Spaltes zwischen einer Elektrode und einer Formkörperoberfläche,
• - eine erfindungsgemäße Vorrichtung zur kontrollierten Erwärmung mit selektiv erhöhtem Energieeintrag in bezüglich des Wärmeabflusses exponierten Stellen wie Kanten oder Seiten an materialbezogen isotropen Formkörpern mit und ohne rauer Oberfläche, gegebenenfalls mit der Notwendigkeit eines Spaltes zwischen einer Elektrode und der Formkörperoberfläche,
• - eine erfindungsgemäße Vorrichtung zur kontrollierten und vorzugsweise homogenen Erwärmung mit einer zusätzlichen Arbeitselektrode, vorzugsweise mit einstellbarem Potenzial bezüglich der anderen beiden Elektroden,
• - eine erfindungsgemäße Vorrichtung zur kontrollierten und vorzugsweise homogenen Erwärmung von Formkörpern mit einem Wasserfilm im gesamten oberflächennahen Bereich,
• - eine erfindungsgemäße Vorrichtung zur kontrollierten und vorzugsweise homogenen Erwärmung von Formkörpern mit einem Wasserfilm im Bereich einer horizontal angeordneten Oberfläche,
• - eine erfindungsgemäße Vorrichtung zur kontrollierten und vorzugsweise homogenen Erwärmung von Formkörpern mit einem Wasserfilm im vertikal angeordneten Randbereich und
• - eine erfindungsgemäße Vorrichtung mit einer zusätzlichen Kühleinrichtung.

In individual cases, the various exemplary embodiments relate to

• - a device according to the invention for the controlled and preferably homogeneous heating of shaped bodies with isotropic dielectric properties,
• - a device according to the invention for the controlled and preferably homogeneous heating of shaped bodies with a rough surface with the need for a gap between an electrode and a shaped body surface,
• - A device according to the invention for controlled heating with selectively increased energy input in terms of heat dissipation exposed areas such as edges or sides on material-related isotropic molded bodies with and without a rough surface, possibly with the need for a gap between an electrode and the molded body surface,
• - a device according to the invention for controlled and preferably homogeneous heating with an additional working electrode, preferably with adjustable potential with respect to the other two electrodes,
• - a device according to the invention for the controlled and preferably homogeneous heating of shaped bodies with a water film in the entire near-surface area,
• - a device according to the invention for the controlled and preferably homogeneous heating of shaped bodies with a film of water in the region of a horizontally arranged surface,
• - A device according to the invention for the controlled and preferably homogeneous heating of shaped bodies with a film of water in the vertically arranged edge region and
• - An inventive device with an additional cooling device.

The flexibility of the device according to the invention also enables it to be used for other applications in dielectric heating using high-frequency energy.

The entire system for radio wave heating of moldings is in the 1 illustrated.

A high-frequency voltage source 1, usually a radio wave generator, is connected to at least two electrodes 5 and 6, preferably via a coaxial cable 2, in a preferred embodiment via an electronic matching network 3 and lines 4. The generator 1 can also be connected directly to the electrodes 5 and 6, but this usually leads to less than optimal energy transmission and reduced energetic efficiency of the heating. The shaped body 7 to be heated is located in the area of influence of the at least two electrodes 5 and 6. A horizontal arrangement of plate-shaped, plane-parallel electrodes 5 and 6 is preferred because the best field homogeneity can thereby be ensured. The design of the electrodes is explained in more detail in the exemplary embodiments. In a preferred variant, there is an air gap 8 above the shaped body 7 and below an electrode 6. In a preferred variant of the arrangement according to the invention, the arrangement is provided with at least one means 9 for measuring the temperature of the shaped body, preferably the surface temperature. In a particularly preferred embodiment variant, the generator 1 and means for measuring the temperature 9 are connected to a control unit 10, as a result of which a predefined heating process can be implemented, preferably by setting and process-specific temporal adjustment of the high-frequency power. All options for achieving control and regulation tasks are to be summarized here under the term control unit. This can preferably be, for example, a fixed electrical circuit, an internal control unit of the generator and/or electronic matching network, a programmable logic controller, an external computer system or a combination of these variants. Also, the term control unit does not necessarily mean a locally delimited or locally delimitable component. Alternatively, it is also possible for the control unit to comprise a plurality of decentrally arranged (partial) components which are operatively connected to one another and thus implement the control of the high-frequency voltage source. In a preferred embodiment variant, the electrode system is surrounded by an electromagnetic shield 11, with one of the electrodes 5, which is then referred to as the “cold” electrode, being electrically conductively connected to the shield 11 in a preferred implementation option. In one embodiment variant, the system can be supplemented by means for measuring the electric field strength 12 , which in turn can be connected to the control unit 10 . For the purpose of occupational and operational safety, this enables the power to be switched off if the field strengths are too high. In a preferred embodiment, the device can be provided with means for feeding in and removing the shaped body 7 or the thermally treated material, which is explained in the following 2 is shown as a detailed view and is explained in more detail below.

In one embodiment variant, a means 13 for feeding the shaped body 7 into the space in the area of influence of the electrodes 5 and 6, preferably between the electrodes 5 and 6, is arranged in the vicinity of the electrodes. In a particularly preferred variant, this is supplemented by a reservoir 14 for shaped bodies 7 . A transport device 15 preferably feeds the shaped bodies 7 into the effective area of the electrodes 5 and 6 .

In a preferred embodiment, the material of the shaped body 7, its consistency tenz may have changed during the heating process and has become pourable in a preferred process variant, removed by a sliding device 17 from the area of the electrodes 5 and 6 and preferably fed to a storage container 18. The container 18 is preferably a thermal container with low heat losses to the environment. To improve the filling process, a funnel 19 can be arranged in the vicinity of the storage container 18 . The device according to the invention can be supplemented by further components in order to improve the functionality for the respective specific applications.

In another preferred variant according to 3 In the device according to the invention there is an outlet 20 for removing the shaped body 7 near the electrodes 5 and 6. Such a device is preferably used if the shaped body 7 remains dimensionally stable or substantially dimensionally stable during the thermal treatment.

In order to control the course of the potential and the energy input, the two electrodes 5 and 6 can be supplemented by an additional electrode 21 with an adjustable potential in one embodiment of the device according to the invention. It is also possible in a preferred embodiment to cool specific areas or surfaces of the shaped body in a targeted manner by means of a cooling device 22 in order to avoid thermal damage to the material on the surface.

By varying the design of the electrodes 5 and 6 and optionally 21, the heating process can be designed optimally for a wide range of shaped bodies and materials according to specific criteria (final temperature and homogeneity of the temperature profiles). This is explained in more detail below for the specific applications already mentioned.

The exemplary embodiments also illustrate possible variants of the technical implementation of the device according to the invention, one of which is shown again as an example in 4 is shown.

Device according to the invention for the controlled heating of an isotropic, dimensionally stable shaped body with little heat dissipation via the side surfaces

In this case, an electrode design is used in which the area of the electrodes is at least as large as that of the shaped body, and the shaped body can therefore be arranged completely between the electrodes. In order to reduce the necessary voltage, the smallest thickness of the solid is preferably selected as the electrode spacing.

In a preferred embodiment, both electrodes protrude beyond the shaped body on all sides ( 5a) . Both flat electrodes touch the surface of the shaped body. A possible application example for this is a wooden structure with flat surfaces that is to be continuously heated to temperatures of 70°C in order to kill the wood pests contained therein. This problem partially exists, for example, for imported timber, which can still contain pest larvae. Such temperatures are known to be sufficient to produce a lethal effect. When heated to moderate temperatures, heat losses to the environment play a lesser role and may not require any special measures to compensate for these heat losses. The simulation of the power input density in 5b shows that a largely homogeneous field can be realized by the protruding electrodes in the edge area, which in turn represents the basis for homogeneous heating. In the technical implementation, the outlet could be 20 in 3 and 4 be used.

Device according to the invention for the controlled heating of molded bodies with a rough or sticky surface that requires a gap between an electrode and the surface of the molded body

This embodiment variant of the device according to the invention is particularly predestined for shaped bodies that have rough surfaces and therefore do not ensure ideal contact between the electrodes and the surface.

Examples of this are wooden moldings with surface models and moldings made of asphalt, concrete or other mineral building materials. The corresponding situation, which makes an air gap appear sensible, also exists when, due to sticky surfaces at the beginning or during heating, contact with the electrode surfaces is to be minimized as much as possible and the removal of the shaped body from the arrangement after heating is to be supported. Another example of the use of this arrangement is the boundary condition that the shaped body should not be mechanically stressed on five sides. In the cases mentioned, an arrangement according to the invention 6a to be selected that ensures an air gap between the material surface and at least one electrode. The air gap is preferably realized between the surface and the live, "hot" electrode. The gap can also be filled with another medium or evacuated if the device is in an appropriate atmosphere sphere or in a vacuum. In this case, too, the electrodes are designed in preferred variants in such a way that they protrude beyond the shaped body. The resulting power input density is exemplary in 6b for the arrangement 6a shown. Increased heat losses via the side surfaces, which were taken into account accordingly in the simulation, result in largely homogeneous temperature profiles with a suitable design of the device according to the invention.

Device according to the invention for the controlled heating of a shaped body with selectively increased energy input in places exposed to heat dissipation, such as edges or sides, with or without overheating of the edge region

There are a number of applications in which an increased energy input into the side surfaces of the shaped body has to be implemented. On the one hand, increased heat dissipation into the environment can be compensated for, which leads to a homogeneous temperature distribution in the entire molded body, including the edge area. On the other hand, it may be desirable to expose the side area to higher temperatures, for example to initiate structural changes, leading to a more dimensionally stable surface. In such cases, there are typically medium and high target temperatures above 100°C.

A device according to the invention for achieving the described effects using an air gap between the material surface and the upper, preferably live, "hot" electrode is 7a shown. As already explained, this variant makes it possible to adequately treat moldings with rough or sticky surfaces.

The achieved profile of the specific power input of the dielectric heating by means of radio waves is in 7b illustrated. With the local power input density realized in this way, the desired effects can be achieved with different boundary conditions (see above and below). In this example it is possible, in the manner shown, to achieve a power input density ( 7 , above) or a power input density increased by about 40% ( 7 , below), compared to the mean power input density in the remaining, predominant part of the panel.

Device according to the invention for controlled homogeneous or selective heating using an additional working electrode, preferably with an adjustable potential with respect to the other two electrodes

In an exemplary application of the device according to the invention, an asphalt slab is to be heated in a controlled manner. In order to prevent or limit sticking when heated, the contact to the electrodes should be reduced by leaving the side surfaces exposed and creating an air gap between the surface and the upper electrode. In addition, with an otherwise unchanged structure, the plate should be heated flexibly (for example, selectively or homogeneously, depending on the application and boundary conditions), by inserting a cage electrode adequately at the desired discretion.

This embodiment variant, which 8a is shown also offers the possibility of specifically compensating for any heat dissipation into the environment and thus ensuring an overall more homogeneous heating. In order to achieve largely flexible heating, a cage-like electrode is also attached perpendicularly to the other two, which can be changed in height and distance from the plate. It is also connected to either the grounded or the live electrode, or fixed at a potential in between, directing the electric fields in such a way that the desired heating is also possible under the given conditions. The results are illustrated by showing the power input densities in 8b illustrated.

In the example shown, either selective heating or as homogeneous a heating as possible should be realized thanks to the cage electrode used on the side. Details are in the various illustrations 8th refer to.

Device according to the invention for the controlled and preferably homogeneous heating of shaped bodies with increased moisture in the entire area close to the surface

Water almost always has a major influence on the dielectric heating of materials. This effect is well known for microwave heating and can be explained by the orientational polarization of the water molecule. However, this influence also occurs for radio wave heating, although the relationships here are more differentiated due to the underlying physical interactions [Roland et al., "On the role of water in dielectric heating with radio waves", Chem. Eng. tech 32 (2009) 754-762; Kraus et al., "Influence of humidity and temperature on the permittivity of zeolite NaY", Phys. Chem. Chem. Phys. 13 (2011) 4119-4125]. The object of the device according to the invention was therefore to be able to react in a targeted manner to the various possible situations of different local moisture in the shaped body and to be able to achieve the desired heating effects even with the existing moisture distribution.

In the first case, this relates to increased moisture in the entire area of the shaped body near the surface, ie in the arrangement according to FIG 9a the two horizontally and the four vertically arranged surfaces. The areas of increased moisture are marked in gray in the figure and identified by arrows, with the panel showing a water layer 1 mm thick all around (arrows). This situation can occur, for example, when the shaped bodies, such as asphalt slabs, have been stored outdoors and have absorbed moisture. A temperature change with condensation can also lead to the formation of a water film in the surface area. Finally, surface treatments with water are common to remove contaminants from wooden objects.

To solve the problem, an electrode arrangement is selected whose geometric extent is greater than that of the plates. The overhang of the two electrodes is approximately the same as the height of the plate to be heated, where one electrode can also be selected to be larger. A largely homogeneous heating, even under these complicated boundary conditions, can be achieved if the two electrodes are thermally insulated as required and the vertical side surfaces are exposed, thus enabling good heat dissipation into the environment. The compensation effect that occurs due to the evaporation of water due to the enthalpy of evaporation must also be taken into account. 9b shows in a simulation of the resulting temperature distribution the homogeneous temperature profile in the molded body that occurs under these conditions during dielectric heating.

Device according to the invention for the controlled and preferably homogeneous heating of shaped bodies with water films in the area of the horizontally arranged surfaces

Higher levels of moisture near the surface can occur, for example, if, due to the surface roughness, there is preferential water absorption on these surfaces, for example during storage under the influence of the weather. This can, for example, relate to prefabricated asphalt slabs that are to be heated to the processing temperature with the device according to the invention. If, for example, a partial panel is cut out of a larger composite, it will have dry side surfaces but moister base and top surfaces.

To solve the task of uniform heating, the air gap arrangement is again selected, with the voltage-carrying electrode being 10 mm smaller than the plate to be heated in order to optimize the energy input. In addition, care must be taken to ensure that a cage electrode is used that is perpendicular to both electrodes, that is placed at about twice the distance between the electrodes and that is connected to ground potential. The corresponding arrangement is in 10a shown schematically, with the plate showing layers of increased moisture 1 mm thick at the top and bottom (arrows).

In the present case, due to increased energy absorption in the edge area (increase in the real part of the relative dielectric constant with increasing water content, for example for the mineral components of the asphalt), overheating of these areas of increased moisture occurs. However, the temperature differences are reduced or overcompensated by a weakening of the electric field. In addition, the heat dissipation via the electrodes, depending on the quality of the thermal insulation, plays a role in the formation of the resulting temperature profile. The areas of increased humidity are in 10a marked in gray and indicated by arrows. By adjusting the parameters of the device according to the invention, it is possible to minimize the temperature differences in the shaped body despite different local moisture levels and to achieve homogeneous heating in the material. This is illustrated by displaying the temperature profile in 10b demonstrated.

Device according to the invention for the controlled and preferably homogeneous heating of shaped bodies with a film of water in the vertically arranged edge area

This device according to the invention is able to treat shaped bodies with increased moisture and therefore increased energy absorption in the vertical areas of the surfaces of the shaped body, so that the desired homogeneous temperature profiles can be achieved. The solution to the problem is of interest, for example, when prefabricated shaped bodies have been moistened on the vertical outer surfaces due to their stacked storage. This can be the case when asphalt slabs are stored in stock for road damage repair and then heated on site and poured into potholes in pourable condition be brought. A schematic for this application is included 11a . The area of increased moisture is marked in gray in the figure and indicated by an arrow, with the board showing a layer of increased moisture 1 mm thick along the short sides (arrow).

To solve the task, the air-gap arrangement is again selected, with the voltage-carrying electrode being 10 mm smaller than the plate to be heated in order to optimize the energy input. In addition, care must be taken to ensure that a cage electrode is used that is perpendicular to both electrodes and is connected to ground potential. This optimizes the input of energy into the humid areas in question and more homogeneous temperature profiles are achieved as desired.

The result of a simulation for the temperature distribution that occurs due to the radio wave treatment is shown 11b . In practical use, the heat flow via the side surfaces must also be taken into account.

Device according to the invention with an additional cooling device

This preferred option of the device according to the invention using a means for cooling relates, for example, to certain shaped bodies such as, for example, historical wooden components with a surface seal or colored version. The aim here is that, while achieving a target temperature inside the shaped body, the surface temperature does not exceed a certain level. In the specific case of the application example, a wooden panel is to be heated to 65°C in order to kill the wood pests in it, but without destroying the artistic painting on the upper side, which should not reach temperatures significantly above 30°C.

In this case, in addition to the options already described, a cooling device can be used for the surface, which reduces the temperature on the surface in a targeted and controlled manner. A possible interpretation is in 12a shown, where the cooled surface (at the same time the live electrode) is marked with an arrow, while the hot electrode, which is located directly above the load to be heated, is continuously cooled (arrow). From a technical point of view, cooling increases the heat flow from the surface to the environment. The result is a reduction in the surface temperature compared to the temperature in the volume of the shaped body.

To solve the problem, an electrode arrangement is selected whose geometric extent is greater than that of the plates. The overhang of the two electrodes is approximately the same as the thickness or height of the plate to be heated, where one electrode can also be selected to be larger. In addition, one electrode (in this case the upper, live one) is cooled to 20°C by a Peltier element applied on top or by capillary cooling inside the plate.

An example of controlled heating with a cool surface and otherwise largely homogeneous temperature distribution based on a thermal simulation is given in 12b shown.

Design example: Modular device for heating prefabricated asphalt slabs

As already shown schematically in the 1 , 2 , 3 and 4 and shown by way of example in the exemplary embodiments, the device according to the invention can be designed and optimized for many application situations, with the specific solution approaches and features presented in the previous exemplary embodiments being available.

For further illustration, a complete system is presented at this point, which can be used in large numbers for the radio wave heating of prefabricated asphalt slabs. The asphalt is heated to such an extent that a pourable material is created, which is transferred to a thermal container and can be stored there until it is used. The principle sketch is in 13 shown.

In accordance with the basic structure given in the 1 , 2 and 3 has been shown, the device according to the invention contains in this case a high-frequency or radio wave generator as a voltage source, an electronic matching network (matchbox), a cooler, two parallel plate electrodes, a shielding housing, a storage container for storing the asphalt plates, a pushing device for feeding the plates into the electrode area and for pushing the heated material through a hopper into the thermal vessel, the thermal vessel itself, a diesel generator for power generation, an uninterruptible power supply, sensors for temperature measurement and positioning, and control components (also compare 1 , 2 and 3 ).

For operation, the asphalt slabs from the storage room are placed between the electrodes by means of a sensor-controlled positioning device. The high-frequency generator is then switched on and the Plate is heated up to approx. 150°C until a pourable state is reached. The asphalt material is then transferred to the storage container using a pusher. Another asphalt sheet can then be prepared for heating in the same way. The total amount of asphalt provided can be flexibly adapted to the respective needs for the repair to be carried out or other measures.

For better illustration let in 14 again listed a construction example for a mobile, modular device according to the invention for repairing road damage. This contains the essential components that are already in the schematic representations of the 1 , 2 and 3 were specified. For reasons of clarity, no detailed information on the individual components is given here. The summary is given in 14 .

Finally, it should be emphasized that the device according to the invention, with its specific design features, can be used for a large number of applications that cannot be presented comprehensively in this context.

Reference List

1

High frequency voltage source

2

coaxial cable

3

Electronic Matching Network

4

cables

5.6

electrodes

7

molding

8th

air gap

9

Means for measuring temperature

10

control unit

11

Electromagnetic shielding

12

Means for measuring the electric field strength

13

Means for feeding the shaped body

14

Storage container for shaped bodies

15

transport device

16

lifting device

17

sliding device

18

reservoir

19

funnel

20

Outlet for removing the molded body

21

Electrode with adjustable potential

22

cooling device

23

hot asphalt

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102013217864 B4 [0006]
• EP 2354349 A2 [0010]
• DE 102016107550 A1 [0010]
• EP 3236710 B8 [0010]
• DE 102016107547 B3 [0010]
• EP 3236711 B1 [0010]

Claims (20)

Having a device for the controlled heating of shaped bodies (7). a) a high-frequency voltage source (1), the high-frequency voltage source (1) providing an electromagnetic field with at least one frequency in the range from 100 kHz to 300 MHz, b) at least two electrodes (5, 6), the shaped body (7) to be heated being arranged in an area of influence of the at least two electrodes (5, 6), c) a control unit (10) for controlling the high-frequency voltage source (1), the control unit (10) being connected to the high-frequency voltage source (1). device after claim 1 , wherein the high-frequency voltage source (1) is a radio wave generator and, wherein the radio wave generator is connected to the at least two electrodes (5, 6) via a coaxial cable or via a binary waveguide (2) via an electronic matching network (3). . device after claim 1 , wherein the high-frequency voltage source (1) is a radio wave generator and wherein the radio wave generator is electrically conductively connected directly to the at least two electrodes (5, 6). Device according to one of the preceding claims, in which the at least two electrodes (5, 6) are designed as a horizontal arrangement of plate-shaped, plane-parallel electrodes (5, 6). Device according to one of the preceding claims, wherein an air gap (8) is arranged between the shaped body (7) to be heated and at least one of the electrodes (5, 6). Device according to one of the preceding claims, wherein the device has a means (9) for measuring the temperature of the shaped body (7). device after claim 6 , wherein the control unit (10) is additionally connected to the means (9) for measuring the temperature of the shaped body (7). Device according to one of the preceding claims, wherein the device comprises an electromagnetic shield (11), the electromagnetic shield (11) surrounding the at least two electrodes (5, 6). device after claim 8 , wherein the electromagnetic shielding (11) is electrically conductively connected to one of the at least two electrodes (5, 6). Device according to one of the preceding claims, wherein the device comprises means (12) for measuring an electric field strength. Device according to one of the preceding claims, wherein the device comprises means (13) for supplying and removing the shaped body (7). Device according to one of the preceding claims, wherein the device comprises a storage container (14) for shaped bodies (7). Device according to one of the preceding claims, wherein the device comprises a transport device (15), the transport device (15) being designed to supply and/or remove the shaped body (7) into the effective area of the electrodes (5, 6). . Device according to one of the preceding claims, wherein the device comprises a lifting device (16), the lifting device (16) being designed to increase the position of the shaped body (7) within the effective range of the electrodes (5, 6) or the distance between the electrodes vary. Device according to one of the preceding claims, wherein the device comprises a pushing device (17) and a second storage container (18), wherein the pushing device (17) is designed to remove the material of the shaped body (7), which can be poured after the treatment, from the effective range of the electrodes ( 5, 6) to be removed and fed into the second reservoir (18). device after claim 15 , wherein the second reservoir (18) is a thermal container. Device according to one of Claims 15 or 16 wherein the device comprises a funnel (19), wherein the funnel (19) is arranged on the second storage container (18). Device according to one of the preceding claims, wherein the device comprises an outlet (20) for removing the shaped body (7). Device according to one of the preceding claims, wherein the device comprises a cooling device (22) for cooling parts of the shaped body (7) or the shaped body (7) as a whole. Device according to one of the preceding claims, wherein the device includes a power supply such as diesel generator, battery riespeicher and / or solar module includes to enable off-grid operation.

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