EP2621246A1 - Arrangement and method for heating a medium by microwave radiation - Google Patents

Abstract

The arrangement has two radiation sources (5) each with individually controllable power amplifier (5.1) which amplifies signal generated by a generator (2) and has microwave frequency. A unit is provided for radiating the amplified signal as a microwave radiation (11) into a working chamber (7). The generator stands in signaling connection with all the power amplifiers so that signal generated by the generator is applied to all the power amplifiers. The generator is tuned over a range of a predetermined frequency sector within the microwave frequency range. An independent claim is included for a method for heating a medium by microwave radiation.

Description

The invention relates to an arrangement and a method for heating a medium located in a working space by means of microwave radiation, as this generic from the EP 1 471 773 A2 are known.

In a variety of known solutions for heating media by means of microwave radiation, there is a need to produce a homogeneous distribution of the microwave radiation in and around a medium to be heated. In particular, the formation of standing waves should be avoided in order to avoid local overheating (hot spots) and local areas where no heating takes place.

Thus, for example, in the design of microwave ovens for heating food, it is customary to dimension the dimensions of the space in which the medium to be heated is located (henceforth: working space), unequal to the wavelength or a multiple of the wavelength of the microwave radiation. This avoids that in the working space radiated microwave radiation is reflected on a wall of the working space in itself and a standing wave is generated.

A combination of static reflections of the microwave radiation at the, an interior bounding walls of a housing and a dynamic reflection of the microwave radiation by means of at least one mode stirrer is in the DE 103 29 411 B4 disclosed.

In order to achieve a uniform distribution of microwave radiation in a work space, is in the technical teaching of the EP 1 471 773 A2 the approach is to arrange a number of radiation sources for microwave radiation (henceforth: radiation sources) on or around a working space. Each radiation source includes an oscillator operating at a preset microwave frequency, a power amplifier amplifying signals generated by the oscillator, and means, e.g. As an antenna, for emitting the amplified signals as microwave radiation in the working space. Each power amplifier of the number of radiation sources is individually controllable, whereby the degree of amplification is controlled. With the solution after the EP 1 471 773 A2 is it basically possible to effect a tuned to a medium radiation pattern in the workspace.

A disadvantage of the solution mentioned, as in the EP 1 471 773 A2 even stated that the number of oscillators that generate signals independently, phase shifts of the radiated microwave radiation can occur to each other. If such a phase shift is not desired, the oscillators must be preset or driven, which in addition to the control of the power amplifier further driving each of the microwave sources is required.

For applications in which a phase shift of the microwave radiation is not desirable, for example in experimental arrangements in materials science or process engineering, the solution is according to the EP 1 471 773 A2 very expensive and expensive. Moreover, it is with an arrangement according to the EP 1 471 773 A2 only possible to generate by each of the oscillators signals of a preset microwave frequency (henceforth: frequency). Thus, the frequency of the entire arrangement is fixed and no variation of the frequency possible. In addition, it is very likely that in the number of oscillators microwave radiation with slightly different frequencies are radiated, whereby a reproducibility of experiments is greatly impaired or even canceled. A change in the frequency of the arrangement would be possible only by an exchange of the number of oscillators. Especially with regard to experimental approaches, the doctrine of EP 1 471 773 A2 apart from its advantages, the question of how the individual contributions of frequencies and amplitudes of the microwave radiation and their interactions with each other and with the medium are to be separated.

The invention has for its object to propose a way to heat media by means of microwave radiation can be avoided by means of the phase shifts between the radiated microwave radiation.

The object is achieved by an arrangement for heating a medium located in a working space by means of microwave radiation, comprising at least two Radiation sources for providing microwave radiation, each with an individually controllable power amplifier, by which a signal generated by a generator, a microwave frequency exhibiting signal is amplified and means for emitting the amplified signal as microwave radiation in a working space by the arrangement of the radiation sources to each other in his spatial dimension is resolved. The arrangement is characterized in that the generator is in signal communication with all power amplifiers, so that the signal generated by the generator is applied to all power amplifiers. In addition, the generator is tunable over a range of a certain frequency section within the microwave frequency range. In the arrangement, measuring means are provided with which measurement data can be detected in the working space. Each microwave source has at least one measuring device each for acquiring measured data.

The microwave frequency range is from 300 MHz to 300 GHz (wavelengths from 1 m to 1 mm). The frequency section may be any section of the microwave frequency range. The electromagnetic waves generated by the generator are referred to as signals, while microwave radiation refers to the radiated signals amplified by one of the power amplifiers. A gain preferably causes the low-energy signals to be amplified into microwave radiation whose energy is sufficient for an intended use of the arrangement according to the invention. The microwave radiation is emitted in the form of fields, wherein the fields can be directed radiated.

The higher the efficiency of the arrangement should be, the smaller the selectable frequency range. In order to advantageously achieve the highest possible efficiency, the generator and the power amplifier are matched to one another. The maximum variability of the generator and power amplifier frequencies is +/- 100 MHz.

The core of the invention is to generate the frequency of the microwave radiation radiated from the at least two radiation sources by only a single generator. It is also essential to the invention that the generator is tunable, so as to allow a controlled change in frequency even during an ongoing heating process.

By connecting only one generator to the radiation sources, a phase shift of the radiated microwave radiation is advantageously avoided. Together with an individual controllability of each power amplifier, it is possible by means of the arrangement according to the invention to radiate microwave radiation of only a single frequency through a number of radiation sources into the working space. The generator may comprise several components. For example, there may be a means for generating the signals (eg, a means for generating signals based on semiconductor devices) and a tunable means for selectively passing (eg, an oscillator, a filter or rectifier) the selected frequency. Deviating from the aforementioned prior art, a radiation source in the sense of this description does not include a generator.

A work space may be a closed space such as the interior of a household or industrial microwave oven in which the medium is stationary. It can also be an open region through which the medium can pass and whose size is determined by an effective range of the emitted microwave radiation. Since media frequency-dependent and temperature-dependent, and thus also power-dependent, react differently to microwave radiation, an effective range is dependent on an interaction between the frequency and amplitude of the microwave radiation and the medium. The range of action is to be understood as the distance between the radiation source and the farthest point of the medium on which an effect can be detected, and is always different from a penetration depth of the microwave radiation into the medium, if the radiation source does not touch directly on the surface of the medium , While an effective range in the vacuum is theoretically infinite, with an irradiation of media as well as solid bodies, effective ranges can only exist in the range of a few nanometers or micrometers.

The work space can be enclosed, for example, by a grid of a material reflecting microwave radiation whose grid width does not allow a passage of microwave radiation, a passage of a, z. B. liquid or gaseous medium is possible. Media may be all solid, liquid and gaseous substances and mixtures or plasmas and combinations thereof.

The measuring means contained in each microwave source for the acquisition of measured data allow the detection and evaluation of variables specific to the measuring means. This can be advantageously used to protect individual, some or all radiation sources. For example, a power amplification by a control can be individually reduced or prevented if the variables detected by the measuring means exceed a predetermined threshold value. Furthermore, each measuring means for detecting quantities for other evaluations, for. B. for investigations of the behavior of a medium when heated by means of microwave radiation, be provided. Also for this purpose, the measuring means is signal-technically connected to the controller.

It is also an advantageous embodiment of the arrangement according to the invention, if in the working space further measuring means present and with the control signal technology, z. B. wired or non-wired Messdatenleitungen connected. For example, variables such as temperatures, radiations, chemical compositions and pressure can be detected spatially resolved by further measuring means. The controller is preferably designed as a computing, control and storage unit. From the controller there may be direct control lines to each of the power amplifiers as well as to each measuring means and to every other measuring means. It is also possible for the power amplifiers, the measuring means and the further measuring means to be controlled with addressed control signals, whereby the number of required control lines and measuring data lines can be reduced.

It is favorable if the measuring means and the further measuring means are shielded and arranged at the edge of the working space. The measuring means and the other measuring means may be, for example, infrared pyrometers or fiber optic sensors.

In a first embodiment of the arrangement according to the invention, the radiation sources with respect to their position relative to the working space are freely selectable. she For example, they may be designed to be manually placed directly on a surface of the medium, e.g. B. a body to be heated, can be arranged. It is advantageous if the radiation sources are designed as a compact and easy to handle unit. They may preferably be arranged in a respective housing and with this on a respective carrier. In such an embodiment of the arrangement, the spatial dimension, ie the specific spatial shape, of the working space is determined by the freely selectable positioning of the radiation sources.

A further embodiment of the arrangement according to the invention is characterized in that at least the means for emitting the microwave radiation are arranged in the working space in at least one support structure. Such a support structure can limit the spatial dimension of the working space in at least one direction. A support structure may in a simple case be a wall or walls of a working space and the means for radiation may be distributed in a certain way on or in the wall or the walls. The support structure may for example also be a support such as a scaffold or a flexible mat.

The support structure can completely or partially enclose the working space. It is also possible that the support structure limits the working space in one direction and the spatial dimension of the working space is determined by the support structure and the effective width of the emitted microwave radiation.

The means for emitting the microwave radiation into the working space may be, for example, antennas. In a preferred embodiment of the arrangement according to the invention, the means for emitting are waveguides. These may also be arranged in planes that extend perpendicular to a longitudinal axis of a working space designed along the longitudinal axis. Preferably, the waveguides are aligned so that the radiation of the microwave radiation takes place in the planes.

Waveguides are usually used to a z. B. to conduct microwave radiation. In a preferred embodiment of the arrangement according to the invention, microwave radiation is emitted via an antenna or transmitter into a waveguide. The microwave radiation is passed through the waveguide to an opening, which is preferably formed as a slot. Through the opening, the microwave radiation is radiated into the working space. The advantage is that the slot harmful back reflections are greatly reduced in the waveguide.

A means for emitting the microwave radiation in the working space may be formed in an advantageous embodiment as a so-called slot radiator. In a waveguide delimited by walls, at least one antenna head of an antenna for coupling microwave radiation into the waveguide is arranged. It is preferred if, in addition, a tuner for influencing the propagation and reflection behavior of the coupled-in microwave radiation is arranged in the waveguide. The coupled-in microwave radiation propagates in the waveguide in a propagation direction. In a wall of the waveguide, a slot for emitting the microwave radiation from the slot radiator is present. The slot preferably extends transversely to the propagation direction and is preferably at a distance from the antenna head which corresponds to half the wavelength (lambda / 2) of the microwave radiation. The length of the slot radiator is greater than half the wavelength (lambda / 2) and smaller than the wavelength (lambda) of the microwave radiation. With an optimum coordination of all elements of the slot radiator successive and on a frequency and power of the microwave radiation efficiencies of the slot radiator of more than 75% to more than 99%, for example, reached 99.7%.

The antenna may have an inner conductor for conducting and coupling in a microwave radiation. In further embodiments, the antenna can also be realized without an inner conductor. The antenna may, for example, be contacted by means of a detachable plug connection (eg SMA plug or N plug). It is also possible that a non-detachable contact, for example by a coaxial cable with a direct transition into the antenna, is present. The antenna head is preferably made of an electrically conductive material such as copper, iron, gold or brass.

It is favorable if the antenna or the antenna head is mounted in the waveguide without fastening elements projecting into the waveguide. For example, at least one blind hole in one of the walls of the waveguide be present, in which an area of the antenna or the antenna head, for example, the inner conductor, engages or plugged. By at least one such storage adverse effects on the propagation and reflection behavior of the coupled microwave radiation are greatly reduced. The antenna or the antenna head can be locked by a device located on the waveguide or outside the waveguide. By way of example, a plug connection (for example an SMA plug) can be provided on a region of the antenna protruding from the waveguide, by means of which the antenna is spatially fixed.

In the arrangement according to the invention means may be provided for the passage of the medium through the working space. In this case, the means for the passage of the medium through the working space may be a guide element with a longitudinal axis of the elements, which is preferably aligned parallel to the longitudinal axis of the working space. If the means for passing the medium through the working space is a bundle of guide elements with a bundle longitudinal axis, then this bundle longitudinal axis is preferably aligned parallel to the longitudinal axis. Guide elements can be, for example, pipes, shafts or channels through which a liquid or gaseous medium flows. But it may also be conveyors by means of solids as z. B. bulk material or as a body through the working space are to lead (dynamic case). A passage of the medium through the working space can take place arbitrarily in time (for example, continuously, discontinuously) and spatially (route of execution). It is also possible that the medium is introduced into the working space, where it remains during its heating and is removed again (static case). For example, a body or a container with the medium to be heated (eg a filled autoclave) can be introduced into the working space.

It is very advantageous if the generator is interchangeable with at least one additional generator. A simple interchangeability can be achieved, for example, that the generator, for. B. in a board, can be inserted. As a result, the generator is easily replaceable in the event of a defect. Particularly favorable is the simple interchangeability in experimental arrangements in which, for example, a region of another frequency section becomes available by exchanging only one component of the arrangement. A physical one Exchange is a way to switch to another generator same.

The arrangement can be used in addition to the heating of a medium by means of microwave radiation, for example, to investigate the response of the medium in the heating.

The object is further achieved by a method for heating a medium located in a working space by means of microwave radiation. The steps of the method according to the invention are successively introducing a medium into a working space. This is followed by the selection of a microwave frequency as a function of properties of the medium from a specific frequency range within the microwave frequency range. Subsequently, a generator is driven with control signals, which lead to generation of a signal with the selected microwave frequency. This is followed by generating the signal at the selected microwave frequency, passing the signal to at least one radiation source, amplifying the signal by means of the at least one radiation source to at least one amplified signal and emitting the at least one amplified signal as microwave radiation into the working space. At each of the radiation sources measurement data is detected, based on which control signals are generated at least for driving the gain of the signal.

The selection of the microwave frequency (frequency) can be based on the knowledge of the material, the dimensioning and other properties (eg state of matter, temperature) of the medium. It is also possible to select a certain frequency on the basis of empirical sentences or arbitrarily. The frequency can be selected in further embodiments of the method before or with the introduction of the medium.

In a preferred variant of the method according to the invention, the working space is determined by an arrangement of a plurality of radiation sources in its spatial dimensions.

The method according to the invention is extremely advantageous for investigating a behavior of the medium when heated by means of microwave radiation. In this case, microwave radiations of at least one first to nth characteristic expression of a certain range of property characteristics of a property of the microwave radiation are radiated into the working space one after the other. The first to nth measurement data assigned to the first to nth property characteristics are recorded and compared with each other. From the measured data as well as their comparison, the behavior of the medium when it is heated by means of microwave radiation of the first to nth characteristics is derived. It is possible to investigate the behavior of the medium over time, in different areas of the working space and under different combinations of the first to nth characteristics of the microwave radiation.

Properties can be, for example, the power of the microwave radiation or the frequency. The property expression is the respective concrete value of the property, eg. B. a concrete representable amplitude of the microwave as the first property characteristic and a specific frequency as a second property characteristic of the power of the microwave radiation.

The method makes it possible to examine media, for example, by irradiating the medium with microwave radiation of the first to nth properties and recording measured data. Thus, for example, optimized combinations of the first to nth property characteristics for a heating of the medium can be found. The method can also be used to search for a suitable spatial positioning of the radiation sources in which, for example, an efficient heating of the medium with simultaneous protection of all radiation sources against damaging influences can be achieved.

In terms of control, it is favorable if the selection of a frequency, the generation of the microwave radiation, the control of the radiation sources and the evaluation of the measured data are effected by means of a central control.

Fig. 1

eine erste Ausführung der erfindungsgemäßen Anordnung;

Fig. 2

eine zweite Ausführung der erfindungsgemäßen Anordnung;

Fig. 3

eine Strahlungsquelle einer dritten erfindungsgemäßen Anordnung und

Fig. 4

ein Ausführungsbeispiel eines Schlitzstrahlers.

By means of the method according to the invention media of any state of matter or their mixture can be heated. It is possible to use the method of fractionating a mixture of a mixture of substances. It can thus also activated at least one ingredient of the medium, as well as catalytic reactions of the medium are performed. It is also possible to generate a plasma from the medium by means of the method according to the invention. With regard to special methods of surface treatment, such. As the PVD (physical vapor deposition) or CVD (chemical vapor deposition), it will be possible to make processes more precise and thereby the homogeneity of z. B. on an object applied layers further increase. Molecules or molecular groups can also be aligned or even polarized by means of microwave radiation. The invention will be explained in more detail below on the basis of exemplary embodiments and illustrations. The pictures show:

Fig. 1

a first embodiment of the inventive arrangement;

Fig. 2

a second embodiment of the arrangement according to the invention;

Fig. 3

a radiation source of a third inventive arrangement and

Fig. 4

an embodiment of a slot radiator.

As essential elements of in Fig. 1 shown schematically very first embodiment of the arrangement are a voltage source 1 for supplying the device, a tunable generator 2 for generating a signal, a distributor 3 for directing the signal via one microwave line 4 to two radiation sources 5, each with a power amplifier 5.1 and a measuring means for Detection of measurement data 5.3, and designed as a computing, control and storage unit controller 6 is present, which is connected to the generator 2 and the radiation sources 5 via control lines 6.1 in combination.

The supplied from the voltage source 1 and controllable by the controller 6 generator 2 includes a vibration generator 2.1, which is composed of semiconductor devices, and an oscillator as a frequency filter 2.2. The generator 2 is over the range of the frequency range 1.8 to 2.8 GHz continuously tunable. By control signals transmitted by the controller 6, the generator 2 is tunable to a selected frequency from a frequency section of the microwave frequency range. By means of the vibration generator 2.1, a signal with the selected frequency can be generated. Any generated signals whose frequencies do not correspond to the selected frequency are suppressed by the function of the frequency filter 2.2. Through the distributor 3, the signal is distributed to the microwave lines 4. The signal provided in the arrangement according to the invention after the frequency filter 2.2 is applied to each of the existing radiation sources 5. The signal is to be amplified by the power amplifier 5.1 and emitted by means of a waveguide 5.2 as a microwave radiation 11 in a working space 7. The working space 7 is bounded in one of its spatial dimensions by a wall of metal reflecting a microwave radiation 11 as a support structure 8, in which the radiation sources 5 are arranged in parallel planes E in the working space 7. The planes E extend perpendicular to a longitudinal axis 7.1 of the working space 7. In its not limited by the support structure 8 dimensions of the working space 7 is determined by an effective width of the microwave radiation 11, the temperature, the frequency and an amplitude of the microwave radiation 11 and the Interactions with an irradiated medium 10 depends. In the working space 7, a solid body to be heated is introduced as the medium 10. The medium 10 remains during the heating with respect to the working space 7 in an always same, stationary position. The measuring means for detecting measured data 5.3 arranged in the radiation source 5 is a diode and serves to detect microwave radiation 11 which is reflected back from the medium 10 to the measuring means for acquiring measured data 5.3. The measuring means for acquiring measured data 5.3 of each radiation source 5 is connected to the controller 6 via a respective measurement data line 5.4. Each power amplifier 5.1 can be controlled directly and individually by the controller 6 via the control lines 6.1. A control takes place as a function of the measurement data of the measuring means for acquiring measured data 5.3 in order to prevent damage to the radiation sources 5 by reflected microwave radiation 11.

A second embodiment of the inventive arrangement according to Fig. 2 corresponds to the basic structure according to Fig. 1 , In addition, a temperature sensor is arranged as a further measuring means 12 for determining the temperature within the working space 7 and connected to the control 6 via a measuring data line 5.4. The working space 7 is delimited in all its dimensions by walls (shown in simplified form as lines) which serve as support structures 8 for the radiation sources 5 (only two radiation sources 5 of a support structure 8 are shown) and through which the working space 7 is closed. In the working space 7, this spanning over its entire length, a trained as a pipe guide element 9.1 as a means for carrying the medium through the working space 9 along a longitudinal axis elements 9.11 available. The element longitudinal axis 9.11 runs parallel to the longitudinal axis 7.1. The guide element 9.1 spans the working space 7 from a support structure 8 opening the media supply opening 9.2 to a Medienabführungsöffnung 9.3.In other embodiments of the arrangement can also outside the working space 7 and / or at the media supply port 9.2 and / or the media discharge opening 9.3 further measuring means 12, z , B. sensors, by which a state of the medium 10 as temperature, physical or chemical composition can be detected, be arranged.

A design of a radiation source 5 according to Fig. 3 is characterized by a carrier structure formed as a support structure 8, on which the power amplifier 5.1, the waveguide 5.2 and the measuring means for detecting measurement data 5.3 are enclosed by a housing 5.5. The radiation source 5 is connected via the microwave line 4 to the distributor 3 (not shown) and via the control line 6.1 and the measurement data line 5.4 to the controller 6. The radiation source 5 is to be mounted manually at a freely selectable position on the surface of a body to be heated as a medium 10. A working space 7 is determined by the radiation source 5 and by the penetration depth of the microwave radiation 11 into the medium 10 (symbolized by dashed microwave radiation 11), which in this case is to be regarded as the effective width. This design can be used, for example, as a flexible system for the gentle drying of wood or other natural substances, as well as all synthetically produced educts and products, wherein by the use of microwave radiation 11 a controllable heating of the medium 10 is effected inside. Water or other solvents are not trapped by already dried layers of the medium 10, but transported by still moist layers to the outside. By heating inside cracking in the medium 10 are largely avoided.

An embodiment of a slot radiator is in Fig. 4 simplified shown. The slot radiator consists of a waveguide 5.2 with a rectangular cross section and has a length L, a width B and a height H. The waveguide 5.2 is bounded by walls 16. Opposite each other are, as walls 16, a first cover 16.1 and a second cover 16.2, a first side wall 16.3 and a second side wall 16.4 and an upper wall 16.5 and a lower wall 6.6. The upper wall 16.6 has a slot 15 through which the microwave radiation 11 can be emitted from the slot radiator. The slot 15 extends in the direction of the width B and is closer to the second lid 16.2 than on the first lid 16.1 available. According to Fig. 4 the slot 15 is one tenth of the length L from the second lid 16.2. The spatial position of the walls 16 and other elements of the slot radiator is not relevant to the operation of the slot radiator. Only their relative position to each other and their dimensions is important. All information on the spatial orientation of the walls 16 are therefore exemplary.

On the lower wall 16.5, a tuner 17 is arranged in the waveguide 5.2, which serves to selectively influence the propagation and reflection behavior of the coupled microwave radiation 11 and projects into the waveguide 5.2. The tuner 17 is disposed opposite to the slot 15. Furthermore, an antenna 13 is present, which is guided by the lower wall 16.5 and which has an antenna head 13.1. The antenna head 13.1 protrudes into the waveguide 5.2 and serves to couple the microwave radiation 11 into the waveguide 5.2. In the direction of the length L of the antenna head 13.1 of the slot 15 (in each case with respect to the center line) is arranged at a distance d. The distance d is around lambda / 2, which corresponds to 6.1 cm in a microwave radiation 11 with a frequency of about 6.1 cm. The direction of the length L is at the same time the propagation direction of the microwave radiation 11.

The antenna head 13.1 is designed as a sleeve made of brass. Inside the antenna head 13.1 there is a connector 18 in the form of a copper rod. The connector 18 protrudes from the antenna head 13.1 through the lower wall 16.5 and is contacted there by a receiving part of a connector 19. On the receiving part of the connector 19, a microwave line 4 can be connected. The receiving part of the connector 19 is disposed directly on the lower wall 16.5, whereby the antenna 13 is fixed. The antenna head 13.1 protrudes from the lower wall 16.5 a first distance 11 perpendicular into the waveguide 5.2 inside. In the antenna head 13.1, an inner conductor 14 is inserted laterally, which extends in the direction of the length L over a second distance I2 to the first lid 16.1. In the first cover 16.1 a blind hole (only indicated) is introduced, in which the inner conductor 14 is inserted with one end. Over the second distance I2, the inner conductor 14 is exposed.

The antenna head 13.1 may be designed differently in further embodiments of the invention.

In further embodiments of the slot radiator, the connector 18 may be replaced by a wire or a strand of a microwave feed line 4. In such an embodiment, the receiving part of the connector 19 is not required. In addition, it is possible for the connector 18 to be implemented as an element of the receiving part of the plug connection 19 or for the connector 18 to be realized as an element of a plug (not shown) of the plug connection 19.

The application of the method according to the invention for investigating a behavior of the medium 10 during its heating by means of microwave radiation 11, is based on the second embodiment according to Fig. 2 explained. On the basis of empirical values, a frequency section of the microwave frequency range at which heating of the medium 10 is known to be selected is selected. In further embodiments, frequency sections can also be selected in which no heating takes place or heating is (still) questionable. By means of the controller 6, the vibration generator 2.1 and the frequency filter 2.2 are controlled so that a signal with the selected frequency is provided. The signal is an electromagnetic wave that vibrates at the selected frequency and has an amplitude. About the distributor 3, the signal on the Distributed microwave lines 4 so that it rests on each of the radiation sources 5. Each of the power amplifiers 5.1 is controlled by the controller 6 via the control lines 6.1 so that the amplitude of the signal amplified by each power amplifier 5.1 equal and the amplified signal is emitted via each waveguide 5.2 as microwave radiation 11 in the working space 7. The incident on the medium 10 microwave radiation 11 is absorbed by the medium 10 according to its properties and / or reflected wholly or proportionately. Reflected and detected by one of the measuring means for the detection of measured data 5.3 microwave radiation 11 causes at least one response signal whose height is sent as measurement data on the measurement data 5.4 to the controller 6 and evaluated there. If the measured data indicate that microwave radiation 11 of a power above a predetermined threshold value is incident on the measuring means for acquiring measured data 5.3, the power amplifier 5.1 is activated and a lower amplification is effected. Since the microwave radiation 11 impinging on the measuring device for acquiring measured data 5.3 can also originate from other radiation sources 5, in a further embodiment of the method the power amplifiers 5.1 of some or all of the other radiation sources 5 are also activated. By a controlled and systematic variation of the amplifications of the signal effected by the power amplifiers 5.1, a desired pattern of the control of the power amplifiers 5.1 for a respective combination of medium 10, positioning of the radiation sources 5 and dimensioning of the working space 7 can be sought. It is also possible in further embodiments of the method to investigate the behavior of the medium 10 at different positions of the radiation sources 5. The explained individual choice of the amplification of the signal is to be regarded as a first characteristic expression of the property "power / amplitude" of the microwave radiation 11. The detection of the measurement data by the measuring means for acquiring measured data 5.3 and its evaluation is once the protection of the respective radiation source 5 from excessive reflection and can also serve to investigate the behavior of the medium 10 when heated with microwave radiation 11.

In order to take into account or rule out effects of the working space 7 (eg reflections on the walls thereof) during an examination, a "standard reflection profile" can be used. of the working space 7 are determined and stored. It is also possible to design the dimensioning of the working space 7 so that reflections of the microwave radiation 11 have no or a negligible influence on the measured data. Also, the walls of the working space 7 can be configured from material that is not reflective for microwave radiation 11, or the working space 7 can be designed in a number of directions of its dimensioning without walls.

As a second property, the frequency is changed by driving the generator 2 by means of the controller 6. The frequency can be set to specific values. Temperature-time curves can be recorded under constant conditions with variation of the frequency in order to determine an optimum frequency for a desired effect. The frequency is tuned to the material. But it can also be changed continuously or discontinuously over a range of the frequency section. Such a change can also take place several times, for example at different temperatures of the medium 10 or of the working space 7. The first to nth properties can be set individually or in any combination.

If further measuring means 12 are present, the measurement data acquired by the further measuring means 12 are likewise transmitted to the controller 6 via measurement data lines 5.4.

In all cases, the acquired measurement data are assigned to the information about the location of the detection of the first to nth property characteristics of the properties, evaluated and stored.

By means of the method according to the invention, it is possible to investigate the behavior of a medium 10 when it is heated in a wide variety of combinations of property characteristics. It is also possible to change the characteristic values controlled during a heating process and to investigate the resulting behavioral responses of the medium 10 associated with the characteristics, the positioning of the microwave sources 5, the design of the working space 7, the material and the dimension of the medium 10, and a default setting an arrangement after its installation or repair or set up. Also, interactions based on common approaches to conducting scientific experiments can be used to investigate interactions between the above parameters. The method may also be used to optimize the process of fractionating a mixture of substances, activating ingredients of the medium, catalytic reactions, generating a plasma, or aligning molecules. The arrangement and the method can also be used when heating z. As contaminated soil or for the drying of bodies such. Of fruits, with the expulsion of water or volatiles and compounds such as alcohols, acetone, phenols, toluene, oils and the like being the primary goal.

LIST OF REFERENCE NUMBERS

• 1 voltage source
• 2 generator
• 2.1 vibration generator
• 2.2 Frequency Filter
• 3 distributors
• 4 microwave line
• 5 radiation source
• 5.1 power amplifier
• 5.2 waveguide
• 5.3 Measuring means for acquiring measured data
• 5.4 Measurement data line
• 5.5Gehäuse
• 6 control
• 6.1 Control line
• 7 workspace
• 7.1 longitudinal axis
• 8 support structure
• 9 Means for the passage of the medium through the working space
• 9.1 Guide element
• 9.11 Element longitudinal axis
• 9.2 Media supply opening
• 9.3 Media discharge opening
• 10 medium
• 11 microwave radiation
• 12 more measuring devices
• 13 antenna
• 13.1 Antenna head
• 14 inner conductors
• 15 slot
• 16 wall (of waveguide 5.2)
• 16.1 first lid
• 16.2 second lid
• 16.3 first side wall
• 16.4 second side wall
• 16.5 lower wall
• 16.6 upper wall
• 17 tuners
• 18 connectors
• 19 receiving part of the connector
• L length (of waveguide 5.2)
• B width (of waveguide 5.2)
• H height (of waveguide 5.2)
• d distance
• 11 first route
• 12 second route
• E level

Claims (15)

Arrangement for heating a medium by means of microwave radiation, comprising
at least two radiation sources (5) each having an individually controllable power amplifier (5.1) which amplifies a signal generated by a generator (2) and having a microwave frequency, and means for emitting the amplified signal as microwave radiation (11) into a working space ( 7), which is determined by the arrangement of the radiation sources (5) to each other in its spatial dimension,
characterized in that
the generator (2) is in signal communication with all power amplifiers (5.1), so that the signal generated by the generator (2) is applied to all power amplifiers (5.1);
the generator (2) can be tuned over a range of a specific frequency range within the microwave frequency range and measuring means (5.3) for acquiring measured data (5.3) can be detected with which measurement data in the working space (7) and each radiation source (5) at least one of the measuring means for the acquisition of measured data (5.3). Arrangement according to claim 1, characterized in that the means for emitting the microwave radiation waveguide (5.2). Arrangement according to claim 2, characterized in that the working space (7) along a longitudinal axis (7.1) is designed and the waveguide (5.2) in planes (E) are arranged, which are perpendicular to the longitudinal axis (7.1) extended. Arrangement according to one of claims 1 to 3, characterized in that the measuring means for the detection of measured data (5.3) are signal technically connected to a controller (6), by the at least the power amplifier (5.2) are individually controlled. Arrangement according to claim 4, characterized in that in the working space (7) further measuring means (12) are present and connected to the control (6) signal technically. Arrangement according to one of the preceding claims, characterized in that
at least one means for carrying a medium through the working space (9) is present. Arrangement according to claim 6, characterized in that the means for the passage of the medium through the working space (9) is a guide element (9.1) with a longitudinal axis elements (9.11), which is aligned parallel to the longitudinal axis (7.1). Arrangement according to one of the preceding claims, characterized in that
the generator (2) is interchangeable with at least one further generator (2). Use of the arrangement according to one of the preceding claims for investigating the behavior of the medium (10) during heating by means of microwave radiation (11). Method for heating a medium by means of microwave radiation, comprising the steps: Introducing a medium (10) into a working space (7), Selecting a microwave frequency as a function of characteristics of the medium (10) from a particular frequency range within the microwave frequency range; Driving a generator (2) with control signals resulting in the generation of a signal at the selected microwave frequency; Generating the signal at the selected microwave frequency; Directing the signal to at least one radiation source (5); Amplifying the signal by means of the at least one radiation source (5) to at least one amplified signal; Emitting the at least one amplified signal as microwave radiation (11) into the working space (7); Acquiring measurement data at each of the radiation sources (5) and generating control signals at least for driving the gain of the signal. Method according to claim 10 for investigating a behavior of the medium (10) during its heating,
wherein successively microwave radiation (11) of at least one first to nth property characteristic of a certain range of characteristic values of at least one property is emitted into the working space (7),
the first to nth characteristic data associated with the first to nth property characteristics are recorded,
the measured data are compared with each other and
from the measured data, the behavior of the medium (10) is derived during its heating by means of microwave radiation (11) first to n-th characteristic expression. Process according to Claim 10 for fractionating a medium (10) consisting of a mixture of substances. Method according to one of claims 10 to 12 for activating at least one ingredient of the medium (10). Method according to one of claims 10 to 13 for carrying out a catalytic reaction of the medium (10). Method according to one of claims 10 or 11 for producing a plasma from the medium (10).

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