Device and method for generating a dielectric barrier discharge

Abstract

The invention relates to a device for generating a dielectric barrier discharge, having a thermoelectric structural element (1), an electrode (2) arranged opposite the thermoelectric structural element (1), and a high-voltage power supply (12) designed to generate a high voltage between the thermoelectric structural element (1) and the electrode (2), which is sufficient to ignite the dielectric barrier discharge. The invention also relates to a method for generating a dielectric barrier discharge.

Description

Technical Field

[0001] The present invention relates to an apparatus for generating dielectric barrier discharge, an apparatus having such an apparatus, and a method for generating dielectric barrier discharge. Background Technology

[0002] Dielectric barrier discharge is frequently used in ozone generators, where ozone is generated from an airflow via surface discharge. The airflow that forms the process gas (from which ozone is produced) is also often used for cooling. To prevent overheating of the unit, a minimum airflow is required, which results in diluted ozone production, thus limiting the ozone concentration that can be produced.

[0003] In medical applications, very high ozone concentrations greater than 10,000 ppm can be advantageous. High ozone concentrations have a strong effect on microorganisms and can significantly reduce the time required to completely kill the initial population. If microorganisms are exposed to high ozone concentrations for a short period, the effect on the surface of the exposed material dominates. Small structures, such as viruses with an elongation of about 50 nm and bacteria with an elongation of less than 1 µm, are severely damaged under high ozone concentrations with short exposure. Thicker structures, such as human skin, are relatively tolerant to short exposures because the depth of action is limited by diffusion and remains very low under short exposures. To kill microorganisms without harming human skin, it is advantageous to expose them to high ozone concentrations for a very short time to achieve a bactericidal effect on the surface, with only a slight effect on volume. Summary of the Invention

[0004] The objective of this invention is to describe an improved apparatus for generating dielectric barrier discharges. This apparatus should, for example, be able to generate ozone with a high concentration without overheating.

[0005] This task is accomplished by the apparatus described below.

[0006] A device for generating a dielectric barrier discharge is proposed, comprising a thermoelectric structural element, such as a Peltier element, electrodes, and a high-voltage power supply. The electrodes are arranged opposite to the thermoelectric structural element. The high-voltage power supply is designed to generate a high voltage between the thermoelectric structural element and the electrodes, sufficient to ignite the dielectric barrier discharge.

[0007] Therefore, the present invention relates to an apparatus for generating a dielectric barrier discharge, wherein a thermoelectric structural element serves as a mating electrode, and wherein the dielectric barrier discharge can be ignited between the electrode and the thermoelectric structural element serving as the mating electrode. The dielectric barrier discharge can be ignited as a surface discharge or a volumetric discharge.

[0008] In particular, the thermoelectric structural element can be a Peltier element or a structural element with thermoelectric ceramic material.

[0009] The thermoelectric structural element here can cool the process gas. Therefore, a high flow rate of process gas for cooling the discharge region is no longer needed. Thus, since ozone concentration dilution is no longer produced, high ozone concentrations, such as greater than 1000 ppm, can now be achieved in dielectric barrier discharge. Here, the process gas can have a flow rate between 1.5 liters per minute and 2.5 liters per minute, for example, 2 liters per minute. In some embodiments, ozone concentrations greater than 2000 ppm can be achieved.

[0010] The thermoelectric structural element further enables the adjustment of the process gas temperature during dielectric barrier discharge. The temperature of the process gas has a significant impact on the composition of the gas generated during dielectric barrier discharge. In particular, the proportions of ozone and nitrogen-containing gases generated are determined by temperature. Therefore, the thermoelectric structural element can adjust the concentration and amount of reactive substances generated during dielectric barrier discharge. Furthermore, they remain stable because the thermoelectric structural element prevents thermal drift. Thus, the device can achieve the generation of precisely defined gas compositions through dielectric barrier discharge. This is important, for example, in medical applications. Moreover, the device ensures that the ignition voltage that triggers plasma ignition remains constant without thermal drift even when exceeded.

[0011] Furthermore, thermoelectric structural elements can also adjust the humidity of process gases. For example, a thermoelectric structural element can cool the process gas before dielectric barrier discharge, thereby reducing its humidity. The humidity of the process gas also affects the composition and concentration of substances generated during dielectric barrier discharge.

[0012] In dielectric barrier discharge, one of the electrodes and thermoelectric structural elements can be at a high voltage potential, and the other can be at a low voltage potential or ground potential. If the electrode is at a low voltage potential or ground potential, the electrode can be formed from any sufficiently capacitive surface and arranged close to the thermoelectric structural element.

[0013] A thermoelectric structural element may have two or more thermoelectric elements, wherein the thermoelectric structural element has a metal bridge that meanders between the thermoelectric elements, wherein the thermoelectric structural element has a first ceramic plate that covers the metal bridge on the upper side of the thermoelectric structural element facing the electrode, and wherein the thermoelectric structural element has a second ceramic plate that covers the metal bridge on the lower side of the thermoelectric structural element. The side of the thermoelectric structural element facing the electrode may be referred to as the upper side. The side of the thermoelectric structural element opposite to the upper side is referred to as the lower side.

[0014] Thermoelectric elements can be arranged in rows, with two adjacent thermoelectric elements connected to each other by metal bridges on their upper or lower sides. Alternatively, the thermoelectric elements can be arranged in a two-dimensional matrix structure, with metal bridges connecting the thermoelectric elements in a two-dimensional meandering shape, wherein adjacent thermoelectric elements along the two-dimensional meandering shape are connected to each other by metal bridges on their upper or lower sides.

[0015] The metal bridges can be separated from each other by non-metallized surfaces, wherein the maximum extension of the non-metallized surface between two adjacent metal bridges is less than the thickness of the first ceramic plate. The metal bridges can be arranged in an island-like pattern on the first and second ceramic plates.

[0016] This size design of the metal bridges prevents parasitic discharges on the inside of the thermoelectric structural elements between the metal bridges.

[0017] The metal bridge and the first ceramic plate can be designed to satisfy the following inequality: D>U zünd / U betrieb × ɛ2 / ɛ1× A Where D represents the thickness of the first ceramic plate. U zünd This represents the ignition voltage, which, when exceeded, causes plasma ignition between the metal bridges. U betrieb This represents the operating voltage applied to the device. ɛ2 represents the dielectric constant of the first ceramic plate. ɛ1 represents the dielectric constant of air, and A represents the spacing between adjacent metal bridges.

[0018] Furthermore, the thermoelectric structural element may have a weakly conductive layer. This weakly conductive layer may be disposed between the first ceramic plate and the metal bridge. The weakly conductive layer may be disposed on the inner side of the first ceramic plate, which faces the metal bridge.

[0019] The weakly conductive layer can directly contact the metal bridge and the first ceramic plate. This weakly conductive layer can balance the potential inhomogeneities in the thermoelectric structural element, which are formed by the island-shaped metal bridge. In this way, the weakly conductive layer ensures uniform discharge. Furthermore, the weakly conductive layer can prevent discharge on the inner side of the ceramic plate.

[0020] The weakly conductive layer may be a layer applied to the first ceramic plate using a thin-layer technique. For example, the weakly conductive layer may be sprayed or printed onto the first ceramic plate.

[0021] Alternatively, the first ceramic plate may have a multilayer structure and be fabricated accordingly using a thick-layer technique. Here, the weakly conductive layer may be a sublayer of the first ceramic plate. For example, the weakly conductive layer may be constructed as the outermost layer of a multilayer structure, wherein the first ceramic plate is arranged at the metal bridge such that the weakly conductive layer faces the metal bridge. Alternatively, the weakly conductive layer may be an inner layer of a multilayer structure, disposed between two ceramic layers.

[0022] The first and second ceramic plates may have alumina and / or aluminum nitride. Alumina provides high thermal conductivity to the respective ceramic plates and thus supports cooling or heating functions. Alumina ensures that the respective ceramic plates are corrosion-resistant and electrically insulating. The ceramic plates may have a multilayer structure consisting of multiple sublayers, wherein the sublayers have, for example, alumina and aluminum nitride. Alternatively, the ceramic plates may consist of a single layer. A ceramic plate made of a single aluminum nitride layer oxidizes on its electrode-facing side during device operation, forming an alumina layer that protects against corrosion.

[0023] The ceramic plate may further have metallized regions, which facilitate field guidance. The metallized regions may be surrounded by alumina or aluminum nitride, thereby preventing corrosion of the metallized regions.

[0024] The ceramic plate may also have an insulating area that the electric field cannot penetrate.

[0025] The weakly conductive layer can be made of a metallide, such as nickel. The weakly conductive layer can have a thickness between 10 nm and 100 nm, preferably between 25 nm and 75 nm. The resistivity of the weakly conductive layer can be in the range of 1 × 10⁻⁶. -2 Ω×mm 2 / m and 1×10 -1 Ω×mm 2 The sheet resistivity of the weakly conductive layer can be between 0.2 Ω and 5 Ω, preferably between 1.0 Ω and 2.0 Ω. For example, the weakly conductive layer can be made of materials with a sheet resistivity of 10⁻² Ω × mm. 2 The resistivity is made of a thin 50 nm layer of nickel with a specific resistance of / m, in which a sheet resistance of 1.4 ohms is obtained.

[0026] The weakly conductive layer can have a resistance at least 100 times that of the thermoelectric element connected via a meandering metal bridge. This prevents the direct current flowing through the thermoelectric structural element from being diverted through the weakly conductive layer. In this way, additional power loss caused by short circuits in the series-connected thermoelectric elements can be avoided. Correspondingly, the weakly conductive layer does not impair the function of the thermoelectric structural element.

[0027] The weakly conductive layer may have at least one element that acts as a conductor, such as Cr or Ni, and / or at least one element that acts as a semiconductor, such as B or Si, and / or at least one material that acts as an insulator, such as SiO2 or Al2O3.

[0028] A weakly conductive layer can influence the surface conductivity of thermoelectric structural elements in a desirable way, thereby preventing parasitic discharges.

[0029] The device may have an electrically conductive structure, which is arranged between the ceramic plate and the metal bridge arranged at the lower side of the thermoelectric element and which is connected to ground potential. The electrically conductive structure may be provided as an alternative or in addition to the weakly conductive layer. The electrically conductive structure may have a similar function to the weakly conductive layer and prevent parasitic discharges at the inner side of the lower side. In one embodiment, the electrically conductive structure is reticulated.

[0030] The thermoelectric structural element may be a Peltier element, wherein the thermoelectric element comprises a semiconductor material. Alternatively, the thermoelectric structural element may be based on a thermoelectric ceramic material, wherein the thermoelectric element comprises the thermoelectric ceramic material.

[0031] The thermoelectric ceramic material may comprise a calcium manganese oxide partially doped with Fe atoms at the positions of Mn atoms. The thermoelectric ceramic material may have a material described by the general formula Ca1-x-yISOxDONyMn1-zFezOn, wherein ISO denotes a divalent element that can substitute for Ca2+ in the crystal lattice, DON denotes an element that can substitute for Ca2+ in the crystal lattice and provides electrons for electrical conductivity, and where 0 ≤ x ≤ 0.5; 0<y ≤ 0.5; 0.0001 ≤ z<0.2; n ≥ 2. The thermoelectric ceramic material may have a material based on the composition (Ca3-xNax)Co4O9-δ, where 0.1 ≤ x ≤ 2.9 and 0<δ ≤ 2.

[0032] The high-voltage power supply may be designed to apply a high-voltage alternating potential to the electrodes. The device may furthermore have a direct voltage power supply, which is designed to apply a low direct voltage to the thermoelectric structural element. A high voltage thus exists between the electrodes and the thermoelectric structural element, by means of which high voltage a dielectric barrier discharge is triggered. In this case, the device may be designed to ignite the dielectric barrier discharge as a volume discharge in the gap between the thermoelectric structural element and the electrodes.

[0033] The thermoelectric structural element may have a metallization on the surface directed toward the electrodes, wherein the high-voltage power supply is designed to apply a high-voltage potential to the thermoelectric structural element. The electrodes may be at ground potential or a potential close to ground. In this case, a dielectric barrier discharge can be triggered between the metallization and the electrodes. The dielectric barrier discharge can be ignited as a surface discharge at the metallization.

[0034] The metallization may be formed of an electrically conductive material and / or of a semiconducting material, for example a mixture formed of bismuth and rhodium. The metallization may be made of a Mo / Mn paste fired under a hydrogen atmosphere or a W paste mixed with an oxidic binder (for example aluminum oxide, manganese oxide, magnesium oxide or titanium oxide).

[0035] The apparatus may additionally include a blower designed to guide process gas through the gap between the electrodes and the thermoelectric structural elements, and / or have a cooling body. In addition to the thermoelectric structural elements, the blower and cooling body may further contribute to cooling the process gas.

[0036] Thermoelectric structural elements can be designed to cool or heat process gases. Alternatively or additionally, the thermoelectric structural elements can be designed to continuously change the temperature of the process gas during the operating cycle. Here, the process gas can experience a wide temperature range. Within this temperature range, dielectric barrier discharge is ignited, which can experience the entire mass spectrum from ROS to RNS. In this way, for example, particularly thorough sterilization of surfaces can be achieved.

[0037] Electrodes and / or thermoelectric structural elements may be coated with a glassy layer. This layer may be a molten glaze or a fired glaze. This layer is chemically and thermally stable and protects the electrodes or thermoelectric structural elements from oxidizing substances generated during dielectric barrier discharge. This layer can correspondingly extend the service life of the device.

[0038] The thermoelectric structural element has a region that is not directly opposite the electrode. Correspondingly, the thermoelectric structural element can have a larger surface area than the electrode. The device can be designed such that the process gas is first guided through the region of the thermoelectric structural element that is not opposite the electrode, and then enters the discharge region where the thermoelectric structural element and the electrode are opposite each other. In the region not directly opposite the electrode, the temperature of the process gas can then be regulated by the thermoelectric structural element. For example, by cooling the process gas, moisture can be condensed from the process gas, and a drier process gas can be achieved.

[0039] The device may have a controller designed to first operate the device in a cooling operation in which no dielectric barrier discharge is triggered and the surface of the device is cooled below the dew point, wherein a water film is generated on the surface by condensation, and then the device is operated in a discharge operation in which a dielectric barrier discharge is generated on the water film.

[0040] The device can be designed to operate in a heated state, in which no dielectric barrier discharge is triggered and the surface of the device is heated to a temperature greater than 100°.

[0041] The device may include at least one sensor selected from a temperature sensor, an ozone sensor, and a humidity sensor, wherein the device is designed to match the power of the thermoelectric structural element and / or the power of the high-voltage power supply in consideration of the measurement results of the at least one sensor. The discharge power in the dielectric barrier discharge can be controlled by adjusting the power of the high-voltage power supply. The heat transfer power of the device can be controlled by adjusting the power of the thermoelectric structural element.

[0042] The electrodes and / or thermoelectric structural elements are individually replaceable. In the case of individual replacement, there is no need to replace other components of the device. Accordingly, the electrodes and / or thermoelectric structural elements can be replaced independently of the high-voltage power supply. Due to plasma generation, the electrodes and thermoelectric structural elements typically exhibit signs of aging and wear.

[0043] On the other hand, it relates to an apparatus having the device described above. This apparatus may be a refrigerator, cooling box, air conditioner, cooling equipment, sterilization equipment, clothes dryer, packaging equipment, equipment from food processing, room purification equipment, equipment for controlling parasites in textiles, waste collector, or small sterilizer.

[0044] When used in cooling boxes, refrigerators, or cooling equipment where perishable items are stored, the combination of cooling and dielectric barrier discharge is particularly advantageous. Undesirable microbial processes, such as rot, mold formation, microfilm formation, or unpleasant odors, are inhibited by generating oxidizing substances during dielectric barrier discharge. Condensation on the cold surfaces of the thermoelectric structural elements is highly effective for odor reduction, as the organic molecules condensed with water are also effectively decomposed by dielectric barrier discharge in a second step without producing excessive ozone. Through surface discharge, the entire surface within the discharge area remains sterile.

[0045] For medical applications, the device provides a high ozone concentration of more than 10,000 ppm within a given volume, thereby enabling a highly efficient sterilization process with low equipment costs.

[0046] On the other hand, a method for generating a dielectric barrier discharge using the apparatus described above is provided, wherein a high voltage is generated between a thermoelectric structural element and an electrode by a high-voltage power supply, and the dielectric barrier discharge is ignited in the gap.

[0047] Advantageous aspects are described below. For simplicity of reference, aspects are numbered consecutively. The characteristics of each aspect are important not only in combination with the specific aspects they relate to but also individually.

[0048] 1. A device for generating dielectric barrier discharge, having Peltier components, Electrodes, which are arranged opposite to the Peltier element, and A high-voltage power supply is designed to generate a high voltage between the Peltier element and the electrode, which is sufficient to ignite the dielectric barrier discharge.

[0049] 2. The apparatus according to aspect 1, The Peltier element comprises two or more semiconductor elements arranged in parallel with each other. The Peltier element has a metal bridge that meanders to connect semiconductor elements, wherein two adjacent semiconductor elements are connected to each other by the metal bridge at their upper or lower sides. The Peltier element has a ceramic plate that covers the metal bridge.

[0050] 3. The apparatus according to aspect 2, The Peltier element has a weakly conductive layer disposed between a ceramic plate pointing toward the electrode and the metal bridge.

[0051] 4. The apparatus according to aspect 3, The weakly conductive layer has a resistance that is at least 100 times the resistance of the semiconductor element via the meandering connection of the metal bridge.

[0052] 5. The apparatus according to any one of the foregoing aspects, The high-voltage power supply is designed to apply a high-voltage alternating potential to the electrodes, and The device has a DC voltage power supply designed to apply a low DC voltage to the Peltier element.

[0053] 6. The apparatus according to any one of the foregoing aspects, The device is designed to ignite a dielectric barrier discharge that is a volumetric discharge between the Peltier element and the electrode.

[0054] 7. The apparatus according to any one of aspects 1 to 4, The Peltier element has a metallization on the surface facing the electrode. The high-voltage power supply is designed to apply a high voltage potential to the Peltier element.

[0055] 8. The apparatus according to aspect 7, The device is designed to ignite a dielectric barrier discharge that serves as a surface discharge at the metallization.

[0056] 9. The apparatus according to any one of the foregoing aspects, The Peltier element is designed for cooling or heating process gases. and / or The Peltier element is designed to continuously change the temperature of the process gas during the operating cycle.

[0057] 10. The apparatus according to any one of the foregoing aspects, The electrodes and / or the Peltier element are coated with a glassy layer.

[0058] 11. The apparatus according to any one of the foregoing aspects, The area of ​​the Peltier element is larger than the area of ​​the electrode. 12. The apparatus according to any one of the foregoing aspects.

[0059] The device has a controller designed to operate the device in a cooling operation in which a dielectric barrier discharge is not triggered and the surface of the device is cooled below the dew point of the process gas, thereby generating a water film on the surface by condensation, and the device then operates in a discharge operation in which the dielectric barrier discharge is generated on the water film.

[0060] 13. The apparatus according to any one of the foregoing aspects.

[0061] The device is designed to operate in a heating mode in which a dielectric barrier discharge is not triggered and the surface of the device is heated to a temperature greater than 100 °C.

[0062] 14. The apparatus according to any one of the foregoing aspects.

[0063] The device includes at least one sensor selected from a temperature sensor, an ozone sensor, and a humidity sensor. The device is designed to match the power of the Peltier element and / or the power of the high-voltage power supply, taking into account the measurement results of the at least one sensor.

[0064] 15. An apparatus having the means according to any one of the foregoing aspects, The equipment includes refrigerators, cooling boxes, air conditioners, cooling equipment, disinfection equipment, clothes dryers, packaging equipment, equipment from food processing, equipment for room purification, equipment for parasite control in textiles, waste collectors, or small disinfection devices.

[0065] 16. A method for generating a dielectric barrier discharge using the apparatus according to any one of aspects 1 to 14, wherein a high voltage is generated between the Peltier element and the electrode by the high-voltage power supply and ignites the dielectric barrier discharge. Attached Figure Description

[0066] Preferred embodiments of the invention are explained in more detail below with reference to the accompanying drawings.

[0067] Figure 1 An apparatus for generating a dielectric barrier discharge according to a first embodiment is shown.

[0068] Figure 2 An apparatus according to a second embodiment is shown.

[0069] Figure 3 and Figure 4 An apparatus according to a third embodiment is shown.

[0070] Figure 5 , 6 Figures 7 and 8 show the apparatus according to the fourth embodiment.

[0071] Figure 8 Another embodiment of the device is shown.

[0072] Figure 9 It shows in Figure 8 The image shows a burning device.

[0073] Figure 10 The diagram schematically illustrates thermoelectric elements connected in a two-dimensional meandering shape by metal bridges.

[0074] Figure 11 It shows crossing in Figure 8 The image shows a cross-section of a portion of the device. Detailed Implementation

[0075] Figure 1 A device for generating dielectric barrier discharge is shown, comprising a thermoelectric structural element 1 and an electrode 2. The thermoelectric structural element 1 is a Peltier element.

[0076] Thermoelectric element 1 is a thermoelectric converter. It is designed to change the temperature of the process gas. When a DC voltage is applied to thermoelectric element 1 and a DC current flows through it, a temperature difference is generated based on the Peltier effect, Seebeck effect, or Thomson effect. Peltier element 1 can be used not only for cooling but also for heating the process gas when the current is reversed.

[0077] The thermoelectric structural element 1 has thermoelectric elements 3, which are connected to each other by metal bridges 4 to form a meandering structure.

[0078] If thermoelectric element 1 is a Peltier element, then a semiconductor element, particularly a ceramic plate that acts as a semiconductor, is used as the thermoelectric element. The semiconductor elements are connected in series with each other via a metal bridge 4, where p-doped and n-doped semiconductor elements alternate. The semiconductor elements may, for example, be bismuth telluride or silicon germanium.

[0079] If the direct current is guided through the thermoelectric structural element 1, heat or cold will occur at the metal bridge 4 due to thermoelectric effects, such as the Peltier effect.

[0080] The thermoelectric structural element 1 has a first ceramic plate 5a and a second ceramic plate 5b. The first ceramic plate 5a is arranged on the upper side, facing the electrode. The second ceramic plate 5b is arranged on the lower side, away from the electrode.

[0081] Ceramic plates 5a and 5b may have alumina or be composed of alumina. Alternatively or additionally, ceramic plates 5a and 5b may have aluminum nitride or be composed of aluminum nitride. Ceramic plates 5a and 5b may have a multilayer structure having layers composed of alumina and layers composed of aluminum nitride. Aluminum nitride has the advantage of high thermal conductivity. Alumina has high corrosion resistance. The multilayer structure of ceramic plates 5a and 5b may have an outermost layer made of alumina as a corrosion-resistant protective layer.

[0082] Ceramic plates 5a and 5b cover metal bridge 4. Figure 1 In the embodiment shown, ceramic plates 5a and 5b are arranged directly on the metal bridge. The metal bridge 4 forms a thermal contact surface through which heat or cold is transferred to the ceramic plates 5a and 5b. The ceramic plates 5a and 5b serve as heat-conducting plates. The ceramic plates 5a and 5b provide heat or cold to the process gas.

[0083] Electrode 2 is arranged parallel to the first ceramic plate 5a. Electrode 2 is positioned opposite to thermoelectric structural element 1 and is spatially separated from thermoelectric structural element 1. A gap 6 is formed between electrode 2 and thermoelectric structural element 1. The gap 6 between thermoelectric structural element 1 and electrode 2 may have a width between 0.01 mm and 1.0 mm, preferably between 0.05 mm and 0.5 mm.

[0084] The device is designed to trigger a dielectric barrier discharge between electrode 2 and thermoelectric structural element 1. The dielectric barrier discharge is the ignition of non-thermal atmospheric pressure plasma.

[0085] Regarding the potential of thermoelectric structural element 1, an alternating voltage potential with high amplitude is applied to electrode 2. A high voltage is thus generated between thermoelectric structural element 1 and electrode 2. A dielectric barrier discharge is ignited between thermoelectric structural element 1 and electrode 2, wherein the ceramic plate 5 facing electrode 1 acts as a dielectric barrier.

[0086] A direct current flows through thermoelectric structural element 1. The DC voltage potential difference through the low-resistance thermoelectric element 3 of thermoelectric structural element 1 is negligible compared to the high voltage required for dielectric barrier discharge. Conversely, the current density typically observed in dielectric barrier discharge is smaller than the DC current flowing through thermoelectric element 3. Consequently, the cooling function of thermoelectric structural element 1 and the discharge function of the device do not negatively affect each other.

[0087] In the device, thermoelectric structural element 1 functions not only as a cooling or heating element for adjusting the temperature of the process gas, but also as a mating electrode that, together with electrode 2, triggers dielectric barrier discharge. Through the combination of thermoelectric structural element 1 and dielectric barrier discharge, the dielectric barrier discharge can operate under precisely adjusted temperature and humidity conditions, and the concentration and composition of the active substances appearing in the dielectric barrier discharge can be adjusted and maintained stably.

[0088] The thermoelectric element 1 enables the regulation of the temperature of the process gas present in the gap 6 between the electrode 2 and the thermoelectric element 1. If the thermoelectric element 1 is used for dielectric barrier discharge, it is feasible to precisely adjust the temperature of the process gas during discharge. The gas composition of the gas generated in the context of dielectric barrier discharge is highly dependent on the air temperature when air is used as the process gas. In particular, the generated ozone (O3) and nitrogen-containing gases (NO, NO2, NO3-) are highly dependent on the air temperature. x The proportion of nitrogen-containing gases is determined by temperature. As temperature increases, the generation of nitrogen-containing gases is favored, and the ozone depletion mechanism of nitrogen-containing gases is accelerated.

[0089] The device can operate in different operating modes. The first operating mode is pure cooling operation, in which the thermoelectric structural element 1 cools the process gas and no high voltage is generated between the thermoelectric element and the electrode 2. If the process gas is cooled below its dew point here, water appears by condensation, which is deposited as a water film on the surface of the thermoelectric structural element 1.

[0090] The second operating mode of the device is discharge operation. In discharge operation, a high voltage is applied between thermoelectric structural element 1 and electrode 2, triggering a dielectric barrier discharge between electrode 2 and thermoelectric structural element 1. Additionally, thermoelectric structural element 1 can simultaneously cool or heat the process gas.

[0091] The discharge operation can be immediately followed by the cooling operation, in which a water film is generated on the surface of the thermoelectric structural element 1 during the cooling operation. In this case, a dielectric barrier discharge is generated on the water film. Here, peroxides are generated, but ozone emissions are low.

[0092] The third operating mode of the device is heating operation. In heating operation, no high voltage is applied between thermoelectric element 1 and electrode 2, and thermoelectric element 1 heats the process gas. Here, thermoelectric element 1 can reach a temperature greater than 100°C. At such a high temperature, ozone decomposes. If thermoelectric element 1 immediately follows its heating operation with a discharge operation, the ozone concentration generated by the discharge through dielectric barrier in the working volume can quickly drop back to a low level. The device can be operated in such a way that cooling operation, discharge operation, and heating operation are repeated sequentially in a preset time sequence.

[0093] The thermoelectric structural element 1 can operate during discharge operation, thereby continuously heating or cooling the process gas over a wide temperature range. This always triggers a dielectric barrier discharge, allowing the process gas to undergo a continuous transition from low to high temperatures. In this way, the entire material spectrum, from ROS (reactive oxygen species) to RNS (reactive nitrogen species), can be generated. This, for example, can facilitate thorough sterilization.

[0094] Furthermore, the thermoelectric structural element 1 can regulate the humidity of the process gas by heating and / or cooling it. For example, moisture can condense from the process gas during cooling. The humidity of the process gas affects the composition of the gas generated in dielectric barrier discharge. For example, the presence of air humidity can lead to the generation of peroxide H2O2.

[0095] The area of ​​thermoelectric structural element 1 is larger than the area of ​​the opposing electrode 2. The thermoelectric structural element 1 has a first region 7 in which the electrode 2 is not directly opposite the thermoelectric structural element 1. Process gas can first be guided through the first region 7 of the thermoelectric structural element 1, where the electrode 2 is not directly opposite the thermoelectric structural element 1, and then the process gas can be guided into a discharge region 8, where the electrode 2 is opposite the thermoelectric structural element 1 and a dielectric barrier discharge is ignited. Thus, before the dielectric barrier discharge occurs, the thermoelectric structural element 1 can cool the process gas in the first region 7. Here, moisture is actively condensed from the process gas before the dielectric barrier discharge. The thus dried process gas can then reach the discharge region. If the process gas is dried outside the discharge region before the dielectric barrier discharge, a higher ozone concentration is achieved during the dielectric barrier discharge compared to the previously undried process gas.

[0096] Figure 2 A second embodiment of the device is shown. Figure 2 In the embodiment shown, an additional cooling body 9 is installed on the ceramic plate of the thermoelectric structural element 1 away from the electrode 2. The additional cooling body 9, in addition to the thermoelectric structural element 1, helps to cool the process gas. Furthermore, in the second embodiment, the electrode 2 is also provided with a cooling body 9. The cooling body 9 connected to the electrode 2 has a gas outlet. The cooling body 9 connected not only to the thermoelectric structural element 1 but also to the electrode 2 is optional and can be omitted in other embodiments.

[0097] exist Figure 2 In the diagram, the direction of heat transfer caused by thermoelectric structural element 1 is indicated by an arrow marked with Q. Thermoelectric structural element 1 cools the process gas. Additional arrows indicate the flow direction of the process gas.

[0098] In addition, the device may optionally or additionally include a fan that supports the flow of process gases along the thermoelectric structural element 1.

[0099] exist Figure 1 and 2 In the embodiment shown, the inner side of the first ceramic plate 5a pointing toward electrode 2 is metallized by a metal bridge 4. The metal bridge 4 does not form a continuous surface on its inner side, but rather forms island-shaped metallizations. This can lead to uneven discharge in dielectric barrier discharge. Additionally, the island-shaped metallizations can cause parasitic discharges on the inner side of the ceramic plate 5a. Figure 3 A third embodiment of the device is shown, which overcomes undesirable side effects.

[0100] In the third embodiment, a weakly conductive layer 10 is disposed between the metal bridge 4 and the first ceramic plate 5a. The weakly conductive layer 10 can balance the potential difference between the island-shaped metallizations. It has resistance that is high compared to the internal resistance of the meandering connection formed by the thermoelectric element 3 and the metal bridge 4. For example, the resistance of the weakly conductive layer 10 can be hundreds of times greater than the resistance of the meandering connection. Correspondingly, the current flowing through the thermoelectric structural element does not flow through the weakly conductive layer, but flows through the metal bridge 4 and the thermoelectric element 3. The weakly conductive layer 10 thus does not interfere with the cooling or heating function of the thermoelectric structural element 1.

[0101] The conductivity of the weakly conductive layer 10 is sufficient for the following: the thermoelectric structural element 1 serves as a mating electrode in a dielectric barrier discharge and avoids uneven discharge. Furthermore, the metal bridges 4 are thus connected to each other via the weakly conductive layer 10, preventing parasitic discharges at the metal bridges 4. The weakly conductive layer 10 thus overcomes the undesirable side effects from the first two embodiments.

[0102] exist Figure 3 In the embodiment shown, a weakly conductive layer 10 is disposed between the metal bridge 4 and the first ceramic plate 5a. No weakly conductive layer 10 is disposed between the metal bridge 4 and the second ceramic plate 5b. In an alternative design, a weakly conductive layer 10 is also disposed between the metal bridge 4 and the second ceramic plate 5b. In another alternative embodiment, a conductive mesh structure is disposed between the metal bridge 4 and the second ceramic plate 5b, which is at a ground potential. The conductive mesh structure prevents parasitic discharge on the inner side of the second ceramic plate 5b. The conductive mesh structure does not have a conductive connection to the metal bridge 4 (the conductive mesh structure is located between the metal bridges 4).

[0103] Figure 4 Similarly, it is shown in Figure 3 The embodiments shown are illustrated in the text. Figure 4The diagram also shows a DC voltage power supply 11 and a high voltage power supply 12. The DC voltage power supply 11 applies a DC voltage in a low voltage range to the thermoelectric structural element 1. Therefore, a DC current flows through the thermoelectric structural element 1. The thermoelectric structural element 1 is located at a low voltage potential. The high voltage power supply 12 applies a high alternating voltage potential to the electrode 2. Correspondingly, a high potential difference appears between the thermoelectric structural element 1 and the electrode 2, and a dielectric barrier discharge is generated in the gap 6 between the electrode 2 and the thermoelectric structural element 2. This dielectric barrier discharge is, in this case, a volumetric discharge.

[0104] Figure 5 , 6 Figures 7 and 8 illustrate a fourth embodiment of the device, wherein a dielectric barrier discharge as a surface discharge is triggered at thermoelectric structural element 1. Figure 5 The middle electrode 2 is not shown. Figure 6 A top view of the thermoelectric structural element 1, which is covered by a first ceramic plate 5a and a metallization 13, is shown.

[0105] In this embodiment, a weakly conductive layer 10 can be disposed between the first ceramic plate 5a and the metal bridge 4. A metallization 13 is disposed on the surface of the first ceramic plate 5a. This metallization 13 serves as an electrode. A high voltage potential can be applied to the metallization 13. The entire thermoelectric structural element 1 is placed on a high alternating voltage potential. The planar electrode 2 works in conjunction with the thermoelectric structural element 1, and this planar electrode 2 can be placed on a ground potential. The electrode 2 has a sufficiently high capacitance to be sufficient for triggering dielectric barrier discharge.

[0106] The metallization 13 has a notch in which the first ceramic plate 5a is not covered. Dielectric barrier discharge is ignited as a surface discharge in the notch.

[0107] exist Figures 5 to 7 In the embodiment shown, the thermoelectric structural element 1 can be cooled and raised to a high alternating voltage potential relative to a surface, such as a segment of human skin or another surface to be processed. A cold dielectric barrier discharge is generated in the gap 6 between the thermoelectric structural element 1 and the surface. Such applications are feasible, for example, in dermatology and wound treatment. Electrodes 2 are formed on the surface here.

[0108] Figure 7 The thermoelectric structural element 1, electrode 2, DC voltage power supply 11, and high voltage power supply 12 are shown. The DC voltage power supply 11 applies a DC voltage to the thermoelectric structural element 1. As a result, a DC current flows through the thermoelectric structural element 1, which triggers the Peltier effect and causes cooling or heating of the process gas.

[0109] The high-voltage power supply 12 applies a high-voltage alternating potential to the thermoelectric structural element 1. The DC voltage power supply 11 is also subjected to a high-voltage alternating potential applied by the high-voltage power supply 12.

[0110] Electrode 2 is at ground potential. It is not connected to high-voltage power supply 12. A high voltage is generated between electrode 2 and metallization 13 of thermoelectric structural element 1, which triggers the ignition of dielectric discharge as a surface discharge at metallization 13 of thermoelectric structural element 1.

[0111] Figure 8 Another embodiment of the device is shown, wherein the device is in Figure 8 It is additionally combined with camera 14. Camera 14 is used here only to capture combustion images generated by the device. Figure 9 An image of the fire is shown, captured by camera 14. Figure 10 The connection of the thermoelectric element 3 via the metal bridge 4 is schematically shown.

[0112] exist Figure 8 In the embodiment shown, the thermoelectric structural element 1 has a plurality of thermoelectric elements 3 arranged in a matrix structure. The thermoelectric elements 3 are further connected to each other via metal bridges 4 in a two-dimensional meandering shape. Figure 9 The combustion images shown reveal the arrangement and connection of thermoelectric element 3. Furthermore, in... Figure 10 The connection of thermoelectric element 3 is shown in detail in the diagram. Here, the metal bridge 4 arranged on the upper side of thermoelectric element 3 is marked with a solid line, and the metal bridge 4 arranged on the lower side of thermoelectric element 3 is marked with a dashed line.

[0113] exist Figure 8 In the embodiment shown, a plate made of indium tin oxide (ITO) is used as electrode 2. A camera 14 is arranged on the side of the indium tin oxide plate away from the thermoelectric structural element. In this way, the camera 14 can capture images of the combustion of the thermoelectric structural element.

[0114] The high-voltage power supply 12 applies an alternating voltage between the thermoelectric structural element 1 and the plate made of indium tin oxide.

[0115] Metal bridges 4 are arranged in an island-like pattern on the first ceramic plate 5a, each connecting two thermoelectric elements to the other. Two adjacent metal bridges 4 are separated from each other by non-metallized surfaces.

[0116] A structured combustion image is obtained, which follows the positional pattern of metal bridge 4. The combustion image is composed of individual combustion spots. The area of ​​the combustion spots is larger than the area of ​​the corresponding metal bridge.

[0117] The ignition voltage for ignition of the dielectric barrier discharge between thermoelectric structural element 1 and electrode 2 is... Figure 8 The embodiment shown is smaller than that in the case of uniform discharge between thermoelectric structural elements and electrodes.

[0118] This embodiment results in the generation of high ozone levels.

[0119] At the point in the combustion image where the highest discharge density exists, the cooling power of thermoelectric structural element 1 is also the highest. This results in a device in which the cooling power density of the thermoelectric structural element is always matched to the heat generated during dielectric discharge.

[0120] Figure 11 It shows crossing in Figure 8 The image shows a cross-section of a portion of the device. According to... Figure 11 As explained below, parasitic discharges on the inner side of the first ceramic plate 5a can be avoided by appropriately dimensionally designing the thickness of the metal bridge 4 and the first ceramic plate 5a.

[0121] exist Figure 10 In the embodiment shown, the direction of the electric field is illustrated within the first ceramic plate 5a and within the gap 6 between the thermoelectric structural element 1 and the electrode 2. Isopotential lines are drawn for this purpose. High density of isopotential lines here is synonymous with high field strength. Alumina is used here as the material of the first ceramic plate 5a. The field strength within the ceramic plate 5a is low. In particular, the field strength within the ceramic plate 5a is at the ignition voltage, and parasitic discharge occurs between the metal bridges when the ignition voltage is exceeded. The ignition voltage can be 300 V / mm.

[0122] A high electric field strength exists in gap 6, which can be, for example, greater than 2 kV / mm. Therefore, a dielectric barrier discharge is ignited within the gap.

[0123] Based on the direction of the equipotential lines, it can be identified that the thickness of the first ceramic plate 5a and the spacing between two adjacent metal bridges 4 significantly affect the electric field strength on the inner side of the first ceramic plate. To avoid parasitic discharge, the spacing between adjacent metal bridges 4 cannot be too large. In particular, the following inequality must be satisfied to prevent parasitic discharge: D>U zünd / U betrieb × ɛ2 / ɛ1× A Here, D represents the thickness of the first ceramic plate. zünd This represents the ignition voltage; exceeding this voltage generates plasma ignition between the metal bridges. U betrieb This represents the operating voltage applied to the device. ɛ2 represents the dielectric constant of the first ceramic plate. ɛ1 represents the dielectric constant of air, and A represents the spacing between adjacent metal bridges.

[0124] Parasitic discharges can also be eliminated in devices that do not have a weakly conductive layer 10 between the metal bridge 4 and the first ceramic plate 5a by appropriate dimensional design of the metal bridge 4.

[0125] In addition, Figures 1 to 10 In each of the embodiments shown, the surface of the thermoelectric structural element 1 facing the electrode 2 and / or the electrode 2 is coated with a glassy layer. This layer can be applied as a molten glaze or fired glaze. The glassy layer is chemically and thermally stable. It protects the thermoelectric structural element 1 or the electrode 2 from oxidizing substances generated during dielectric barrier discharge. Accordingly, the layer improves the lifespan of the device, especially when used in high humidity conditions.

[0126] Instead of a single-stage thermoelectric structural element 1, multiple thermoelectric structural elements can be combined into a multi-stage thermoelectric structural element to achieve a higher temperature difference.

[0127] The operating modes described above (discharge operation, cooling operation, and heating operation) can be used in each of the four illustrated embodiments.

[0128] As a thermoelectric structural element, the following thermoelectric structural element can be used as an alternative to the Peltier element, namely, it has a thermoelectric element made of thermoelectric ceramic material.

[0129] Reference Symbol List 1. Thermoelectric structural elements 2 electrodes 3. Thermoelectric elements 4 Metal Bridge 5a First Ceramic Plate 5b Second ceramic plate 6 gaps 7. First Area 8 Discharge Region 9 cooling body 10 Weakly conductive layer 11 DC voltage power supply 12 High-voltage power supply 13 Metallic compounds 14 cameras

Claims

1. A device for generating dielectric barrier discharge, comprising: Thermoelectric structural element (1), Electrode (2), which is arranged opposite to the thermoelectric structural element (1), and A high-voltage power supply (12) is designed to generate a high voltage between the thermoelectric structural element (1) and the electrode (2), which is sufficient to ignite the dielectric barrier discharge. in, The high-voltage power supply (12) is designed to generate a high alternating voltage potential between the thermoelectric structural element (1) and the electrode (2). The thermoelectric structural element (1) is designed to cool and heat process gases. The thermoelectric structural element (1) is designed to continuously change the temperature of the process gas during the operating cycle. The area of ​​the thermoelectric structural element (1) is larger than the area of ​​the electrode (2), and The process gas is first guided through a first region of the thermoelectric structural element (1), in which the electrode (2) is not directly opposite the thermoelectric structural element (1), and then the process gas is guided to a discharge region, in which the electrode (2) is opposite the thermoelectric structural element (1) and the dielectric barrier discharge is ignited in the discharge region.

2. The apparatus according to claim 1, in, The thermoelectric structural element (1) has two or more thermoelectric elements (3), wherein the thermoelectric structural element (1) has a metal bridge (4) connecting the thermoelectric elements (3). The thermoelectric structural element (1) has a first ceramic plate (5a) that covers the metal bridge (4) on its upper side, which points towards the electrode. The thermoelectric structural element has a second ceramic plate (5b) that covers the metal bridge (4) on the underside of the thermoelectric structural element.

3. The apparatus according to claim 2, in, The first ceramic plate (5a) has aluminum oxide and / or aluminum nitride.

4. The apparatus according to claim 2, in, The first ceramic plate (5a) has an insulating region that the electric field does not penetrate, and / or a conductive region that the electric field is guided along the conductive region.

5. The apparatus according to claim 2, in, The thermoelectric elements (3) are arranged in a row. In this configuration, two adjacent thermoelectric elements are connected to each other in a meandering manner by a metal bridge (4) on their upper or lower sides respectively.

6. The apparatus according to claim 2, in, The thermoelectric elements are arranged in a two-dimensional matrix structure. The metal bridge (4) connects the thermoelectric elements in a two-dimensional meandering shape, wherein thermoelectric elements adjacent to each other along the two-dimensional meandering shape are connected to each other by the metal bridge (4) on their upper or lower sides.

7. The apparatus according to claim 2, in, The metal bridges (4) are separated from each other by non-metallized surfaces. The maximum extension of the non-metallized surface between two adjacent metal bridges (4) is less than the thickness of the first ceramic plate (5a).

8. The apparatus according to claim 2, in, The metal bridge (4) and the first ceramic plate (5a) are designed to be sized such that the following inequality must be satisfied: D > U zünd / U betrieb × ɛ2 / ɛ1 × A, Where D represents the thickness of the first ceramic plate (5a), U zünd This represents the ignition voltage, which, when exceeded, generates plasma ignition between the metal bridges. U betrieb The voltage applied to the device is represented by ɛ2, the dielectric constant of the first ceramic plate (5a) is represented by ɛ1, the dielectric constant of air is represented by ɛ1, and A represents the spacing between adjacent metal bridges.

9. The apparatus according to claim 2, in, The device has a weakly conductive layer (10) disposed on the inner side of the first ceramic plate (5a), which points toward the metal bridge (4). The weakly conductive layer (10) has a resistance that is at least 100 times the resistance of the thermoelectric element (3) via the metal bridge (4).

10. The apparatus according to claim 9, in, The weakly conductive layer (10) is a layer applied to the first ceramic plate (5a) using a thin-layer technique. The weakly conductive layer can have a thickness between 10 nm and 100 nm.

11. The apparatus according to claim 9, in, The first ceramic plate (5a) has a multilayer structure, wherein the weakly conductive layer is constructed as a sublayer of the first ceramic plate.

12. The apparatus according to claim 9, in, The weakly conductive layer (10) has a resistance that is at least 100 times the resistance of the thermoelectric element via the meandering connection of the metal bridge (4).

13. The apparatus according to claim 9, in, The weakly conductive layer (10) has at least one element that conducts electricity and / or at least one element that conducts electricity.

14. The apparatus according to claim 2, in, The device has a conductive structure arranged between the second ceramic plate (5b) and the metal bridge (4) located on the lower side of the thermoelectric element, and this conductive structure is connected to the ground potential. The conductive structure therein does not have a conductive connection to the metal bridge (4), and the conductive structure is located between the metal bridges.

15. The apparatus according to claim 14, in, The structure that conducts electricity is a mesh.

16. The apparatus according to claim 2, in, The thermoelectric structural element (1) is a Peltier element, and The thermoelectric element (3) is made of semiconductor material or ceramic material that acts as a semiconductor.

17. The apparatus according to claim 2, in, The thermoelectric element is made of thermoelectric ceramic material.

18. The apparatus according to claim 17, in, The thermoelectric ceramic material includes calcium manganese oxides in which Fe atoms are partially doped at the positions of Mn atoms, or The thermoelectric ceramic material comprises materials of the general formula Ca 1-x-y ISO x DON y Mn 1-z Fe z O n The material described, where ISO indicates the ability to substitute Ca in the crystal lattice. 2+ divalent element, DON indicates that it can replace Ca in the crystal lattice. 2+ And elements that donate electrons for conductivity, and Where 0 ≤ x ≤ 0.5; 0 < y ≤ 0.5; 0.0001 ≤ z < 0.2; n ≥ 2, or The thermoelectric ceramic material is based on (Ca 3-x Na x Co4O 9-δ The material composition has 0.1 ≤ x ≤ 2.9 and 0 < δ ≤ 2.

19. The apparatus according to claim 1, in, The high-voltage power supply (12) is designed to apply a high-voltage alternating potential to the electrode (2), and The device has a DC voltage power supply (11) designed to apply a low DC voltage to the thermoelectric structural element (1).

20. The apparatus according to claim 1, in, The device is designed to ignite the dielectric barrier discharge, which is a volumetric discharge between the thermoelectric structural element (1) and the electrode (2).

21. The apparatus according to claim 1, in, The thermoelectric structural element (1) has a metallide (13) on the surface facing the electrode (2). The high-voltage power supply (12) is designed to apply a high voltage potential to the thermoelectric structural element (1), thereby igniting the dielectric barrier discharge as a surface discharge at the metallization (13).

22. The apparatus according to claim 21, in, The metallization (13) is composed of a conductive material and / or a semiconductive material.

23. The apparatus according to claim 21, in, The metallization (13) consists of a Mo / Mn slurry that is burned in a hydrogen atmosphere or a W slurry mixed with an oxidizing adhesion promoter.

24. The apparatus according to claim 1, in, The electrode (2) and / or the thermoelectric structural element (1) are coated with a glassy layer.

25. The apparatus according to claim 1, in, The area of ​​the thermoelectric structural element is larger than the area of ​​the electrode (2).

26. The apparatus according to claim 1, in, The device has a controller designed to operate the device in a cooling operation in which a dielectric barrier discharge is not triggered and the surface of the device is cooled below the dew point of the process gas, thereby generating a water film by condensation on the surface, and then to operate the device in a discharge operation in which the dielectric barrier discharge is generated on the water film.

27. The apparatus according to claim 1, in, The device is designed to operate in a heated operation in which a dielectric barrier discharge is not triggered and the surface of the device is heated to a temperature greater than 100 °C.

28. The apparatus according to claim 1, in, The device has at least one sensor selected from a temperature sensor, an ozone sensor, and a humidity sensor, and The device is designed to match the power of the thermoelectric structural element (1) and / or the power of the high-voltage power supply (12) in consideration of the measurement results of the at least one sensor.

29. The apparatus according to claim 1, in, The electrode (2) can be replaced individually, and / or the thermoelectric structural element (1) can be replaced individually.

30. The apparatus according to claim 10, in, The weakly conductive layer can have a thickness between 25 nm and 75 nm.

31. The apparatus according to claim 13, in, The element that conducts electricity is Cr or Ni.

32. The apparatus according to claim 13, in, The element that plays a semiconductive role is B or Si.

33. The apparatus according to claim 13, in, The weakly conductive layer (10) has at least one material that serves as an insulating layer.

34. The apparatus according to claim 33, in, The insulating material is SiO2 or Al2O3. 3。 35. The apparatus according to claim 22, in, The metallization (13) is composed of a mixture of bismuth and rhodium.

36. The apparatus according to claim 23, in, The oxidative adhesion promoter is aluminum oxide, manganese oxide, magnesium oxide, or titanium oxide.

37. An apparatus having the means according to any one of claims 1-36, in, The equipment is an air conditioner, cooling equipment, disinfection equipment, clothes dryer, packaging equipment, equipment from food processing, room purification equipment, equipment for parasite control in textiles, or waste collector.

38. The device according to claim 37, in, The cooling device is a refrigerator.

39. The device according to claim 37, in, The cooling device is a cooling box.

40. A method for generating a dielectric barrier discharge using the apparatus according to any one of claims 1-36, wherein a high voltage is generated between the thermoelectric structural element (1) and the electrode (2) by the high voltage power supply (12) and ignites the dielectric barrier discharge.

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