Device and method for generating dielectric barrier discharge, method for setting operating parameters of control device, computer program and computer-readable storage medium

Abstract

The invention relates to a device for generating a dielectric barrier discharge, comprising a discharge reactor and a control device (13). The discharge reactor has a thermoelectric component (1) and an electrode (2). According to the invention, the control device (13) has a high-voltage source (12) which is designed to apply a high-voltage potential to the electrode (2), which high-voltage potential is sufficient to ignite the dielectric barrier discharge, by means of which a gas is enriched in a reactive substance. The control device (13) is designed to suitably set operating parameters of the high-voltage source (12) and of the discharge reactor for a desired composition of the enriched gas. Another aspect relates to a method for generating a dielectric barrier discharge. Further aspects relate to a method for setting operating parameters of a control device, a computer program and a computer-readable storage medium.

Description

Technical Field

[0001] The subject of this application is an apparatus and method for generating dielectric barrier discharge, a method for setting operating parameters of a control apparatus, a computer program, and a computer-readable storage medium. Background Technology

[0002] A plasma reactor is known from WO 2022 / 058 333 A1, which is designed to cool process gases by means of Peltier elements. Summary of the Invention

[0003] The present invention aims to provide an improved apparatus for generating dielectric barrier discharge, as well as an improved method for operating the apparatus and for setting operating parameters. A further objective is to provide a computer program for performing the method and a computer-readable storage medium for performing the computer program.

[0004] The objective is achieved through the subject matter of the independent claims.

[0005] A device for generating a dielectric barrier discharge is proposed, the device comprising a discharge reactor and a control device. The discharge reactor has a thermoelectric structural element and electrodes. The control device has a high-voltage source and a low-voltage source. The high-voltage source is designed to apply a high-voltage potential to the electrodes, the high-voltage potential being sufficient to ignite the dielectric barrier discharge, wherein the gas is enriched with reactants through the dielectric barrier discharge. The low-voltage source is designed to set the current passing through the thermoelectric structural element. The control device is designed to appropriately set the operating parameters of the high-voltage source and the low-voltage source for the desired composition of the enriched gas.

[0006] Therefore, the control equipment can be designed to always select the optimal operating point for the equipment. Here, the control equipment can take into account the influence of various operating parameters on the generated reactants, as well as the interactions between these operating parameters.

[0007] The operating point or run point of a device is characterized by setting its operating parameters. These parameters determine the quantity and amount of reactants produced during dielectric barrier discharge. Multiple operating parameters can now be specifically set within the device to obtain the desired composition of the enriched gas containing the reactants.

[0008] The high-voltage source can be an AC voltage source. Correspondingly, the high-voltage potential applied to the electrodes can change with the frequency of the AC voltage generated by the high-voltage source. An AC voltage with an amplitude of 1kV or higher can be referred to as high voltage here.

[0009] The low-voltage source can be a DC voltage source. Correspondingly, DC current can flow through thermoelectric structural elements. Depending on the direction of the DC current, the thermoelectric structural elements can cool or heat / heat the gas in the discharge reactor.

[0010] The control equipment can determine the operating parameters by applying input signals to the low-voltage source and the high-voltage source.

[0011] In the first embodiment, a thermoelectric barrier discharge can be ignited in the discharge reactor, in which the thermoelectric structural element acts as the corresponding electrode. A dielectric barrier discharge can be ignited between the electrode and the thermoelectric structural element acting as the corresponding electrode.

[0012] Thermoelectric structural elements can be placed in the reactor so that the temperature of the gas can be changed by the thermoelectric structural elements. The thermoelectric structural elements can either cool or heat the gas before and / or during dielectric barrier discharge.

[0013] Thermoelectric structural elements can specifically refer to Peltier elements or structural elements made of thermoelectric ceramic materials.

[0014] Because the device can be designed to select operating parameters that consistently yield the desired gas composition for activation, errors can be eliminated when the device is used by the user, for example, in sterilization. Correspondingly, additional system components for delivering chemicals can be eliminated, and consumables can be saved. If the reactants involve semi-stable chemical actives with short half-lives, for which storage and external provision are not feasible, the device enables the production of the actives in situ for direct application.

[0015] The equipment can be designed to set each operating parameter independently of its respective individual operating parameters. These operating parameters can be set dynamically, meaning they can be adjusted continuously during operation. Here, different processes with different in-situ effective substances can be described in a single piece of equipment.

[0016] The operating parameters of the high-voltage source may include at least one selected from the amplitude of the high-voltage potential, the frequency of the high-voltage potential, and the pulse width modulation of the high-voltage potential, wherein the duty cycle and / or modulation frequency are set in the pulse width modulation.

[0017] The amplitude of the high-voltage potential generated by the AC voltage signal from the high-voltage source can be set to determine the amount of reactants produced during dielectric barrier discharge and the relationship between the amounts of reactants. Generally, the amount of reactants produced increases with increasing amplitude. However, the proportion of each reactant in the gaseous composition of the enriched gas is related to the amplitude of the selected high-voltage AC voltage.

[0018] The amplitude of the high voltage can reach up to 8kV. The high voltage AC voltage can have frequencies between 15kHz and 100kHz, preferably between 20kHz and 40kHz.

[0019] The duty cycle can be set via pulse width modulation of a high-voltage voltage. The duty cycle describes the relationship between the time period during which a signal is applied to the electrode and a corresponding dielectric barrier discharge occurs, and the time period during which no signal is applied to the electrode and a dielectric barrier discharge does not ignite. In this way, pulse width modulation can regulate the power of the dielectric barrier discharge. Therefore, pulse width modulation of a high-voltage AC voltage alters the power density in the reactor, which directly affects the type of reactants produced during the dielectric barrier discharge. The modulation frequency can also be set by a control device during pulse width modulation.

[0020] The operating parameters of the low-pressure source, set by the control equipment, can include the current intensity flowing through the thermoelectric structural element. By changing the current intensity, the intensity and direction of heat transported via the module can be set, thereby regulating the temperature on one side of the thermoelectric structural element.

[0021] Thermoelectric structural elements can be used not only for cooling but also for heating gases in a discharge reactor. In particular, cooling the gas can increase the ozone concentration in the enriched gas. Conversely, heating the gas produces more nitrogen oxides as reactants, which reduce ozone, thus causing a decrease in the ozone concentration in the enriched gas.

[0022] The operating parameters mentioned herein are not considered independently of each other. Rather, the control equipment can be designed to always consider together the effect of each of the mentioned operating parameters on the composition of the enriched gas.

[0023] The control device can also be designed to control the chemical composition of the reactants generated during dielectric barrier discharge by means of pulse width modulation of the high-voltage potential and / or setting the current intensity of the current flowing through the thermoelectric structural element and / or setting the amplitude and / or setting the frequency of the high-voltage potential. Preferably, all four operating parameters mentioned herein are always matched to the desired chemical composition.

[0024] The control equipment can also be designed to take into account environmental parameters that also have a significant impact on the composition of the reactants generated during dielectric barrier discharge.

[0025] The control equipment can be specifically designed to consider at least one or more of the following environmental parameters when setting operating parameters: the gas flow rate through the discharge reactor, the gas composition, and / or the gas temperature before and / or upon entering the discharge reactor. Alternatively or additionally, the control equipment can consider the ambient temperature when setting operating parameters. Considering these environmental parameters allows for more accurate modeling of the plasma chemistry mapping function and a more precise match between the enriched gas composition and the desired composition.

[0026] As gases, such as air, pure oxygen, synthetic air, or compressed dry air (CDA) can be introduced into the discharge reactor. The gases mentioned behave differently in dielectric barrier discharge, so the type of gas used affects the type and amount of reactants produced. For example, the humidity of the air used affects the type and amount of substances produced during dielectric barrier discharge.

[0027] The device can be equipped with sensors to measure environmental parameters. Alternatively, the influence of environmental parameters can be considered indirectly by detecting and evaluating the current pulses generated in the discharge reactor. Alternatively, the influence of environmental parameters can be considered indirectly by comparing the composition of the generated material with the desired composition and adjusting operating parameters taking the comparison results into account.

[0028] The surface of the electrode pointing towards the thermoelectric structural element may have protrusions. Surface dielectric barrier discharge (SDBD) can occur at these protrusions, while volume dielectric barrier discharge (VDBD) can be induced in the intermediate space between two protrusions (where the electrode is spaced from the thermoelectric structural element). Correspondingly, the device can achieve a hybrid operating mode in which both surface and volume discharges exist.

[0029] The protrusions of the electrode can be attached to the thermoelectric structural element. Here, the protrusions can serve not only as discharge points for surface discharge but also as spacing retainers defining the distance between the non-protruding areas of the thermoelectric structural element and the electrode. In this way, the volume for volumetric discharge can be determined by the length of the protrusions.

[0030] The thermoelectric structural element can have multiple thermoelectric elements and metal bridges, where each metal bridge connects two adjacent thermoelectric elements to each other. In particular, the metal bridges can connect the thermoelectric elements in a meandering manner, with the metal bridges alternately arranged on the upper side of the thermoelectric structural element facing the electrode and on the lower side of the thermoelectric structural element away from the electrode. The protrusions of the electrodes can be configured such that each protrusion is opposite to exactly one metal bridge on the upper side of the thermoelectric structural element. The protrusions can be centrally located on the metal bridges. The metal bridges can be covered by a dielectric barrier layer, such as a ceramic layer. The protrusions can abut against the dielectric barrier layer.

[0031] The protrusions on the electrodes can dissipate the heat generated on the electrode surface during dielectric barrier discharge. By centering the protrusions relative to the metal bridge, heat transfer can be designed particularly effectively and unwanted parasitic discharges inside the thermoelectric structural element can be prevented.

[0032] A high-voltage source can be self-resonant. If a high-voltage source is designed to constantly readjust the frequency of the high-voltage signal it generates, such that the discharge reactor operated by it operates in a resonant mode, then the high-voltage source is described as self-resonant. In an alternative embodiment, the discharge reactor can operate at a frequency that does not correspond to the resonant frequency of the discharge reactor.

[0033] The control device may have a computing unit designed to determine suitable operating parameters for the desired composition of the enriched gas. The control device can then set the operating parameters according to the preset parameters of the computing unit.

[0034] The computing unit can be designed to obtain operating parameters using analytical methods, regression methods, numerical methods, computer-implemented methods, or by means of self-learning algorithms.

[0035] The device may include sensors designed to determine the composition of the enriched gas, wherein the control device is designed to compare the composition determined by the sensors with the desired composition and adjust operating parameters based on the comparison result. Correspondingly, the sensors can provide feedback, in which a signal describing the gas composition in the enriched gas is compared with the desired gas composition. Operating parameters can be iteratively set via feedback to achieve the desired gas composition.

[0036] In dielectric barrier discharge, current pulses can be generated in the discharge reactor. The device can be designed to measure these current pulses and determine the reactants produced based on the frequency and / or height of the measured current pulses. The control device can be designed to adjust operating parameters based on the measured current pulses. The control device can also be designed to adjust operating parameters based on the measured current pulses, wherein the control device may additionally consider one or more of the following parameters: the gas flow rate through the discharge reactor, the gas composition and / or temperature upon entering the discharge reactor, and / or the ambient temperature.

[0037] This can be achieved by using sensors or evaluating the current pulses generated in the discharge reactor, taking into account the influence of environmental parameters on the composition of the enriched gas, without having to measure any environmental parameters here.

[0038] On the other hand, a method for generating dielectric barrier discharge is provided. The aforementioned apparatus can be used in particular in this method.

[0039] The method uses a device having a discharge reactor and a high-voltage source, wherein the discharge reactor has thermoelectric structural elements and electrodes, and wherein the control device has a high-voltage source and a low-voltage source. The high-voltage source is designed to generate a high-voltage potential on the electrodes. The method comprises the following steps:

[0040] - Set the current through the thermoelectric structural element, wherein the current is set by a low-voltage source.

[0041] - A high-voltage potential is applied to the electrodes, igniting a dielectric barrier discharge, wherein the gas is enriched with reactants through the dielectric barrier discharge, wherein the high-voltage potential is applied by a high-voltage source, and

[0042] - The operating parameters of the high-pressure source and the low-pressure source are set to produce the desired components of the enriched gas, wherein the control device sets the operating parameters.

[0043] The operating parameters of the high-voltage source may include at least one selected from the amplitude of the high-voltage potential, the frequency of the high-voltage potential, and the pulse width modulation of the high-voltage potential, wherein the duty cycle and / or modulation frequency are set in the pulse width modulation, and wherein the operating parameters of the low-voltage source include the current intensity of the current flowing through the thermoelectric structural element.

[0044] The setting of the operating parameters can be determined by using a modeling function, which is set by the control device to produce the desired composition of the enriched gas. The modeling function obtains the output variables describing the gas discharged from the discharge reactor from the input variables describing the gas entering the discharge reactor and from the operating parameters.

[0045] Input variables may include at least one of the following: the chemical composition of the gas entering the discharge reactor, the temperature of the gas entering the discharge reactor, and the flow rate of the gas entering the discharge reactor.

[0046] Input variables may include at least one selected from ambient temperature and current pulses generated in the discharge reactor.

[0047] Output variables may include at least one selected from the temperature of the gas discharged from the discharge reactor, the flow rate of the gas discharged from the discharge reactor, and the composition of the gas discharged from the discharge reactor.

[0048] On the other hand, a method is provided for setting operating parameters of a control device for manipulating a discharge reactor. This may involve the aforementioned control device having a high-voltage source and a low-voltage source, and the aforementioned discharge reactor having electrodes and thermoelectric structural elements. The method for setting the operating parameters of the control device may be part of the aforementioned method for generating dielectric barrier discharge.

[0049] The method for setting the operating parameters of a control device includes the following steps:

[0050] - Determine the operating parameters of the high-voltage and low-voltage sources to induce dielectric barrier discharge on the electrodes, thereby generating the desired composition of the enriched gas during the dielectric barrier discharge.

[0051] - Adjust the running parameters to the values ​​determined in the previous steps.

[0052] The operating parameters of the high-voltage source may include at least one selected from the amplitude of the high-voltage potential, the frequency of the high-voltage potential, and the pulse width modulation of the high-voltage potential, wherein the duty cycle and / or modulation frequency are set in the pulse width modulation, and wherein the operating parameters of the low-voltage source include the current intensity of the current flowing through the thermoelectric structural element.

[0053] The setting of the operating parameters can be determined by using a modeling function, which is set by the control device to produce the desired composition of the enriched gas. The modeling function obtains the output variables describing the gas discharged from the discharge reactor from the input variables describing the gas entering the discharge reactor and from the operating parameters.

[0054] Input variables may include at least one selected from the chemical composition of the gas entering the discharge reactor, the temperature of the gas entering the discharge reactor, and the flow rate of the gas entering the discharge reactor.

[0055] Input variables may include at least one selected from ambient temperature and current pulses generated in the discharge reactor.

[0056] Output variables may include at least one selected from the temperature of the gas discharged from the discharge reactor, the flow rate of the gas discharged from the discharge reactor, and the composition of the gas discharged from the discharge reactor.

[0057] On the other hand, a computer program is involved that executes the aforementioned method for determining operating parameters. The computer program includes: a first step in which a desired component of the enriched gas is input; and a second step in which the method is executed. The input of the desired gas component can be performed by a user or through a higher-level system connected to the device. The first step can alternatively be performed by a fixed programmed input of the desired gas component.

[0058] The determination of operating parameters can be carried out using analytical methods, regression methods, numerical methods, computer-implemented methods, or self-learning algorithms.

[0059] On the other hand, it relates to a computer-readable storage medium having the aforementioned computer program, wherein the computer program has... Attached Figure Description

[0060] Preferred embodiments are described below with reference to the accompanying drawings.

[0061] Figure 1 The discharge reactor is shown.

[0062] Figure 2 The discharge reactor and control equipment are shown.

[0063] Figure 3 A schematic diagram is shown, illustrating the effect of operating parameters on the generated reactants.

[0064] Figure 4 The diagram illustrates a method for generating dielectric barrier discharge.

[0065] Figure 5 This illustration shows which variables are affected by operating parameters that can be set by the control equipment.

[0066] Figure 6 A discharge reactor according to an alternative embodiment is shown. Detailed Implementation

[0067] Figure 1 A discharge reactor for generating dielectric barrier discharge is shown, the discharge reactor having a thermoelectric structural element 1 and an electrode 2. The thermoelectric structural element 1 relates to a Peltier element.

[0068] Thermoelectric element 1 is an electrothermal converter. It is designed to change the temperature of the gas introduced into the discharge reactor as a process gas and discharged from the discharge reactor as a enriched 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—when the current direction is reversed—for heating the process gas.

[0069] The thermoelectric structural element 1 has thermoelectric elements 3, which are connected to each other in a meandering structure by metal bridges 4.

[0070] If thermoelectric element 1 is a Peltier element, then semiconductor elements are used as thermoelectric elements. The semiconductor elements are connected in series with each other via metal bridge 4, where p-doped and n-doped semiconductor elements alternate. The semiconductor elements can be, for example, bismuth telluride or silicon germanium.

[0071] If direct current is guided through thermoelectric structural element 1, a temperature difference is generated at metal bridge 4 due to thermoelectric effects, such as the Peltier effect, which in turn creates a hot side and a cold side of the structural element.

[0072] The thermoelectric structural element 1 has a first ceramic plate 5a and a second ceramic plate 5b. The first ceramic plate 5a is disposed on the upper side facing the electrode. The second ceramic plate 5b is disposed on the lower side away from the electrode.

[0073] 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.

[0074] Ceramic plates 5a and 5b cover metal bridge 4. Figure 1 In the embodiment shown, ceramic plates 5a and 5b are directly disposed on the metal bridge 4. 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 function as heat-conducting plates. The ceramic plates 5a and 5b extract heat from the process gas or transfer heat to the process gas.

[0075] Electrode 2 is arranged parallel to the first ceramic plate 5a. Electrode 2 is opposite to thermoelectric structural element 1 and is located thereon. Figure 1 The embodiment shown is spatially separated from the thermoelectric structural element 1. A gap 6 exists between the electrode 2 and the thermoelectric structural element 1. The gap 6 between the thermoelectric structural element 1 and the electrode 2 can have a width between 0.01 mm and 1.0 mm, preferably between 0.05 mm and 0.5 mm.

[0076] This device is designed to initiate a dielectric barrier discharge between electrode 2 and thermoelectric structural element 1. The dielectric barrier discharge involves igniting a non-thermal atmospheric pressure plasma. During the dielectric barrier discharge, the process gas is enriched with reactants.

[0077] A high-amplitude alternating current potential is applied to electrode 2 regarding the potential of thermoelectric structural element 1. Therefore, a high-voltage alternating current is generated between thermoelectric structural element 1 and electrode 2. A dielectric barrier discharge (DBD) is ignited between thermoelectric structural element 1 and electrode 2, wherein the ceramic plate 5a facing electrode 1 acts as a dielectric barrier.

[0078] Alternatively or additionally, the layer acting as a dielectric barrier may be disposed on the side of electrode 2 facing thermoelectric structural element 1.

[0079] A direct current flows through thermoelectric structural element 1. The DC voltage potential difference through the low-ohm 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 small compared to the DC current flowing through thermoelectric element 3. Correspondingly, the cooling function of thermoelectric structural element 1 and the discharge function of the device do not negatively affect each other.

[0080] In an alternative embodiment, the thermoelectric structural element is not disposed opposite to the electrode. In an alternative embodiment, the device may be designed to ignite a dielectric barrier discharge between the electrode and a surface to which a ground potential is applied.

[0081] In this device, thermoelectric element 1 serves not only as a cooling or heating element for setting the temperature of the process gas, but also as a corresponding electrode that, together with electrode 2, initiates dielectric barrier discharge. By combining thermoelectric element 1 with dielectric barrier discharge, dielectric barrier discharge can be operated at precisely set temperature and humidity, and the concentration and composition of the active material generated in the dielectric barrier discharge can be set and stably maintained.

[0082] The thermoelectric element 1 can regulate the temperature of the process gas in the gap 6 between the electrode 2 and the thermoelectric element 1. If the thermoelectric element 1 is used for dielectric barrier discharge, the temperature of the process gas can be precisely set during discharge. The gas composition of the gas generated during dielectric barrier discharge is particularly strongly dependent on the temperature of the process gas. In particular, the generated ozone (O3) and nitrite gases (NO, NO2, NO3-) are highly dependent on the temperature of the process gas. x The proportion of nitrite is determined by temperature. As temperature increases, it favors the production of nitrite and accelerates the decomposition mechanism of ozone, thereby generating more nitrite.

[0083] The device also includes a cooling body 9, which is positioned on a ceramic plate 5b away from the electrode 2 of the thermoelectric element 1. The cooling body 9, in addition to the thermoelectric element 1, helps to cool the process gas.

[0084] The discharge reactor has a gas inlet 7 and a gas outlet 8. Process gas enters the discharge reactor through the gas inlet 7. The process gas is enriched with reactants within the discharge reactor. The gas enriched in the discharge reactor exits through the gas outlet 8.

[0085] In addition, the device may alternatively or supplementally include a fan 10, which is designed to remove heat from the cooling body and thereby contribute to cooling.

[0086] Figure 2 Shown in Figure 1 The discharge reactor and control device 13 are shown in the diagram, with the control device connected to the discharge reactor. The control device 13 has a low-voltage source 11 and a high-voltage source 12. The low-voltage source 11 applies a DC voltage in the 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 at a low voltage potential. The high-voltage source 12 applies a high AC potential to the electrode 2. Correspondingly, a high potential difference is generated between the thermoelectric structural element 1 and the electrode 2, and a dielectric barrier discharge occurs in the gap 6 between the electrode 2 and the thermoelectric structural element 1. This dielectric barrier discharge relates to volumetric discharge.

[0087] The control device 13 is designed to control the operating parameters of the low-voltage source 11 and the high-voltage source 12. For this purpose, the control device 13 may have a computing unit 14, such as a microcontroller, designed to send control commands to the high-voltage source 12 and the low-voltage source 11.

[0088] The control device 13 is designed to set operating parameters to obtain the desired composition of the enriched gas. Here, the control device 13 can take into account not only the temperature of the thermoelectric structural element 1, but also the amplitude and pulse width modulation of the high-voltage AC potential applied to the electrode 2 by the high-voltage source 12, influencing the type and amount of the generated reactants.

[0089] Correspondingly, control device 13 can specifically produce effective substances or combinations of effective substances in the gas at desired concentrations and proportions by correspondingly setting operating parameters. For each desired product gas composition, control device 13 selects the optimal and most efficient operating point as the device's operating point. The device's operating point or working point is characterized here by the corresponding setting of the operating parameters of the high-pressure source 12 and the low-pressure source 11.

[0090] Since the reactants generated in the process gas are also related to environmental conditions, such as the type of process gas, the temperature of the process gas entering the discharge reactor, and the flow rate of the process gas through the discharge reactor, these environmental conditions can be taken into account by the control device 13 when setting the operating parameters.

[0091] The control equipment is designed to generate the desired composition of activated gas by selectively combining operating parameters, taking into account the interrelationships of operating parameters and environmental conditions.

[0092] Figure 3 This schematically illustrates how operating parameters affect the production of reactants, including... Figure 2 The equipment shown uses air as the process gas.

[0093] In the curves plotted in the first row, the amplitude of the high voltage potential applied to the electrodes is varied, while keeping the temperature of the thermoelectric structural element constant and without pulse width modulation of the high voltage signal.

[0094] In the four figures shown, the concentrations of ozone, nitrogen oxides, peroxides, and acids in the activated gas are plotted from left to right for different amplitudes of the high-voltage signal.

[0095] As shown in the first curve illustrating ozone concentration, the ozone concentration initially increases with increasing amplitude until it reaches a maximum. If the amplitude continues to increase beyond this maximum, the ozone concentration in the excited-state gas decreases. The reason for the decrease in ozone concentration in the enriched gas at high amplitudes is that when the high-voltage signal has sufficiently large energy, it excites the mechanisms for ozone decomposition. Nitrogen oxides are then generated, particularly during dielectric barrier discharge, which induce ozone decomposition.

[0096] The second curve shows the concentration of nitrogen oxides in the enriched gas for different amplitudes of the high-voltage signal. The curves show that at relatively small amplitudes, almost no nitrogen oxides are produced. Only when the amplitude is sufficiently large does the concentration of nitrogen oxides in the enriched gas increase continuously with increasing amplitude.

[0097] The third curve shows the concentration of peroxide in the enriched gas for different amplitudes of the high-voltage signal. The concentration has a maximum value for medium amplitude.

[0098] The fourth curve shows the concentration of acid in the enriched gas for different amplitudes of the high-voltage signal.

[0099] The second line assumes pulse width modulation (PWM) of the high-voltage signal. The power of the high-voltage signal can be adjusted by setting the duty cycle between the time the signal is applied and the time the signal is not applied. The power, directly proportional to the PWM duty cycle, is plotted on the horizontal axis of the curve shown in the second line. The corresponding concentrations of the reactants are plotted in arbitrary units on the vertical axis. The temperature and the amplitude of the high-voltage signal remain constant during gas discharge.

[0100] As can be seen from the curve in the second row, the concentrations of all reactants increase with increasing power. However, it should be noted that the curves shown here are purely illustrative and arbitrary units are used. In particular, the relationship between the proportions of the reactants changes with increasing power.

[0101] The third row shows four curves where the temperature of the thermoelectric structural element changes while the power and amplitude of the high-voltage signal remain constant. The first curve, viewed from the left, shows the ozone concentration. It can be seen that the ozone concentration decreases with increasing temperature. To achieve a high ozone concentration, the thermoelectric structural element must therefore cool the process gas. The second curve shows that the concentration of nitrogen oxides increases with increasing temperature. The third curve shows that the concentration of peroxides decreases with increasing temperature. The fourth curve shows that the concentration of acids increases with increasing temperature.

[0102] exist Figure 3 The curves shown are purely schematic and do not take into account the interactions between operating parameters with respect to the reactants produced. To select the optimal operating point, that is, to optimally set the operating parameters, a mapping function with precise modeling of plasma chemistry is required.

[0103] Figure 4 Schematic illustration of the use of in Figure 2 The device shown in the figure generates a dielectric barrier discharge.

[0104] The gas flowing into the discharge reactor is described here by input variables, which are summarized into an input vector U. These input variables include the ambient temperature T of the equipment. U The gas entering gas inlet 7 has, and is particularly likely to, deviate from, the ambient temperature T. U Temperature T in The gas here is described as the flow rate of the mass flow of all gaseous components and the concentration c of each chemical component constituting the gas flowing into the discharge reactor. i 1. c i 2、……、c i m .

[0105] The gas discharged from the discharge reactor is described by output variables, which are aggregated into an output vector W. The output variables include the temperature T of the gas discharged from the discharge reactor. out The flow rate of the gas discharged from the discharge reactor and the concentrations (c) of the various chemical components constituting the gas discharged from the discharge reactor. a 1. c a 2、……、c a n The gas discharged from the discharge reactor contains all the chemical components of the gas entering the discharge reactor, and may also contain additional chemical components generated during dielectric barrier discharge. For this purpose, it may include, for example, ozone, nitrogen oxides, or peroxides. Therefore, the quantity n of the chemical components in the discharged gas is greater than or equal to the quantity m of the chemical components in the gas flowing into the discharge reactor.

[0106] The control unit is now designed to influence dielectric barrier discharge and the reactants produced therein. To this end, the control unit can adjust the operating parameters of the high-voltage source 12 and the low-voltage source 11. The operating parameters are... Figure 4 The values ​​of these variables are aggregated into a vector V, which is the adjustment variable. The adjustment variable includes the amplitude U of the high-voltage potential applied to electrode 2 by high-voltage source 12. D The frequency f of the high-voltage potential applied to electrode 2 by high-voltage source 12, the pulse width modulation (PWM) of the high-voltage potential with a set duty cycle and modulation frequency f, and the current intensity I of the current. tec The current is set by the low-voltage source 11 through the thermoelectric structural element 1 and the temperature of the thermoelectric structural element 1 is regulated by the current.

[0107] In the discharge reactor, short current pulses are generated during dielectric barrier discharge, with frequencies ranging from 10 MHz to 50 MHz or exceeding 50 MHz. These current pulses are generated by the current flowing between electrode 2 and its corresponding electrode, wherein... Figure 2 In the embodiment shown, thermoelectric structural element 1 forms the corresponding electrode. The height of the current pulse is proportional to the discharge intensity under a first-order approximation and also proportional to the concentration of newly generated chemical substances over a wide range. If pure oxygen is used as the process gas, the height of the current pulse is proportional to the amount of ozone produced. The reactants produced can be inferred from the frequency of the current pulse.

[0108] The current pulses generated in the discharge reactor can be detected and evaluated by the control device 13. In this way, the control device 13 can measure the type and amount of reactants produced.

[0109] exist Figure 4In this context, the current pulse is described as S. The current pulse is coupled out from the discharge reactor and converges in the input vector U. Therefore, the input vector U contains input variables that describe the environmental conditions and the gas entering the discharge reactor, as well as information obtained from the current pulse.

[0110] In control devices, output variables are now pre-calculated using a modeling function f(U,V), where the input vectors U and V, summed from the adjustment variables, are considered as parameters in the modeling function f(U,V). The modeling function f(U,V) is a multidimensional function with multiple variables. The modeling function f(U,V) can be a purely analytical function, computed using analytical methods. The modeling function f(U,V) can be computed using regression methods. The modeling function f(U,V) can be computed using numerical methods. The modeling function f(U,V) can be a computer-implemented method, such as by a self-learning algorithm. The modeling function f(U,V) can be a combination of the methods mentioned herein.

[0111] In the modeling function f(U,V), the output vector W is calculated. r Output variables in the form of W. The calculated output vector W. r This includes the calculated temperature T of the gas as it exits the discharge reactor. r out The calculated flow rate and the calculated concentration c of the chemical composition of the gas discharged from the discharge reactor. r 1. c r 2、……、c r n The calculated output vector W is then summarized. r The variables are approximations of the actual output variables. The more accurately the plasma chemistry during dielectric barrier discharge is described by the modeling function f(U,V), the smaller the deviation between the calculated output variables and the actual output variables.

[0112] The desired chemical composition of the enriched gas is transmitted to the control equipment by the user or by a higher-level system connected to the device. The calculation unit 14 then determines the optimal operating point of the discharge reactor for producing the desired chemical composition. To this end, the calculation unit 14 calculates the values ​​to which the operating parameters of the low-pressure source 11 and the high-pressure source 12 should be set based on the modeling function f(U,V). Here, the calculation unit 14 can perform the determination of the operating parameters using analytical methods, regression methods, numerical methods, computer-implemented methods, or self-learning algorithms.

[0113] Subsequently, the computing unit 14 transmits the operating parameters to the high-voltage source 12 and the low-voltage source 11, which can be set in a common drive module.

[0114] The control unit 13 is also designed to combine the input vector U, the vector V describing the controlled variable, and the calculated output vector W. r The data is then transmitted to the higher-level system. These variables can then be displayed on the monitor by the higher-level system.

[0115] Figure 5 This demonstrates how operating parameters, which can be changed by control device 13, affect the generated reactants.

[0116] exist Figure 5 On the left, the operating parameters that can be changed by the control device 13 and other parameters describing the gas flowing into the discharge reactor are plotted. On the right, the process parameters describing the dielectric barrier discharge are plotted. Arrows indicate which operating parameters or gas-describing parameters affect which process parameters.

[0117] Operating parameters that can be changed by the control device 13 include: the amplitude of the high voltage applied to electrode 2, the pulse width modulation of the high voltage applied to electrode 2, and the current intensity through thermoelectric structural element 1. Furthermore, the type of gas used and its flow rate are shown on the left.

[0118] The type of gas used is basically determined, and which molecules are available as reaction participants in dielectric barrier discharge.

[0119] The amplitude of the high-voltage potential applied to electrode 2 affects the energy and power density of the dielectric barrier discharge. Furthermore, the amplitude of the high-voltage potential applied to electrode 2 also affects the process temperature. Here, a higher amplitude, compared to a lower amplitude, results in higher energy and higher power density in the dielectric barrier discharge. This, in turn, generates more heat, increasing the process temperature.

[0120] The duty cycle of pulse width modulation affects the power density and process temperature of dielectric barrier discharge. If the proportion of the time period during which no high voltage potential is applied to electrode 2 is increased at this duty cycle, the power density decreases and less heat is generated.

[0121] The process temperature is affected by the current intensity of the thermoelectric structural element 1. Here, the thermoelectric structural element 1 can cool or heat the gas in the discharge reactor.

[0122] The flow rate of the gas through the discharge reactor affects the power density and process temperature of the dielectric barrier discharge.

[0123] Not only the ozone concentration but also the ozone generation rate increases with the increase of the high voltage signal amplitude, with saturation occurring when the amplitude is large enough, and the ozone concentration and ozone generation rate no longer increase as the amplitude of the high voltage signal continues to rise.

[0124] If the gas flow rate increases, the generated reactants, such as ozone, are carried away from the discharge reactor more quickly. Correspondingly, the concentration of reactants in the exhaust gas decreases with increasing flow rate. Simultaneously, the faster delivery of process gas to the discharge reactor causes the rate of reactant formation to increase with increasing flow rate. As the flow rate increases, the thermal barrier between electrode 2 and the dielectric barrier of the discharge reactor becomes smaller, improving heat dissipation and lowering the temperature of the process gas. The lower temperature results in an increased formation rate of certain reactants, such as ozone. Furthermore, the decrease in the thickness of the thermal barrier with increasing flow rate causes better diffusion of reaction products from the dielectric barrier discharge, thereby also increasing the rate of reactant formation.

[0125] The ozone concentration in the exhaust gas increases with increasing duty cycle, which is controlled by pulse width modulation of a high-voltage signal. As the duty cycle increases, the ozone concentration initially increases approximately linearly until a plateau appears. Not only the increased amplitude but also the increased duty cycle can trigger an ozone decomposition mechanism, which explains the plateau in ozone concentration at higher duty cycles. The higher the amplitude of the high-voltage signal, the lower the corresponding duty cycle at which the plateau is reached. During the transition from the pulse-width modulated signal to a continuous signal, charge accumulation at the dielectric barrier causes a voltage increase during micro-discharges. Correspondingly, when the load exceeds 90% and the signal is approximately continuous, a strong increase in ozone concentration occurs.

[0126] The cooling of thermoelectric structural elements affects ozone concentration, with ozone concentration decreasing as temperature increases. There is an approximately linear relationship between the temperature in the discharge reactor and the ozone concentration in the exiting process gas.

[0127] In general, each of the operating parameters—namely, the temperature of the thermoelectric structural elements, the amplitude of the applied high voltage, and the pulse width modulation of the applied high voltage—affects the generation of reactants in the discharge reactor. Significant interactions arise under the influence of these operating parameters, and environmental conditions, particularly temperature, the composition of the inflowing gas, and its flow rate, must also be considered. Taking all these parameters into account, a well-modeled mapping function for the plasma chemistry during dielectric barrier discharge is derived, which is considered by the control device 13 of the existing equipment.

[0128] Figure 6 Another embodiment of the discharge reactor is shown. Electrode 6 has a protrusion 15. The protrusion 15 is disposed on the upper side of electrode 2 pointing towards thermoelectric structural element 1. Here, the protrusion 15 is configured such that one protrusion 15 is centrally opposite a metal bridge 4, which is disposed on the upper side of the thermoelectric structural element and connects two adjacent thermoelectric elements 3 to each other. The protrusion 15 abuts against the ceramic layer 15a of the thermoelectric structural element 1.

[0129] The protrusions 15 perform different functions within the structural element. Surface discharge occurs in the region of the protrusion. Correspondingly, dielectric barrier discharge occurs in the discharge reactor in the form of both volume discharge and surface discharge. The ignition voltage for surface discharge is lower than that for volume discharge.

[0130] The protrusion 15 also functions as a spacing maintainer between the electrode 2 and the thermoelectric structural element 1, thereby determining the volume of the volume discharge. The protrusion 15 can also conduct heat generated on the electrode 2 to the thermoelectric structural element 1 via direct contact, thereby reducing the temperature in the discharge space. This effect is particularly enhanced by having one protrusion centrally positioned opposite the metal bridge 4, because the metal bridge 4 has a particularly high thermal conductivity.

[0131] Furthermore, the protrusion 15 obstructs the gas flow through the discharge reactor and thereby enables better mixing of the process gas, which in turn leads to improved cooling and thus an increased ozone generation rate in the discharge reactor.

[0132] List of reference numerals

[0133] 1 thermoelectric structural element

[0134] 2 electrodes

[0135] 3 thermoelectric elements

[0136] 4 metal bridges

[0137] 5a First Ceramic Plate

[0138] 5b Second Ceramic Plate

[0139] 6 gaps

[0140] 7 Gas Inlet

[0141] 8 Gas outlets

[0142] 9 cooling body

[0143] 10 fans

[0144] 11 Low-voltage source

[0145] 12 high-voltage sources

[0146] 13 Control Equipment

[0147] 14 computing units

[0148] 15 protrusions

Claims

1. An apparatus for generating dielectric barrier discharge, the apparatus comprising: - A discharge reactor having thermoelectric structural elements (1) and electrodes (2), and - A control device (13) having a high-voltage source (12) and a low-voltage source (11), wherein the high-voltage source (12) is designed to apply a high-voltage potential to the electrode (2) sufficient to ignite the dielectric barrier discharge, wherein the dielectric barrier discharge enriches the gas with reactants. The low-pressure source (11) is designed to set the current through the thermoelectric structural element (1). The control device (13) is designed to appropriately set the operating parameters of the high-pressure source (12) and the low-pressure source (11) for the desired composition of the enriched gas.

2. The device according to claim 1, The operating parameters of the high voltage source (12) include at least one selected from the amplitude of the high voltage potential, the frequency of the high voltage potential, and the pulse width modulation of the high voltage potential, wherein the duty cycle and / or modulation frequency are set in the pulse width modulation.

3. The device according to any one of the preceding claims, The operating parameters of the low-pressure source (11) include the current intensity of the current flowing through the thermoelectric structural element (1).

4. The device according to any one of the preceding claims, The control device (13) is designed to control the chemical composition of the reactants generated during the dielectric barrier discharge by means of: the control device (13) performing pulse width modulation of the high voltage potential and / or setting the current intensity through the thermoelectric structural element (1) and / or setting the amplitude of the high voltage potential and / or setting the frequency of the high voltage potential.

5. The device according to any one of the preceding claims, The control device (13) is designed to take into account the flow rate of gas through the discharge reactor when setting the operating parameters.

6. The device according to any one of the preceding claims, The control device (13) is designed to take into account the composition and / or temperature of the gas as it enters the discharge reactor and / or the ambient temperature when setting the operating parameters.

7. The device according to any one of the preceding claims, The thermoelectric structural element (1) is a Peltier element.

8. The device according to any one of the preceding claims, The surface of the electrode (2) has a protrusion (15).

9. The device according to claim 8, The electrode (2) is positioned opposite the thermoelectric structural element (1), and The protrusion (15) is attached to the thermoelectric structural element (1).

10. The device according to claim 9, The thermoelectric structural element (1) has multiple thermoelectric elements (3). The thermoelectric structural element (1) has a metal bridge (4). Each metal bridge (4) connects two adjacent thermoelectric elements (3) to each other. The protrusions (15) are configured such that each protrusion (15) is opposite to exactly one metal bridge (4) on the upper side of the thermoelectric structural element (1), wherein the upper side of the thermoelectric structural element (1) faces the electrode (2).

11. The device according to any one of the preceding claims, The high-voltage source (12) mentioned therein is self-resonant.

12. The device according to any one of the preceding claims, The control device (13) therein has a computing unit (14) designed to determine suitable operating parameters for the desired composition of the enriched gas.

13. The device according to the preceding claim, The computing unit (14) is designed to obtain the operating parameters by means of analytical methods, regression methods, numerical methods, computer-implemented methods or by means of self-learning algorithms.

14. The device according to any one of the preceding claims, The device described herein includes a sensor designed to determine the composition of the enriched gas. The control device (13) is designed to compare the components obtained by the sensor with the desired components and adjust the operating parameters based on the result of the comparison.

15. The device according to any one of the preceding claims, The thermoelectric structural element (1) is positioned opposite the electrode (2) and is designed to function as a corresponding electrode relative to the electrode (2) during dielectric barrier discharge. or The electrode (2) therein is designed and configured to ignite the dielectric barrier discharge relative to a surface at a ground potential.

16. The device according to any one of the preceding claims, During the dielectric barrier discharge, a current pulse is generated in the discharge reactor. The device is designed to measure the current pulse and determine the reactants produced based on the frequency and / or height of the measured current pulse. The control device is designed to adjust the operating parameters based on the measured current pulses.

17. A method for generating dielectric barrier discharge by means of a device having a discharge reactor having a thermoelectric structural element (1) and an electrode (2), and the device having a control device (13) having a high-voltage source (12) and a low-voltage source (11). The method comprises the following steps: - Apply current to the thermoelectric structural element, wherein the current is set by the low-voltage source (11). - A high voltage potential is applied to the electrode (2) to ignite a dielectric barrier discharge, wherein the gas is enriched with the reactants by the dielectric barrier discharge, wherein the high voltage potential is applied by the high voltage source (12), and - Set the operating parameters of the high-pressure source (12) and the low-pressure source (11) to generate the desired components of the enriched gas, wherein the control device (12) sets the operating parameters.

18. The method according to claim 17, The operating parameters of the high-voltage source (12) include at least one selected from the amplitude of the high-voltage potential, the frequency of the high-voltage potential, and pulse width modulation of the high-voltage potential, wherein the duty cycle and / or modulation frequency are set in the pulse width modulation. and The operating parameters of the low-pressure source (11) include the current intensity of the current flowing through the thermoelectric structural element (1).

19. The method according to claim 17 or claim 18, The setting of the operating parameters is determined using a modeling function (f(U,V)), which is performed by the control device (13) to generate the desired components of the enriched gas. The modeling function obtains the output variable (W) describing the gas discharged from the discharge reactor from the input variable (U) describing the gas entering the discharge reactor and the operating parameters (V). r ).

20. The method according to claim 19, The input variable (U) includes at least one selected from the chemical composition of the gas entering the discharge reactor, the temperature of the gas entering the discharge reactor, and the flow rate of the gas entering the discharge reactor.

21. The method according to claim 19 or claim 20, The input variable (U) includes at least one selected from ambient temperature and current pulses generated in the discharge reactor.

22. The method according to any one of claims 19 to 21, The output variable (W) r The gas discharged from the discharge reactor includes at least one selected from the temperature of the gas discharged from the discharge reactor, the flow rate of the gas discharged from the discharge reactor, and the composition of the gas discharged from the discharge reactor.

23. A method for setting operating parameters of a control device (13), said control device operating a discharge reactor, The control device (13) mentioned therein has a high voltage source (12) and a low voltage source (11). The discharge reactor described therein has electrodes (2) and thermoelectric structural elements (1). The high-voltage source (12) is designed to apply a high-voltage potential to the electrode (2) sufficient to ignite a dielectric barrier discharge, wherein the dielectric barrier discharge enriches the gas with reactants. The low-pressure source (11) is designed to set the current on the thermoelectric structural element (1). The method described herein comprises the following steps: - Determine the operating parameters of the high-voltage source (12) and the low-voltage source (11) such that a dielectric barrier discharge is generated on the electrode (2), and a desired component of the gas-enriched gas is generated in the dielectric barrier discharge. - Adjust the operating parameters to the values ​​determined in the previous steps.

24. The method according to claim 23, The operating parameters of the high-voltage source (12) include at least one selected from the amplitude of the high-voltage potential, the frequency of the high-voltage potential, and pulse width modulation of the high-voltage potential, wherein the duty cycle and / or modulation frequency are set in the pulse width modulation. and The operating parameters of the low-pressure source (11) include the current intensity of the current flowing through the thermoelectric structural element (1).

25. The method according to claim 23 or claim 24, The setting of the operating parameters is determined using a modeling function (f(U,V)), which is performed by the control device (13) to generate the desired components of the enriched gas. The modeling function obtains the output variable (W) describing the gas discharged from the discharge reactor from the input variable (U) describing the gas entering the discharge reactor and the operating parameters (V). r ).

26. The method according to claim 25, The input variable (U) includes at least one selected from the chemical composition of the gas entering the discharge reactor, the temperature of the gas entering the discharge reactor, and the flow rate of the gas entering the discharge reactor.

27. The method according to claim 25 or claim 26, The input variable (U) includes at least one selected from ambient temperature and current pulses generated in the discharge reactor.

28. The method according to any one of claims 25 to 27, The output variable (W) r The gas discharged from the discharge reactor includes at least one selected from the temperature of the gas discharged from the discharge reactor, the flow rate of the gas discharged from the discharge reactor, and the composition of the gas discharged from the discharge reactor.

29. A computer program that performs the method according to any one of claims 23 to 28, wherein the computer program comprises: The first step involves inputting the desired components of the enriched gas. The second step involves performing the method according to any one of claims 23 to 28.

30. The computer program according to claim 29, The determination of the operating parameters is carried out by means of analytical methods, regression methods, numerical methods, computer-implemented methods, or self-learning algorithms.

31. A computer-readable storage medium having a computer program for performing the method according to any one of claims 23 to 28, wherein the computer program has: The first step involves inputting the desired components of the enriched gas, and... The second step involves performing the method according to any one of claims 23 to 28.

32. The computer-readable storage medium according to claim 31, The determination of the operating parameters is carried out by means of analytical methods, regression methods, numerical methods, computer-implemented methods, or self-learning algorithms.

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