METHOD AND ARRANGEMENT FOR THE USE OF COMBUSTION PRODUCTS OR PROPERTIES OF THE AIR IN THE COMBUSTION AIR PATH OF A GAS-FIRED HEATING APPLIANCE FOR ITS CONTROL AND / OR CONDITION ANALYSIS

Description

[0001] The invention relates to a method and an arrangement for using measured values ​​of components or properties, in particular the humidity of the air in the combustion path of a gas-fired heating appliance for its control and / or condition analysis.

[0002] Gas-fired heating appliances utilize electronically controlled gas-air mixtures, which, as part of a closed control loop, employ control variables such as an ionization current measurable during combustion, which correlate with a defined gas-air ratio. This correlation is subject to the influence of disturbances, which means that the resulting gas-air mixture can deviate from the target value when in a regulated state. This deviation is evaluated within the framework of tolerance analyses and taken into account when defining operating limits.

[0003] The invention deals in particular with the detection and measurement of selected disturbance variables and, based on this, offers concepts for how the detection of a disturbance variable, in conjunction with knowledge of its influence on the gas-air mixture, can be used to achieve more robust and extended device operation. To enable the safe and robust operation of gas-fired heating appliances with electronically controlled gas-air mixtures, the tolerance analyses mentioned above realistically combine all relevant influences on the target gas-air mixture and attribute any resulting deviation, relative to a constant heating load, to the mixture.

[0004] The mixture deviations determined here directly affect the operating limits of the heating appliance, which, within its permissible operating range, must, for example, comply with market-compliant emission limits for carbon monoxide and nitrogen oxides and prevent thermoacoustic disturbances. The described consequences of potential mixture deviations lead to a narrowing of the operating range, which, due to the lack of knowledge of the disturbance variables present during operation, must take their full influence into account, thus necessarily reducing the heating appliance's performance.

[0005] Furthermore, in particularly vulnerable operating phases, such as the purely controlled ignition process, influences on the mixture formation can have a particularly destabilizing effect on the combustion to be initiated, thereby necessitating a complex ignition algorithm with multiple ignition attempts and acceptable thermoacoustic disturbances.

[0006] In principle, qualitative and / or quantitative knowledge of disturbances during heating operation and their specific influence on gas-air mixture formation can reduce assumed tolerance bands, thus offering significant optimization potential. Furthermore, this knowledge can also be used to detect and display (e.g., in a control panel during device commissioning) leakage flows between the exhaust gas path and the combustion air path (fresh air supply), which can result from installation errors when laying exhaust gas-air piping or, for example, from wear or growth on an exhaust pipe.

[0007] US Patent 6,095,792 A discloses a method for improving the efficiency of flue gas recirculation and / or minimizing nitrogen oxides ("NOx") in the exhaust gas of various combustion processes, whereby a percentage of the flue gas recirculation is calculated using temperature sensors. However, the determination of disturbances in the above sense, as well as the determination of their specific influence on the gas-air mixture formation, is not addressed therein. US Patent 500,248 A1 discloses a method with the features of the preamble of the first claim.

[0008] US 2012 / 034568 A1 discloses the detection of false air in a boiler firing system.

[0009] The object of the present invention is to at least partially solve the problems described with reference to the prior art. In particular, the invention aims to provide a method and an arrangement for using properties of the air in the combustion air path of a gas-fired heating appliance for its control and / or state analysis.

[0010] The methods, arrangements, and computer program product according to the independent claims serve to solve this problem. Advantageous embodiments and further developments of the invention are specified in the respective dependent claims. The description, particularly in conjunction with the drawing, illustrates the invention and provides further exemplary embodiments.

[0011] This involves a method for the targeted adjustment or modification of exhaust gas recirculation using an actuator, as well as a method for determining the size and location of a leak between an exhaust gas path and a combustion air path. Both methods utilize at least one property of the air in a combustion air path of a gas-fired heating appliance to measure exhaust gas recirculation and to control and / or analyze its condition. The property is measured using at least one sensor, and its behavior is compared with empirical values ​​or calibration data in relation to known processes in the heating appliance, so that changes in the property can be detected and used for controlling the heating appliance and / or for status reporting. The measured air property is used to measure exhaust gas recirculation.Exhaust gas recirculation affects the properties of the air in the combustion air path and therefore allows conclusions to be drawn about potential leaks and, more generally, the composition of the air. The combustion air path of a gas-fired heating appliance can, for example, be a section of pipe located between an air intake and the burner or combustion chamber. It is possible that the combustion air path where the property is measured should, or is, primarily supplying only combustion air. The combustion air path can also be part of an exhaust gas recirculation system, i.e., a section in which air is (re)supplied to the burner together with recirculated exhaust gas from the combustion chamber. The behavior of the property, e.g., with regard to measured average values, limit values, fluctuations, etc., is then analyzed.This can be related to desired, predefined empirical values ​​or calibration data, which are stored, for example, in a data repository and / or automatically retrievable. Empirical values ​​can include, for example, mean values ​​and tolerance ranges for the behavior of the characteristic, which can also be adjusted system-specifically based on the history of the gas-fired heating appliance. Calibration data can be fixed and / or variably adjustable target values ​​for the gas-fired heating appliance, which can be specified or set during commissioning and / or over the course of operation. In particular, changes that indicate deviations from normal operation can also be detected. If an undesirable or unexpected change / deviation of a characteristic is detected, the heating appliance's control system can be intervened (automatically), e.g.,This is achieved by initiating or implementing measures to adjust the gas-air mixture formation and / or to influence the air. It is possible that, upon detection of such a change in this property, status messages will be (automatically) triggered and sent to the user, a central control unit, an evaluation unit, etc., which may then further analyze this change and trigger additional measures on the heating appliance.

[0012] Fluctuations in the humidity of the combustion air (water vapor content in the air) and / or the occurrence of exhaust gas recirculation, i.e., the partial introduction of exhaust gas into the combustion air, as permitted up to certain limits according to local regulations, are regularly to be expected environmental influences or, up to predefined limits, permissible operating modes that affect the gas-air mixture formation as disturbance variables and are accordingly taken into account within the tolerance analysis. Since these two influences have the strongest impact on mixture deviation, considering their actual effects during operation offers particularly great optimization potential.Furthermore, as previously described, incorrectly installed or damaged exhaust air piping can also be identified, the resulting leakage flow of which is above permissible limits, because the effect can also be detected by the humidity of the combustion air.

[0013] The invention relates to the quantitative and local determination of the current exhaust gas recirculation by providing information about the combustion products contained in the combustion air path and possibly at other reference points (in the present example, humidity, but this can also be replaced by carbon dioxide, carbon monoxide, oxygen, nitrogen, nitrogen oxides, optionally in conjunction with temperature or any combination of all the aforementioned components) in conjunction with defined measurement methods or further signal processing methods (cross-correlation). This information can then be taken into account for the detection of piping installation errors or the correction of the gas-air mixture formation. The resulting reduction of tolerance limits for the air-gas mixture can be used to improve the performance and robustness of the device.

[0014] As mentioned, the measured property can preferably be at least one of the following: humidity, temperature, carbon dioxide, carbon monoxide, oxygen, nitrogen, and nitrogen oxides. Since humidity sensors are part of standard instrumentation, this property, optionally in conjunction with the temperature at the measuring point, is preferably used.

[0015] In particular, the humidity and / or temperature of the air in the combustion path upstream of a combustion chamber are measured, and their temporal profile during an ignition process is monitored and analyzed. The ignition process is a controlled process with precisely defined sequences and parameters, so that it reproducibly generates very specific profiles of measured and / or calculated values, a so-called signature, which can be stored in a control unit. Such a signature can, for example, be used to correlate the humidity profile in the combustion air path, and the resulting correlation signal can be analyzed.

[0016] To increase the accuracy of analyses based on a measured air property, it is particularly useful to correct the measured property using environmental data. This data can be obtained through measurements in the environment and / or from other data sources. For example, humidity and / or temperature at the location of the heating device can be used for correction, either from sensors that are often already present or from data services.

[0017] The described measurements can be performed not only passively during normal operation of the heating appliance, but also actively by making targeted changes to settings during startup and / or operation of the heating appliance and determining their effects on the sensor readings. This opens up further diagnostic possibilities at times when they would not be possible during normal operation of the heating appliance.

[0018] To solve the problem, an arrangement is also used for utilizing at least one property of the air (which changes with exhaust gas recirculation) in a combustion air path of a gas-fired heating appliance for measuring exhaust gas recirculation and for its control and / or state analysis. This arrangement is configured to carry out the described method and includes at least one sensor for measuring the property of the air in the combustion air path, which is connected to evaluation electronics configured to generate and evaluate a correlated signal of the temporal profile of the property with the temporal profile of at least one other measured value and / or parameter. Furthermore, the evaluation electronics are configured to detect current exhaust gas recirculation.

[0019] The evaluation electronics are particularly preferably configured to determine the size and / or location of a leak between an exhaust gas path and the combustion air path if the current recirculation deviates from empirical values ​​and / or calibration data.

[0020] In a preferred embodiment, the evaluation electronics are connected to a control unit and configured to transmit data on humidity, temperature, and / or current exhaust gas recirculation to it. This allows the control unit to utilize current data for the relevant properties and perform more precise control with lower tolerances than would be possible with unknown properties of the air in the combustion air path.

[0021] In a particular embodiment, the heating appliance features an exhaust gas recirculation system with an actuator, and the sensor is located downstream of the exhaust gas recirculation inlet in the combustion air path. This allows for the targeted adjustment and / or modification of the exhaust gas recirculation and observation of its effect on the measured air properties. In this way, additional information about the heating appliance and the measurement systems used can be obtained.

[0022] In order to be able to measure not only relative humidity but also absolute humidity in the air, which is important for controlling the heating device, at least one humidity sensor and one temperature sensor are arranged at one measuring point.

[0023] Another aspect concerns a computer program product comprising commands that cause the described arrangement to execute the described procedure. The evaluation of the data measured by the sensor and its further use in the heating device require a program and data for analyzing the measured values, both of which must be updated occasionally.

[0024] The explanations of the procedure can be used to further characterize the arrangement, and vice versa. The arrangement can also be set up in such a way that the procedure is carried out using it.

[0025] According to another aspect, the use of at least one property of the air in the combustion air path of a gas-fired heating appliance for its control and / or condition analysis increases operational safety and / or reduces tolerance limits in the control of a heating appliance, so that it can be operated more efficiently and robustly, at least under certain conditions. Regarding preferred uses, reference is also made in full to the explanations of the method, particularly in connection with the occurrence of exhaust gas recirculation.

[0026] A schematic embodiment of the invention, to which it is not limited, and the functioning of the method will now be explained in more detail with reference to the drawing. The drawing shows: Fig. 1: schematic diagram of a heating appliance with a sensor in the combustion air path, Fig. 2: diagram illustrating the principle of cross-correlation, Fig. 3: diagram illustrating an unusual course of a moisture measurement, Fig. 4: diagram illustrating the course of a measurement of the recirculation of exhaust gas, and Fig. 5: diagram illustrating a test measurement and an actual malfunction during the operation of a heating appliance.

[0027] Fig. 1 Figure 1 schematically shows a heating appliance 1, which is, for example, located in an interior space 4 of a building (not shown). Air (fresh air) from the outside environment 2 enters the interior space 4 through an air inlet 3, from where it is drawn in as combustion air through an air intake 5 and directed onto a combustion air path 21 (hatched). Passing through a vibration damper 6, it reaches a mixing element 8, where a fuel gas from a fuel gas inlet 7 is added to the air. The resulting gas-air mixture 22 (shown with cross-hatching) is forced by a fan 9 (blower) into a combustion chamber 10, where the mixture of air and fuel gas is combusted and the resulting heat is released for heating purposes. The resulting combustion gases (exhaust gas) are routed through an exhaust gas path 11 to an exhaust gas outlet 12 and released into the outside environment 2.Optionally, an exhaust gas recirculation 13 can branch off from the exhaust gas path 11, which, via an actuator 14, feeds exhaust gas back into the gas-air mixture 22 through an inlet 20. A control and regulation unit 16 controls and regulates all processes taking place in the heating appliance 1. At a suitable point in the combustion air path 21, 22 (the path of the gas-air mixture is also considered part of the combustion air path here), a first sensor 17 is arranged to measure a property of the combustion air. In the following, humidity is considered the property to be measured, but the explanations would apply analogously to other properties of the air as well. The first sensor 17 is connected to an evaluation unit 15, which also has other signals and / or measured values ​​available, for example, from the control and regulation unit 16 or from a reference sensor 18 for measurement in the free environment 2.Additional sensors can be arranged in the combustion air path 21, 22, for example, a second sensor 19 for humidity measurement. Sensors 17, 18, 19 can also be combined sensors, for example, for measuring humidity and temperature. The depicted position of the second sensor 19 is necessary when exhaust gas recirculation 13 is present, so that the second sensor 19 can also measure changes caused by recirculated exhaust gas. The first sensor 17 is then not strictly necessary.

[0028] Fig. 2 This illustrates the procedure for evaluating measurement signals from the first sensor 17 and / or the second sensor 19 in the evaluation electronics 15. Top left in Fig. 2 A symbolic diagram is shown in which the course of a first signal A (e.g., a fan speed when starting the heating appliance 1) is correlated with a measured course of a second signal B (e.g., the humidity in the combustion air) in a cross-correlator K to a cross-correlated signal C (in a symbolic diagram at the bottom right). Fig. 2 (as shown). The correlation can also detect or process a time offset S (shift) between the signals.

[0029] The basis of all considerations here is the fact that the (absolute) humidity of the combustion air plays a crucial role in precise combustion control. Accurate humidity measurement alone can improve state-of-the-art control systems. Even more importantly, however, the exhaust gas from the combustion of fuel gases (from natural gas to hydrogen) always contains water vapor, i.e., moisture. A humidity measurement in the combustion air path 21, 22 therefore also allows conclusions to be drawn about the amount of exhaust gas that may be contained in the combustion air (the same applies to several other measurable properties of the exhaust gas or the air). Since the exhaust path 11 of a heating appliance 1 usually runs through the interior space 4 in which the heating appliance 1 is located, leaks in the exhaust path 11 can unintentionally draw exhaust gas in with the combustion air, which can be detected by a humidity measurement.Exhaust gas from the exhaust outlet 12 of the heating appliance 1, or possibly also from a neighboring (external) heating appliance, can enter the air inlet 3.

[0030] Fig. 3 This diagram schematically and qualitatively illustrates the information that, for example, a simple humidity measurement can provide. Humidity is plotted on the Y-axis using an arbitrary scale, and time t on the X-axis. If humidity is measured at the first sensor 17, there is an essentially constant value before the heater 1 starts. This value adjusts to the humidity Fu in the free environment 2 at time V when the heater 1 starts with the fan 9 running. Experience shows that this results in a value within the hatched area, and it remains there. Without humidity measurement, the heater's control system would, as a precaution, consider a tolerance range with a maximum possible humidity Fmax (dashed line), which is unnecessary with the described procedure involving humidity measurement. Furthermore, additional information can be obtained by using a humidity sensor (especially in combination with a temperature sensor).

[0031] For this purpose, the absolute humidity or the expected steady-state humidity is measured after a defined period of inactivity of the heating unit 1 during the fan start-up phase and compared with the expected maximum humidity Fmax, which can be based on both in-house measurements and available weather data. If the measurement reveals absolute humidity values ​​that exceed the maximum expected value (i.e., excessive humidity Fex), this can be used as an indicator of external recirculation (exhaust gas introduction due to the operation of another device and its unintended exhaust gas recirculation back to the device under consideration). Furthermore, the results of this humidity measurement during the fan start-up phase can be used as reference values ​​for further measurements carried out during operation of the fired unit, as well as the first recorded value for humidity-corrected gas-air mixture formation for ignition and operation of the unit.

[0032] Fig. 4 This shows what additional information can be obtained after ignition of the heater 1. The graph again plots the humidity F (measured at the first sensor 17 and / or the second sensor 19) on the Y-axis against time t on the X-axis. As described above, when heater 1 starts, the fan 9 begins to run from time V, so that the ambient humidity is initially established. At time Z, the mixture ignites, resulting in an increase in humidity due to exhaust gas recirculation after a certain time delay. The dotted curve Rnorm shows a normal humidity profile during typical operation with permitted recirculation. The dashed curve Rmax indicates the maximum value up to which recirculation is allowed (e.g., according to local regulations). If the humidity exceeds this permitted value Rmax (e.g.,Curve R) indicates a leak in the exhaust gas path 11 or unauthorized intake from the environment 2. The increase in humidity caused by recirculation only becomes visible at sensor 17, 19 after a certain delay following ignition time Z. A humidity maximum is then reached, followed by a characteristic curve. Overall, this results in a signal shape (signature) characteristic of a typical ignition process, which can provide further information. For example, the location of a leak can be determined from a localization interval L, which specifies the time between ignition time Z and the first maximum of the humidity curve (Rnorm or R). The first difference M1 between an initial minimum (or a constant initial value) and a first maximum of the humidity measurements, relative to a second difference M2 between the first maximum and a subsequent minimum (M1:M2), provides information about the amount of recirculated exhaust gas.In any case, typical changes resulting from exhaust gas recirculation in a signature based on stored empirical values, e.g., during the ignition process, allow conclusions to be drawn about the location and / or amount of recirculation occurring in the described measurements and their evaluation, especially through cross-correlation.

[0033] According to Fig. 5Even after ignition, further information can be obtained during the continuous operation of the heating unit 1. This can be achieved through targeted modifications during operation, particularly if an exhaust gas recirculation system 13 with an actuator 14 is present. The effects of such a modification for testing purposes are illustrated by the dotted curve T. This allows for the acquisition of empirical data with which subsequent measured values ​​can be compared. If an unexpected fault occurs during operation, such as a sudden, strong exhaust gas recirculation (curve Fex), the magnitude of the measured fault can be compared with the empirical data to trigger appropriate measures, ranging from a warning message to the shutdown of the heating unit 1. In summary, the following can be said:

[0034] The ignition of a heating device 1 occurs according to a fixed pattern, which is stored in the control unit 16 by parameters (ignition speed of the fan 9, gas valve position, etc.). This ignition signature is thus known to the device electronics. The known ignition signature can be investigated using a sensor 17, 19 (e.g., a humidity sensor) in the combustion air path 21, 22, for example, by means of cross-correlation. If sufficient coupling exists between the fresh air and the exhaust gas path 11 (e.g., due to a leak), the cross-correlation can detect the presence of this coupling and can also be used for leak detection.

[0035] Alternatively, based on the previously mentioned reference measurement of humidity after fan start-up, a humidity level can now be defined that correlates with a standard-compliant maximum permissible recirculation. After ignition, if recirculation is present, both a characteristic signature caused by the ignition and, in the longer term, a positive deviation in the humidity profile can be observed. This deviation then provides input for gas-air mixture corrections or error / warning messages in comparison with the maximum permissible humidity. However, the measured signature alone, based on its characteristics (difference from the reference value as well as the local minima and maxima) and the time of its occurrence, can also provide information about the presence of exhaust gas recirculation and / or the amount and / or location of the recirculation.

[0036] Based on the evaluation of the initial signature, deliberately induced, defined signatures can also be used to evaluate the location and / or the amount of recirculation.

[0037] Specifically, a signature can be created by changes in the actuators involved in combustion (e.g., gas valve position, fan speed) in the exhaust gas or recirculated combustion air stream. However, a signature can also be created by influencing condensation in a heating circuit (due to a short-term change in return temperature, the load on the unit, or the hydraulic mode) and can be detected by changes in humidity in the combustion air path and evaluated based on known correlations.

[0038] The evaluation can take into account both the time and intensity of the measurement as well as any temporal compression or stretching of the signature.

[0039] Furthermore, recirculation detection using signatures offers the advantage that it can correctly evaluate humidity values ​​superimposed by external recirculation and assign them to a possible internal recirculation, as well as providing a redundant measurement method for measuring absolute humidity.

[0040] If the humidity of the combustion air changes during stationary operation of the device, or if the change in humidity does not correspond to the controlled device behavior, this can detect the beginning or end of external recirculation, which in turn can be used to trigger error or warning messages.

[0041] The invention enables an increase in operational safety and a reduction in tolerance limits when controlling a heating device, so that it can be operated more efficiently and robustly, at least under some conditions. Reference symbol list

[0042] 1 Heater 2 Ambient 3 Air inlet 4 Interior 5 Air intake 6 Vibration damper 7 Fuel gas inlet 8 Mixing element 9 Fan / Blower 10 Combustion chamber 11 Exhaust gas path 12 Exhaust gas outlet 13 Exhaust gas recirculation 14 Actuator 15 Evaluation electronics 16 Control and regulation unit 17 First sensor 18 Reference sensor 19 Second sensor 20 Exhaust gas recirculation inlet 21 Combustion air path 22 Gas-air mixture A First signal with a typical signature B Second signal C Cross-correlated signal F Humidity F Excessive humidity F Ambient humidity (tolerance interval) Fmax Maximum possible humidity K Cross-correlator L Localization interval M1 First difference between first minimum and first maximum M2 Second difference between first maximum and second minimum R Exhaust gas recirculation Rmax Maximum permissible recirculation Rnorm Normal Recirculation Time offset (shift) between the signals tTime TTest progress VStart Blower pre-run ZZignition time

Claims

1. Method for the targeted adjustment or modification of an exhaust gas recirculation (13) with an actuator (14) of a gas-fired heating appliance (1), wherein a sensor (19) is arranged downstream of a junction of the exhaust gas recirculation (13) in the combustion air path (22) for measuring a property of the air, wherein the combustion air path (22) is part of an exhaust gas recirculation (13), characterised in that the sensor (19) observes the effect of the setting and / or change of the exhaust gas recirculation (13) on the measured property of the air and its behaviour is compared in relation to known processes in the heating appliance (1) with empirical values or calibration data, so that changes in the property are detected and used to control the heating appliance (1) and / or for status messages.

2. Method for determining the size and location of a leak between an exhaust gas path and a combustion air path of a gas-fired heating appliance (1) with an evaluation electronics system, wherein a property of air in a combustion air path (20, 21) is detected by means of at least one sensor (17, 19) and its behaviour in relation to known processes in the heating appliance (1) is compared with empirical values or calibration data, so that changes in the property can be detected and used to control the heating appliance (1) and / or for status messages, and the evaluation electronics (15) are designed to generate and evaluate a correlated signal of a temporal progression of the detected property of the air with respect to a temporal progression of at least one other measured value and / or parameter and to determine a current exhaust gas recirculation, and, in the event of a deviation of the current recirculation from empirical values and / or calibration data, to determine the magnitude and / or the location of a leak between an exhaust gas path (11) and the combustion air path (21, 22).

3. Method according to claim 1 or 2, wherein the property is at least one from the group consisting of humidity, temperature, carbon dioxide content, carbon monoxide content, oxygen content, nitrogen content, and nitrogen oxide content.

4. Method according to claims 1 to 3, wherein at least the humidity or the temperature of the air in the combustion air path (21, 22) upstream of a combustion chamber (10) is measured and its temporal course during an ignition process is monitored and analysed.

5. Method according to one of the preceding claims, wherein the measured property is corrected on the basis of ambient data obtained by measurement with a reference sensor (18) in the environment (2) and / or from other data sources.

6. Method according to one of the preceding claims, wherein, at least at start-up or during operation of the heating appliance (1), changes are made to settings and their effects on the measured values of the sensor (17, 18) are determined.

7. Arrangement designed to carry out a method according to claim 1, comprising a gas-fired heating appliance (1) with an exhaust gas recirculation system (13) with an actuator (14) and a sensor (19) for measuring the properties of the air, which is arranged downstream of a junction (20) of the exhaust gas recirculation (13) in the combustion air path (22), and which is connected to an evaluation electronics system (15) which is designed to generate and evaluate a correlated signal of the temporal progression of the property with the temporal progression of at least one other measured value and / or parameter, and wherein the evaluation electronics system (15) is designed to determine a current exhaust gas recirculation.

8. Arrangement for carrying out a method according to claim 2, comprising a gas-fired heating appliance (1), at least one sensor (17, 19) for measuring a property of the air in the combustion air path (22), and evaluation electronics (15) connected to the sensor (17, 19), which are designed to generate and evaluate a correlated signal of the temporal progression of the property with the temporal progression of at least one other measured value and / or parameter, and wherein the evaluation electronics (15) are designed to determine a current exhaust gas recirculation and, in the event of a deviation of the current recirculation from empirical values and / or parameters, to trigger a control action.parameter, and wherein the evaluation electronics (15) are designed to determine a current exhaust gas recirculation and, in the event of a deviation of the current recirculation from empirical values and / or calibration data, to determine the size and / or location of a leak between an exhaust gas path (11) and the combustion air path (21, 22).

9. Arrangement according to one of claims 7 or 8, wherein the evaluation electronics (15) are connected to a control and regulation unit (16) and are designed to transmit data on humidity, temperature and / or current exhaust gas recirculation to the latter.

10. Arrangement according to one of claims 7 to 9, wherein at least one humidity sensor and one temperature sensor are arranged at a measuring point as sensors (17, 19).

11. Computer program product comprising instructions that cause the arrangement according to claim 7 to execute the method according to claim 1 and / or the arrangement according to claim 8 to execute the method according to claim 2.