WO2024104773A1 - Procédé et dispositif d'étalonnage d'une sonde en verre pour réfrigérant - Google Patents

Procédé et dispositif d'étalonnage d'une sonde en verre pour réfrigérant Download PDF

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Publication number
WO2024104773A1
WO2024104773A1 PCT/EP2023/080237 EP2023080237W WO2024104773A1 WO 2024104773 A1 WO2024104773 A1 WO 2024104773A1 EP 2023080237 W EP2023080237 W EP 2023080237W WO 2024104773 A1 WO2024104773 A1 WO 2024104773A1
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WO
WIPO (PCT)
Prior art keywords
gas
refrigerant
concentration
probe
calibrating
Prior art date
Application number
PCT/EP2023/080237
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German (de)
English (en)
Inventor
Philipp NOLTE
Matthias Guenther
Chi Trung NGO
Wenwen Chen
P Nallasivam MAHESH KUMAR
Philipp Pfander
Original Assignee
Robert Bosch Gmbh
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Application filed by Robert Bosch Gmbh filed Critical Robert Bosch Gmbh
Publication of WO2024104773A1 publication Critical patent/WO2024104773A1/fr

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/0004—Gaseous mixtures, e.g. polluted air
    • G01N33/0006—Calibrating gas analysers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/0004—Gaseous mixtures, e.g. polluted air
    • G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
    • G01N33/0027—General constructional details of gas analysers, e.g. portable test equipment concerning the detector
    • G01N33/0036—General constructional details of gas analysers, e.g. portable test equipment concerning the detector specially adapted to detect a particular component
    • G01N33/0047—Organic compounds

Definitions

  • the invention relates to a method and a device for calibrating a gas probe for detecting refrigerant.
  • the invention also relates to a device for detecting refrigerant with a gas probe that has been calibrated using a method according to the invention and/or with a device according to the invention.
  • Sensor systems are known that make it possible to detect the leakage of refrigerant from refrigeration and air conditioning systems, especially from air conditioning systems in motor vehicles.
  • the sensor systems known to date are not able to distinguish between different types of refrigerant.
  • the invention comprises a method for calibrating a gas probe for refrigerants, wherein the gas probe has at least two gas sensors that have different sensitivities for different refrigerant types.
  • a method according to the invention comprises the following steps:
  • step (C) repeating steps (A) and (B) several times, the method comprising adjusting the concentration of the at least one gaseous refrigerant and/or varying the concentration of the at least one background gas in the measuring chamber before repetition;
  • the invention also includes a device for calibrating a gas probe for refrigerants, which is equipped with at least two gas sensors having different sensitivities for different types of refrigerants.
  • the device comprises:
  • a measuring chamber for accommodating a gas mixture and the gas probe to be calibrated
  • a gas dosing device designed to specifically dose different gases, in particular different types of refrigerant and/or different background gases, into the measuring chamber;
  • control and evaluation unit which can be connected to the gas dosing device and the gas probe to be calibrated and which is designed to carry out a method according to the invention for calibrating the gas probe with the previously described steps (A) to (D).
  • a device according to the invention can in particular comprise a random generator which makes it possible to randomly vary the concentration and/or the type of the at least one gaseous refrigerant and/or the concentration and composition of the at least one background gas in the measuring chamber.
  • the concentration and/or type of the at least one gaseous refrigerant and/or the concentration and composition of the at least one background gas in the measuring chamber can be randomly varied anew in each run, i.e. on the basis of random numbers newly generated in each run.
  • a random profile can be generated using the random generator that emulates several leak searches, and this profile can then be used for the emulated leak search without generating new random numbers each time. In this way, the computational effort for the Emulation of leak detection can be reduced because the repeated generation of random numbers can be omitted.
  • a method according to the invention and a device according to the invention for calibrating a gas probe for refrigerants make it possible to provide a gas probe that is able to reliably distinguish between different refrigerants, for example between R134a and R1234yf.
  • a method according to the invention and a device according to the invention also make it possible to increase the reliability of the calibration with respect to potentially interfering background substances that are contained in the detected gas mixture.
  • the invention also includes a gas probe for detecting refrigerant with at least two gas sensors that have different sensitivities for different refrigerant types and that have been calibrated using a method according to the invention for calibrating a gas probe; and with an evaluation device that is designed to evaluate measurement data provided by the gas sensors using the algorithm calibrated when calibrating the gas probe in order to determine the type of refrigerant detected.
  • the device can in particular be designed to differentiate between at least two different refrigerant types and/or to determine the concentration of the detected refrigerant.
  • the type and concentration of detected refrigerants can be determined very efficiently and reliably.
  • One embodiment includes methods for calibrating the gas probe, repeating the steps of generating the gas mixture and detecting the gas mixture more than ten times, in particular between twenty times and one hundred times, in order to provide a sufficiently large data set for calibrating the algorithm.
  • the quality of the calibration can be increased even further by using a large data set.
  • the method comprises determining the concentration of the at least one gaseous refrigerant and/or the concentration of the to increase and/or reduce at least one background gas in the measuring chamber several times in order to generate measuring points that can be used to calibrate the algorithm.
  • the method can in particular comprise varying the concentration of the at least one gaseous coolant and/or the concentration of the at least one background gas in the measuring chamber in a step-like or continuous manner.
  • the concentration of the refrigerant in the measuring volume can, for example, be varied in a range from 0 ppm to 200 ppm.
  • Organic background gases that can be used include ethanol, acetone and/or other hydrocarbons in concentrations between 0 ppm and 4 ppm.
  • the method may also include keeping the concentration of the at least one gaseous refrigerant and the concentration of the at least one background gas constant over time.
  • the method comprises calculating the time derivative of the concentration of the at least one gaseous refrigerant and/or the time derivative of the concentration of the at least one background gas in the measuring chamber and taking these derivatives into account when calibrating the algorithm. By taking the time derivatives of the concentrations into account, the quality of the calibration can be improved even further.
  • the method comprises randomly varying the concentration of the at least one gaseous refrigerant and/or the concentration of the at least one background gas in the gas mixture.
  • concentration of the at least one gaseous coolant is varied continuously or almost continuously, in particular in a stepped manner. This can be done, for example, by randomly varying the temporal gradient of the concentration of the coolant within a predetermined range and adjusting the concentration of the coolant accordingly.
  • the method comprises varying the concentration of the at least one gaseous refrigerant and/or the concentration of the at least one background gas in the gas mixture according to at least one predetermined profile.
  • the at least one predetermined profile can in particular comprise at least one profile that corresponds to human behavior when searching for a refrigerant leak.
  • the at least one predetermined profile can contain random components and/or be randomly selected from a plurality of predetermined profiles. This can prevent the algorithm from being trained on a fixed predetermined profile and therefore from poorly recognizing deviating profiles.
  • the method comprises measuring the humidity contained in the gas mixture, e.g. with a humidity sensor provided in the gas probe, and taking this into account when calibrating the algorithm. By taking the humidity contained in the gas mixture into account, the quality of the calibration can be further improved.
  • the method may also include deliberately varying the humidity contained in the gas mixture in order to calibrate the algorithm with gas mixtures containing different humidities.
  • the quality of the calibration can be further improved in this way.
  • the method comprises varying the type of refrigerant contained in the gas mixture between different measurement series.
  • the refrigerant contained in the gas mixture can vary between the different In particular, measurement series are varied randomly to prevent the algorithm from being trained on fixed refrigerant change patterns.
  • the method includes calibrating the algorithm using artificial intelligence methods.
  • the method can in particular include the use of a neural network, a decision tree and/or classic regression models.
  • the algorithm can be calibrated particularly efficiently and reliably.
  • the method comprises using a first gas sensor to record a calibration curve for each type of refrigerant to be detected by the gas probe, which describes the measured value provided by the first gas sensor as a function of the concentration of the refrigerant in the gas mixture, and forming the inverse function of this function; for a second gas sensor, the previously described steps (A) of generating a gas mixture containing at least one gaseous refrigerant and at least one background gas in the measuring chamber, (B) detecting the gas mixture generated in the measuring chamber with the gas probe to be calibrated and storing the measurement data provided by the gas sensors of the gas probe for different gas mixtures containing different background gases and different background gas concentrations; carrying out a zero measurement in which no refrigerant is contained in the gas mixture; correcting the measurement data provided by the second gas sensor by the result of the zero measurement; to evaluate the frequency of the measurement results as a function of the corrected measured values and to define a threshold value from this in order to assign measured values below the threshold value to a first refrigerant
  • Figure 1A shows a schematic representation of a device for calibrating a gas probe for refrigerants according to an embodiment of the invention.
  • Figure 1B shows a schematic representation of another device for calibrating a gas probe for refrigerants according to an embodiment of the invention.
  • Figure 2A shows a schematic representation of the gas probe according to an embodiment of the invention.
  • Figure 2B shows a schematic representation of another device for calibrating gas sensors for refrigerants according to an embodiment of the invention.
  • Figure 3A shows a diagram in which the concentration of a refrigerant is plotted as a function of time.
  • Figure 3B shows an example of measurement data provided by the two gas sensors as a function of time t.
  • Figure 4A shows two calibration curves recorded for the first gas sensor.
  • Figure 4B shows a histogram in which the frequency of the respective measurement result is plotted against the zeroed measurement results of the second gas sensor.
  • Figure 1A shows a schematic representation of a device 1 for
  • the device 1 comprises a measuring chamber 2 which comprises a measuring volume 3 for receiving a gas mixture.
  • the device 1 also comprises a gas dosing device 4, which is designed to specifically dose different gases, in particular different types of gaseous refrigerant and/or different background gases, into the measuring volume 3.
  • a gas dosing device 4 which is designed to specifically dose different gases, in particular different types of gaseous refrigerant and/or different background gases, into the measuring volume 3.
  • a gas probe 6 to be calibrated can be attached to the measuring chamber 2 in order to take a portion of the gas mixture from the measuring volume 3 and to be able to determine the composition of the gas mixture.
  • a humidity sensor (not shown in Figure 1A) can be provided in the measuring chamber 2, which measures the humidity of the gas mixture contained in the measuring volume 3.
  • the device 1 also comprises a control and evaluation unit 8, which can be connected to the gas dosing device 4, to the gas probe 6 to be calibrated and, if necessary, to the humidity sensor.
  • the control and evaluation unit 8 is designed to control the gas dosing device 4 and to receive measurement data from the gas probe 6 in order to be able to calibrate the gas probe 6.
  • the control and evaluation unit 8 can comprise a random generator 9, the function of which will be described later.
  • the gas dosing device 4, the gas probe 6 and, if applicable, the humidity sensor can each be connected to the control and evaluation unit 8 via cables, as shown in Figure 1A.
  • the gas dosing device 4, the gas probe 6 and, if applicable, the humidity sensor can also be connected wirelessly, e.g. via a WiFi or Bluetooth® connection, to the control and evaluation unit 8.
  • the gas probe 6 can also be designed to initially store the measured values measured by the gas probe 6 and only transmit them wirelessly or by wire to the control and evaluation unit 8 after the measurements have been completed. Excess gas which has been introduced into the measuring volume 3 by the gas dosing device 4 but is not absorbed by the gas probe 6 can escape through a gas outlet 7 provided on the measuring chamber 2.
  • gas probe 6 Although only one gas probe 6 is shown in Figure 1A, several gas probes 6 can be connected to the measuring chamber 2 and the control and evaluation unit 8 and calibrated simultaneously.
  • the measuring volume 3 of the measuring chamber 2 dampens changes in the concentration of the gases introduced into the measuring chamber 2. This is particularly advantageous if the gas dosing device 4 can only change the concentrations of the gases introduced into the measuring chamber 2 in stages, but not continuously.
  • this damping effect of the measuring volume 3 limits the size of the maximum possible temporal gradients of the change in the gas concentration.
  • the damping effect can be varied by choosing the size of the measuring volume 3: the smaller the measuring volume 3, the smaller the damping effect, and vice versa.
  • the measuring chamber 2 with a minimum measuring volume 3 can be designed as a T-piece, as shown in Figure 1B.
  • Figure 2A shows a schematic representation of a gas probe 6 designed according to the invention.
  • the gas probe 6 comprises a gas inlet 10, which can be at least partially designed as a flexible hose, so that the gas mixture to be detected can be conveniently taken from different locations, for example in the engine compartment of a motor vehicle.
  • the gas probe 6 may comprise a gas pumping device 12 for sucking gas through the gas inlet 10, passing it through a gas sensor unit 14 in the gas probe 6 and discharging it through a gas outlet 16.
  • the gas probe 6 can be forced through by the gas to be measured by an externally induced flow.
  • the gas probe 6 has no gas pump device 12, or the gas probe 6 is provided with a bypass that can be switched on and off, which enables the Gas pumping device 12 to prevent the forced flow of the gas probe 6 from being blocked by the gas pumping device 12.
  • the gas sensor unit 14 comprises at least two gas sensors 14a, 14b with different properties.
  • the two gas sensors 14a, 14b have in particular different sensitivities to different types of coolant that may be contained in the gas mixture to be detected.
  • the gas sensors 14a, 14b can be, for example, metal oxide gas sensors 14a, 14b with different properties.
  • gas sensors 14a, 14b can be used which are intended by the manufacturer for detecting hydrocarbons, e.g. methane.
  • the gas sensors 14a, 14b can provide an electrical resistance R or an electrical conductivity as a measuring signal S.
  • the gas sensors 14a, 14b can also provide other physical quantities, e.g. varying voltages, currents or capacitances as measurement signals S.
  • the gas sensors 14a, 14b can be designed on the input side with a filter layer 15a, 15b made of a chemical absorber, e.g. activated carbon. If such a filter layer 15a, 15b is not present, it can be subsequently attached in front of the respective gas sensor 14a, 14b.
  • a filter layer 15a, 15b made of a chemical absorber, e.g. activated carbon. If such a filter layer 15a, 15b is not present, it can be subsequently attached in front of the respective gas sensor 14a, 14b.
  • the detection properties of identical gas sensors 14a, 14b can be changed by attaching different filter layers 15a, 15b so that they differ from one another.
  • the properties of the gas sensors 14a, 14b and/or the filter layers 15a, 15b can also be varied by operating them at different temperatures.
  • the gas probe 6 also comprises a humidity sensor 5 which is designed to measure the humidity of the gas mixture flowing through the gas probe 6.
  • the gas probe 6 also has a control unit 18 with a memory 24, which is designed to control the gas pumping device 12, to receive measurement data from the gas sensors 14a, 14b, to store and process them in the memory 24, and to transmit the measurement results via a data interface 20 and/or to display it on a display device 22.
  • An acoustic output device 26 can also be provided which is designed to emit an acoustic signal which is dependent on a measured refrigerant concentration c.
  • the gas sensors 14a, 14b can also be calibrated separately, i.e. independently of a gas probe 6.
  • the gas sensors 14a, 14b and the humidity sensor 5 are introduced into a measuring chamber 2, as shown in Figure 2B.
  • One or more gas sensors 14a, 14b can be introduced into the measuring chamber 2 at the same time.
  • the gas sensors 14a, 14b and the humidity sensor 5 are removed from the measuring chamber 2 and installed in a gas probe 6.
  • Figure 3A shows a diagram in which the concentration c of a refrigerant in the measuring volume 3 is plotted on the vertical axis as a function of time t (horizontal axis).
  • a simulated measurement process typically covers a period of 30 seconds to 30 minutes, in particular a period of between 5 and 10 minutes.
  • the gas dosing device 6 is controlled by the control unit 18 such that the concentration c of the refrigerant in the measuring volume 3, which changes over time, simulates the search for a refrigerant leak by moving the gas probe 6 in the vicinity of a suspected refrigerant leak.
  • the concentration c of the refrigerant detected by the gas probe 6 increases as the gas probe 6 approaches the refrigerant leak.
  • the concentration c of the refrigerant measured by the gas probe 6 decreases as the gas probe 6 moves away from the refrigerant leak.
  • the gas probe 6 is not moved. Instead, the approach of the gas probe 6 to a virtual refrigerant leak and the removal of the gas probe 6 from the virtual refrigerant leak is achieved by varying the concentration c of the refrigerant in the measuring volume 3 over time t is simulated, as shown by way of example in Figure 3A.
  • the concentration c of the refrigerant in the measuring volume 3 can, for example, be varied in a range from 0 ppm to 200 ppm.
  • the gas probe 6 Before the first dosing, the gas probe 6 is exposed to the gas for a period of time to of about 30 to 45 seconds, the length of which is deliberately chosen randomly. A longer period of time to is advantageous here, but leads to a longer overall calibration time, so an appropriate compromise must be made here.
  • An additional interval of, for example, 5-10 minutes can be maintained from previous runs, during which background gases but no refrigerant are metered into the measuring chamber 2 in order to obtain the most complete decay possible of the measured values S from the previous measuring cycle provided by the gas sensors 14a, 14b.
  • the measured values S delivered in this preceding decay phase are discarded.
  • a criterion of sensor signal stability can be used to flexibly design the length of the decay phase depending on the properties of the gas sensors 14a, 14b. In the case of "perfect” or almost “perfect” gas sensors 14a, 14b that do not show any significant decay behavior, the additional decay phase can be dispensed with.
  • the graph shown in Figure 3A which describes the concentration c of the refrigerant in the measuring volume 3 changing with time t, comprises regions 32 with a positive slope in which the concentration c of the detected refrigerant increases with increasing time. These regions 32 with a positive slope correspond to an approach of the gas probe 6 to the refrigerant leak.
  • the graph also includes regions 34 with a negative slope in which the concentration c of the detected refrigerant decreases with increasing time t. These regions 34 of decreasing concentration c correspond to a situation in which the gas probe 6 moves away from the refrigerant leak.
  • the graph shown in Figure 3A also includes flat areas ("plateaus") 36 in which the concentration c of the detected refrigerant is constant for a certain period of time. The concentration c of the detected refrigerant remains constant when the gas probe 6 is not moved or when the gas probe 6 is moved along a path on which the concentration of the refrigerant is constant.
  • the holding times over which the concentration c of the detected refrigerant is kept constant can, for example, be randomly selected from a range between 5 s and 20.
  • the gradients c' can be in a range between -100 ppm/min. and +100 ppm/min.
  • the gradients can be selected in a range between -25 ppm/min. and +25 ppm/min.
  • the behavior of a human user when searching for a refrigerant leak can also be simulated.
  • a user When searching for a refrigerant leak, a user will, for example, move the gas probe 6 for as long as possible along a path with increasing concentration of the refrigerant.
  • the random generator 9 can therefore be used in such a way that the probability of a further increase in the concentration c of the refrigerant along the simulated path is greater than the probability of a decrease.
  • the profiles generated by the random generator 9, which describe the concentration c of the detected refrigerant as a function of time t, can be smoothed in order to adapt "angular" changes in concentrations, which can result from the targeted injection of gases into the measuring volume 3, to the more "smooth" changes in concentrations which are detected when the gas probe 6 is moved by a person in search of a refrigerant leak.
  • behaviors of human users can also be determined empirically in order to generate movement profiles that are close to the typical behavior of human users when searching for a refrigerant leak.
  • the type of refrigerant introduced into the measuring volume 3 can also be randomly changed between runs. With two possible refrigerant types, the probability for each of the two possible refrigerant types can be 50%.
  • probability distributions can also be used during calibration, e.g. with probability distributions of 20%:80%, 30%:70% or 40%:60%, or 80%:20%, 70%:30% or 60%:40%.
  • the impact of a priori and conditional probabilities must be taken into account so that even rarely used substances can be detected just as reliably as a frequently used substance. In particular, even rarely used substances must be measured approximately equally often during calibration.
  • the algorithm can also be trained with refrigerant mixtures that contain different proportions of two or more different refrigerant types in order to be able to recognize such refrigerant mixtures.
  • the humidity can be varied at room temperature, i.e. at temperatures between 20 °C and 25 °C, for example in the range between 30% and 70%.
  • Organic background gases can be, for example, ethanol, acetone and/or other hydrocarbons in concentrations between 0 ppm and 4 ppm.
  • the concentrations of the background gases can be determined, for example, by a random generator or by methods of statistical experimental design. It is important to have good coverage of the test area with a variety of different combinations.
  • the gas dosing device 4 does not allow for exactly linear gas profiles when dosing the time-dependent gas profiles.
  • the gas concentration in the measuring volume 3 can therefore also be graduated in the form of "steps". Depending on the mixing of the gases in the measuring volume 3 until they reach the gas sensors 14a, 14b, a “smoothing" of these "steps” is possible. This "smoothing" can also be modeled mathematically for refinement.
  • the time interval between the injection of the background gas and the injection of the refrigerant into the measuring volume 3 can be set randomly. This can prevent the algorithm from "memorizing" a fixed time interval between the injection of the background gas and the injection of the refrigerant into the measuring volume 3 and subsequently making an incorrect prediction based on the time elapsed between the start of the injection of the background gas and the start of the injection of the refrigerant. It can also be advantageous to wait a predetermined minimum time after each emulated leak search, ie after a gas profile as shown by way of example in Figure 3A has been run through, before starting a new simulation run in order to allow the sensor signal to decay. This can be particularly advantageous if the previous run ended with a high refrigerant concentration c.
  • Figure 3B shows an exemplary curve S a , Sb of the measurement data S provided by the two gas sensors 14a, 14b as a function of time t.
  • the curves S a , Sb of the measurement data S provided by the two gas sensors 14a, 14b are not identical. They also do not directly represent the temporal curve of the gas dosing, as shown in Figure 3A.
  • the first gas sensor 14a is slower than the second gas sensor 14b.
  • the temporal profile S a of the sensor signal provided by the first gas sensor 14a is therefore delayed compared to the profile Sb provided by the second gas sensor 14b and compared to the "real" concentration of the refrigerant generated by the metering of the refrigerant into the measuring volume 3, which is shown in Figure 3A.
  • the curves S a and S b of the measurement signals provided by the two gas sensors 14a, 14b do not differ trivially from one another, even along the vertical axis. This may be due, for example, to the fact that the second gas sensor 14b reacts differently to organic interfering gases than the first gas sensor 14a.
  • the measurement data S provided by the two gas sensors 14a, 14b can differ both in their respective absolute values ("offset") and in their respective slope.
  • the two gas sensors 14a, 14b can also have different response times, so that the signal curve S a supplied by one of the two gas sensors 14a, 14b is attenuated and/or delayed in time compared to the signal curve Sb supplied by the other of the two gas sensors 14a, 14b.
  • a humidity sensor 5 (see Figure 1B) present in the probe 6, which measures the humidity of the gas mixture flowing from the measuring volume 3 through the gas probe 6, delivers a signal that is constant over time t.
  • the extracted features are used to train an algorithm designed to determine the type of refrigerant in the gas mixture from the measured values provided by the two gas sensors 14a, 14b.
  • the concentration c of the detected refrigerant in the gas mixture can also be determined.
  • the earlier times t; - At can be, for example, 10 s, 20 s, 30 s, 40 s, 50 s or 60 s in the past.
  • the concentration c(t) of the refrigerant generated by the gas dosing device 4 in the measuring volume 3 and the type of refrigerant dosed into the measuring volume 3 are known and are used to train the algorithm in addition to the measured values c(tj) supplied by the two gas sensors 14a, 14b.
  • concentrations of the background gases in measurement volume 3 are assumed to be unknown. They are therefore not used to train the algorithm. Instead of the full concentration information, reduced, summarized information can also be used to train the algorithm. For example,
  • Algorithms that have been trained with reduced information can then predict from the sensor signals only the reduced information that was used to train the algorithm, instead of the concentration of the refrigerant.
  • Algorithms that can be trained with the supplied measurement data include neural networks, decision trees or classic regression models.
  • the gas sensors 14a, 14b can be "zeroed” at the beginning of each measurement. During “zeroing”, a “baseline” is subtracted from the measured values, which is based on the humidity of the gas mixture and the organic background in the measuring volume 3.
  • Such “zeroing” is particularly advantageous when the background gases are only reflected in the “baseline” and do not change the sensitivity of the gas sensors 14a, 14b for the refrigerant gases. Since the contribution of the humidity to the measurement results is already included in the offset of the "zeroing", a humidity sensor 5 can be dispensed with in this case.
  • the gas sensors 14a, 14b can measure the "zero values" immediately after switching on the gas probe 6, on the basis of which the measurement is carried out before the user is informed that the gas probe 6 is ready for operation.
  • the first gas sensor 14a is sensitive to two different refrigerants, e.g. R134a and R1234yf, and to humidity; and the second gas sensor 14b is only sensitive to humidity, organic (background) substances and the second refrigerant, e.g. R1234yf, but not to the first refrigerant.
  • a calibration curve S a (cj) is recorded for the first gas sensor 14a.
  • Figure 4A shows examples of such calibration curves S a (ci), S a (c2) that were recorded for the first gas sensor 14a.
  • the gas mixture flowing from the measuring volume 3 through the gas probe 6 has an average relative humidity in the range between 40% and 60%, in particular an average relative humidity in the range between 45% and 55%.
  • the emulated leak searches are plotted in a histogram (see Figure 4B), in which the frequency of the respective measurement result n(St>) is plotted against the zeroed measurement results Sb.
  • the histogram shows a bimodal distribution of the measurement results.
  • a threshold value Sth can now be defined that lies between the two distributions.
  • the concentration c> of the respective refrigerant can be determined using the previously defined inverse function Cj(S a ) from the measured value S a provided by the first gas sensor 14a.

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Abstract

Procédé d'étalonnage d'une sonde en verre (6) pour réfrigérant ayant au moins deux capteurs de gaz (14a, 14b) qui ont des sensibilités différentes pour différents réfrigérants, comprenant les étapes consistant à : (A) produire un mélange gazeux contenant au moins un réfrigérant gazeux et au moins un gaz de fond, dans une chambre de mesure (3) ; (B) détecter le mélange gazeux dans la chambre de mesure (3) avec la sonde à gaz (6) à étalonner et stocker les données de mesure fournies par les capteurs de gaz (14a, 14b) de la sonde à gaz (6) ; (C) répéter les étapes (A) et (B) plusieurs fois, le procédé consistant à faire varier la concentration (c) dudit réfrigérant gazeux et/ou la concentration dudit gaz de fond dans la chambre de mesure (3) ; et (D) utiliser les données de mesure fournies par les capteurs de gaz (14a, 14b) pour étalonner un algorithme ce qui permet de déterminer le type et la concentration (c) du réfrigérant contenu dans le mélange gazeux à partir des données de mesure fournies par les capteurs de gaz (14a, 14b).
PCT/EP2023/080237 2022-11-16 2023-10-30 Procédé et dispositif d'étalonnage d'une sonde en verre pour réfrigérant WO2024104773A1 (fr)

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DE102022212187.2 2022-11-16
DE102022212187.2A DE102022212187A1 (de) 2022-11-16 2022-11-16 Verfahren und Vorrichtung zum Kalibrieren einer Gassonde für Kältemittel

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