Measuring device and method for measuring and outputting dew point temperature of surrounding medium

Abstract

To provide a measuring device and a method for measuring and outputting the dew point temperature.SOLUTION: A first humidity sensor unit is configured to determine at least one dew point correction parameter and includes a first humidity sensor, a first temperature sensor and a temperature change element. A second humidity sensor unit is configured to continuously measure a dew point temperature and includes a second humidity sensor and a second temperature sensor. A controller is used to change a temperature of the first humidity sensor unit via the temperature change element and thereby determine the dew point correction parameter, and the dew point correction parameter from the first humidity sensor unit is used to correct measured values of the second humidity sensor unit and to continuously output corrected dew point temperatures based on the corrected measured values.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a measurement device and method for measuring and outputting the dew point temperature of a surrounding medium, particularly for accurately measuring low dew point temperatures. [Background technology]

[0002] Measuring the dew point of a gas is an important measurement task in process technology and meteorology. The dew point or dew point temperature indicates the gas temperature below which the moisture contained in the gas condenses, or the gas temperature at which the gas above the water surface is completely saturated with water vapor. In some cases, dew point temperatures below 0°C are also called frost point temperatures. The frost point temperature indicates the temperature at which the gas above the ice surface is completely saturated with water vapor. In contrast, the dew point indicates the temperature at which the gas above the water surface is completely saturated. In the following, dew point temperatures below 0°C will also be referred to as dew point temperatures.

[0003] Condensation, for example, in compressed air systems, can cause damage to the system and a decrease in the quality of the final product. In building engineering, measuring devices (dew point meters and dew point monitors) are used to measure the dew point temperature in order to detect the risk of condensation occurring, for example, in air-conditioning ceilings, ductwork or electrical cabinets, before it causes damage. In this case, the measurement of the dew point temperature is usually not carried out directly, but rather by measuring the temperature and relative humidity and performing an appropriate calculation of these variables.

[0004] When a capacitive humidity sensor is used to measure relative humidity, it can be beneficial in many ways to periodically heat the humidity sensor. This is necessary, for example, for persistently high humidity values ​​exceeding 80% rH, because capacitive humidity sensors exhibit a so-called high humidity drift. That is, at high relative humidity values, the humidity sensor will display very high humidity values ​​for a longer period of time, resulting in a very high dew point temperature. At low dew points, very small relative humidity measurements must be detected. In this case, high accuracy is required for the humidity measurement. When using a capacitive humidity sensor, the change in capacitance of a suitable polymer is typically used as the measurement variable for relative humidity. To ensure that the polymer used is always in a predetermined calibration state during the measurement, it is common to periodically heat the measuring device, for example, every 10 minutes.

[0005] Furthermore, if the humidity sensor is used in a chemically aggressive environment with a gas mixture that may be incorporated into the wet polymer instead of water molecules, it may be necessary to periodically heat the humidity sensor. This causes capacitance changes that cannot be distinguished from capacitance changes due to humidity. In this case, the humidity sensor can be frequently returned to a predetermined calibration state by cyclic heating. This can be advantageous even for humidity sensors that are not based on capacitive detection principles.

[0006] However, such cyclical heating has a certain effect on the dew point measurement: during the heating and cooling phases, no measurements are provided for measuring the dew point temperature. These corresponding periods can sometimes last several minutes. Furthermore, after cooling, it takes a certain time before the actual dew point temperature can be accurately detected. The dew point temperature is then measured accurately for a similarly limited period, after which it drifts towards higher values. In this context, the time course of the dew point measurement is also referred to as the "sawtooth effect."

[0007] The above method is illustrated in the graph of FIG. 1, which shows the progression of the measured dew point temperature over a longer period of time. In this diagram, the capacitive humidity sensor is heated or cooled every 30 minutes. Furthermore, the exact dew point temperature or the target dew point temperature is shown as a continuous horizontal line. After the heating step, a cooling phase occurs, as can be seen in the diagram. During this cooling phase, the humidity sensor returns to ambient temperature, and an accurate dew point temperature is no longer measurable. After this cooling phase, a certain time period then elapses until an accurate dew point temperature can be measured again. After this, due to changes in the humidity-sensing polymer, the dew point temperature then shifts towards higher values ​​until heating occurs again. After the new cooling phase, an accurate dew point temperature can again be measured within the specified measurement period. This process is repeated.

[0008] A possible method for minimizing errors caused by cyclic heating of multiple capacitive sensor devices in a sensor installation is known from JP 2012-154632. By alternately heating two sensor devices, errors caused by polymer contamination or drift in measured values ​​at very high humidity are avoided. However, the above-mentioned problems, especially when measuring dew points at low dew point temperatures, cannot be solved by the measures known from this document. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent Publication No. 2012-154632 [Non-patent literature]

[0010] [Non-Patent Document 1] R. Dirksen, "Uniform calculation method for relative humidity at Lindenberg weather stations" (MOL-RAO Aktuell, 2019, No. 2) Summary of the Invention [Problem to be solved by the invention]

[0011] The object of the present invention is to provide a measuring device and a method for measuring and outputting the dew point temperature of an ambient medium that are particularly suitable for measuring low dew point temperatures, where accurate measurement of the dew point temperature of the ambient medium must be ensured as consistently as possible. [Means for solving the problem]

[0012] According to the invention, this problem is solved by a measuring device having the features of claim 1.

[0013] Advantageous configurations of the measuring device according to the invention result from the measures set forth in the claims dependent on claim 1.

[0014] An inventive measurement device for measuring and outputting a dew point temperature of an ambient medium includes a first humidity sensor device configured to measure at least one dew point correction parameter and including a first humidity sensor and a temperature changing element. A second humidity sensor device configured to continuously measure dew point temperatures and including a second humidity sensor and a second temperature sensor is also provided. A control device is configured and adapted to vary the temperature of the first humidity sensor device with the temperature changing element and determine the dew point correction parameter. The dew point correction parameter from the first humidity sensor device is used by the control device to correct measurements from the second humidity sensor device and continuously output corrected dew point temperatures based on the corrected measurements.

[0015] Preferably, the second humidity sensor device is thermally coupled to a cooling element that transfers heat from the second humidity sensor device to the surroundings.

[0016] Advantageously, the second humidity sensor device is arranged thermally separated from the first humidity sensor device.

[0017] moreover, the two humidity sensor devices are arranged at opposite ends of a support element formed of reduced material in an area for thermal isolation between the two humidity sensor devices, The support element (115) is surrounded by a housing (150) having a plurality of opening windows (151, 152), It can be proposed that.

[0018] Furthermore, both humidity sensor devices are arranged on separate support elements, and a heat shield is arranged between the support elements, which dissipates heat transferred to the heat shield by thermal radiation in the direction of a heat sink connected to the heat shield. It is possible.

[0019] Preferably, as the second humidity sensor device, a heat sink made of a material that conducts heat well is arranged on the support element as a cooling element.

[0020] Additionally, at least one support element may have electrical terminals for connection to a controller to transmit data and control signals between the humidity sensor device and the controller.

[0021] In a preferred embodiment, both humidity sensor devices are configured as an integrated module.

[0022] Furthermore, the above problem is solved by a method having the features of claim 9.

[0023] A preferred configuration of the invention results from the measures set forth in the claims dependent on claim 9.

[0024] In accordance with the method of the present invention for measuring and outputting a dew point temperature of an ambient medium, a first humidity sensor device is provided. At least one dew point correction parameter is determined from the measured values ​​of the first humidity sensor device relating to temperature and relative humidity. A second humidity sensor device is also provided. A dew point temperature parameter is continuously measured and output from the measured values ​​of the second humidity sensor device relating to temperature and relative humidity. The temperature of the first humidity sensor device is changed, and the dew point correction parameter is determined each time. The dew point correction parameter is then used to correct the measured values ​​of the second humidity sensor device and continuously output corrected dew point temperatures based on the corrected measured values.

[0025] Preferably, the above-mentioned temperature modification and determination of the at least one dew point correction parameter are performed periodically.

[0026] To this end, at least one dew point correction parameter is determined by the first humidity sensor device at at least two defined time points for different temperatures, whereby a respective dew point temperature is determined from the measured temperature and relative humidity, and if the two dew point temperatures do not coincide, the measured value for the relative humidity is corrected so that the dew point temperatures coincide for different temperatures. It can be proposed that.

[0027] moreover, determining at least one dew point correction parameter by the first humidity sensor device; - at least two defined times for different temperatures, the respective dew point temperatures are determined from the respective measured temperatures and relative humidity, the ideal relative humidity is determined from the calculated dew point at the lower temperature and the measured higher temperature; a first humidity correction parameter is determined from the difference between the ideal relative humidity and the measured relative humidity at the higher temperature; a dew point correction parameter is determined using the first humidity correction parameter as an absolute dew point value; the absolute dew point value is used to determine a second humidity correction parameter, which is subsequently added to the relative humidity measurement value of the second humidity sensor device to produce a corrected relative humidity measurement value, so as to continuously output a corrected dew point temperature; It is possible.

[0028] Furthermore, the incorporation (addition) of the second humidity correction parameter into the measurement value for relative humidity of the second humidity sensor device can be performed step by step.

[0029] Beneficially, the first humidity sensor device cyclically passes through a heating phase, a cooling phase and a measurement phase, with the dew point temperature being continuously measured by the second humidity sensor device during all phases and a corrected dew point temperature being output.

[0030] The inventive measures therefore ensure that accurate measurements of the dew point temperature are possible continuously throughout the entire measurement period, with no period during which the actual value of the dew point temperature is unavailable, and therefore it is always possible to react quickly to changes in the dew point temperature in the respective application.

[0031] Furthermore, it is ensured that the "sawtooth effect" caused by cyclic heating of the humidity sensor can be eliminated when measuring the dew point temperature, thus enabling consistent and highly accurate measurement of the dew point temperature.

[0032] The sensor part of the measuring device of the present invention can be integrated into a so-called rod sensor, and no additional sensor technology is required, so that the device can be used very easily in a variety of applications.

[0033] Further details and advantages of the invention will be explained on the basis of the following description of an embodiment in conjunction with the figures. [Brief explanation of the drawings]

[0034] [Figure 1]FIG. 1 is a diagram illustrating the "sawtooth effect" that occurs in conventional techniques when measuring dew point temperature. [Figure 2] 1 is a schematic block diagram of an embodiment of a measurement device of the present invention; [Figure 3a] FIG. 2 is an exploded view of a sensor portion of the first embodiment of the measuring device of the present invention. [Figure 3b] 1 is a diagram of a part of a first embodiment of a measuring device of the invention in an assembled state; [Figure 3c] 2A and 2B are views of a sensor portion of the first embodiment of the measuring device of the present invention from different viewpoints. [Figure 3d] 2A and 2B are views of a sensor portion of the first embodiment of the measuring device of the present invention from different viewpoints. [Figure 4a] FIG. 10 is an exploded view of a sensor portion of a measuring device according to a second embodiment of the present invention. [Figure 4b] FIG. 2 is a view of a portion of a second embodiment of the measuring device of the invention in an assembled state. [Figure 4c] FIG. 10 is a side view of a sensor portion of a measuring device according to a second embodiment of the present invention. [Figure 5] FIG. 1 is a diagram for explaining the method of the present invention. [Figure 6] 10 is a graph of dew point temperatures detected by two humidity sensors during different phases. [Figure 7] 10 is a further graph illustrating the temperature progression when determining the dew point correction parameter; DETAILED DESCRIPTION OF THE INVENTION

[0035] The basic structure of the measuring device according to the invention for measuring and outputting the dew point temperature of a medium is explained below based on the block diagram shown very diagrammatically in Figure 2. In this case, the medium in question surrounds the measuring device, and the measurement object is typically air or another gas.

[0036] The measuring device of the present invention comprises a first humidity sensor device 10, a second humidity sensor device 20 and a control device 30. A power supply device supplying current or voltage to the various components is indicated by the reference numeral 40. Components showing particular measures for thermal isolation between the first humidity sensor 10 and the second humidity sensor 20 are indicated diagrammatically by TE. More details on this point are provided below.

[0037] As will be explained in more detail below, the first humidity sensor device 10 detects the dew point temperature Td, which is also used as a dew point correction parameter. absolut To this end, the first humidity sensor device 10 comprises a first humidity sensor 11, a first temperature sensor 12 and a temperature changing element 13.

[0038] In this case, the humidity sensor 11 may be configured in a known manner, for example as a capacitive humidity sensor 11, and may consist of two electrodes. A polymer whose capacitance changes depending on the humidity is present between these electrodes. Similarly, the temperature sensor 12 may be configured in a known manner, for example as a temperature-dependent resistor or as a semiconductor element. The temperature change element 13 may be, for example, a heating element in the form of a heating wire or a semiconductor element. Furthermore, the temperature change element 13 may be configured as a Peltier element, which can be operated in both heating and cooling modes and makes it possible to change the temperature of the first humidity sensor device 10.

[0039] In a preferred embodiment, the first humidity sensor device 10 is configured as an integrated module or ASIC (Application Specific Integrated Circuit) sold by the applicant under the designation "HTE501", for example, which allows for high resolution and very accurate humidity measurements.

[0040] The second humidity sensor device 20 is configured to continuously measure the dew point temperature and includes a second humidity sensor 21 and a second temperature sensor 22. Furthermore, in the illustrated example, the second humidity sensor device 20 is thermally coupled to a cooling element 23. Heat can be dissipated from the second humidity sensor device 20 to the surroundings via the cooling element 23. The second humidity sensor device 20 is configured essentially identically to the first humidity sensor device 10 with respect to the humidity sensor 21 and the temperature sensor 22 and is preferably also configured as an integrated module or ASIC. To ensure heat transfer to the surrounding medium, the cooling element 23 can be a heat sink made of a material with good thermal conductivity, for example, with appropriately formed cooling ribs. In one preferred embodiment, the thermal resistance of the cooling element 23 is selected to be 100 times (or more) smaller than the thermal resistance between the first humidity sensor device 10 and the second humidity sensor device 20. For example, if the cooling element 23 has a thermal resistance of 30 K / W to the environment, the thermal isolation or thermal resistance between the humidity sensor device 10 and the humidity sensor device 20 is at least 3000 K / W. Basically, the cooling element 23 is not an essential component of the device of the present invention, but it can significantly improve the performance of the device.

[0041] A component indicated by TE is shown diagrammatically between the humidity sensor device 10 and the humidity sensor device 20. This shows that the two humidity sensor devices 10, 20 are arranged in such a way that they are thermally separated as much as possible from each other. This means that heat is transferred as little as possible from the first humidity sensor device 10 to the second humidity sensor device 20, or that thermal crosstalk occurs as little as possible between the two humidity sensor devices 10, 20. Such thermal separation TE can be ensured in various ways in terms of construction. Suitable possibilities and measures in this regard will be explained in more detail below in the description of the exemplary embodiments.

[0042] The control device 30, which is configured, for example, as a microcontroller and is shown very simply in Fig. 2, has functional components which can be realized in various forms in software and / or hardware. For communication with the two humidity sensor devices 10, 20, the control device 30 has a communication interface 33, configured, for example, as an I2C interface. Data and control signals can be transmitted via this communication interface 33. Furthermore, a first calculation device 31 and a second calculation device 32 are provided. Each of these calculation devices processes the measured values ​​of the first sensor device 10 or the second sensor device 20, i.e. the temperature and relative humidity detected by these sensor devices.

[0043] The correction and output of the dew point temperature, as described below, is carried out by a correction output unit 34. To transmit the output signal, in particular the dew point temperature, to subsequent electronics—not shown—the control device 30 further comprises an output interface 35. Data can be transmitted via this output interface 35, for example in a suitable digital or analog protocol.

[0044] In this example, the temperature of the first humidity sensor device 10 is periodically changed, i.e., periodically heated, by a suitably configured and set control device 30, thereby adjusting the at least one dew point correction parameter Td absolut Furthermore, the measured value rH2 of the second humidity sensor device 20 is corrected, and the corrected measured value rH2 korr Based on the corrected dew point temperature Td2 korr Since the dew point correction parameter Td is output continuously, absolut is used by the controller 30. A detailed description of this method will be given below with reference to Figures 5-7.

[0045] In this case, using the first humidity sensor device 10, which in this example is periodically heated, in the absolute measurement operating mode, the absolute value of the relative humidity is periodically measured and the dew point correction parameter Td absolutIn contrast, the second humidity sensor device 20 is always operated without being heated. Therefore, by measuring the temperature T2 and the relative humidity rH2, the target dew point temperature can be continuously measured, and the corrected dew point temperature Td2 can be obtained. korr In this case, the second humidity sensor device 20 operates in a relative measurement operation mode for the relative humidity rH2. That is, the measurement is not interrupted, and the changes in the relative humidity rH2 are continuously analyzed. The absolute value of the relative humidity obtained from the first humidity sensor device 10 is obtained by calculation only. As described above, the dew point correction parameter Td measured by the first humidity sensor device 10 is absolut The dew point measurement of the second humidity sensor device 20 is continuously corrected, and the corrected dew point temperature Td2 korr is used to output the

[0046] In the following, the sensor-side part of a first embodiment of the inventive measuring device is described with reference to Figures 3a-3d. This part is configured as a so-called rod sensor and can be flexibly used in various measuring applications. The control device of the measuring device is not shown. Figure 3a is an exploded view of this part of the measuring device. Figures 3b-3d are further views or partial views of Figure 3a.

[0047] In this example, the two humidity sensor devices 110, 120 are configured as an integrated module or ASIC located at opposite ends of an elongated support element 115. The support element 115 is, for example, a printed circuit board made of FR4 material. Wiring is provided on the board for connecting the humidity sensor devices 110, 120 or the ASIC. These components are powered via the wiring, and data and control signals can be transmitted via the wiring. As shown, the support element 115 is formed with reduced material in the area between the two humidity sensor devices 110, 120. Specifically, the printed circuit board in this area is formed from a serpentine residual area of ​​the printed circuit board. In this example, this structure of the support element 115 ensures thermal isolation between the two humidity sensor devices 110, 120. This essentially prevents heat transfer from the periodically heated humidity sensor device 110 at the bottom end of the support element 115 to the second humidity sensor device 120 located at the top end of the support element 115.

[0048] In the illustrated example, the second humidity sensor device 120 is surrounded by a cooling element 123, which may be a single or two-part heat sink. Heat generated by the second humidity sensor device 120 is dissipated to the surroundings via the cooling element 123 very efficiently. As a result, the temperature of the medium to be measured influences the humidity sensor device 120 as much as possible. Therefore, the temperature of the temperature sensor follows the temperature of the medium as accurately as possible. The heat sink is made of, for example, copper or another material with good thermal conductivity and has an elongated groove-like access channel 123.1. This access channel ensures access for the surrounding medium, e.g., air, to the second humidity sensor device 120. To ensure a good thermal connection of the cooling element 123 to the support element 115 or the ASIC, the heat sink is soldered directly to the support element 115.

[0049] The support element 115 is surrounded by a cylindrical housing 150 having a number of openings 151, 152 in the region below the heat sink 123. In this case, a slightly larger opening 152 is present in the region of the first humidity sensor device 110, allowing the surrounding medium to access the first humidity sensor device 110. A further opening 151 in the form of an elongated vent is provided in the housing 150 adjacent to the central region of the support element 115 where the material is reduced. Here, the opening 151 also contributes to the thermal isolation between the two humidity sensor devices 110, 120, since heat that may be generated in the support element 115 can be easily dissipated due to the possible airflow through the housing 150.

[0050] For transmitting data and control signals between the humidity sensor device and a control device (not shown), the support element 115 further has electrical terminals 116 at its lower end, which in the assembled state are electrically connected to the control device and the energy supply device by means of the electrical terminals 116.

[0051] The sensor side of a second embodiment of the measuring device of the present invention will now be described with reference to Figures 4a-4c. However, the control device of the measuring device is likewise not shown. Figure 4a shows an exploded view of the device. Figures 4b and 4c are separate or partial views.

[0052] In the second embodiment, the first humidity sensor device 210 and the second humidity sensor device 220 are arranged on separate, opposing support elements 215.1, 215.2. These support elements 215.1, 215.2 are preferably formed as thin, flexible printed circuit boards. In their lower regions, the flexible printed circuit boards are connected to a rigid support element region 215.3 made of FR4 printed circuit board material via flexible transverse connections. A rectangular heat shield 240 is arranged between the two support elements 215.1, 215.2, which dissipates heat transferred to the heat shield 240 by thermal radiation or thermal transport toward the metallic cooling element 223. The heat shield 240 is primarily made of rigid FR4 printed circuit board material. In the region of the cooling element 230 (not shown), the heat shield 240 has multiple copper surfaces on the printed circuit board material, each of which functions as a heat conductor, while its intermediate portion is formed as a thermal insulator. In addition to the single layer structure shown here, multi-layer FR4 printed circuit boards can also function as heat shields.

[0053] Therefore, in this embodiment of the invention, the thermal isolation between both humidity sensor devices 210, 220 is ensured mainly by the material of the heat shield 240 and both support elements 215.1, 215.2.

[0054] At the upper end of the measuring device, support elements 215.1 and 215.2 are formed with retainers to ensure the mechanical stability of the structure. For this reason, as can be seen in Fig. 4a, cooling element 223 is formed as a metal heat sink. At the lower end of the device, the flexible printed circuit board is connected via flexible transverse connections to rigid support element 215.3, which is made of FR4 printed circuit board material. Rigid support element 215.3 and heat shield 240 are also well thermally isolated from each other.

[0055] To protect the two humidity sensor devices 210, 220, each support element 215.1, 215.2 is surrounded by a hollow cylindrical filter cap that is permeable to the surrounding medium in the installed state, for example made of PTFE sintered material.

[0056] The method of the present invention for measuring and outputting the dew point temperature of an ambient medium is described in detail below with reference to FIGS. 5-7.

[0057] Figure 5 shows various operating phases of the two humidity sensor devices of the measuring device of the present invention. Figure 6 shows the dew point temperatures measured by these humidity sensor devices in various operating phases. In Figure 6, the dew point temperature measured by the first humidity sensor device is indicated by Td1. The corrected dew point temperature continuously measured and output by the second humidity sensor device is indicated by Td2. korr is shown by

[0058] The upper part of FIG. 5 shows various operating phases of the first humidity sensor device. These operating phases, which are preferably performed or repeated cyclically, include a heating phase, a cooling phase, and a measurement phase. In the heating phase, the first humidity sensor device is heated by a temperature change element to a predetermined temperature, for example, about 125° C. In the subsequent cooling phase, cooling to ambient temperature is performed. In the case of very high ambient temperatures or very low dew point temperatures, active cooling below ambient temperature can instead be performed, for example, by a Peltier element. As can be seen from FIG. 6, in the heating and cooling phases, it is not possible to accurately determine the actual dew point temperature Td1 from the measurements (temperature, relative humidity) of the first humidity sensor device. In both these operating phases, the dew point temperature Td1 measured by the measurements of the first humidity sensor device is clearly too high or too low. Only in the subsequent measurement phase does the dew point temperature Td1 measured by the first humidity sensor device become closer to the actual dew point temperature Td1. soll approaching.

[0059] The lower part of Figure 5 shows the behavior of the second humidity sensor device, which is independent of the first humidity sensor device. This second humidity sensor device is always in the measurement phase. In this measurement phase, the actual or corrected dew point temperature Td2 korr is continuously measured from the measured values ​​for temperature T2 and relative humidity rH2. The second humidity sensor device therefore always maintains the measurement phase as its only operating phase. In this case, the behavior of the second humidity sensor device independent of the first humidity sensor device is guaranteed by the above-mentioned thermal isolation of both humidity sensor devices in the inventive measuring device. The ongoing dew point measurement of the second humidity sensor device is corrected to obtain the corrected dew point temperature Td2 korr During the subsequent measurement phase, at least one dew point correction parameter determined by the first humidity sensor device is repeatedly used only for specific points in time on the side of the second humidity sensor device in order to output the dew point correction parameter.

[0060] As will be explained in more detail below, determining the dew point correction parameter by the first humidity sensor device requires measuring temperature and humidity for at least two points in time t1, t2 at different temperatures T1(t1), T1(t2), where corresponding points in time t1, t2 are selected as close as possible. In this case, for example, the first point in time t1 at ambient temperature (or below ambient temperature) is in the measurement phase, and the second point in time t2 at a higher temperature of 125°C is in the heating phase. That is, T1(t1)=25°C, T1(t2)=125°C.

[0061] 4a-4c, an exemplary method is explained below on the basis of which the dew point correction parameter is determined by the first humidity sensor device. The graphs show, on the one hand, the time course of the temperature T1 measured by the first humidity sensor device during the measurement phase, the heating phase and the cooling phase, and, on the other hand, the time course of the dew point temperature Td1 calculated from the measured temperature T1 and the relative humidity rH1 of the first humidity sensor device.

[0062] As can be seen from the figure, for a time t1 in the measurement phase immediately preceding the heating phase, the dew point temperature Td1(t1) is determined in a known manner, for example by the so-called Magnus formula, as a function f1 of the measured value for the temperature T1(t1) and the relative humidity rH1(t1), i.e. Td1(t1) = f1(T1(t1), rH1(T1)). With T1(t1) = 25 °C and rH1(t1) = 3%, we obtain approximately Td1(t1) = -23.18 °C.

[0063] For more information on the function f1 and the Magnus formula, see the publication: R. Dirksen, "Uniform calculation method for relative humidity at Lindenberg weather stations" (MOL-RAO Aktuell, 2019, No. 2). More information: https: / / www.dwd.de / DE / forschung / atmosphaerenbeob / lindenbergersaeule / rao_download / aktuell_2019_02.pdf.

[0064] At the end of the heating phase, also for time t2, the dew point temperature Td1(t2) is determined from the measurements T1(t2) and rH1(t2), i.e., Td1(t2) = f1(T1(t2), rH1(t2)). For example, T1(t2) = 125°C and rH1(t2) = 0.04%, resulting in a dew point temperature Td1(t2) = -23.49°C.

[0065] The values ​​thus measured for the dew point temperatures Td1(t1) and Td1(t2) at the two temperatures T1(t1) and T1(t2) are compared. If these dew point temperatures Td1(t1) and Td1(t2) are not equal, as in this example, the first humidity correction parameter rH Offset_1 Therefore, when the dew point temperature Td1(t1) at the low temperature T1(t1) is assumed as a prerequisite, the ideal relative humidity rH1(t2) at the high temperature T1(t2) is calc is determined first, i.e., rH1(t2) calc=f2(T1(t2),Td1(t1)). For the function f2, see the Magnus formula above. Therefore, the relative humidity is obtained from the ratio of the saturated vapor pressure at the dew point temperature to the saturated vapor pressure at the medium temperature. In this case, using the data in the example above, the ideal relative humidity rH1(t2) calc =f2(125℃,-23.18℃)=0.0411% is obtained.

[0066] At this time, rH Offset_1 =rH1(t2) calc -rH1(t2) according to the first humidity correction parameter rH Offset_1 is the calculated ideal relative humidity rH1(t2) calc is obtained by comparing the relative humidity rH1(t2) measured at high temperature T1(t2) with the relative humidity rH1(t2) measured at high temperature T1(t2). Thus, using the data from the example above, rH Offset_1 = 0.0411% - 0.04% = 0.0011%. According to this method, the first humidity correction parameter rH Offset_1 is adjusted or updated each cycle.

[0067] At this time, the humidity correction parameter rH calculated in this way Offset_1 Using the measured relative humidity rH 1korr The correction value for rH 1korr =rH1+rH Offset_1 Using the above data, rH1 korr =0.04%+0.0011%=0.0411% is obtained.

[0068] At this time, the humidity correction parameter rH Offset_1 Use the absolute dew point value Td absolut However, the dew point correction parameter Td absolut =f1(T1,rH1 korr )=f1(T1,rH1+rH Offset_1 In this case, the dew point correction parameter Td absolut corresponds to the dew point value Td1(t1) at the corrected first temperature T1(t1). By using the above values, the dew point correction parameter Td absolut, that is, the absolute dew point value is Td absolut =f1(25℃,3%+0.0011%)=-23.18℃.

[0069] At this time, the dew point correction parameter Td absolut is subsequently used to correct the dew point calculated by the second relative humidity sensor device, where the correction is performed by an offset change to the humidity rH2 measured by the second humidity sensor device. In this case, the absolute dew point calculated by the first humidity sensor device or the dew point correction parameter Td absolut is considered to be the correct value, and the ideal relative humidity rH2 ideal However, using the temperature measurement value T2 of the second humidity sensor device, rH2 ideal =f2(T2,Td absolut ) using the data from the example above and T2 = 25°C, rH2 ideal =f2(25℃, -22.18℃) =3.0011% is obtained.

[0070] At this time, the ideal relative humidity rH2 calculated in this way ideal Therefore, the above offset change in the relative humidity rH2 measured by the second humidity sensor is Offset_2 =rH2 ideal -rH2. Therefore, using the data in this example, for the measured value rH2=2%, rH Offset_2 =3.0011%-2%=1.0011% is obtained.

[0071] In this case, the corrected measurement value rH2 korr rH2 korr =rH2+rH Offset_2 Therefore, the offset change rH calculated in this way is used until the next correction parameter is determined. Offset_2 is used. In this case, rH2=2% and rH Offset_2 = 1.011%, rH2 korr =3.0011% is obtained.

[0072] In this case, the offset change or the second humidity correction parameter rH Offset_2 The correction of the humidity measurement value of the second humidity sensor by adding (adding) to the measurement value rH2 is not performed in a single correction step but in multiple sub-steps to avoid very sudden changes in the dew point temperature output in the method, so that, for example, a method of correcting an error that gradually increases linearly with time can be used.

[0073] At this time, the corrected measurement value rH2 korr From the corrected dew point temperature Td2 korr But Td2 korr =f1(T2=25C,rH2 korr = 3.0011%) = -23.18°C. Therefore, at the time of correction or compensation, the measured dew points Td1 of the first humidity sensor device and the second humidity sensor device can be calculated according to absolut and Td2 korr is equal to Td1 in this example. absolut =Td2 korr =-23.18°C. As can be seen from Figure 6, these values ​​move apart again during further measurement phases, until the next correction is performed again.

[0074] In addition to the specifically described and alternative embodiments described above, further configurations are, of course, possible within the scope of the present invention.

[0075] In principle, therefore, instead of the capacitive humidity sensor used in the example, it is also possible to use a humidity sensor based on another detection principle, for example a resistive humidity sensor.

[0076] Furthermore, it is not necessary for each of the humidity sensor devices to be implemented as an ASIC, but instead, the humidity sensor devices may be implemented as separate components, i.e., as separate sensors.

[0077] Naturally, there are also alternative options for constructing the cooling element associated with the second humidity sensor device, i.e., it does not have to be constructed in two parts, for example, an integrated cooling element can be used that can be suspended on a support element and fixed by clamps.

[0078] Furthermore, it is conceivable that the first and second humidity sensor devices are swapped after a certain period of time, with each taking over the function of the other. This is particularly possible in the case of the second embodiment. Such variations can be beneficial, for example, with regard to the time stability of the polymers used for capacitive humidity measurement.

[0079] Furthermore, the heating of the first humidity sensor device does not have to be performed strictly periodically or periodically, but may be performed irregularly in any suitable manner.

[0080] Furthermore, within the scope of the described method, it is not necessary to carry out measurements at exactly two temperatures, namely at room temperature and at 125° C. Basically, the first humidity correction parameter rH Offset_1 In addition to the humidity correction parameter rH gain_1 It is also possible to determine the correction variable rH as the rH / T characteristic curve. Offset_1 ,rH gain_1 It is believed that variations in rH / T will result in a measured dew point temperature that has minimal error relative to the theoretical rH / T characteristic curve.

Claims

1. - at least one dew point correction parameter (Td ａｂｓｏｌｕｔ a first humidity sensor device (10; 110; 210) configured to determine the humidity of the air and including a first humidity sensor (11), a first temperature sensor (12) and a temperature-changing element (13); a second humidity sensor device (20; 120; 220) adapted to continuously measure the dew point temperature and including a second humidity sensor (21) and a second temperature sensor (2); - changing the temperature of the first humidity sensor device (10; 110; 210) by means of a temperature change element (13) and determining the dew point correction parameter (Td ａｂｓｏｌｕｔ ) to determine - dew point correction parameter (Td ａｂｓｏｌｕｔ ) to correct the measured value (rH2) of the second humidity sensor device (20; 120; 220), and the corrected measured value (rH2 ｋｏｒｒ ) based on the corrected dew point temperature (Td2 ｋｏｒｒ a control device (30) configured and adapted to continuously output A measuring device for measuring and outputting the dew point temperature (Td) of a surrounding medium having a temperature of 0.15° C. to 1.25° C.

2. 2. The measuring device according to claim 1, wherein the second humidity sensor device (20; 120; 220) is thermally coupled to a cooling element (23; 123; 223) for dissipating heat from the second humidity sensor device (20; 120; 220) to the surroundings.

3. 3. Measuring device according to claim 1 or 2, characterized in that the second humidity sensor device (20; 120; 220) is arranged thermally separated from the first humidity sensor device (10; 110; 210).

4. the two humidity sensor devices (110, 120) are arranged at opposite ends of a support element (115) made of reduced material in the area for thermal isolation between the two humidity sensor devices (110, 120); - Measuring device according to claim 3, characterized in that the support element (115) is surrounded by a housing (150) having a plurality of opening windows (151, 152).

5. 4. The measuring device according to claim 3, wherein the two humidity sensor devices (210, 220) are arranged on separate support elements (215.1, 215.2), and a heat shield (240) is arranged between the support elements (215.1, 215.2), which dissipates heat transferred to the heat sink (223) by thermal radiation in the direction of the heat sink (223) connected to the heat shield (240).

6. 5. The measuring device according to claim 2, wherein a heat sink made of a material having good thermal conductivity is arranged on the support element (115) as a cooling element (123) adjacent to the second humidity sensor device (120).

7. 6. The measuring device according to claim 4 or 5, wherein at least one support element (115; 215.1, 215.2) has electrical terminals for connection to a control device (30) for transmitting data and control signals between the humidity sensor device (10, 20; 110, 120; 210, 220) and the control device (30).

8. 8. Measuring device according to claim 1, wherein both humidity sensor devices (10, 20; 110, 120; 210, 220) are constructed as an integrated module.

9. A method for measuring and outputting a dew point temperature of a surrounding medium by means of a first humidity sensor device (10; 110; 210) and a second humidity sensor device (20; 120; 220), comprising: - at least one dew point correction parameter (Td ａｂｓｏｌｕｔ ) is determined from measurements of the first humidity sensor device (10; 110; 210) relating to temperature (T1(t1), T1(t2)) and relative humidity (rH1(t1), rH1(t2)), - the dew point temperature is continuously measured and output from the measurements of the second humidity sensor device (20; 120; 220) of temperature (T2) and relative humidity (rH2), - the temperature of the first humidity sensor device (10; 110; 210) is changed and the dew point correction parameter (Td ａｂｓｏｌｕｔ ) is decided on a case-by-case basis, - correcting the measured value (rH2) of the second humidity sensor device (20; 120; 220) and calculating the corrected measured value (rH2 ｋｏｒｒ ) based on the corrected dew point temperature (Td2 ｋｏｒｒ ) is continuously output, the dew point correction parameter (Td ａｂｓｏｌｕｔ ) indicates the method used.

10. Changes in temperature and at least one dew point correction parameter (Td ａｂｓｏｌｕｔ 10. The method of claim 9, wherein the determination of (a) is performed periodically.

11. At least one dew point correction parameter (Td) is determined by the first humidity sensor device (10; 110; 210) at at least two defined times (t1, t2) for different temperatures. ａｂｓｏｌｕｔ 11. The method according to claim 9 or 10, wherein, to determine the relative humidity (rH1(t1), rH1(t2)), respective dew-point temperatures (Td1(t1), Td1(t2)) are determined from the measured temperatures (T1(t1), T1(t2)) and relative humidity (rH1(t1), rH1(t2)), and if the dew-point temperatures (Td1(t1), Td1(t2)) do not coincide, the measured value for the relative humidity (rH1(t2)) is corrected so that the dew-point temperatures (Td1(t1), Td1(t2)) coincide with those for the different temperatures (T1(t1), T1(t2)).

12. At least one dew point correction parameter (Td ａｂｓｏｌｕｔ ) to determine - at least two defined times (t1, t2) for different temperatures, the respective dew point temperatures (Td1(t1), Td1(t2)) are determined from the respective measured temperatures (T1(t1), T1(t2)) and relative humidities (rH1(t1), rH1(t2)), - Ideal relative humidity (rH1(t2) ｃａｌｃ ) is determined from the calculated dew point (Td1(t1)) for the lower temperature (T1(t1)) and the measured higher temperature (T1(t2)); - first humidity correction parameter (rH Ｏｆｆｓｅｔ＿１ ) is the ideal relative humidity (rH1(t2)) at a higher temperature (T2) ｃａｌｃ ) and the measured relative humidity (rH1(t2)), - dew point correction parameter (Td ａｂｓｏｌｕｔ ) is used as the absolute dew point value to calculate the first humidity correction parameter (rH Ｏｆｆｓｅｔ＿１ ) is determined using - corrected dew point temperature (Td2 ｋｏｒｒ ) is continuously output, the absolute dew point value is adjusted to the second humidity correction parameter (rH Ｏｆｆｓｅｔ＿２ ) and a second humidity correction parameter (rH Ｏｆｆｓｅｔ＿２ ) is subsequently incorporated into the measurement value of the relative humidity (rH2) of the second humidity sensor device (20; 120; 220) to obtain the relative humidity (rH2 ｋｏｒｒ 11. The method of claim 9 or 10, wherein a corrected measurement for

13. The second humidity correction parameter (rH Ｏｆｆｓｅｔ＿２ 13. The method according to claim 12, wherein the incorporation of the second humidity sensor device (20; 120; 220) into the measurement value for relative humidity (rH2) is carried out step by step.

14. The first humidity sensor device (10; 110; 210) cyclically passes through a heating phase, a cooling phase and a measurement phase, and the dew point temperature is continuously measured by the second humidity sensor device (20; 120; 220) during all phases and a corrected dew point temperature (Td2 ｋｏｒｒ 11. The method of claim 10, wherein the output is

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