CN117420175A - Cold mirror dew point meter with automatic compensation function and use method thereof - Google Patents
Cold mirror dew point meter with automatic compensation function and use method thereof Download PDFInfo
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- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 34
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- G01N25/00—Investigating or analyzing materials by the use of thermal means
- G01N25/56—Investigating or analyzing materials by the use of thermal means by investigating moisture content
- G01N25/66—Investigating or analyzing materials by the use of thermal means by investigating moisture content by investigating dew-point
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/47—Scattering, i.e. diffuse reflection
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/47—Scattering, i.e. diffuse reflection
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Abstract
The invention belongs to the field of dew point instruments, and relates to a chilled-mirror dew point instrument with an automatic compensation function and a use method thereof. In the cold mirror dew point meter, the upper part and the lower part of the test cavity are provided with a photoelectric detection unit matrix, a mirror surface and a refrigeration unit matrix, the photoelectric detection unit matrix comprises a dew detection luminous tube, a dew detection receiving tube, a compensation luminous tube and a compensation receiving tube, the singlechip is sequentially connected with a digital-analog converter, a voltage control current source, the compensation luminous tube and the dew detection luminous tube, the dew detection receiving tube and the compensation receiving tube are connected with a multipath analog-digital converter, and the multipath analog-digital converter is connected with the singlechip. The using method of the cold mirror dew point meter comprises the steps of monitoring a voltage value V output by a compensation receiving tube, adjusting an output current I to enable the voltage value V output by the compensation receiving tube to be restored to V0, enabling the output voltage of the detection receiving tube to be restored to be near a typical value U0, and enabling response characteristics of the detection receiving tube to be close to an optimal state. The invention improves the measurement precision and reduces the fluctuation of the measured value of the dew point meter.
Description
Technical Field
The invention belongs to the technical field of dew point instruments, and particularly relates to a chilled-mirror dew point instrument with an automatic compensation function and a use method thereof.
Background
The cold mirror dew point meter adopts the dew point principle, namely adopts an isobaric cooling method to lead the vapor in the measured gas to start to show a mirror dew layer of dew or frost, and measures the temperature at the moment, namely the dew point of the gas. The cold mirror dew point meter consists of photoelectric detection unit, mirror surface, refrigerating unit, mirror surface temperature detection and control circuit, etc. The mirror cooling part is used to control the temperature drop of the mirror, and the photoelectric detection unit is used to detect the formation of the mirror dew layer. When the exposed layer appears on the mirror surface, the light irradiated to the mirror surface by the exposure luminous tube is scattered, the light quantity received by the exposure receiving tube is reduced, and the reduced light quantity is approximately proportional to the thickness of the exposed layer. When the temperature of the mirror surface is reduced to the dew point of the mirror surface and the dew layer reaches an equilibrium state, the temperature of the mirror surface at the moment is measured by a platinum resistance thermometer closely attached below the mirror surface, namely the dew point of the gas.
When the dew point of the gas is very low, the water content in the gas is very low, the mirror surface balance dew layer is very thin, so that the change of photoelectric detection signals is very weak, and as the dew detection luminous tube and the dew detection receiving tube are both devices with larger response characteristics along with the influence of temperature, when the temperature change is larger in the measurement process, the signal introduced by the change of the mirror surface dew layer can be submerged due to the change of the response signal of the dew detection receiving tube, so that larger measurement errors and fluctuation are caused, and the balance time is longer. Therefore, in the dew point measurement with a large temperature change, it is necessary to perform temperature automatic compensation with good performance for the chilled-mirror dew point meter.
Evaluation of temperature compensation performance of a chilled-mirror dew point hygrometer: in order to reduce the influence of non-linearity of response characteristic as much as possible, when the temperature of the test cavity changes under the condition that the mirror surface is kept dry, the voltage signal output by the detection dew receiving tube can be kept near a typical value, and the smaller the change is, the better the temperature compensation performance is. Typical values of the dew receiving tube are values depending on the actual measurement experience of the instrument, and the sensitivity and linearity of the dew receiving tube are good near the values, and the response performance is near the best.
The photoelectric detection system of the current cold mirror dew point meter mainly adopts the following modes:
(1) A single optical path system is adopted: the cold mirror dew point meter only has one path of dew point luminous tube and dew point receiving tube, the dew point luminous tube irradiates the mirror surface, the light signal reflected from the mirror surface is received by the dew point receiving tube and is converted into voltage signal. After the cold mirror dew point meter is started or reset, after the test cavity and the mirror surface in the test cavity are purged by dry gas, the dew point meter collects the voltage signal of the dew point receiving tube, if the voltage signal is found to have a larger difference with the typical value, the voltage signal of the dew point receiving tube is changed by manually adjusting the potentiometer on the front panel or the circuit board, so that the driving current input to the dew point receiving tube is changed, and the voltage signal of the dew point receiving tube is changed until the voltage signal is adjusted to the typical value. When the ambient temperature of the measuring cavity changes, the luminous intensity of the detecting luminous tube and the voltage signal output by the detecting receiving tube can change along with the temperature. This approach is suitable for the case where the temperature of the test chamber is relatively stable, which can lead to large dew point measurement errors if the temperature of the test chamber varies significantly during the measurement.
(2) Adopts a double-light path system: on the basis of the existing one-way dew-point detecting luminous tube and dew-point detecting receiving tube, a compensating luminous tube and a compensating receiving tube are additionally arranged, and light emitted by the compensating luminous tube directly irradiates the compensating receiving tube through a pipeline. After the cold mirror dew point meter is started or reset, the potentiometer on the front panel or the circuit board is regulated according to the same manual regulation mode as the single light path system (1), and the driving current input to the detection dew luminous tube is changed, so that the voltage signal of the detection dew receiving tube is regulated to a typical value. In the dew point measurement process, when the ambient temperature of the measurement cavity changes, the luminous intensity of the detection luminous tube and the compensation luminous tube and the voltage signals generated by the detection receiving tube and the compensation receiving tube can change along with the temperature. According to the change rate of the voltage signal of the compensation receiving tube (for example, the change rate is 85% as compared with the 15% of the decrease of the voltage signal of the compensation receiving tube when the power is turned on), the voltage signal of the detection receiving tube is multiplied by the same change rate (for example, multiplied by 85%) so as to realize compensation.
Because the cold mirror dew point meter does not allow manual adjustment of the potentiometer after entering the measuring process, the performance curves of the dew point luminous tube and the dew point receiving tube are different after the temperature of the measuring cavity is changed, so that the compensation effect is limited according to the method for compensating the voltage signal change rate of the receiving tube, and the measuring dew point balancing time is prolonged and the measuring error is larger.
Disclosure of Invention
Aiming at the technical problem that the performance of the cold mirror dew point meter is influenced by the change of the environmental temperature of the test cavity in the prior art, the invention provides a method for improving the temperature stability of a photoelectric detection system, and the cold mirror dew point meter with the automatic compensation function and stable performance is realized. The technical scheme adopted by the invention is as follows:
a chilled-mirror dew point meter with automatic compensation function, comprising: the single chip microcomputer, multichannel analog-to-digital converter, digital-to-analog converter, voltage control current source and test cavity, the upper portion and the lower part of test cavity set up photoelectric detection unit base member and mirror surface and refrigeration unit base member respectively, mirror surface and refrigeration unit base member include the mirror surface, photoelectric detection unit base member includes: the single chip microcomputer is electrically connected with the digital-to-analog converter, the voltage control current source, the compensation luminotron and the exposure luminotron in sequence, the exposure luminotron and the compensation receiving tube are electrically connected with the multipath analog-to-digital converter respectively, and the multipath analog-to-digital converter is electrically connected with the single chip microcomputer.
Preferably, the compensation luminotron and the compensation receiving tube are horizontally and fixedly arranged at the upper part of the photoelectric detection unit matrix in parallel and are connected through a closed channel, and the exposure luminotron and the exposure receiving tube are respectively and fixedly arranged at the lower part of the photoelectric detection unit matrix.
Preferably, the mirror surface and the refrigerating unit matrix further comprise a platinum resistance thermometer and a mirror surface refrigerating component, the mirror surface is fixedly arranged at the opening part right above the mirror surface and the refrigerating unit matrix, the platinum resistance thermometer is fixedly arranged on the lower surface of the mirror surface in a fitting mode, and the mirror surface refrigerating component is fixedly arranged below the platinum resistance thermometer.
Preferably, the platinum resistance thermometer is electrically connected with the mirror surface temperature detection circuit, the mirror surface refrigerating component is electrically connected with the mirror surface refrigerating driving control circuit, the mirror surface temperature detection circuit is electrically connected with the multipath analog-to-digital converter, and the mirror surface refrigerating driving control circuit is electrically connected with the singlechip.
Preferably, the mirror refrigeration component comprises a semiconductor refrigerator and an auxiliary heat dissipation system.
Preferably, the lower part of the photoelectric detection unit matrix is provided with an incident window for the light emitted by the detection luminous tube to enter and an emergent window for the reflected light to come out, and the central extension lines of the incident window and the emergent window are aligned with the center of the mirror surface.
Preferably, the substrate of the photoelectric detection unit is monolithic copper, monolithic aluminum alloy or monolithic polytetrafluoroethylene.
The application method of the cold mirror dew point meter with the automatic compensation function comprises the following steps:
the singlechip adjusts the output voltage of the digital-to-analog converter, controls the output current I of the voltage control current source through the output voltage, adjusts the luminous intensity of the compensation luminous tube and the detection luminous tube through the output current I, adjusts the voltage value U output by the detection receiving tube and the voltage value V output by the compensation receiving tube through the luminous intensity adjustment of the compensation luminous tube and the detection luminous tube, so that the voltage value U output by the detection receiving tube is equal to a typical value U0, and records the voltage value V output by the compensation receiving tube as V0;
the method comprises the steps of starting to measure the dew point of gas, monitoring the voltage value V output by a compensation receiving tube at any time, wherein DV is an empirical threshold value, adjusting the output voltage of a digital-to-analog converter by a singlechip when I is V-V0I > DV, controlling the output current I of a current source by adjusting the voltage through the output voltage of the digital-to-analog converter, and enabling the voltage value V output by the compensation receiving tube to be recovered to V0 through adjusting the output current I;
the single chip microcomputer collects a new voltage value U of the dew-detecting receiving tube through the multipath analog-digital converter, the voltage value U output by the dew-detecting receiving tube and the voltage value output by the compensating receiving tube increase and decrease in the same direction, because the voltage value V of the compensating receiving tube is recovered to V0, if the mirror surface is kept in a dry state, the output voltage of the dew-detecting receiving tube is recovered to be near a typical value U0, the response characteristic of the dew-detecting tube is near an optimal state near the typical value U0, when the mirror surface is condensed, the error caused by the temperature change of a test cavity is minimum, the temperature stability of a photoelectric detection system of the cold mirror dew-point meter is enhanced, and the photoelectric detection system is kept to work near an optimal response area.
Preferably, the typical value U0 of the output voltage value of the dew receiving tube of the cold mirror dew point meter is obtained through experiments, and the typical value U0 of the output voltage value of the dew receiving tube is an actual measurement experience value depending on instruments.
Preferably, the chilled-mirror dew point meter is purged of the mirror surface with gas at power-on or reset so that the test cavity and the mirror surface remain dry.
The invention has the beneficial effects that:
after the invention is adopted, the temperature stability of the photoelectric detection system of the cold mirror dew point meter is enhanced, so that the photoelectric detection system is kept near the optimal response area, and the influence of nonlinearity of response characteristics is reduced, thereby improving the measurement precision and reducing the fluctuation of the measured value of the dew point meter.
Drawings
FIG. 1 is a schematic block diagram of a prior art chilled-mirror dew point meter employing a single optical path system;
FIG. 2 is a schematic block diagram of a prior art chilled-mirror dew point meter employing a dual optical path system;
FIG. 3 is a schematic view showing a structure of a chilled-mirror dew point meter with an automatic compensation function according to a first embodiment of the present invention;
in the figure, 1 is a singlechip, 2 is a direct-current voltage source, 3 is an adjustable potentiometer, 4 is a multipath analog-to-digital converter, 5 is a detection luminous tube, 6 is a detection receiving tube, 7 is a mirror surface, 8 is a platinum resistance thermometer, 9 is a mirror surface refrigerating component, 10 is a mirror surface temperature detection circuit, 11 is a mirror surface refrigerating drive control circuit, 12 is a photoelectric detection unit matrix, 13 is a mirror surface and refrigerating unit matrix, 14 is a digital-to-analog converter, 15 is a voltage control current source, 16 is a compensation luminous tube, and 17 is a compensation receiving tube.
Detailed Description
The following description of the embodiments of the present invention will be made apparent and complete in conjunction with the accompanying drawings, in which it is evident that the embodiments described are some, but not all embodiments of the present invention.
Example 1
As shown in fig. 1, a schematic block diagram of a single-optical-path chilled-mirror dew point meter in the prior art is shown. The single light path cold mirror dew point hygrometer mainly includes: the temperature-sensing device comprises a singlechip 1, a direct-current voltage source 2, an adjustable potentiometer 3, a multipath analog-to-digital converter 4, a detection luminous tube 5, a detection receiving tube 6, a mirror 7, a platinum resistance thermometer 8, a mirror refrigerating component 9, a mirror temperature detection circuit 10, a mirror refrigerating driving control circuit 11, a photoelectric detection unit matrix 12 and a mirror and refrigerating unit matrix 13.
The detecting dew luminous tube 5 and the detecting dew receiving tube 6 are arranged in the photoelectric detecting unit matrix 12, the photoelectric detecting unit matrix 12 is formed by processing a whole metal (such as copper and aluminum alloy) or nonmetal (such as polytetrafluoroethylene) material, a gas channel of a testing cavity is arranged below the photoelectric detecting unit matrix, and a mirror surface and refrigerating unit matrix 13 consisting of a mirror surface 7, a platinum resistance thermometer 8 and a mirror surface refrigerating component (such as a semiconductor refrigerator and an auxiliary heat dissipation system thereof) are arranged below the gas channel. The two ends of the testing cavity are provided with an inlet and an outlet of the tested gas, the horizontal arrow in the figure is the flowing direction of the tested gas, and the tested gas passes over the mirror 7.
The lower part of the photoelectric detection unit matrix 12 is provided with an incident window of the exposure light emitting tube 5 and an emergent window of the exposure receiving tube 6. The direct-current voltage source 2 is connected with the adjustable potentiometer 3 and the detecting light-emitting tube 5, and the driving current input to the detecting light-emitting tube 5 can be changed by manually adjusting the adjustable potentiometer 3, so that the light-emitting intensity of the detecting light-emitting tube 5 is changed. The emitted light of the detecting dew luminous tube 5 passes through the incident window and the detected gas, irradiates the mirror surface 7 and is reflected by the mirror surface 7, the reflected light irradiates the detecting dew receiving tube 6 through the emergent window, is converted into a voltage signal U and is sent to the multipath analog-digital converter 4, and the voltage signal U is collected and processed through the singlechip 1.
The voltage signal U output by the dew receiving tube 6 is substantially stable before the mirror surface 7 appears as a mirror dew layer. The singlechip 1 obtains the temperature value of the mirror 7 through the analog-to-digital converter 4, and controls the mirror refrigeration component 9 through the mirror refrigeration driving control circuit 11 to realize the temperature regulation control of the mirror 7. When the dew layer appears on the mirror surface 7, the incident light is scattered, and the light quantity received by the dew receiving tube 6 is reduced, and the reduced light quantity is approximately proportional to the thickness of the dew layer. When the mirror dew appears, the temperature of the mirror is controlled so that the mirror dew is in a stable equilibrium state, and the temperature value of the mirror 7, namely the dew point temperature, is obtained by a platinum resistance thermometer 8 closely attached below the mirror 7.
The dew point measuring precision of the cold mirror dew point meter directly depends on the performances of the dew point luminous tube 5 and the dew point receiving tube 6, and the signals sent by the dew point luminous tube 5 and the signals received by the dew point receiving tube 6 change along with the temperature, so that the mode is suitable for the condition that the temperature of the test cavity is relatively stable, and if the temperature of the test cavity changes greatly in the measuring process, a larger dew point measuring error can be caused.
As shown in fig. 2, a schematic block diagram of a dual-optical-path chilled-mirror dew point meter in the prior art is shown. The double-light path chilled-mirror dew point meter mainly comprises: the device comprises a singlechip 1, a direct-current voltage source 2, an adjustable potentiometer 3, a multipath analog-to-digital converter 4, a detection luminous tube 5, a detection receiving tube 6, a mirror 7, a platinum resistance thermometer 8, a mirror refrigerating component 9, a mirror temperature detection circuit 10, a mirror refrigerating drive control circuit 11, a photoelectric detection unit matrix 12, a mirror and refrigerating unit matrix 13, a compensation luminous tube 16 and a compensation receiving tube 17.
On the basis of the existing single-light-path cold mirror dew point meter, a compensation luminous tube 16 and a compensation receiving tube 17 are additionally arranged, and light emitted by the compensation luminous tube 16 directly irradiates the compensation receiving tube 17 through a pipeline with a certain length, so that the double-light-path cold mirror dew point meter is formed.
After the dual-light path chilled-mirror dew point meter is started or reset, the adjustable potentiometer 3 on the front panel or the circuit board is adjusted according to the same manual adjustment mode as a single-light path system, and the size of the driving current I input to the detection dew luminous tube 5 is changed, so that the signal of the detection dew receiving tube 6 is adjusted to a typical value. When the environmental temperature of the measuring cavity changes, the luminous intensity of the detecting luminous tube 5 and the compensating luminous tube 16 and the voltage signals generated by the detecting receiving tube 6 and the compensating receiving tube 17 can change along with the temperature. According to the rate of change of the voltage signal of the compensation receiving tube 17 (for example, 15% of decrease compared with the turn-on voltage V signal, that is, 85%) the voltage signal U of the dew receiving tube 6 is multiplied by the same rate of change (for example, by 85%) to realize the compensation.
Because the cold mirror dew point meter cannot manually adjust the potentiometer after entering the measuring process, the compensation effect is limited according to the voltage signal change rate method of the compensation receiving tube 17 due to the difference of the performance curves of the detection luminous tube 5 and the detection receiving tube 6 after the temperature change, so that the dew point measuring error is still larger, and the balancing time is longer due to fluctuation.
Fig. 3 is a schematic structural diagram of a chilled-mirror dew point meter with automatic compensation function according to an embodiment of the present invention. This embodiment is actually a hardware replacement of the existing dc power supply 2 and adjustable potentiometer 3 of the dual-path dew point meter shown in fig. 2 with a digital-to-analog converter 14 and a voltage controlled current source 15, and a new compensation algorithm is adopted in software. The concrete description is as follows:
a cold mirror dew point meter with automatic compensation function mainly comprises: the device comprises a singlechip 1, a multipath analog-digital converter 4, a detection luminous tube 5, a detection receiving tube 6, a mirror 7, a platinum resistance thermometer 8, a mirror refrigeration component 9, a mirror temperature detection circuit 10, a mirror refrigeration driving control circuit 11, a photoelectric detection unit matrix 12, a mirror and refrigeration unit matrix 13, a digital-analog converter 14, a voltage control current source 15, a compensation luminous tube 16 and a compensation receiving tube 17.
The detecting dew luminous tube 5, the compensating luminous tube 16, the detecting dew receiving tube 6 and the compensating receiving tube 17 are all arranged in the photoelectric detection unit matrix 12, and the photoelectric detection unit matrix 12 is formed by processing a whole metal (such as copper and aluminum alloy) or nonmetal (such as polytetrafluoroethylene) material, so that the temperature consistency of all parts in the photoelectric detection unit matrix is kept. Below the photodetection unit substrate 12 is a mirror and refrigeration unit substrate 13, and the mirror and refrigeration unit substrate 13 includes a mirror 7, a platinum resistance thermometer 8, and a mirror refrigeration component 9 (e.g., a semiconductor refrigerator and an auxiliary heat dissipation system). The two ends of the testing cavity are provided with an inlet and an outlet of the tested gas, the horizontal arrow in the figure is the flowing direction of the tested gas, and the tested gas passes over the mirror 7. The lower part of the photoelectric detection unit matrix 12 is provided with an incident window for the light emitted by the detection luminous tube 5 to enter and an emergent window for the reflected light to come out (namely, a receiving window of the detection receiving tube 6), and the central extension lines of the incident window and the emergent window are aligned with the center of the mirror 7.
The singlechip 1 controls the output voltage of the digital-to-analog converter 14, thereby controlling the output current I of the voltage control current source 15, outputting the output current I to the compensation luminous tubes 16 connected in series, and outputting the output current I to the exposure luminous tubes 5 connected in series after the output current I flows out from the compensation luminous tubes 16. The output current I can be changed at any time by the singlechip 1, so that the luminous intensity of the compensation luminous tube 16 and the luminous intensity of the exposure luminous tube 5 are changed at the same time, and the voltage U output by the exposure receiving tube 6 and the voltage V output by the compensation receiving tube 17 are changed.
The emitted light of the detecting dew luminous tube 5 passes through the incident window and the detected gas to irradiate on the mirror surface 7 to be reflected by the mirror surface, and the reflected light is irradiated on the detecting dew receiving tube 6 from the emergent window to be converted into a voltage signal U; the emitted light of the compensation luminous tube 16 passes through the pipeline and irradiates the compensation receiving tube 17 to be converted into a voltage signal V; the voltage signals U and V are transmitted to a multipath analog-to-digital converter 4 and are collected and processed through a singlechip 1. The platinum resistance thermometer 8 is connected with a mirror temperature detection circuit 10, the singlechip 1 obtains the temperature value of the mirror 7 through the analog-to-digital converter 4, and the mirror refrigeration part 9 is controlled through a mirror refrigeration driving control circuit 11 to realize the temperature regulation control of the mirror 7.
The light flux incident and reflected is substantially stable before the mirror surface 7 is exposed, and when the mirror surface 7 is exposed, the incident light is scattered, and the light quantity received by the exposure receiving tube 6 is reduced, and the reduced light quantity is approximately proportional to the thickness of the exposed layer. When the mirror surface dew layer appears, the temperature of the mirror surface 7 is controlled so that the mirror surface dew layer is in a stable equilibrium state, and the temperature value at this time is the dew point temperature.
Example two
The application method of the cold mirror dew point meter with the automatic compensation function in the first embodiment comprises the following steps:
step 1, obtaining a typical value U0 of an output voltage value of the dew-point receiver tube 6 of the cold mirror dew-point meter through experiments, wherein the typical value U0 of the output voltage value of the dew-point receiver tube 6 is an actual measurement experience value depending on the instrument, and the sensitivity and linearity of the dew-point receiver tube 6 are good near the typical value U0 in a measuring range of the dew-point meter aiming at the maximum variation range of the dew-point thickness, and the response performance is close to the best. After the typical value U0 for each dew point meter is determined, it can be used effectively throughout the year.
Step 2, after starting up, the mirror 7 is purged by a period of gas to enable the test cavity and the mirror 7 to be kept dry, then the singlechip 1 adjusts the output voltage of the digital-to-analog converter 14, controls the voltage control current source 15 to output current I, and adjusts the luminous intensity of the compensation luminous tube 16 and the exposure luminous tube 5 through the output current I, so as to adjust the voltage value U output by the exposure receiving tube 6 and the voltage value V output by the compensation receiving tube 17, so that the voltage value U output by the exposure receiving tube 6 is equal to a typical value U0, and the voltage value V output by the compensation receiving tube 17 is recorded to be V0.
Step 3, when the dew point is measured, the voltage value V output by the compensation receiving tube 17 is monitored at any time, when the voltage value V is equal to V-V0-DV, DV is an empirical threshold value, which indicates that the change of the voltage value V output by the compensation receiving tube 17 exceeds the threshold value DV, and then the singlechip 1 adjusts the output current I to restore the voltage value V output by the compensation receiving tube 17 to V0.
And 4, acquiring a new voltage value U of the detection dew receiving tube 6 by the singlechip 1 through the multipath analog-to-digital converter 4. Since the compensation light emitting tube 16 and the exposure light emitting tube 5 are connected in series, the driving current is I, and the change of the light emitting intensity of the two is increased and decreased in the same direction, so that the voltage value U output by the exposure receiving tube 6 is also increased and decreased in the same direction as the voltage value output by the compensation receiving tube 17, and since the voltage value V of the compensation receiving tube 17 is restored to V0, if the mirror surface 7 is kept in a dry state, the output voltage of the exposure receiving tube 6 is restored to be near the typical value U0, and since the response characteristic of the exposure receiving tube 6 is near the optimal state near the typical value, when the mirror surface is condensed, the error introduced by the temperature change of the test cavity is minimal. Therefore, after the invention is adopted, the temperature stability of the photoelectric detection system of the cold mirror dew point meter is enhanced, the photoelectric detection system keeps working near the optimal response area, and the influence of nonlinearity of response characteristics is reduced, thereby improving the measurement precision and reducing the fluctuation of the measured value of the dew point meter.
In the embodiments of the present invention, technical features that are not described in detail are all existing technologies or conventional technical means, and are not described herein.
Finally, it should be noted that: the above examples are only specific embodiments of the present invention, and are not intended to limit the scope of the present invention. Those skilled in the art will appreciate that: any person skilled in the art may modify or easily conceive of changes to the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features within the technical scope of the present disclosure; such modifications, changes or substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention, and are intended to be included in the scope of the present invention.
Claims (10)
1. A chilled-mirror dew point meter with automatic compensation function, comprising: the single chip microcomputer, multichannel analog-to-digital converter, digital-to-analog converter, voltage control current source and test cavity, the upper portion and the lower part of test cavity set up photoelectric detection unit base member and mirror surface and refrigeration unit base member respectively, mirror surface and refrigeration unit base member include the mirror surface, photoelectric detection unit base member includes: the single chip microcomputer is electrically connected with the digital-to-analog converter, the voltage control current source, the compensation luminotron and the exposure luminotron in sequence, the exposure luminotron and the compensation receiving tube are electrically connected with the multipath analog-to-digital converter respectively, and the multipath analog-to-digital converter is electrically connected with the single chip microcomputer.
2. The chilled-mirror dew point meter with an automatic compensation function according to claim 1, wherein the compensation light emitting tube and the compensation receiving tube are horizontally and fixedly arranged at the upper part of the photoelectric detection unit base body in parallel and are connected through a closed channel, and the exposure light emitting tube and the exposure receiving tube are respectively and fixedly arranged at the lower part of the photoelectric detection unit base body.
3. The chilled mirror dew point meter with an automatic compensation function according to claim 2, wherein the mirror surface and the refrigerating unit base body further comprise a platinum resistance thermometer and a mirror surface refrigerating component, the mirror surface is fixedly installed at an opening right above the mirror surface and the refrigerating unit base body, the platinum resistance thermometer is fixedly installed on the lower surface of the mirror surface in a fitting mode, and the mirror surface refrigerating component is fixedly arranged below the platinum resistance thermometer.
4. The chilled mirror dew point meter with automatic compensation function according to claim 3, wherein the platinum resistance thermometer is electrically connected with a mirror surface temperature detection circuit, the mirror surface refrigerating component is electrically connected with a mirror surface refrigerating driving control circuit, the mirror surface temperature detection circuit is electrically connected with a multi-channel analog-to-digital converter, and the mirror surface refrigerating driving control circuit is electrically connected with a singlechip.
5. A chilled mirror dew point meter with automatic compensation function according to claim 3, wherein the specular refrigeration component comprises a semiconductor refrigerator and an auxiliary heat dissipation system.
6. The chilled mirror dew point meter with automatic compensation function according to claim 1, wherein an incident window for light emitted from the light emitting tube to enter and an exit window for reflected light to exit are provided at a lower portion of the base body of the photodetection unit, and central extension lines of the incident window and the exit window are aligned with a center of the mirror surface.
7. The chilled mirror dew point meter with automatic compensation function according to claim 1, wherein the photoelectric detection unit substrate is monolithic copper, monolithic aluminum alloy, or monolithic polytetrafluoroethylene.
8. The method for using a cold mirror dew point meter with automatic compensation function according to claim 1, comprising the following steps:
the singlechip adjusts the output voltage of the digital-to-analog converter, controls the output current I of the voltage control current source through the output voltage, adjusts the luminous intensity of the compensation luminous tube and the detection luminous tube through the output current I, adjusts the voltage value U output by the detection receiving tube and the voltage value V output by the compensation receiving tube through the luminous intensity adjustment of the compensation luminous tube and the detection luminous tube, so that the voltage value U output by the detection receiving tube is equal to a typical value U0, and records the voltage value V output by the compensation receiving tube as V0;
the method comprises the steps of starting to measure the dew point of gas, monitoring the voltage value V output by a compensation receiving tube at any time, wherein DV is an empirical threshold value, adjusting the output voltage of a digital-to-analog converter by a singlechip when I is V-V0I > DV, controlling the output current I of a current source by adjusting the voltage through the output voltage of the digital-to-analog converter, and enabling the voltage value V output by the compensation receiving tube to be recovered to V0 through adjusting the output current I;
the single chip microcomputer collects a new voltage value U of the dew-detecting receiving tube through the multipath analog-digital converter, the voltage value U output by the dew-detecting receiving tube and the voltage value output by the compensating receiving tube increase and decrease in the same direction, because the voltage value V of the compensating receiving tube is recovered to V0, if the mirror surface is kept in a dry state, the output voltage of the dew-detecting receiving tube is recovered to be near a typical value U0, the response characteristic of the dew-detecting tube is near an optimal state near the typical value U0, when the mirror surface is condensed, the error caused by the temperature change of a test cavity is minimum, the temperature stability of a photoelectric detection system of the cold mirror dew-point meter is enhanced, and the photoelectric detection system is kept to work near an optimal response area.
9. The method of using a chilled-mirror dew point meter with automatic compensation according to claim 8, wherein the typical value U0 of the output voltage value of the dew point receiving tube of the chilled-mirror dew point meter is obtained through experiments, and the typical value U0 of the output voltage value of the dew point receiving tube is an actual measurement experience value depending on the instrument.
10. The method of claim 9, wherein the cold mirror dew point meter is turned on or reset by purging the mirror with gas to keep the test cavity and the mirror dry.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311572595.3A CN117420175A (en) | 2023-11-23 | 2023-11-23 | Cold mirror dew point meter with automatic compensation function and use method thereof |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311572595.3A CN117420175A (en) | 2023-11-23 | 2023-11-23 | Cold mirror dew point meter with automatic compensation function and use method thereof |
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| Publication Number | Publication Date |
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| CN117420175A true CN117420175A (en) | 2024-01-19 |
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| CN202311572595.3A Pending CN117420175A (en) | 2023-11-23 | 2023-11-23 | Cold mirror dew point meter with automatic compensation function and use method thereof |
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| Country | Link |
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| CN (1) | CN117420175A (en) |
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- 2023-11-23 CN CN202311572595.3A patent/CN117420175A/en active Pending
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