CN212111124U - NDIR (non-dispersive infrared radiation) detection water vapor concentration sensor and absolute humidity detector - Google Patents
NDIR (non-dispersive infrared radiation) detection water vapor concentration sensor and absolute humidity detector Download PDFInfo
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- CN212111124U CN212111124U CN202020545292.8U CN202020545292U CN212111124U CN 212111124 U CN212111124 U CN 212111124U CN 202020545292 U CN202020545292 U CN 202020545292U CN 212111124 U CN212111124 U CN 212111124U
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Abstract
The utility model relates to a NDIR detects vapor concentration sensor, include: an infrared light source for emitting infrared light; the infrared detector is used for detecting the intensity of infrared light; a narrowband filter disposed between the infrared light source and the infrared detector, the narrowband filter being disposed to cover a plurality of absorption lines of water vapor; the water vapor concentration sensor is arranged in such a way that after the infrared light source emits infrared light, part of the infrared light is absorbed by water vapor molecules between the infrared light source and the narrow-band filter, the infrared detector detects the intensity of the rest infrared light, and the narrow-band filter is used for cutting off the infrared light with non-transmission wavelength to detect the water vapor concentration. The utility model provides a NDIR detects vapor concentration sensor adopts NDIR infrared technology to detect a plurality of absorption peaks of vapor simultaneously, the vapor content of detectable lower concentration, and has promoted the detection precision of vapor by a wide margin.
Description
Technical Field
The utility model relates to a humidity detects technical field, relates to a NDIR detects vapor concentration sensor and absolute moisture detector.
Background
Humidity generally refers to the amount of water vapor in the air, which is used to reflect the dry and wet composition of the atmosphere. With the development of modernization, the environment humidity needs to be accurately measured and controlled in the fields of industrial and agricultural production, weather, environmental protection, national defense, scientific research, aerospace and the like. Humidity measurement requires the use of a humidity sensor, which is a sensor that senses the level of water vapor in the gas and converts it into a usable output signal.
At present, the mainstream humidity sensor mainly comprises a humidity-sensitive resistance type and a humidity-sensitive capacitance type, when water vapor in air is adsorbed on a humidity-sensitive material, the resistance or the capacitance of the humidity-sensitive resistance or the humidity-sensitive capacitance changes, and the humidity-sensitive resistance or the humidity-sensitive capacitance is converted into a voltage signal, so that the humidity in the environment can be measured. In addition to the resistive and capacitive humidity sensors, there are electrolyte ion type humidity sensors, weight type humidity sensors (in which the oscillation frequency is changed by the change in the weight of the humidity sensing film), light intensity type humidity sensors, surface acoustic wave humidity sensors, and the like.
The existing humidity sensor of the humidity sensitive element has lower precision, generally within +/-3% RH to +/-5% RH, and can not meet the requirement of measuring the water vapor content of high-precision ppm level. The humidity sensitive element has a large temperature drift coefficient, and the humidity measurement linearity and accuracy are poor under the condition of high or low temperature. Because the humidity sensitive element is in contact measurement in the using process and needs to be exposed in an environment to be measured for a long time, the humidity sensitive element is easy to be polluted, so that the measurement precision is reduced, the long-term stability is poor, and the service life is short.
Patent CN102680412A, "providing a method for detecting trace water vapor concentration by using photoacoustic spectroscopy", utilizes infrared light to irradiate water vapor, the water vapor absorbs the infrared light to generate temperature variation to cause pressure fluctuation to generate sound wave, and utilizes a microphone to detect the sound wave to detect the water vapor concentration.
Patent CN106338490A, which provides a sensor device for infrared detection of water concentration, the device includes a signal generator, a first and a second optical fibers, an infrared light generating device, a first and a second calibration filter and collimating mirror, a water vapor absorption chamber, an infrared photoelectric signal converter, a signal processor, etc. the patent uses a single absorption peak of water vapor to detect water vapor concentration, and the absorption efficiency is low.
SUMMERY OF THE UTILITY MODEL
The main object of the present invention is to provide a high-precision NDIR sensor for detecting water vapor concentration.
In order to achieve the above object, the present invention adopts the following technical solution for NDIR detection of the water vapor concentration sensor:
the water vapor concentration sensor includes:
an infrared light source for emitting infrared light;
the infrared detector is used for detecting the intensity of infrared light;
the narrow-band filter is arranged between the infrared light source and the infrared detector and is arranged to cover the absorption line of the water vapor;
the water vapor concentration sensor is arranged in such a way that after the infrared light source emits infrared light, part of the infrared light is absorbed by water vapor molecules between the infrared light source and the narrow-band filter, the infrared detector detects the intensity of the rest infrared light, and the narrow-band filter is used for cutting off the infrared light with non-transmission wavelength to detect the water vapor concentration.
Preferably, the narrow-band filter is configured to allow infrared light with a wavelength range of 2.9 to 3.1 micrometers to pass through.
Preferably, the center wavelength of the narrow-band filter is 3 microns, and the half-peak width is 200 nm.
Preferably, the infrared detector is set to cover the infrared detection wavelength of 2.7-3.4 microns.
Preferably, the infrared light source is configured to emit infrared light having a peak intensity of 3 microns.
The utility model provides an absolute moisture detector, include NDIR detect vapor concentration sensor.
The NDIR sensor for detecting the water vapor concentration adopts the NDIR infrared technology to simultaneously detect a plurality of absorption peaks of water vapor, so that the detection precision of the water vapor is greatly improved, and the detection precision can be improved from hundreds of ppm to dozens of ppm; the non-contact optical physical principle is adopted to detect the concentration of the water vapor, the temperature performance of the sensor is stable, the influence of the temperature is small, the non-contact anti-pollution capacity is strong, and the service life can reach more than 10 years.
Drawings
Fig. 1 is a schematic structural diagram of a NDIR detection water vapor concentration sensor according to the present invention.
Fig. 2 is an absorption spectrum of an infrared light source.
Fig. 3 is a transmittance spectrum of the narrowband filter.
Fig. 4 is an infrared absorption spectrum of water vapor.
Fig. 5 shows the peak absorption peak, the peak transmittance, and the peak radiation intensity, which are superposed.
Detailed Description
In order to clearly understand the technical contents of the present invention, the following embodiments are specifically illustrated in detail.
As shown in fig. 1, in order to provide an embodiment of the NDIR sensor for detecting water vapor concentration according to the present invention, the water vapor concentration sensor includes: an infrared light source for emitting infrared light; the infrared detector is used for detecting the intensity of infrared light; the narrow-band filter is arranged between the infrared light source and the infrared detector, covers a plurality of absorption lines of water vapor and has a certain bandwidth width.
The water vapor concentration sensor is arranged in such a way that after the infrared light source emits infrared light, part of the infrared light is absorbed by water vapor molecules between the infrared light source and the narrow-band filter, the infrared detector detects the intensity of the rest infrared light, and the narrow-band filter is used for cutting off the infrared light with non-transmission wavelength to detect the water vapor concentration.
The narrow-band filter is set to allow infrared light with the wavelength range of 2.9-3.1 micrometers to penetrate through. Preferably, the center wavelength of the narrow-band filter is 3 microns, and the half-peak width is 200 nm.
The infrared detector is set to cover the infrared detection wavelength of 2.7-3.4 microns. Preferably, the infrared light source is arranged to emit infrared light with a peak light intensity of 3 microns. The infrared detector can be selected from pyroelectric infrared detector, thermopile infrared detector or photodiode infrared detector.
As shown in FIG. 4, the infrared absorption peak of the water vapor is discontinuous and is between 2.7 and 3.4 microns, and different wavelengths correspond to different absorption intensities, and the absorption is strongest at the position of 3 microns.
As shown in fig. 2, the operating temperature of the infrared light source can be adjusted by adjusting the current or voltage of the infrared light source to be about 1000K, so that infrared light with a peak light intensity of about 3 microns can be emitted, and the light intensity distribution of the infrared light emitted by the infrared light source meets the blackbody radiation law.
As shown in fig. 3, the narrowband filter is designed by adjusting the film structure to have a center wavelength of 3 μm, a half-peak width of about 200nm, and a transmittance of 80% or more. The filter only allows infrared light with the wavelength range of 2.9-3.1 micrometers to penetrate through, and infrared light with other wavelengths is cut off so that the infrared light cannot reach the infrared detector. The distance between the infrared light source and the infrared detector can be properly increased, and the water vapor detection precision can reach the ppm level.
As shown in fig. 5, when the wavelength corresponding to the infrared spectrum peak emitted by the infrared light source, the wavelength corresponding to the central transmittance of the infrared narrowband filter, and the wavelength corresponding to the strongest infrared absorption peak of the water vapor coincide, the water vapor absorption effect is the best.
From this, when using the utility model discloses a when detecting vapor concentration sensor, infrared light source sends the infrared light of spectral range broad and the directive is used for receiving the infrared detector of infrared light, and the wavelength range is inInfrared light of 2.7-3.4 microns is absorbed by water vapor, the absorption intensity and the concentration of the water vapor form an exponential relationship, and the Lambert-beer law is satisfied: i ═ I0e-αCLIn which I0The infrared light intensity is the infrared light intensity emitted by an infrared light source, alpha is the infrared absorption coefficient of the target gas, C is the concentration of water vapor, I is the intensity of the light received by an outer detector, and L is the distance of the infrared light from the light source to the detector; the infrared detector converts the received infrared light signal into an electric signal, and the electric signal can be represented as the concentration of water vapor through fitting.
The utility model provides a NDIR detects vapor concentration sensor can be used for detecting absolute humidity.
The utility model provides a NDIR detects vapor concentration sensor adopts NDIR infrared technology to detect a plurality of absorption peaks of vapor simultaneously, can detect the vapor content of lower concentration, and has promoted the detection precision of vapor by a wide margin, and the detection precision can be promoted to tens ppm from several hundred ppm; the non-contact optical physical principle is adopted to detect the concentration of the water vapor, the temperature performance of the sensor is stable, the influence of the temperature is small, the non-contact anti-pollution capacity is strong, and the service life can reach more than 10 years.
The utility model uses NDIR method to detect the concentration of water vapor, and has simple structure and convenient operation; the method has the advantages of small temperature drift coefficient, strong pollution resistance, long service life and the like; meanwhile, compared with the traditional humidity sensitive element, the method greatly improves the precision of water vapor detection and improves the water vapor detection to a new height.
In this specification, the invention has been described with reference to specific embodiments thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.
Claims (6)
1. A NDIR detection water vapor concentration sensor, said water vapor concentration sensor comprising:
an infrared light source for emitting infrared light;
the infrared detector is used for detecting the intensity of infrared light;
a narrowband filter disposed between the infrared light source and the infrared detector, the narrowband filter being disposed to cover a plurality of absorption lines of water vapor;
the water vapor concentration sensor is arranged in such a way that after the infrared light source emits infrared light, part of the infrared light is absorbed by water vapor molecules between the infrared light source and the narrow-band filter, the infrared detector detects the intensity of the rest infrared light, and the narrow-band filter is used for cutting off the infrared light with non-transmission wavelength to detect the water vapor concentration.
2. The NDIR sensor for detecting water vapor concentration of claim 1, wherein the narrow band filter is configured to allow infrared light having a wavelength in the range of 2.9 to 3.1 microns to pass therethrough.
3. The NDIR detection water vapor concentration sensor of claim 1 or 2, wherein the narrowband filter has a center wavelength of 3 microns and a half-peak width of 200 nm.
4. The NDIR sensor for detecting water vapor concentration of claim 1, in which the infrared detector is configured to cover an infrared detection wavelength of 2.7-3.4 microns.
5. The NDIR sensor for detecting water vapor concentration of claim 1, wherein the infrared light source is configured to emit infrared light having a peak light intensity of 3 microns.
6. An absolute humidity sensor comprising the NDIR sensor of claim 1, wherein the NDIR sensor detects water vapor concentration.
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| CN113155771A (en) * | 2021-03-24 | 2021-07-23 | 华中农业大学 | Split type quick accurate blade water potential survey device |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113155771A (en) * | 2021-03-24 | 2021-07-23 | 华中农业大学 | Split type quick accurate blade water potential survey device |
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