Fiber bragg grating dry and wet bulb temperature and humidity measuring device

Abstract

The utility model discloses a fiber bragg grating dry and wet bulb temperature and humidity measuring device, and belongs to the technical field of temperature and humidity measurement. The device comprises an explosion-proof box, an optical fiber box, an evaporation reagent tank, absorbent gauze, an FBG optical fiber dry bulb grating and an FBG optical fiber wet bulb grating, the temperature of a dry bulb and the temperature of a wet bulb are calculated by measuring the reflection wavelength change of the gratings through an optical fiber demodulator, and therefore real-time online measurement of the environment temperature and humidity is achieved. The device adopts a dry and wet bulb grating combination mode, a humidity-sensitive material is not needed, irregular fluctuation of grating spacing and central wavelength caused by stress and temperature changes is avoided, and the accuracy and stability of measurement are ensured. The device has the advantages of electromagnetic interference resistance, short response time, high precision, small error and the like, is particularly suitable for temperature and humidity measurement in flammable and explosive environments, and provides a reliable environment monitoring means for the fields of industry, agriculture, meteorology, aerospace and the like.

Description

Technical Field

[0001] The utility model relates to the technical field of temperature and humidity measurement, and more specifically, to a fiber Bragg grating dry and wet bulb temperature and humidity measurement device. Background Art

[0002] In many fields such as industrial and agricultural production, meteorology, medicine, aerospace, etc., the accurate measurement of environmental temperature and humidity is crucial for ensuring production and storage safety. Especially in the storage environment involving flammable and explosive substances (such as explosives), the monitoring of temperature and humidity not only affects the preservation quality of items but also directly relates to safety. However, there are still many deficiencies in the actual application of traditional environmental temperature and humidity measurement methods. Among them, the dry and wet bulb thermometer is widely used due to its relatively simple principle and low cost. The dry and wet bulb thermometer is based on the principle of temperature change brought by the evaporation of water vapor in the air, and calculates the relative humidity of the air by measuring the temperature difference between the dry bulb and the wet bulb. However, in the actual use process, this method cannot achieve real-time online measurement and must rely on manual reading and calculation. This method is not only inefficient but also may cause large measurement errors due to improper operation. In addition, the dry and wet bulb thermometer is sensitive to environmental wind speed, has limited use scenarios, and is prone to accuracy degradation in harsh environments such as dust and oil stains, resulting in limited application in complex environments.

[0003] In recent years, the development of fiber optic sensing technology has provided a new path for temperature and humidity measurement. In particular, the fiber Bragg grating (FBG) technology has attracted much attention due to its advantages such as anti-electromagnetic interference and high accuracy. Currently, the fiber Bragg grating humidity sensor on the market first writes a 1 cm long fiber Bragg grating (FBG) on a highly germanium-doped photosensitive fiber. The cladding mode of this grating is sensitive to the refractive index of the external environment and works in the reflection mode. Polyimide mixed with plasma water is used as the humidity-sensitive material and coated on the surface of the fiber Bragg grating to form a film. Humidity demodulation and conversion are realized by detecting the wavelength change of the reflected light and using the temperature compensation of the dry bulb grating for the wet bulb grating. The research of this technology has the following drawbacks: 1. The characteristics of the humidity-sensitive material used cannot fully meet the principle of humidity measurement. The changes in temperature and stress on the grating cross-affect the grating spacing and the change of the central wavelength, forming an irregular change, and it is difficult to eliminate the cross-influence law; 2. After long-term use of the humidity-sensitive material used, the moisture absorption and desorption performance of the humidity-sensitive material will decline, and the grating measurement function will fail; 3. For the saturation state of moisture in the environment of the humidity-sensitive material used, the grating spacing reacts sluggishly or overly during the humidity measurement process, and the spectrum of the grating under the spectrometer cannot be accurately described, and the humidity conversion cannot be performed by the method of temperature and pressure compensation. These problems still pose many challenges to the stability and accuracy of the existing fiber Bragg grating humidity sensors in long-term use, restricting their popularization in practical applications. Summary of the Utility Model

[0004] In view of the above problems, the present utility model proposes a fiber Bragg grating dry and wet bulb temperature and humidity measuring device, aiming to solve the problem that traditional dry and wet bulb thermometers cannot achieve on-line measurement, and overcome the limitations of the humidity-sensitive materials in existing fiber Bragg grating humidity sensors. The present utility model realizes the real-time measurement of environmental temperature and humidity through the combination of a dry bulb grating and a wet bulb grating, avoiding the problems of the decline in the moisture absorption performance of the humidity-sensitive material during long-term use and the cross-influence of stress and temperature, and ensuring the accuracy and stability of the measurement.

[0005] To solve the above technical problems, the technical solution of the present utility model is as follows:

[0006] A fiber Bragg grating dry and wet bulb temperature and humidity measuring device includes an explosion-proof box, an optical fiber box is installed on the outer wall of the explosion-proof box, and an FBG optical fiber dry bulb grating and an FBG optical fiber wet bulb grating are installed in the optical fiber box;

[0007] An evaporation reagent tank is arranged inside the explosion-proof box, a degreased gauze is arranged on the FBG optical fiber wet bulb grating, one end of the degreased gauze wraps the FBG optical fiber wet bulb grating, and the other end of the degreased gauze extends into the evaporation reagent tank;

[0008] An optical fiber perforation is opened on the box wall of the explosion-proof box, the FBG optical fiber dry bulb grating and the FBG optical fiber wet bulb grating are connected to an optical fiber demodulator through the optical fiber perforation, and the optical fiber demodulator is configured to determine the dry bulb temperature and the wet bulb temperature by measuring the change in the reflection wavelength of the FBG optical fiber dry bulb grating and the FBG optical fiber wet bulb grating.

[0009] Furthermore, the explosion-proof box includes an explosion-proof box body and two baffles, and the explosion-proof box body is a hollow structure with openings at both ends;

[0010] The two baffles are respectively fixedly installed at the openings at both ends of the explosion-proof box body through a plurality of first fixing screws to close the openings at both ends of the explosion-proof box body.

[0011] Furthermore, the optical fiber box includes a cover plate and a bottom plate, the cover plate and the bottom plate are fixedly connected through a plurality of second fixing screws, and an FBG optical fiber dry bulb grating installation part and an FBG optical fiber wet bulb grating installation part are arranged on the bottom plate;

[0012] The FBG optical fiber dry bulb grating installation part is an installation groove opened on one side of the bottom plate, and the FBG optical fiber dry bulb grating is installed in the installation groove;

[0013] The FBG optical fiber wet bulb grating installation part is a hollowed-out plate arranged on the other side of the bottom plate, and the FBG optical fiber wet bulb grating is arranged on the hollowed-out plate;

[0014] The bottom plate is provided with a first FBG fiber optic dry bulb grating perforation and a first FBG fiber optic wet bulb grating perforation. On the outer wall of the explosion-proof box, a second FBG fiber optic dry bulb grating perforation aligned with the first FBG fiber optic dry bulb grating perforation is provided, and a second FBG fiber optic wet bulb grating perforation aligned with the first FBG fiber optic wet bulb grating perforation is also provided on the outer wall of the explosion-proof box;

[0015] One end of the FBG fiber optic dry bulb grating enters the interior of the explosion-proof box through the first FBG fiber optic dry bulb grating perforation and the second FBG fiber optic dry bulb grating perforation; one end of the FBG fiber optic wet bulb grating enters the interior of the explosion-proof box through the first FBG fiber optic wet bulb grating perforation and the second FBG fiber optic wet bulb grating perforation; one end of the FBG fiber optic dry bulb grating and the FBG fiber optic wet bulb grating that enter the interior of the explosion-proof box are connected to the fiber optic demodulator through the fiber optic perforation.

[0016] Furthermore, several first strip-shaped holes are provided in the part of the cover plate located above the installation groove.

[0017] Furthermore, several second strip-shaped holes are provided in the part of the cover plate located above the hollow plate.

[0018] Furthermore, several through holes communicating with the installation groove are provided through both the front and rear sides of the bottom plate.

[0019] Furthermore, guide rails are installed on the inner side walls of both the left and right sides of the explosion-proof box, and U-shaped sliding grooves adapted to the guide rails are installed on the outer walls of both the left and right sides of the evaporation reagent tank. The evaporation reagent tank is configured to be able to slide inside the explosion-proof box through the cooperation of the guide rails and the U-shaped sliding grooves.

[0020] Furthermore, a first threaded hole is provided on the top wall of the explosion-proof box, and a second threaded hole is provided on the top wall of the evaporation reagent tank. The evaporation reagent tank is positioned at a predetermined position below the top wall of the explosion-proof box by a positioning screw passing through the first threaded hole and the second threaded hole.

[0021] Furthermore, hanging ears are fixedly installed on the side walls of both the left and right sides of the explosion-proof box.

[0022] Compared with the prior art, the beneficial effects of the technical solution of the present utility model are:

[0023] 1. Different from the dry and wet bulb thermometer hygrometer, on the basis of enhancing the safety performance and protection ability inside buildings containing explosive hazards, through the method of online measurement of fiber optic grating dry and wet bulbs, the humidity is calculated by obtaining the dry bulb temperature and the wet bulb temperature, so as to realize passive (without external power supply) temperature and humidity monitoring;

[0024] 2. In the actual calculation process of the present utility model, factors such as the wind speed on the sensor surface and the atmospheric pressure intensity are considered. The surface layer of the fiber grating coating has a fast response speed to surface evaporation, and the Raman reflection wavelength can be analyzed by the fiber optic demodulator in real time. The saturated water vapor pressure at the current temperature and the water vapor pressure of the wet bulb are calculated based on different geographical locations and altitudes at different heights, thereby calculating the relative humidity of the atmosphere;

[0025] 3. The present utility model can avoid the cross influence of temperature and stress on the grating pitch, ensure that the grating is always in a relaxed state during the actual assembly process, reduce the drift amount during grating measurement, and ensure the measurement accuracy from the single linear relationship between grating pitch and temperature;

[0026] 4. The surface of the fiber grating used in the present utility model does not need to be coated with a humidity-sensitive material, completely avoiding the problem of the failure of the humidity-sensitive material. The moisture absorption and desorption process of the humidity-sensitive material takes a long time, and the commonly used humidity-sensitive materials belong to organic substances. Repeated moisture absorption and desorption accelerate aging, making it easy to peel off from the optical fiber, resulting in the failure of the moisture absorption and desorption function. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0028] Figure 1 is a schematic structural diagram of a fiber grating dry and wet bulb temperature and humidity measuring device provided in an embodiment of the present application;

[0029] Figure 2 is Figure 1 a partial enlarged schematic diagram of part A in;

[0030] Figure 3 is a schematic structural diagram of the evaporation reagent tank sliding into the explosion-proof box inside the fiber grating dry and wet bulb temperature and humidity measuring device provided in an embodiment of the present application;

[0031] Figure 4 is an assembly diagram of a fiber grating dry and wet bulb temperature and humidity measuring device provided in an embodiment of the present application;

[0032] Figure 5 is an internal schematic diagram of a fiber grating dry and wet bulb temperature and humidity measuring device provided in an embodiment of the present application;

[0033] Figure 6 is a schematic diagram of the through hole on the fiber optic box of a fiber grating dry and wet bulb temperature and humidity measuring device provided in an embodiment of the present application;

[0034] Figure 7 It is a schematic diagram of the temperature test record of the FBG fiber optic dry bulb grating;

[0035] Figure 8 It is a schematic diagram of the temperature test record of the FBG fiber optic wet bulb grating;

[0036] Description of the markings in the figure:

[0037] 1. Explosion-proof box; 101. First fixing screw; 102. Baffle;

[0038] 2. Fiber optic box; 201. Cover plate; 202. Bottom plate; 203. Second fixing screw; 204. First strip hole; 205. Second strip hole; 206. Through hole;

[0039] 3. FBG fiber optic dry bulb grating;

[0040] 4. FBG fiber optic wet bulb grating;

[0041] 5. Absorbent cotton gauze;

[0042] 6. Hanging ear;

[0043] 7. Evaporation reagent tank;

[0044] 8. Positioning screw;

[0045] 9. Ground wire hole;

[0046] 10. Fiber optic perforation. Detailed implementation manner

[0047] In order to better understand the purpose, structure and function of the present utility model, the technical solutions of the present utility model will be further described in detail below with reference to the accompanying drawings and specific preferred embodiments.

[0048] In the description of the present utility model, it should be understood that the orientation or positional relationship indicated by terms such as "left side", "right side", "upper part", "lower part", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. "First", "second", etc. do not represent the importance of the components, so they cannot be understood as limitations to the present utility model. The specific dimensions adopted in the embodiments are only for illustrative purposes of the technical solutions and do not limit the protection scope of the present utility model. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0049] Unless otherwise clearly specified and defined, terms such as "installation", "setting", "connection", "fixation", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0050] Embodiment 1:

[0051] As Figures 1-6 shown, the present utility model provides a technical solution:

[0052] An optical fiber grating dry and wet bulb temperature and humidity measuring device, including an explosion-proof box 1, an optical fiber box 2 is installed on the outer wall of the explosion-proof box 1, and an FBG optical fiber dry bulb grating 3 and an FBG optical fiber wet bulb grating 4 are installed in the optical fiber box 2;

[0053] An evaporation reagent tank 7 is arranged inside the explosion-proof box 1, a degreased gauze 5 is arranged on the FBG optical fiber wet bulb grating 4, one end of the degreased gauze 5 wraps the FBG optical fiber wet bulb grating 4, and the other end of the degreased gauze 5 extends into the evaporation reagent tank 7;

[0054] An optical fiber through hole 10 is opened on the box wall of the explosion-proof box 1, and the FBG optical fiber dry bulb grating 3 and the FBG optical fiber wet bulb grating 4 are connected to an optical fiber demodulator through the optical fiber through hole 10, and the optical fiber demodulator is configured to determine the dry bulb temperature and the wet bulb temperature by measuring the change in the reflection wavelength of the FBG optical fiber dry bulb grating 3 and the FBG optical fiber wet bulb grating 4.

[0055] This embodiment proposes an optical fiber grating dry and wet bulb temperature and humidity measuring device, which solves the problem that traditional dry and wet bulb temperature and humidity meters cannot achieve online measurement, and overcomes the limitations of the humidity-sensitive materials in existing optical fiber grating humidity sensors; through the combination of the dry bulb grating and the wet bulb grating, the real-time measurement of environmental temperature and humidity is realized, without using humidity-sensitive materials, avoiding the cross-influence of stress and temperature and the uncertainty and failure problems of humidity-sensitive materials. The response time of continuous humidity increase step and humidity decrease step is not much different, its performance is stable in a high humidity environment, and the response characteristics are essentially not affected by the humidity value of the environment where it is located, ensuring the accuracy and stability of the measurement.

[0056] Embodiment 2:

[0057] On the basis of Embodiment 1, referring to Figures 1-6 , the explosion-proof box 1 includes an explosion-proof box body and two baffles 102, and the explosion-proof box body is a hollow structure with openings at both ends;

[0058] The two baffles 102 are respectively fixedly installed at the openings at both ends of the explosion-proof box body through a plurality of first fixing screws 101, and are used to close the openings at both ends of the explosion-proof box body.

[0059] Furthermore, the optical fiber box 2 includes a cover plate 201 and a bottom plate 202. The cover plate 201 and the bottom plate 202 are fixedly connected through a plurality of second fixing screws 203. An FBG optical fiber dry bulb grating installation part and an FBG optical fiber wet bulb grating installation part are arranged on the bottom plate 202;

[0060] The FBG optical fiber dry bulb grating installation part is an installation groove opened on one side of the bottom plate 202, and the FBG optical fiber dry bulb grating 3 is installed in the installation groove;

[0061] The FBG optical fiber wet bulb grating installation part is a hollowed-out plate arranged on the other side of the bottom plate 202, and the FBG optical fiber wet bulb grating 4 is arranged on the hollowed-out plate;

[0062] A first FBG optical fiber dry bulb grating perforation and a first FBG optical fiber wet bulb grating perforation are opened on the bottom plate 202. A second FBG optical fiber dry bulb grating perforation aligned with the first FBG optical fiber dry bulb grating perforation is opened on the outer wall of the explosion-proof box 1. A second FBG optical fiber wet bulb grating perforation aligned with the first FBG optical fiber wet bulb grating perforation is also opened on the outer wall of the explosion-proof box 1;

[0063] One end of the FBG optical fiber dry bulb grating 3 enters the interior of the explosion-proof box 1 through the first FBG optical fiber dry bulb grating perforation and the second FBG optical fiber dry bulb grating perforation; one end of the FBG optical fiber wet bulb grating 4 enters the interior of the explosion-proof box 1 through the first FBG optical fiber wet bulb grating perforation and the second FBG optical fiber wet bulb grating perforation; one end of the FBG optical fiber dry bulb grating 3 and the FBG optical fiber wet bulb grating 4 that enter the interior of the explosion-proof box 1 are connected to an optical fiber demodulator through the optical fiber perforation 10.

[0064] Furthermore, a plurality of first strip-shaped holes 204 are opened in the part of the cover plate 201 located above the installation groove.

[0065] Furthermore, a plurality of second strip-shaped holes 205 are opened in the part of the cover plate 201 located above the hollowed-out plate.

[0066] Furthermore, a plurality of through holes 206 communicating with the installation groove are penetrated through both the front and rear sides of the bottom plate 202.

[0067] Furthermore, guide rails are installed on the inner walls on both sides of the explosion-proof box 1, and U-shaped slide grooves adapted to the guide rails are installed on the outer walls on both sides of the evaporative reagent tank 7. The evaporative reagent tank 7 is configured to be able to slide inside the explosion-proof box 1 through the cooperation of the guide rails and the U-shaped slide grooves.

[0068] Furthermore, a first threaded hole is formed on the top wall of the explosion-proof box 1 , and a second threaded hole is formed on the top wall of the evaporative reagent tank 7 . The evaporative reagent tank 7 is positioned at a predetermined position below the top wall of the explosion-proof box 1 by a positioning screw 8 passing through the first threaded hole and the second threaded hole.

[0069] Furthermore, hanging ears 6 are fixedly mounted on the side walls on the left and right sides of the explosion-proof box 1 .

[0070] Furthermore, the fiber grating dry-bulb and wet-bulb temperature and humidity measuring device is mainly used to measure the temperature and humidity in a daily ventilated environment on a pure horizontal liquid surface. The temperature involved is above 0°C, and the wet-bulb surface is not frozen, where the humidity is the percentage of the water vapor pressure in the air to the saturated water vapor pressure at the same temperature. According to the evaporative dry-bulb and wet-bulb temperature and humidity measurement principle, the size of the dry-bulb and wet-bulb grating temperature difference is mainly related to the air humidity at the time. The lower the ambient humidity, the faster the water on the wet-bulb grating surface evaporates, the more the wet-bulb grating temperature drops, and the greater the dry-bulb and wet-bulb grating temperature difference; when the ambient humidity is high, the wet-bulb grating water evaporates slowly, the wet-bulb grating temperature drops less, and the dry-bulb and wet-bulb grating temperature difference is small.

[0071] Furthermore, the FBG fiber dry-ball grating 3 and the FBG fiber wet-ball grating 4 in the fiber grating dry-bulb and wet-bulb temperature and humidity measuring device are bend-resistant FBG fiber gratings, the wavelength range of the bend-resistant FBG fiber gratings is 1529nm-1569nm, and the change of wavelength per unit temperature is 10pm / ℃. A double grating is used to encapsulate them on the grating ABS base in a relaxed and stress-free state, and the yellow plastic hoses are fixed with glue at both ends to prevent the grating area from being disturbed, thereby realizing single parameter sensing of temperature.

[0072] Furthermore, in order to achieve the measurement and test of relative humidity, the fiber optic wet-bulb grating is covered with double-layer absorbent gauze. The ester material of the wet-bulb grating cross section has good moisture sensitivity, which can better protect the longitudinal stretching of the grating, while reducing the temperature gradient change in the cross-sectional direction, and the evaporation and heat absorption of the water on the grating surface reaches a normal level. At different temperatures: 0℃, 10℃, 20℃, 30℃, 40℃, 50℃, 40℃, 30℃, 20℃, 10℃, the temperature measurement capability of the grating under different temperature cycles and the actual simulated linear R square meet the requirements, please refer to Figures 7-8 , Figure 7 and Figure 8Temperature test records for the dry bulb grating and the wet bulb grating respectively.

[0073] Furthermore, a ground wire hole 9 is provided at the top of the explosion-proof box 1. The fiber Bragg grating dry and wet bulb temperature and humidity measuring device provides explosion-proof connection and space reservation for fiber laying at the places such as the inlet and outlet of the optical cable line and the component connection inside the building containing explosive hazards. Cooperating with the grounding on the galvanized steel pipe, it can achieve the effects of lightning protection and explosion protection.

[0074] Furthermore, a water filling port and a water absorption port are provided at the top of the evaporation reagent tank 7. The water absorption port is used for the degreased gauze 5 to extend into and absorb water, and the water filling port is provided with an openable and closable sealing cover.

[0075] On the basis of Embodiment 1, in this embodiment, by adding the structural design of the explosion-proof box, such as the cooperation of the baffle, the guide rail and the chute, the evaporation reagent tank can move flexibly. In addition, the design of the fiber optic box enables the FBG fiber dry bulb grating and the wet bulb grating to be firmly installed, and through the arrangement of the strip holes and the through holes, the temperature measurement accuracy of the grating is ensured. The design of the explosion-proof box further improves the use safety of the device in a complex environment, and at the same time, through the reasonably arranged through holes, the stable connection between the optical fiber and the demodulator is ensured, and the overall reliability and durability of the device are improved.

[0076] Embodiment 3:

[0077] The present utility model provides a technical solution:

[0078] A fiber Bragg grating dry and wet bulb temperature and humidity measurement method, which uses the aforementioned fiber Bragg grating dry and wet bulb temperature and humidity measurement device, and the measurement steps are as follows:

[0079] Use the FBG fiber dry bulb grating 3 to measure the current ambient temperature T d , use the FBG fiber wet bulb grating 4 to measure the wet bulb temperature T w , the wet bulb temperature T w represents the temperature measured when the water on the surface of the FBG fiber wet bulb grating 4 evaporates and cools down due to heat absorption; in an environment with a certain humidity, there is a flowing air current on the surface of the wet bulb grating, so that the evaporation of water absorbs heat and makes T w lower than the ambient temperature T d ;

[0080] Calculate the saturated water vapor pressure E at the current ambient temperature T d according to the modified Tetens formula; calculate the saturated water vapor pressure E 饱和干 at the current wet bulb temperature T according to the formula; w Calculate the saturated water vapor pressure E 饱和湿 at the current wet bulb temperature T

[0081] Due to the small surface area of the bending-resistant FBG fiber wet-bulb grating, the temperature on the surface of the wet-bulb grating is related to the ventilation speed, air pressure, etc. near the wet-bulb grating. According to the calculation formula E = E 饱和湿 - A×P×(T d - T W ), the actual water vapor pressure in the air is calculated. Among them, E represents the actual water vapor pressure in the air, and E 饱和湿 is the saturated water vapor pressure at the wet-bulb temperature T w , A is the wet and dry hygrometric coefficient, P is the atmospheric pressure, T d is the ambient temperature, and T w is the wet-bulb temperature; the wet and dry hygrometric coefficient A is a variable that changes with the wind speed and air pressure around the wet-bulb grating;

[0082] When the wet-bulb grating is not frozen, the corresponding relationship of the wet and dry psychrometer hygrometric coefficient A of the object surface under different ventilation environments is as follows:

[0083] Wet-bulb model A×10-3(℃-1) Wet bulb not frozen Aspirated psychrometer (ventilation speed 2.5 m / s) 0.665 Spherical psychrometer (natural ventilation) 0.857 Cylindrical psychrometer (natural ventilation) 0.815 Spherical psychrometer (natural ventilation speed 0.8 m / s) 0.7947 Cylindrical psychrometer (ventilation speed 3.5 m / s) 0.667

[0084] According to the formula calculate the relative humidity, where RH represents the relative humidity, expressed as a percentage; E is the actual water vapor pressure in the air, and E 饱和干 is the saturated water vapor pressure at the ambient temperature T d .

[0085] Since the relative humidity RH is the percentage of the water vapor pressure E in the air to the saturated water vapor pressure E 饱和干 at the same temperature, therefore, under ventilation conditions, the relative humidity cannot simply substitute the above calculation results into the formula to represent, and detailed experiments and calculations need to be carried out on the actual water vapor pressure E in the air.

[0086] The water vapor pressure E in the air is also called the water vapor evaporation pressure in the air, which is the partial pressure (partial pressure) generated by the water vapor in the air. Considering that in actual applications, the sensor is in the same area, that is, the atmospheric pressure P remains unchanged and has no impact on the actual measurement experiment. In the actual calculation process, the atmospheric pressure P is taken as the standard atmospheric pressure of 101325 Pa. The value of A changes greatly with the wind speed. As the wind speed increases, A decreases rapidly. There are differences in the values of A for different types of thermometers, but the differences are very small when the wind speed is high; when the wind speed exceeds 3 m / s, the hygrometric coefficient A value tends to be constant.

[0087] In the actual experiment, a stable ventilation of more than 3 m / s is applied to the surface of the wet-bulb grating. Therefore, the value of the hygrometric coefficient A is 0.000665. Through the calculation of the formula E = E 饱和湿 - A×P×(T d - T W ), the following experimental records of different hygrometric coefficients are obtained in daily experiments:

[0088]

[0089] From the analysis of the above test records, when the standard atmospheric pressure P remains unchanged, the smaller the moisture absorption coefficient A, the closer the tested relative humidity result is to the standard value, and the overall temperature and humidity response characteristics are close to the temperature and humidity of the actual environment.

[0090] The device described in this patent uses degreased gauze as the water absorbing material of the wet bulb. The gauze is double-layer degreased gauze, one end of which is inserted into the evaporation reagent tank for absorbing water, and the other end is wrapped in the FBG fiber wet bulb grating for evaporation on the surface of the wet bulb grating. Distilled water is used in the reagent tank, and the wet and dry thermometer is numbered 1.

[0091] Ordinary cotton cloth is used as water-absorbing material, and distilled water is used in the evaporation reagent tank, which is numbered 2; double-layer degreased gauze is used as the water-absorbing material of the wet bulb, and ordinary tap water is used in the evaporation reagent tank, which is numbered 3; ordinary cotton cloth is used as the water-absorbing material, and tap water is used in the evaporation reagent tank, which is numbered 4. Measure the temperature and relative humidity at 20℃, 40%RH, 20℃, 60%RH. The measurement data are as follows:

[0092]

[0093] From the analysis of the above test records, the double-layer absorbent gauze is used as a water-absorbing and evaporating material in combination with distilled water, and its overall response characteristics to the temperature and humidity test are close to the temperature and humidity of the actual environment.

[0094] This embodiment provides a temperature and humidity measurement method based on the aforementioned device, and describes in detail the steps of measuring ambient temperature and humidity using FBG fiber dry-ball grating and wet-ball grating. The saturated water vapor pressure is calculated by the modified Tayden formula, and the relative humidity value is finally obtained by combining the calculation of the actual water vapor pressure in the air. In this method, the humidity measurement accuracy is improved by adjusting the hygrometric coefficient A to adapt to different ventilation conditions. This method not only simplifies the humidity measurement process in complex environments, but also verifies the measurement accuracy and reliability of the device through a series of experiments, ensuring the measurement consistency under different environmental conditions.

[0095] Obviously, the above embodiments of the utility model are only examples for clearly explaining the utility model, and are not intended to limit the implementation methods of the utility model. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made on the basis of the above description. It is not necessary and impossible to list all the implementation methods here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the utility model should be included in the protection scope of the claims of the utility model.

Claims

1. A fiber Bragg grating dry-bulb and wet-bulb temperature and humidity measuring device, characterized in that: It comprises an explosion-proof box (1), an optical fiber box (2) is installed on the outer wall of the explosion-proof box (1), and an FBG optical fiber dry ball grating (3) and an FBG optical fiber wet ball grating (4) are installed in the optical fiber box (2); An evaporative reagent tank (7) is arranged inside the explosion-proof box (1), and an absorbent gauze (5) is arranged on the FBG optical fiber wet-ball grating (4), one end of the absorbent gauze (5) wraps the FBG optical fiber wet-ball grating (4), and the other end of the absorbent gauze (5) extends into the evaporative reagent tank (7); The explosion-proof box (1) has an optical fiber perforation (10) formed on its wall. The FBG optical fiber dry-ball grating (3) and the FBG optical fiber wet-ball grating (4) are connected to an optical fiber demodulator via the optical fiber perforation (10). The optical fiber demodulator is configured to determine the dry-bulb temperature and the wet-bulb temperature by measuring the change in the reflection wavelength of the FBG optical fiber dry-bulb grating (3) and the FBG optical fiber wet-bulb grating (4).

2. The fiber Bragg grating dry-bulb and wet-bulb temperature and humidity measuring device according to claim 1, characterized in that: The explosion-proof box (1) comprises an explosion-proof box body and two baffles (102); the explosion-proof box body is a hollow structure with openings at both ends; The two baffles (102) are respectively fixedly mounted at the openings at both ends of the explosion-proof box body through a plurality of first fixing screws (101) and are used to close the openings at both ends of the explosion-proof box body.

3. The fiber Bragg grating dry-bulb and wet-bulb temperature and humidity measuring device according to claim 1, characterized in that: The optical fiber box (2) comprises a cover plate (201) and a bottom plate (202), wherein the cover plate (201) and the bottom plate (202) are fixedly connected via a plurality of second fixing screws (203), and an FBG optical fiber dry ball grating mounting portion and an FBG optical fiber wet ball grating mounting portion are arranged on the bottom plate (202); The FBG fiber dry ball grating installation portion is a mounting groove provided on one side of the base plate (202), and the FBG fiber dry ball grating (3) is installed in the mounting groove; The FBG fiber wet-ball grating mounting portion is a hollow plate arranged on the other side of the base plate (202), and the FBG fiber wet-ball grating (4) is arranged on the hollow plate; The bottom plate (202) is provided with a first FBG fiber dry ball grating perforation and a first FBG fiber wet ball grating perforation, the outer wall of the explosion-proof box (1) is provided with a second FBG fiber dry ball grating perforation aligned with the first FBG fiber dry ball grating perforation, and the outer wall of the explosion-proof box (1) is also provided with a second FBG fiber wet ball grating perforation aligned with the first FBG fiber wet ball grating perforation; One end of the FBG fiber dry ball grating (3) enters the interior of the explosion-proof box (1) through the first FBG fiber dry ball grating perforation and the second FBG fiber dry ball grating perforation; one end of the FBG fiber wet ball grating (4) enters the interior of the explosion-proof box (1) through the first FBG fiber wet ball grating perforation and the second FBG fiber wet ball grating perforation; the ends of the FBG fiber dry ball grating (3) and the FBG fiber wet ball grating (4) entering the interior of the explosion-proof box (1) are connected to the optical fiber demodulator through the optical fiber perforation (10).

4. The fiber Bragg grating dry-bulb and wet-bulb temperature and humidity measuring device according to claim 3, characterized in that: A portion of the cover plate (201) located above the mounting groove is provided with a plurality of first strip-shaped holes (204).

5. The fiber Bragg grating dry-bulb and wet-bulb temperature and humidity measuring device according to claim 3, characterized in that: A portion of the cover plate (201) located above the hollow plate is provided with a plurality of second strip-shaped holes (205).

6. The fiber Bragg grating dry-bulb and wet-bulb temperature and humidity measuring device according to claim 3, characterized in that: A plurality of through holes (206) communicating with the mounting grooves are formed through both the front and rear sides of the bottom plate (202).

7. The fiber Bragg grating dry-bulb and wet-bulb temperature and humidity measuring device according to claim 1, characterized in that: Guide rails are installed on the inner side walls on both sides of the explosion-proof box (1), and U-shaped slide grooves adapted to the guide rails are installed on the outer walls on both sides of the evaporative reagent tank (7). The evaporative reagent tank (7) is configured to be able to slide inside the explosion-proof box (1) through the cooperation of the guide rails and the U-shaped slide grooves.

8. The fiber Bragg grating dry-bulb and wet-bulb temperature and humidity measuring device according to claim 7, characterized in that: A first threaded hole is formed on the top wall of the explosion-proof box (1), and a second threaded hole is formed on the top wall of the evaporative reagent tank (7). The evaporative reagent tank (7) is positioned at a predetermined position below the top wall of the explosion-proof box (1) via a positioning screw (8) passing through the first threaded hole and the second threaded hole.

9. The fiber Bragg grating dry-bulb and wet-bulb temperature and humidity measuring device according to claim 1, characterized in that: Hanging ears (6) are fixedly mounted on the side walls on both the left and right sides of the explosion-proof box (1).

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