CN113587976B - Wide temperature range air temperature humidity sampling measurement device - Google Patents
Wide temperature range air temperature humidity sampling measurement device Download PDFInfo
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- CN113587976B CN113587976B CN202110642679.4A CN202110642679A CN113587976B CN 113587976 B CN113587976 B CN 113587976B CN 202110642679 A CN202110642679 A CN 202110642679A CN 113587976 B CN113587976 B CN 113587976B
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Abstract
The invention belongs to the technical field of air temperature and humidity measurement, and particularly relates to a wide-temperature-range air temperature and humidity sampling and measuring device. The device comprises an insulation box body, an air sampler and a sampling air measuring assembly which are arranged on the outer side of the insulation box body, and a heating air measuring assembly which is arranged in the insulation box body; the air sampling device comprises an air sampling device, a sampling air measuring assembly and a heating air measuring assembly, wherein the air sampling device, the sampling air measuring assembly and the heating air measuring assembly are sequentially connected through an air pipe to form an integrated air channel, an air heater is arranged between the sampling air measuring assembly and the heating air measuring assembly, and the tail end of the heating air measuring assembly is connected with a fan. The device adopts a constant-humidity reheating method to heat the sampling air to be measured and then measures each parameter, the measuring method is simple and easy to realize, and the integrated high-precision measurement of the air temperature and humidity under the conditions of wide temperature range of minus 30 ℃ to 80 ℃ can be realized.
Description
Technical Field
The invention belongs to the technical field of air temperature and humidity measurement, and particularly relates to a wide-temperature-range air temperature and humidity sampling and measuring device.
Background
The ambient atmosphere in which we are located is a mixture of dry air and water vapor, commonly referred to as humid air. Unlike the conventional ambient temperature concept, the temperature commonly referred to in the drying, heating, air conditioning, cooling tower and other engineering is the dry bulb temperature of the humid air, which can be measured directly. The humidity state parameter of the wet air is generally represented by physical quantities such as wet bulb temperature or relative humidity and absolute humidity (also called as absolute moisture content) of the ambient atmosphere, so that the analysis and calculation of the thermodynamic process of the wet air in the thermodynamic field are convenient. Humidity parameters such as wet bulb temperature, relative humidity and absolute humidity can be used for representing the moisture content in air or the humidity degree of the air, and are very important physical quantities which are difficult to accurately measure in the wet air state parameters.
The method for measuring the humidity of the air generally can directly measure the dry bulb temperature and the wet bulb temperature of the wet air to obtain the relative humidity or absolute humidity parameter of the wet air by adopting a certain calculation method, and also can directly measure and obtain the relative humidity parameter of the wet air by using a measuring instrument, and can calculate and obtain other parameters of the humidity characterization of the wet air according to the existing calculation formula.
The current method for measuring the humidity parameter of the humid air comprises the following steps: 1. the humidity measurement is carried out by utilizing the characteristic that substances such as fibers and hairs stretch along with the change of the air humidity, and the like, and the method has the advantages of simplicity, lower cost and poorer measurement accuracy. 2. The humidity method has the advantages of high precision, and when the air temperature is 20-30 deg.c and the measurement error of the dry and wet ball temperature is not higher than 0.1 deg.c, the dry and wet meter with constant ventilation device may be considered as the second class standard for humidity measurement and the measurement error is not higher than + -2% RH. However, since the saturated vapor pressure of water is an exponential function of temperature, the saturated vapor pressure at low temperature is far lower than the normal temperature corresponding data, so that the dry and wet bulb humidity method for measuring the humidity of the wet air is not applicable any more at the temperature lower than 0 ℃, and the measurement range is generally 5-40 ℃.3. Dew point temperature method. The method is used for indirectly measuring the humidity by measuring the dew point temperature of air, and mainly comprises a cooling device, a junction surface and a temperature sensor. The method has higher measurement precision under the low-temperature and low-humidity conditions, but the device is complex, the cost is higher, and the accurate control of the temperature of the condensation surface is difficult to realize. 4. Humidity sensitive humidity sensor method. Its advantages are quick response, low wet stagnation, wide measuring range, nominal measuring precision of medium and low wet sections being +/-2% RH, and nominal measuring precision of high wet section being +/-4% RH. However, the third party test results show that it is very difficult to achieve this accuracy even in a ventilation state of 20 to 30 ℃, and that the measurement errors in the low temperature section and the high humidity section are more difficult to ensure. In addition, since the humidity sensor needs to be exposed to the environment to be measured for a long time, the humidity sensor is easily polluted to influence the accuracy and stability of the humidity sensor.
In performance testing of refrigeration and air conditioning products, measurement of air temperature and humidity in a wide temperature range is often involved. The dry and wet bulb method is generally adopted to measure the air humidity at normal temperature, and the humidity sensor method is adopted to measure the air humidity at low temperature. Because the humidity sensor method test can not meet the problem of accuracy of air humidity measurement in a low-temperature state, the air humidity parameter test carried out by adopting the humidity sensor method at low temperature is only used as an operation condition parameter and is not used as the calculation of refrigerating and heating capacity.
Along with the continuous development of society, novel products such as various low temperature heat pump units are developed and applied, humidity parameters at low temperature also need to pass through the test, the calculation of basic performance of the products is participated in through the calculation of an air enthalpy difference method, the stability of the existing humidity-sensitive humidity sensor is poor, the precision requirement of low temperature humidity measurement is difficult to meet, the cost of a high-precision dew point temperature sensor and the like is increased by multiple, and the device is complex and difficult to realize the precise measurement and control of the temperature of a dew point. Therefore, a new measuring device is urgently needed to achieve accurate and stable integrated measurement of air humidity in a wide temperature range, particularly low temperature air.
Disclosure of Invention
In order to solve the technical problems, the invention provides a wide-temperature-range air temperature and humidity measurement and calculation method, which has higher measurement precision for the wet air wet bulb temperature below 0 ℃ and is simultaneously suitable for measuring the wet air temperature and humidity in normal temperature and higher temperature ranges.
The invention adopts the following technical scheme: the wide temperature range air temperature and humidity sampling and measuring device comprises an insulation box body, an air sampler and a sampling air measuring assembly which are arranged on the outer side of the insulation box body, and a heating air measuring assembly which is arranged in the insulation box body; the air sampler, the sampling air measuring assembly and the heating air measuring assembly are sequentially connected through the air pipes to form an integrated air channel, an air heater is arranged between the sampling air measuring assembly and the heating air measuring assembly, the tail end of the heating air measuring assembly is connected with a fan, the heating air measuring assembly comprises a second dry bulb thermodetector and an air wet bulb thermodetector which are arranged in the air channel, and the second dry bulb thermodetector is electrically connected with the air heater.
The air heater is a fin type electric heater, and the temperature of the heated air dry bulb is controlled by the feedback adjustment of the measured temperature of the second dry bulb thermometer, so that the constant humidity heating process of the air to be measured is realized.
Preferably, the sampling air measurement assembly comprises a first air pressure gauge and a first dry bulb temperature gauge which are arranged in the air duct.
Preferably, the air inlet end of the sampling air measuring assembly in the air duct is provided with a first mixer, and the air inlet end of the heating air measuring assembly in the air duct is provided with a second mixer.
Preferably, the heating air measuring assembly further comprises a wind speed measuring instrument, the wind speed measuring instrument is arranged close to the second mixer, the wind speed measuring instrument is electrically connected with the fan, the fan receives a measuring result of the wind speed measuring instrument and adjusts the running frequency of the fan, and therefore the wind speed in the air duct is constant. Because wind speed has influence on pressure and heat transfer, the wind speed of the fan is preferably 5+/-1 m/s.
Preferably, the fan is arranged in the heat preservation box body and is connected to the outer side of the heat preservation box body through an air outlet pipe for discharging the measured heating air.
Preferably, the air wet bulb thermometer comprises an air wet bulb thermometer body and a water supplementing cup, wherein the space above the liquid level in the water supplementing cup is communicated with the air duct and is used for keeping the wet environment in the air duct; one end of the air wet bulb thermometer body is inserted under the liquid level of the water supplementing cup, and the other end of the air wet bulb thermometer body stretches into the air duct for measurement.
The air wet bulb thermometer further comprises a hydraulic water supplementing tank, and the water level in the water supplementing cup is kept constant by the hydraulic water supplementing tank.
Preferably, the heat insulation box body is made of a heat insulation material, and the heat insulation material is made of a heat insulation material with the thickness of more than 75mm and the heat conductivity coefficient of less than 0.23W/m.K, such as a double-sided color steel plate or a flame-retardant polyurethane warehouse plate; the air pipe is arranged in the heat insulation box body, and is wrapped with materials for isolating heat radiation, and the materials comprise porous materials, heat reflection materials and vacuum materials, such as glass fiber, asbestos, rock wool, silicate and other traditional heat insulation materials or aerogel felt, vacuum plates and other novel heat insulation materials.
Preferably, the insulation box body is provided with an inspection door and a monitoring screen, the inspection door is provided with an observation window, and the bottom of the insulation box body is also provided with universal wheels for allowing universal movement.
Preferably, the first air pressure gauge, the second air pressure gauge, the first dry bulb temperature gauge, the second dry bulb temperature gauge and the air wet bulb temperature gauge are all electrically connected with the same PLC processing system, and measurement data and a temperature and humidity measurement result are output to the monitoring screen.
Preferably, in order to avoid the case body from leaking heat to influence the measurement of the dry and wet ball temperature, a heat leak compensation device is further arranged in the heat insulation case body, the heat leak compensation device comprises a heating lamp and a thermocouple, when the temperature of the thermocouple is lower than 20 ℃, the heating lamp is started and heats the internal environment of the heat insulation case body, and when the temperature of the thermocouple is higher than 25 ℃, the heating lamp is closed.
The invention has the beneficial effects that:
1. in this device, be connected the tuber pipe parcel thermal radiation protection material with the air conditioner heater and can effectively prevent the influence of the interior air heater of insulation can to the measurement accuracy of heating air measurement assembly. The arrangement of the heat preservation box body improves the safety and convenience of the device in running under a low-temperature environment. Particularly, the water supplementing cup is arranged inside the heat insulation box body, so that automatic water supplementing of the air wet bulb thermometer can be realized, and the situation that the air wet bulb thermometer cannot be used due to frost cracking under the condition of low temperature is avoided.
2. The device can adopt a conventional instrument to measure the humidity of low-temperature air, so that the investment and maintenance cost are greatly reduced; the PLC system is arranged, so that the device integrates data measurement, calculation and output functions, and can be independently applied to various occasions. And by calculating the measurement data, the measurement of other various state parameters of the sampled air, such as relative humidity, dew point temperature and the like, can also be realized.
3. The device adopts a constant-humidity reheating method to heat low-temperature air and then measures all parameters, but does not need to directly measure the electric heating quantity, so that the measurement process is simplified, and the measurement link with errors is reduced; meanwhile, the constant humidity heating process of the air is realized through adjustable electric heating, and the theoretical range is limited only by the range of the low-temperature side temperature sensor.
4. The device only relates to measurement of two state point parameters, namely the dry bulb temperature and the air pressure of the sampled air and the dry bulb temperature and the wet bulb temperature and the air pressure of the heated air, and the measurement method is simple and easy to realize, and has the advantage of high measurement precision for measuring the low-temperature air humidity parameters. Specifically, by improving the measurement precision of the humidity parameter of the low-temperature wet air, the deviation between the wet air wet bulb temperature obtained by measurement and the adiabatic saturation temperature is reduced to improve the measurement precision of the humidity parameter of the low-temperature wet air, and the deviation between the wet air wet bulb temperature obtained by measurement and the adiabatic saturation temperature is reduced. Meanwhile, when the subsequent calculation is carried out, the difference between the absolute saturation temperature and the wet bulb temperature in the physical sense can be ignored, the calculation process is simplified by utilizing the fact that the absolute saturation temperature and the wet bulb temperature are very similar in numerical value, and the measurement result with higher accuracy is obtained. Finally, the integrated accurate measurement of the air temperature and humidity under the conditions of wide temperature range of minus 30 ℃ to 80 ℃ is realized.
Drawings
FIG. 1 is a schematic diagram of a wide temperature range air temperature and humidity sampling and measuring device;
FIG. 2 is a side sectional view of the wide temperature range air temperature and humidity sampling and measuring device;
FIG. 3 is a side view of the wide temperature range air temperature and humidity sampling and measuring device;
fig. 4 is an isometric view of the wide temperature range air temperature and humidity sampling and measuring device.
The meaning of the reference symbols in the figures is as follows:
10-air sampler
20-sample air measurement assembly 21-first air pressure gauge 22-first dry bulb thermometer
30-heating air measuring component 31-second air pressure gauge 32-second dry bulb thermometer
33-air wet bulb thermometer 331-water supplementing cup 34-wind speed measuring instrument 40-air heater
50-air duct 60-heat preservation box 61-inspection door 611-observation window 62-monitoring screen
71-first mixer 72-second mixer 80-fan 81-air outlet pipe
90-heat leakage compensation device 100-return air inlet 101-working condition environment of machine to be tested
Detailed Description
The technical scheme of the invention is more specifically described below with reference to the examples and the accompanying drawings:
example 1
As shown in fig. 1 to 3, a wide temperature range air temperature and humidity sampling and measuring device comprises an insulation box 60, an air sampler 10 and a sampling air measuring assembly 20 arranged outside the insulation box, and a heating air measuring assembly 30 arranged inside the insulation box 60. The air sampler 10, the sampling air measuring assembly 20 and the heating air measuring assembly 30 are sequentially connected through air pipes to form an integrated air duct 50. In this embodiment, the air sampler 10 is a sampling rake.
The sample air measurement assembly 20 includes a first air pressure gauge 21 and a first dry bulb temperature gauge 22 disposed within the air tunnel. An air heater 40 is disposed between the sample air measurement assembly 20 and the heated air measurement assembly 30, and the end of the heated air measurement assembly 30 is connected to a fan 80. The heated air measuring assembly 30 includes a second air pressure gauge 31, an air velocity gauge 34, a second dry bulb temperature gauge 32, and an air wet bulb temperature gauge 33 disposed within the air duct 50. The anemometer 34 is disposed adjacent to the second mixer 72.
The wind speed measuring instrument 34 is electrically connected with the fan 80, and the fan 80 receives the measurement result of the wind speed measuring instrument 34 and adjusts the operation frequency of the fan 80 to enable the wind speed in the air duct 50 to be constant. Because wind speed has influence on pressure and heat transfer, the wind speed of the fan is preferably 5+/-1 m/s. The blower 80 is disposed in the heat insulation box 60 and connected to the outside of the heat insulation box 60 through an air outlet pipe 81 for discharging the measured heated air.
The second dry bulb thermometer 22 is electrically connected to the air heater 40. In this embodiment, the air heater 40 is a fin-type electric heater, and the temperature of the heated air dry bulb is controlled by the feedback adjustment of the measured temperature of the second dry bulb thermometer 32, so as to realize the constant humidity heating process of the air to be measured. Specifically, the temperature measured by the second dry bulb thermometer 32 is collected in real time by the programmable logic controller, the temperature is continuously compared with the set target temperature, and an instruction is sent to the power regulator to regulate the running current value of the air heater 40, so that the temperature of the heated air dry bulb is controllable.
The front end of the sampling air measuring assembly 20 in the air duct 50, namely the air inlet end, is provided with a first mixer 71, the front end of the heating air measuring assembly 30 in the air duct 50, namely the air inlet end, is provided with a second mixer 72, and the mixers are used for guaranteeing that the temperature and humidity of air flowing into the sampling air measuring assembly 20 and the heating air measuring assembly 30 are uniform, and reducing measuring errors.
The air wet bulb thermometer 33 comprises an air wet bulb thermometer body, a water supplementing cup 331 and a hydraulic water supplementing tank, wherein the upper space of the liquid level in the water supplementing cup 331 is communicated with the air duct 50 and used for maintaining the wet environment in the air duct 50, the liquid level in the water supplementing cup 331 is kept constant by the hydraulic water supplementing tank, and the liquid in the water supplementing cup 331 is prevented from entering the air duct 50. One end of the air wet bulb thermometer body is inserted under the liquid level of the water supplementing cup 33, and the other end of the air wet bulb thermometer body extends into the air duct 50 for measurement.
The heat preservation box 60 is made of a heat preservation material with the thickness of more than 75mm and the heat conductivity coefficient of less than 0.23W/m.K, such as a double-sided color steel plate or a flame-retardant polyurethane warehouse plate; the air pipes arranged in the heat preservation box body 60 are all wrapped with materials for isolating heat radiation on the surfaces.
The thermal insulation box 60 is provided with an inspection door 61 which is convenient for installation and debugging of each device, and the inspection door 61 is provided with an observation window 611. The insulation box 60 is also provided with a monitor screen 62. In this embodiment, the first air pressure gauge 21, the second air pressure gauge 31, the first dry bulb thermo gauge 22, the second dry bulb thermo gauge 32 and the air wet bulb thermo gauge 33 are all electrically connected to the same data acquisition device, the data acquisition device uses a relay output type PLC as a control core, and configures an analog input and analog output module, the PLC system collects all measured data electrical signals, and performs operation through an internal program, and finally outputs each measured data and a temperature and humidity measurement result to the monitor screen 62.
The bottom of the insulation box 60 can be provided with universal wheels for convenient movement.
In order to avoid the influence of the heat leakage of the box body on the measurement of the temperature of the wet and dry balls, a heat leakage compensation device 90 is further arranged in the heat insulation box body 60, the heat leakage compensation device 90 consists of a ceramic heating lamp and a thermocouple, a measured temperature signal of the thermocouple is introduced into a programmable logic controller through an analog quantity acquisition module, and the ceramic heating lamp is judged and controlled to be opened and closed by comparing instructions through program editing. When the temperature of the thermocouple is lower than 20 ℃, the ceramic heating lamp is turned on to heat the environment in the heat insulation box 60, and when the temperature of the thermocouple is higher than 25 ℃, the output of the control signal is stopped, and the ceramic heating lamp is turned off.
Example 2
The temperature and humidity measurement and calculation of the sampled air are carried out by using the device, and the steps are as follows:
s1, starting a fan 80, wherein the fan 80 works to generate suction force so that low-temperature air flows through a sampling air measuring assembly 20 after passing through a first mixer 71 by an air sampler 10, flows through a heating air measuring assembly 30 after passing through an air heater 40 and a second mixer 72, and finally flows out of an insulation box 60 from an air outlet pipe 81;
s2, heating the air measuring assembly 30 to work, and enabling the fan 80 to receive the wind speed value measured by the second air pressure gauge 31 and adjust the operation frequency of the fan 80 to the wind speed of 5 m/s+/-1 m/s; the air heater 40 receives the temperature result measured by the second dry bulb thermometer 32, and adjusts the power of the air heater 40 until the air temperature in the right end, namely the downstream air duct, reaches a set temperature value;
s3, the sampling air measuring assembly 20 works, and the first air pressure measuring instrument 21 measures the pressure P of the sampling air before heating 1 Air temperature t before heating by first dry bulb thermometer 22 1 The heated air pressure P is measured by the heated air measuring assembly 30 2 Temperature t of heated air dry bulb 2 And the heated wet bulb temperature t w2 ；
S4, calculating the relative humidity of the heated air according to an absolute humidity calculation formula according to the measured result of the S3The calculation process is as follows: first, the absolute humidity d of the wet air is calculated 2 The absolute humidity calculation formula is as follows:
wherein d 2 For the absolute humidity value of saturated water vapor of the heated air, the unit kg (water vapor)/kg (dry air), d s (t w2 ) To heat the air at the wet bulb temperature t w2 Saturated humidity per kg (water vapor)/kg (dry air), r (t) w2 ) To heat the air at the wet bulb temperature t w2 Latent heat of gasificationUnit kJ/kg;
r(t w2 )＝-2.4114t w2 +2501.7 (2)
wherein P is s (t w2 ) To heat the air at the wet bulb temperature t w2 The corresponding saturated steam pressure, unit Pa.
Based on the measured wet bulb temperature t of the heated wet air w2 And (2) by combining the values of the formulas (2) to (4), and calculating to obtain r (t) w2 )，d s (t w2 )，P s (t w2 ) A parameter, according to the measured value t of the dry bulb temperature of the heated wet air 2 Calculating the absolute moisture content value d of the heated humid air by combining the formula (1) 2 。
D, based on the principle that the absolute moisture content of the wet air is unchanged before and after heating 2 I.e. the absolute moisture content of the air before heating is sampled.
r(t w1 )＝-2.4114t w1 +2501.7 (7)
P s (t w1 ) At t w1 Saturated water vapor pressure at temperature, unit Pa;
substituting (5) to (7) into (8) to obtain:
pre-heating pressure P of sampled air 1 And the dry bulb temperature t before heating 1 And d is calculated 2 Substituting the temperature and humidity data into the formula (9) to obtain the temperature and humidity data of the sampled and measured low-temperature air.
The above formula utilizes the principle that the absolute moisture content is kept unchanged before and after heating, and because the difference between the wet air wet bulb temperature obtained by measurement and the adiabatic saturation temperature is reduced by the device, the difference between the absolute saturation temperature and the wet bulb temperature in the physical sense can be ignored in the calculation process, and the calculation process is simplified by utilizing the fact that the absolute saturation temperature and the wet bulb temperature are very similar in numerical value, so that the measurement result with higher accuracy is obtained.
Example 3
In a stable operating environment 101, the air sampler 10 of the wide temperature range air temperature and humidity sampling measurement device of the present invention is placed at the return air inlet 100 of the machine to be tested, and the fan 80 is turned on, and the measurement is performed according to the procedure of example 2.
At a certain moment, the wind speed measuring instrument 34 measures the current wind speed to be 5m/s, and the sampling air measuring component 20 measures the pre-heating pressure P of the sampling low-temperature air 1 ＝100510P a Temperature t of air before heating 1 -10 ℃; the heated air measuring assembly 30 measures the heated air pressure P 2 ＝100360P a Temperature t of heated air dry bulb 1 Temperature of heated wet bulb of air t=23.4℃ w2 =9.1 ℃. The measurement precision of the sensors of the dry and wet bulb thermometers used in the device is +/-0.1 ℃.
In this embodiment, the enthalpy value h of the low-temperature air can be sampled by using known data 1 Data such as relative humidity, dew point temperature, etc. Such as:
substituting equation (5) into equation (10) yields:
h 1 ＝1.005t 1 +(2501+1.846t 1 )d 1 (12)
substituting each parameter into formulas (11) and (12) to calculate to obtain the enthalpy value h of the low-temperature air before sampling 1 And relative humidity parameter
The enthalpy value h of the sampled low-temperature air is calculated in the embodiment 1 For-6.493 KJ/Kg, the relative humidity is 80.71% RH, and the dew point temperature is-12.18 ℃.
The above embodiments are only for illustrating the technical scheme of the present invention, and are not limiting to the present invention; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (7)
1. The wide-temperature-range air temperature and humidity sampling and measuring device is characterized by comprising an insulation box body (60), an air sampler (10) and a sampling air measuring assembly (20) which are arranged on the outer side of the insulation box body, and a heating air measuring assembly (30) which is arranged in the insulation box body (60); the air sampler is characterized in that the air sampler (10), the sampling air measuring assembly (20) and the heating air measuring assembly (30) are sequentially connected through air pipes to form an integrated air duct (50), an air heater (40) is arranged between the sampling air measuring assembly (20) and the heating air measuring assembly (30), the tail end of the heating air measuring assembly (30) is connected with a fan (80), the heating air measuring assembly (30) comprises a second dry bulb thermometer (32) and an air wet bulb thermometer (33) which are arranged in the air duct (50), and the second dry bulb thermometer (32) is electrically connected with the air heater (40);
the sampling air measurement assembly (20) comprises a first air pressure gauge (21) and a first dry bulb thermometer (22) which are arranged in the air duct; the sampling air measuring assembly (20) is provided with a first mixer (71) at the air inlet end in the air duct (50), and the heating air measuring assembly (30) is provided with a second mixer (72) at the air inlet end in the air duct (50);
the heating air measurement assembly (30) further comprises a second air pressure gauge (31) and an air velocity gauge (34), the air velocity gauge (34) is close to the second flow mixer (72), the air velocity gauge (34) is electrically connected with a fan (80), and the fan (80) is subjected to variable frequency adjustment and is used for adjusting the air velocity in the air duct (50).
2. A wide temperature range air temperature and humidity sampling measurement device according to claim 1, characterized in that the fan (80) is arranged in the heat insulation box (60) and is connected to the outer side of the heat insulation box (60) through an air outlet pipe (81) for discharging the measured heating air.
3. The wide temperature range air temperature and humidity sampling measurement device according to claim 1, wherein the air wet bulb thermometer (33) comprises an air wet bulb thermometer body and a water supplementing cup (331), and a liquid surface upper space in the water supplementing cup (331) is communicated with the air channel (50) and used for maintaining a wet environment in the air channel (50); one end of the air wet bulb thermometer body is inserted under the liquid level of the water supplementing cup (33), and the other end of the air wet bulb thermometer body extends into the air duct (50) for measurement.
4. The wide temperature range air temperature and humidity sampling and measuring device according to claim 1, wherein the heat insulation box body (60) is made of heat insulation materials with the thickness of more than 75mm and the heat conductivity coefficient of less than 0.23W/m-K, and the air pipe arranged in the heat insulation box body (60) is wrapped with materials for insulating heat radiation.
5. The wide temperature range air temperature and humidity sampling measurement device according to claim 1, wherein an inspection door (61) and a monitoring screen (62) are arranged on the heat insulation box body (60), an observation window (611) is arranged on the inspection door (61), and universal wheels are further arranged at the bottom of the heat insulation box body (60).
6. The wide temperature range air temperature and humidity sampling measurement device according to claim 1, wherein the first air pressure gauge (21), the second air pressure gauge (31), the first dry bulb temperature gauge (22), the second dry bulb temperature gauge (32) and the air wet bulb temperature gauge (33) are all electrically connected to the same PLC processing system, and output measurement data and temperature and humidity measurement results to the monitor screen (62).
7. A wide temperature range air temperature and humidity sampling measurement device according to any one of claims 1 to 6, characterized in that a heat leakage compensation device (90) is further arranged in the heat insulation box body (60), the heat leakage compensation device (90) is composed of a heating lamp and a thermocouple, when the temperature of the thermocouple is lower than 20 ℃, the heating lamp is started and heats the environment in the heat insulation box body (60), and when the temperature of the thermocouple is higher than 25 ℃, the heating lamp is stopped.
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