CN113899476A - An in-situ environment simulated wet bulb temperature calibration device - Google Patents
An in-situ environment simulated wet bulb temperature calibration device Download PDFInfo
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- 238000011065 in-situ storage Methods 0.000 title claims abstract description 18
- 238000001035 drying Methods 0.000 claims abstract description 27
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims abstract description 18
- 238000000034 method Methods 0.000 claims abstract description 16
- 238000005259 measurement Methods 0.000 claims abstract description 13
- 229910052697 platinum Inorganic materials 0.000 claims abstract description 9
- 230000007935 neutral effect Effects 0.000 claims abstract description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical class O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 59
- 229920006395 saturated elastomer Polymers 0.000 claims description 32
- 238000003756 stirring Methods 0.000 claims description 14
- 238000012360 testing method Methods 0.000 claims description 10
- 238000004088 simulation Methods 0.000 claims description 9
- 238000004364 calculation method Methods 0.000 claims description 6
- 238000012544 monitoring process Methods 0.000 claims description 4
- 230000002265 prevention Effects 0.000 claims description 4
- 239000007787 solid Substances 0.000 claims description 3
- 230000000087 stabilizing effect Effects 0.000 claims description 3
- 238000005457 optimization Methods 0.000 abstract description 15
- 238000004422 calculation algorithm Methods 0.000 abstract description 9
- 238000013461 design Methods 0.000 description 12
- 230000000694 effects Effects 0.000 description 9
- 238000010586 diagram Methods 0.000 description 8
- 230000007613 environmental effect Effects 0.000 description 3
- 238000012795 verification Methods 0.000 description 3
- 206010070245 Foreign body Diseases 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000010835 comparative analysis Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000012806 monitoring device Methods 0.000 description 1
- -1 pressure Chemical compound 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
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- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
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Abstract
本发明的原位环境模拟湿球温度校准装置，其特征在于：包括外壳、安装在外壳内的矩形的环形循环风道，以及安装在环形风道中心空挡处的内壳体；该校准装置还包括干燥装置、加湿装置、传感器装置、风速可调空气循环装置、恒温装置和控制器。本发明还提供了一种原位环境模拟湿球温度校准装置的湿度校准方法。本发明可实现装置内风速、温湿度同时可控。对导风板和整流板进行了优化设计，保证装置测量区风速均匀性。本专利方案中为提高湿度调控效率，采用优化算法输出所需干/湿气体。该校准装置运行高效、操作简单，通过优化算法有效的缩短了校准时间，通过模拟实际使用环境对测量结果做进一步的验证，可直观的判断被校湿球铂电阻是否准确可靠。The in-situ environment simulated wet bulb temperature calibration device of the present invention is characterized in that: it comprises an outer casing, a rectangular annular circulating air duct installed in the outer casing, and an inner casing installed at the center neutral of the annular air duct; the calibration device also has the following characteristics: Including drying device, humidifying device, sensor device, air circulation device with adjustable wind speed, constant temperature device and controller. The invention also provides a humidity calibration method of the in-situ environment simulated wet bulb temperature calibration device. The invention can realize that the wind speed, temperature and humidity in the device can be controlled at the same time. The wind deflector and rectifier plate are optimized to ensure the uniformity of wind speed in the measurement area of the device. In this patent scheme, in order to improve the humidity control efficiency, an optimization algorithm is used to output the required dry/wet gas. The calibration device is efficient in operation and simple in operation. The calibration time is effectively shortened through the optimization algorithm, and the measurement results are further verified by simulating the actual use environment, which can intuitively judge whether the calibrated wet bulb platinum resistance is accurate and reliable.
Description
Technical Field
The invention belongs to the field of household appliance detection equipment, and relates to an in-situ environment simulation wet bulb temperature calibration device.
Background
At present, a wind tunnel with independently adjustable wind speed and a constant temperature and humidity box with independently adjustable temperature and humidity are common, but a portable calibration device with adjustable wind speed and controllable temperature and humidity is not found on the market.
In the process of calibrating a laboratory of a household appliance enterprise, the method for monitoring the environmental temperature by a dry-wet ball method is a commonly adopted mode, and has the characteristics of high accuracy, good stability, low cost, convenience in maintenance and the like. According to the requirements of various effective laboratory calibration standards, dry and wet balls need to be put into a constant temperature furnace for temperature calibration on site, and whether the temperature measured after the wet balls are wrapped with gauze is accurate or not is not concerned.
According to the working principle of the dry and wet ball method, the measurement result is influenced by the matching degree of the gauze size and the wet ball, the water quality of water used for infiltrating the wet ball, the wind speed flowing through the wet ball and other factors. Through long-term laboratory calibration work discovery, because enterprise personnel mobility is great, personnel's training will be in time, target in place not so much sometimes, lead to personnel's quality to be uneven, can have some nonstandard operations inevitable when putting, setting up wet bulb. In addition, as the service life of the laboratory increases, the equipment is aged to different degrees, and the factors have certain influence on the measurement result. Therefore, a laboratory with high environmental humidity requirements needs to perform a verification calibration of the wet bulb temperature under normal operating conditions.
Currently, it is common practice to perform a verification calibration: after the temperature of the dry/wet ball is calibrated, the wet ball is sleeved with gauze and is watered, a laboratory is stabilized under common temperature and humidity conditions, a standard hygrothermograph is placed beside a dry-wet ball temperature sampler for data comparison, and whether the environmental temperature and humidity measured by the standard hygrothermograph are consistent with the set values of the laboratory to be calibrated or not is judged. However, this approach also has the following disadvantages:
1) the time required for the laboratory to be stable is longer, so that the time cost of the laboratory calibration work is increased;
2) the laboratory space is large, the common area is 10m 2-40 m2, the temperature field has certain fluctuation, the sampling period of the calibrated laboratory and the standard hygrothermograph cannot be ensured to be synchronous, and the data comparison is not facilitated;
3) the standard hygrothermograph is placed beside the hygrothermograph, is only as close as possible to a wet bulb to be calibrated, is not in the same environment, and is not an optimal calibration mode.
Disclosure of Invention
The invention provides the in-situ environment simulation wet bulb temperature calibration device with quick calibration and accurate data to make up the defects of the prior art.
The invention discloses an in-situ environment simulation wet bulb temperature calibration device, which is characterized in that: the air conditioner comprises a shell, a rectangular annular circulating air duct arranged in the shell, and an inner shell arranged at a central neutral position of the annular air duct; the calibration device also comprises a drying device, a humidifying device, a sensor device, an air circulation device with adjustable air speed, a constant temperature device and a controller; wherein, the drying device and the humidifying device are arranged in the inner shell; the controller is arranged on the shell;
1) a drying device: the air dryer comprises a drying cavity, an air pump, a filter screen, a stirring fan and a connecting pipeline, wherein an air dryer (namely a dehumidifier) and the stirring fan are installed in the drying cavity; dry air is provided for the inside of the circulating air duct of the calibration device, so that the relative humidity of circulating air is reduced, and dry air with a specified volume can be output according to the program design;
2) a humidifying device: the ultrasonic humidifying device comprises an ultrasonic humidifying cavity, an air pump, a filter screen, a stirring fan and a connecting pipeline, wherein the air pump is installed at an air inlet pipe of the ultrasonic humidifying cavity, the filter screen is installed at an air outlet pipe, an ultrasonic steam generator (namely a humidifier) and the stirring fan are installed in the ultrasonic humidifying cavity, and the air inlet pipe and the air outlet pipe are respectively connected with different positions of a circulating air channel; saturated wet steam is provided for the calibration device in the circulating air duct and is used for increasing the relative humidity of circulating gas, and saturated water vapor with a specified volume can be output according to the program design;
3) a sensor device: the device comprises a hot-bulb anemometer, a platinum resistance temperature sensor and a dry-wet integrated temperature and humidity sensor (namely a standard temperature and humidity meter), wherein the platinum resistance temperature sensor is respectively arranged in a drying cavity and a saturated ultrasonic humidifying cavity, the hot-bulb anemometer, the dry-wet integrated temperature and humidity sensor and a calibrated wet bulb are arranged in a circulating air duct, and the hot-bulb anemometer, the dry-wet integrated temperature and humidity sensor and the calibrated wet bulb are close to each other in the circulating air duct and are used for monitoring the temperature, humidity and air speed in the circulating air duct, a dryer and a saturated steam generator and transmitting information to a controller in real time; two dry-wet integrated temperature and humidity sensors are arranged on the same cross section behind the calibrated wet bulb, and the accuracy and reliability of the sensors and the temperature and humidity in the wind measuring channel are verified by comparing the feedback data of the two sensors;
4) air circulation device that the wind speed is adjustable: comprises an air duct, a frequency converter, a stabilized voltage power supply, a fan, a guide plate and a rectifying plate; the circulating air duct is a rectangular closed annular channel, arc-shaped bent guide plates are arranged at each corner of the circulating air duct, and straight pipe section rectifying plates are arranged on the straight pipe sections close to the corners; a fan is arranged in the circulating air duct and is connected with the frequency converter and the stabilized voltage power supply; the air circulation device is a closed type gas internal circulation device, does not exchange gas with the outside in the operation process, and provides a stable and controllable wind speed environment for the calibrated sensor;
5) a constant temperature device: the device comprises a Peltier patch, wherein the Peltier patch is respectively arranged in a drying cavity, an ultrasonic humidifying cavity and a circulating air duct; and supplying heat and cold required for stabilizing the temperature to the circulating air duct, the dryer and the saturated steam generator of the calibrating device.
In the circulating air duct, a foreign matter prevention gauze is arranged in front of the straight pipe section rectifying plate; the drying device, the humidifying device, the frequency converter and the stabilized voltage supply are arranged in the inner shell together; the controller adopts a PLC controller or a singlechip; adopting a mode of combining an optimization algorithm and PID regulation; and calculating and executing corresponding programs according to the measurement information fed back by the wind speed and temperature/humidity sensors so as to meet the requirement of a set value.
In the circulating air duct, the calibration device test area is arranged by the humidity calibration ball and the hot ball anemometer side by side, is positioned in the same section and is positioned in the straight pipe section of the circulating air duct.
In the circulating air duct, the guide plates at the right-angle bend are designed into circular arcs with the radius of 5cm and the radius of 1/4, and are uniformly distributed at the bend; the guide plate is made of a solid plate with the thickness of 0.5-1 mm.
When the width of the circulating air duct is 150mm, 5 guide plates are uniformly arranged at the right-angle bend.
In the circulating air duct, extension plates with the length equal to the radius of the circular arc are additionally arranged at the two ends of the guide plate, and the extension plates are arranged in parallel with the circulating air duct; the turbulence can be reduced, the pressure difference between the air inlet end and the air outlet end on the two sides of the guide plate is synchronously reduced, and the air quantity loss is reduced.
In the circulating air duct, the straight pipe section rectifying plate adopts a hexagonal section, the hole height is 10mm, and the thickness is 100mm, the section of the rectifying plate is honeycomb-shaped, and the central line of the hole is vertical to the plate surface.
In the circulating air duct, the section hexagon of the straight pipe section rectifying plate is a hexagon unit with an opening on the side wall, and the function of balancing the pressure among the units is achieved when airflow just enters the rectifying plate; meanwhile, in order to ensure that the airflow does not form new turbulence in the rectifying plate due to the opening, a steady flow section with a certain length needs to be ensured to ensure that the airflow flowing out of the rectifying plate is uniform and stable, the length of the opening section accounts for 1/3 of the length of the hexagonal unit, namely the thickness of the plate, and the opening ratio (namely the total area of the unit openings/the unit sectional area) is about 40 percent.
The invention has the beneficial effects that:
1) according to the scheme, the wind speed and the temperature and humidity in the device can be controlled simultaneously.
2) In the scheme of the patent, in order to ensure the wind speed uniformity of a measuring area of the device, the air deflector and the rectifying plate are optimally designed.
3) In order to improve the humidity regulation efficiency, the required dry/wet gas is output by adopting an optimization algorithm.
4) The calibration device is efficient in operation and simple in operation, calibration time is effectively shortened through an optimization algorithm, further verification is carried out on a measurement result through simulation of an actual use environment, and whether the platinum resistor of the calibrated wet bulb is accurate and reliable can be visually judged. Meanwhile, the calibration device can be used for simulating different use conditions and checking whether the measurement result is linearly changed under different conditions.
5) Through the optimal design of guide plate, cowling panel, can reduce the requirement to straight section length greatly, realize the miniaturized design of device volume, portable uses to the scene. The wind speed uniformity optimization design method can effectively achieve uniformity and stability of wind speeds at different positions in a test area, meets calibration requirements, and has the advantages that the main wind speed measurement range of the device is smaller than 6m/s according to the requirements of a working environment of a calibration object, and the effect of the wind speed uniformity optimization design scheme is better for low wind speed calibration.
Drawings
The attached drawing is a structural schematic diagram of the invention.
Fig. 1 is a top view of an internal structure diagram, fig. 2 is a laminar flow and turbulent flow distribution diagram of 1 guide plate (quarter circular arc), fig. 3 is a laminar flow and turbulent flow distribution diagram of 5 guide plates (quarter circular arc), fig. 4 is a laminar flow and turbulent flow distribution diagram of 8 guide plates (quarter circular arc), fig. 5 is a laminar flow and turbulent flow distribution diagram of 5 guide plates (quarter circular arc with extension plates at two ends), fig. 6 is a guide plate with extension plates, fig. 7 is a square hole section with uniformly distributed straight pipe section rectifier plates, fig. 8 is a hexagonal hole section with uniformly distributed straight pipe section rectifier plates, fig. 9-13 are flow velocity distribution diagrams of one-to-five schemes of the straight pipe section rectifier plates in sequence, fig. 14 is a side wall perforated hexagonal unit of the hexagonal hole of the straight pipe section rectifier plate, and fig. 15 is a longitudinal wind velocity distribution curve behind the rectifier plate.
In the figure: the device comprises a drying cavity 1, an air pump 2, a filter screen 3, a stirring fan 4, an ultrasonic humidifying cavity 5, an air pump 6, a filter screen 7, a stirring fan 8, an air dryer 9, an ultrasonic saturated steam generator 10, a rectifying plate 11, a hot-bulb anemometer 12, a platinum resistance temperature sensor 13, a dry-wet integrated temperature and humidity sensor 14 (a standard temperature and humidity meter), a circulating air duct 15, a frequency converter 16, a stabilized voltage power supply 17, a small-torsion-degree fan 18, a foreign-matter-preventing gauze 19, a guide plate 20, a Peltier 21, a calibrated wet bulb 22, a shell 23, an inner shell 24, a controller 25, an extension plate 26 and holes 27.
Detailed Description
The attached drawing is an embodiment of the invention.
In order to calibrate the wet bulb under the actual working state on site more scientifically, accurately and efficiently, a calibration device capable of simulating a real working environment is developed. At present, a wind tunnel with independently adjustable wind speed and a constant temperature and humidity box with independently adjustable temperature and humidity are common, but a portable calibration device with adjustable wind speed and controllable temperature and humidity is not available on the market.
The in-situ environment simulation wet bulb temperature calibration device comprises a shell 23, a rectangular annular circulating air duct 15 arranged in the shell, and an inner shell 24 arranged at a central neutral position of the annular air duct; the calibration device also comprises a drying device, a humidifying device, a sensor device, an air circulation device with adjustable air speed, a constant temperature device and a controller; wherein, the drying device and the humidifying device are arranged in the inner shell; the controller 25 is mounted on the housing. (see FIG. 1 for the structural drawing).
1) A dryer: the drying device is composed of a drying cavity 1, an air pump 2, a filter screen 3, a stirring fan 4 and a connecting pipeline, wherein the stirring fan and an air dryer 9 (namely dehumidifying air) are installed in the drying cavity, the air pump 2 is installed in an air inlet pipe of the drying cavity, the filter screen 3 is installed in an air outlet pipe, and the air inlet pipe and the air outlet pipe are respectively connected with different positions of a circulating air duct 15. The calibration device is provided with dry air in the circulating air duct for reducing the relative humidity of the circulating air, and a specified volume of dry air can be output according to the programming.
2) A saturated steam generator: the ultrasonic humidifier comprises an ultrasonic humidifying cavity 5, an air pump 6, a filter screen 7, a stirring fan 8 and a connecting pipeline, wherein the stirring fan 8 and an ultrasonic saturated steam generator 10 (namely a humidifier) are installed in the ultrasonic humidifying cavity, the air pump is installed in an air inlet pipe of the ultrasonic humidifying cavity, the filter screen is installed on an air outlet pipe, and the air inlet pipe and the air outlet pipe are respectively connected with different positions of a circulating air duct 15. Saturated wet steam is provided in the circulating air duct of the calibration device to increase the relative humidity of the circulating air, and a specified volume of saturated steam can be output according to the programming.
3) Wind speed, temperature/humidity sensor: the device is composed of a hot-bulb anemometer 12, a platinum resistance temperature sensor 13 and a dry-wet integrated temperature and humidity sensor 14 (a standard hygrothermograph), wherein the platinum resistance temperature sensor 13 is respectively arranged in a drying cavity 1 and a saturated ultrasonic humidifying cavity 5, the hot-bulb anemometer 12, the dry-wet integrated temperature and humidity sensor 14 and a calibrated wet bulb 22 are arranged in a circulating air duct 15, and the three devices are close to each other in the circulating air duct. The temperature, humidity and wind speed monitoring device is used for monitoring the temperature, humidity and wind speed in the circulating air duct, the dryer and the saturated steam generator and transmitting information to the logic controller in real time. Two dry-wet integrated temperature and humidity sensors are arranged on the same cross section behind the humidity-corrected ball 22, and the accuracy and reliability of the temperature and humidity in the sensor and the air measuring channel are verified by comparing feedback data of the two sensors.
4) Air circulation system that the wind speed is adjustable: the device consists of a circulating air duct 15, a frequency converter 16, a stabilized voltage power supply 17, a small-twist-degree fan 18, a foreign-body-preventing gauze 19, a guide plate 20 and a rectifying plate 11. The circulating air duct is a rectangular closed annular channel, a small-torsion-degree fan 18 is arranged in the circulating air duct, arc-shaped bent guide plates 20 are arranged at each corner of the circulating air duct, and a straight pipe section rectifying plate 11 is arranged at a straight pipe section close to the corner (air outlet end of the corner); the front surface of the straight pipe section rectifying plate is provided with a foreign matter prevention gauze 19. The fan 18 is connected with the frequency converter 16 and the stabilized voltage power supply 17; the system is a closed gas internal circulation, does not exchange gas with the outside in the operation process, and provides a stable and controllable wind speed environment for the calibrated sensor.
5) A constant temperature device: the device consists of a Peltier, and Peltier 21 is respectively arranged in the drying chamber 1, the ultrasonic humidifying chamber 5 and the circulating air duct 15. And supplying heat and cold required for stabilizing the temperature to the circulating air duct, the dryer and the saturated steam generator of the calibrating device.
6) The logic controller 25: a PLC controller or a singlechip is adopted. And a mode of combining an optimization algorithm and PID regulation is adopted. And calculating and executing corresponding programs according to the measurement information fed back by the wind speed and temperature/humidity sensors so as to meet the requirement of a set value.
In the circulating air duct 15, a foreign matter prevention gauze 19 is arranged in front of the straight pipe section rectifying plate 11; the drying device, the humidifying device, the frequency converter and the stabilized voltage supply are arranged in the inner shell 24 together; the controller 25 adopts a PLC controller or a single chip microcomputer, and calculates and executes a corresponding program according to measurement information fed back from the wind speed and temperature/humidity sensor by combining an optimization algorithm and PID adjustment to meet the requirement of a set value.
In the circulating air duct, the calibration device test area is arranged by the humidity calibration ball 22 and the hot ball anemometer 12 side by side, is in the same section and is positioned in the straight pipe section of the circulating air duct.
In the circulating air duct, the guide plates 20 at the right-angle bend are designed into circular arcs with the radius of 5cm and the radius of 1/4, and are uniformly distributed at the bend; the guide plate is made of a solid plate with the thickness of 0.5-1 mm.
When the width of circulation wind channel is 150mm, 5 guide plates 20 are evenly installed at the right angle bend.
In the circulating air duct, extension plates 26 with the length equal to the radius of the circular arc are additionally arranged at two ends of the guide plate 20 and are arranged in parallel with the circulating air duct; the turbulence can be reduced, the pressure difference between the air inlet end and the air outlet end on the two sides of the guide plate is synchronously reduced, and the air quantity loss is reduced.
In the circulating air duct, the straight pipe section rectifying plate 11 adopts a rectifying plate with a hexagonal section, a hole height of 10mm and a thickness of 100mm, the section of the rectifying plate is honeycomb-shaped, and the central line of the hole is vertical to the plate surface.
In the circulating air duct, the section hexagon of the straight pipe section rectifying plate 11 is a hexagon unit with an opening 27 on the side wall, and the hexagonal unit plays a role in balancing pressure among the units when airflow just enters the rectifying plate; meanwhile, in order to ensure that the airflow does not form new turbulence in the rectifying plate due to the opening, a steady flow section with a certain length needs to be ensured to ensure that the airflow flowing out of the rectifying plate is uniform and stable, the length of the opening section accounts for 1/3 of the length of the hexagonal unit, namely the thickness of the plate, and the opening ratio (namely the total area of the unit openings/the unit sectional area) is about 40 percent.
1 wind speed uniformity optimization design
The calibration device test area is placed by the school wet ball side by side with the hot bulb anemograph, is in same cross-section, for guaranteeing that the wind speed of surveying promptly by the wind speed of school wet ball department, just needs this cross-section department to have better wind speed homogeneity, in order to reach this purpose, this paper emphatically carries out optimal design to right angle bend guide plate and straight tube section cowling panel.
The flowing air flow in the air channel can be divided into fully developed pipe flow and non-fully developed pipe flow, and the straight pipe section where the test area of the calibration device is located is limited in length and belongs to the non-fully developed pipe flow, and turbulence can be formed under the influence of various resistances, so that the uniformity of the wind speed of the same section is poor.
1.1 optimized design of quarter bend guide plate
Because the airflow is affected by the inertia force after flowing through the bend to form turbulent flow, the flow field becomes very complicated, the flow velocity distribution is uneven, and no rule can be followed. The guide plate can be additionally arranged to guide airflow to flow, the influence of inertia force is reduced, the influence of viscous force is increased, flow velocity distribution is laminar distribution, layering can occur to airflow, and the directions of all flow layers are parallel to the axis of the air duct.
To achieve the aim, the guide plates are designed in an arc shape with the radius of 5cm and 1/4, and are uniformly distributed at the bent part. The baffles will be optimally designed in terms of quantity and style.
1.1.1 number of baffles
The guide plate plays the effect of guiding its stream, and the quantity is too little effect not obvious, and too much will lead to the wind channel narrowly to obstruct the air current to pass through, selects suitable quantity according to the wind channel diameter and just can play the effect of improving wind speed homogeneity, reduction wind speed loss. The following compares the laminar flow and turbulent flow distribution patterns of 1, 5 and 8 guide plates to select the optimal scheme, such as fig. 2, 3 and 4.
TABLE 1 pressure difference between air inlet end and air outlet end of guide plate
It can be seen that after 5 guide plates are additionally arranged, the turbulence of the testing section is obviously less, the effect of 8 guide plates is not greatly improved compared with that of 5 guide plates, and from the aspects of processing cost and difficulty, 5 guide plates are ideal choices.
1.1.2 baffle pattern
As can be seen from the figure, certain turbulent flow still exists in the testing section after the guide plate is additionally arranged, and the guide plate can be further improved. Extension plates (as shown in figure 6) with the length of arc radius are additionally arranged at the two ends of the guide plate, and the laminar flow and turbulent flow distribution diagram of the 5 guide plates is as shown in figure 5.
TABLE 2 pressure difference between air inlet end and air outlet end of the two sides of the improved guide plate
Therefore, the turbulence is reduced after the guide plate is improved, the pressure difference between the air inlet end and the air outlet end on the two sides of the guide plate is synchronously reduced, and the air quantity loss is reduced. Through comparative analysis, it is more ideal to arrange 5 guide plates of installing the extension plate additional in right angle return bend department.
1.2 optimization design of straight pipe section rectifying plate
The installation of the rectifying plate can further ensure the uniformity and stability of the airflow in the testing area, and in order to achieve the optimal effect, the rectifying plate is optimally designed in the aspects of rectifying plate structure (section shape, hole height and thickness), pressure loss and pressure balance.
1.2.1 Structure of flow straightener (section shape, hole height, thickness)
The most common two kinds of rectifying plates with square cross sections and hexagonal cross sections (such as fig. 7 and 8) are selected, and different hole heights and thicknesses are selected for comparison (see table 3) to determine the optimal scheme.
TABLE 3 summary of fairing solutions
| Cross-sectional shape | Height of hole/mm | Thickness/ |
| Square shape | ||
| 20 | 100 | |
| |
10 | 100 |
| |
20 | 100 |
| |
40 | 100 |
| |
10 | 50 |
The velocity profiles are shown in FIGS. 9 to 13.
Through comparison, the hexagonal section rectifying plate is superior to the square section rectifying plate, the rectifying plate with the smaller hole height and the larger thickness has better rectifying effect, the hole height cannot be reduced and the thickness cannot be increased without limit in consideration of the influence of the resistance coefficient on the air output, and the rectifying plate with the hexagonal section, the hole height of 10mm and the thickness of 100mm is selected to be ideal according to the size of the calibrating device.
1.2.2 pressure loss, pressure balance
When the airflow flows through the rectifying plate, certain pressure loss is generated due to the influence of on-way resistance and local resistance, so that the wind speed is reduced, the air supply system is forced to select a fan with higher power, and the energy is saved and the stability of the internal environment of the air duct is not facilitated.
Because the air current is not even through the wind field behind the quarter bend, at the cowling panel air inlet end, the hexagon unit air inlet wind speed of different positions can be different, corresponding air inlet end wind pressure will be different, in principle need put longer straight tube section behind the cowling panel and make the air current stable, because the restriction of the device volume, can't satisfy the requirement of straight tube section length, just need think the way and realize the balance of pressure between the cowling panel hexagon unit in short distance, make the difference in wind pressure between each hexagon unit of cowling panel air outlet end reduce as far as possible, in order to shorten the requirement to straight tube section length.
Meanwhile, if the air inlet end of the rectifying plate can balance the air pressure difference among the hexagonal units, the influence of on-way resistance and local resistance can be reduced, and the pressure loss caused by the rectifying plate is reduced.
Here, a hexagonal cell with an opening in the side wall (fig. 14) is designed to effectively balance the pressure between the cells when the gas flow enters the rectifying plate. Simultaneously, in order to guarantee that the air current can not form new turbulent flow because of the trompil in the cowling panel, need guarantee to have the stationary flow section of certain length to guarantee that the air current of outflow cowling panel is even, stable. And selecting different schemes of the number of the holes, the hole spacing and the hole diameter for comparison, wherein the specific scheme is shown in a table 4, and a flow direction and wind speed distribution curve is shown in a figure 15.
TABLE 4 summary of fairing solutions
It can be seen from the figure that the wind speed distribution of the cross section is low in the middle and high on two sides, the symmetry of the distribution of the flow direction wind speed is not good in the state of the first scheme, the symmetry is obviously improved after the perforated rectifying plate is adopted, and the second scheme has the best effect. Thus, the open cell length is about 1/3% of the hexagonal cell length, and the open cell fraction (total cell opening area/cell cross-sectional area) is about 40%, as shown in table 4 and fig. 14.
More than synthesizing, through the optimal design of guide plate, cowling panel, can reduce the requirement to straight section length greatly, realize the miniaturized design of device volume, portable uses to the scene. The wind speed uniformity optimization design method can effectively achieve uniformity and stability of wind speeds at different positions in a test area, meets calibration requirements, and has the advantages that the main wind speed measurement range of the device is smaller than 6m/s according to the requirements of a working environment of a calibration object, and the effect of the wind speed uniformity optimization design scheme is better for low wind speed calibration.
2 control run logic
The wind speed and temperature regulation is simple to realize, and the realization method of the humidity control with higher efficiency is mainly described.
2.1 wind speed control operation logic:
adopts two adjusting modes of automation and manual operation:
a. and PID adjustment is adopted, and the frequency of the fan frequency converter is adjusted according to feedback data of the hot-bulb anemometer so as to reach a set wind speed value.
b. Because the requirement of the household appliance laboratory on the wind speed in the air sampler is not high (for example, the requirement in GB/T7725 is not less than 5 m/s), the wind speed can be manually adjusted according to the feedback value of the hot-bulb anemometer.
2.2 temperature control run logic:
and PID regulation is adopted, and the heat quantity and the cold quantity required by the Peltier are up to a set temperature value according to the feedback data of the temperature sensor.
2.3 humidity control run logic:
and calculating the difference rho' of the unsaturated water vapor density under the current temperature and humidity and the set temperature and humidity according to the result measured by the standard temperature and humidity sensor by adopting an optimization algorithm, so that how many grams of water vapor are lacked or excessive per cubic meter can be obtained. Because the volume V of the air channel of the calibrating device is fixed and the value can be measured, the mass m of the air channel with the lack or the excessive water vapor can be calculated by using the volume V and the density difference rho1。
When the measured value is lower than the set value, because the device is a closed cavity, the saturated steam generator outputs gas with the volume which needs to be sucked from the air duct, and the saturated steam density rho is usedqbSubtracting the unsaturated water vapor density rho under the actual temperature and humidity stateq1The saturated steam generator can be obtained by exchanging 1m for each time3Mass m of water vapor added by gas2，m1/m2Obtaining the volume of saturated vapor to be output in the air duct with the volume V;
when the measured value is higher than the set value, because the device is a closed cavity, the drier needs to suck gas with the volume from the air duct according to the output gas with the volume, and the drier exchanges 1m every time3Mass m of water vapor reduced by gas2Is numerically equal to the density rho of unsaturated water vapor in the actual measurement stateq1，m1/m2The volume of the dry air to be output in the air duct with the volume V is obtained.
3 theoretical basis of humidity control optimization algorithm
Dry air at normal temperature and pressure can be regarded as ideal gas, while water vapor in wet air is generally in a superheated state and has little content, and can be regarded as ideal gas approximately. In this way, the equation of state of the ideal gas can be used to express the correlation between the main state parameters of dry air and water vapor, namely pressure, temperature, specific volume, etc., namely:
PgV＝mgRgt or Pgvg＝RgT
PqV＝mqRqT or Pqvq＝RqT
In the formula:
Pg、Pq-the pressure of dry air and water vapour, Pa;
v-total volume of humid air, m3；
mg、mq-mass of dry air and water vapour, kg;
Rg、Rqgas constants, R, of dry air and water vaporg＝287J/(kg·K)，Rq＝461J/(kg·K)；
vgSpecific dry air volume, m3/kg；
vqSpecific volume of water vapor, m3/kg；
T-dry air thermodynamic temperature, (273.15+ T). degree.C. t is the measured temperature.
The specific volumes of the dry air and the water vapor are respectively as follows:
the dry air and water vapor densities are equal to the inverse of the specific volume:
in the formula:
ρgdry air density, kg/m3；
ρqWater vapor density, kg/m3。
According to dalton's law, the pressure of the humid air should be equal to the sum of the dry air pressure and the water vapor pressure, i.e.:
B＝Pg+Pq
in the formula:
b-generally referred to as atmospheric pressure, the standard atmospheric pressure at sea level is 101325 Pa.
The density ρ of the humid air is equal to the sum of the dry air density and the water vapor density, i.e.:
in the formula:
rho-wet air density, kg/m3。
Relative humidity
Defined as the ratio of the water vapor pressure of humid air to the water vapor pressure of saturated humid air at the same temperature, i.e.:
in the formula:
Pq·bsaturated water vapour pressure, Pa.
P can be calculated by using the following Hyland-Wexler empirical formulaq·bWhen t is (0-200) DEG C
The method comprises the following steps: (t is measured temperature of air duct)
In the formula:
c1-5800.2206, constant;
c21.3914993, constant;
c3-0.048640239, constant;
c40.000041764768, constant;
c5——-1.4452093×10-8constant;
c66.5459673, constant.
The simplified calculation formula can be obtained from the above control operation logic and formula:
the volume calculation formula of the saturated water vapor required to be output when the humidity needs to be increased is as follows:
the volume calculation formula of the required output dry air when the humidity needs to be reduced is as follows:
in the formula:
V′1-volume of saturated water vapour, m, required to be output3；
V′2Required output of volume of dry air, m3；
V-volume in air duct of calibrating device, m3；
m1The mass of saturated steam is required to be increased in the space with the volume of V, kg;
m2-1 m per exchange3The mass of water vapor added to the gas, kg;
m3in the space with the volume V, the mass of saturated steam needs to be reduced, kg;
m4-1 m per exchange3Mass of water vapor reduced by the current gas, kg;
rho' -the density difference of unsaturated water vapor under the current temperature and humidity and the set temperature and humidity, kg/m3；
ρqbSaturated steam density, kg/m3；
ρq0-setting the state of the unsaturated water vapour density, kg/m3；
ρq1Current state of unsaturated water vapor density, kg/m3；
4 examples of
Table 5 assumed experimental conditions
Table 6 example 1: when the humidity needs to be increased
Table 7 example 2: when humidity needs to be reduced
Claims (10)
1. The utility model provides an in situ environment simulation wet bulb temperature calibrating device which characterized in that: the air conditioner comprises a shell, a rectangular annular circulating air duct arranged in the shell, and an inner shell arranged at a central neutral position of the annular air duct; the calibration device also comprises a drying device, a humidifying device, a sensor device, an air circulation device with adjustable air speed, a constant temperature device and a controller; wherein, the drying device and the humidifying device are arranged in the inner shell; the controller is arranged on the shell;
1) a drying device: the air dryer comprises a drying cavity, an air pump, a filter screen, a stirring fan and a connecting pipeline, wherein an air dryer (namely a dehumidifier) and the stirring fan are installed in the drying cavity; dry air is provided for the inside of the circulating air duct of the calibration device, so that the relative humidity of circulating air is reduced, and dry air with a specified volume can be output according to the program design;
2) a humidifying device: the ultrasonic humidifying device comprises an ultrasonic humidifying cavity, an air pump, a filter screen, a stirring fan and a connecting pipeline, wherein the air pump is installed at an air inlet pipe of the ultrasonic humidifying cavity, the filter screen is installed at an air outlet pipe, an ultrasonic steam generator (namely a humidifier) and the stirring fan are installed in the ultrasonic humidifying cavity, and the air inlet pipe and the air outlet pipe are respectively connected with different positions of a circulating air channel; saturated wet steam is provided for the calibration device in the circulating air duct and is used for increasing the relative humidity of circulating gas, and saturated water vapor with a specified volume can be output according to the program design;
3) a sensor device: the device comprises a hot-bulb anemometer, a platinum resistance temperature sensor and a dry-wet integrated temperature and humidity sensor, wherein the platinum resistance temperature sensors are respectively arranged in a drying cavity and a saturated ultrasonic humidifying cavity, the hot-bulb anemometer, the dry-wet integrated temperature and humidity sensor and a calibrated wet bulb are arranged in a circulating air channel, and the hot-bulb anemometer, the dry-wet integrated temperature and humidity sensor and the calibrated wet bulb are close to each other in the circulating air channel and are used for monitoring the temperature, humidity and air speed in the circulating air channel, a dryer and a saturated steam generator and transmitting information to a controller in real time; two dry-wet integrated temperature and humidity sensors are arranged on the same cross section behind the calibrated wet bulb, and the accuracy and reliability of the sensors and the temperature and humidity in the wind measuring channel are verified by comparing the feedback data of the two sensors;
4) air circulation device that the wind speed is adjustable: comprises an air duct, a frequency converter, a stabilized voltage power supply, a fan, a guide plate and a rectifying plate; the circulating air duct is a rectangular closed annular channel, arc-shaped bent guide plates are arranged at each corner of the circulating air duct, and straight pipe section rectifying plates are arranged on the straight pipe sections close to the corners; a fan is arranged in the circulating air duct and is connected with the frequency converter and the stabilized voltage power supply; the air circulation device is a closed type gas internal circulation device, does not exchange gas with the outside in the operation process, and provides a stable and controllable wind speed environment for the calibrated sensor;
5) a constant temperature device: the device comprises a Peltier patch, wherein the Peltier patch is respectively arranged in a drying cavity, an ultrasonic humidifying cavity and a circulating air duct; and supplying heat and cold required for stabilizing the temperature to the circulating air duct, the dryer and the saturated steam generator of the calibrating device.
2. The in-situ environment simulated wet bulb temperature calibration device of claim 1, wherein: in the circulating air duct, a foreign matter prevention gauze is arranged in front of the straight pipe section rectifying plate; the drying device, the humidifying device, the frequency converter and the stabilized voltage supply are arranged in the inner shell together; and the controller adopts a PLC controller or a singlechip.
3. The in-situ environment simulated wet bulb temperature calibration device of claim 1 or 2, wherein: in the circulating air duct, the calibration device test area is arranged by the humidity calibration ball and the hot ball anemometer side by side, is positioned in the same section and is positioned in the straight pipe section of the circulating air duct.
4. The in-situ environment simulated wet bulb temperature calibration device of claim 1 or 2, wherein: in the circulating air duct, the guide plates at the right-angle bend are designed into circular arcs with the radius of 5cm and the radius of 1/4, and are uniformly distributed at the bend; the guide plate is made of a solid plate with the thickness of 0.5-1 mm.
5. The in-situ environment simulated wet bulb temperature calibration device of claim 1 or 2, wherein: when the width of the circulating air duct is 150mm, 5 guide plates are uniformly arranged at the right-angle bend.
6. The in-situ environment simulated wet bulb temperature calibration device of claim 1 or 2, wherein: in the circulating air duct, extension plates with the length equal to the radius of the circular arc are additionally arranged at the two ends of the guide plate, and the extension plates are arranged in parallel with the circulating air duct; the turbulence can be reduced, the pressure difference between the air inlet end and the air outlet end on the two sides of the guide plate is synchronously reduced, and the air quantity loss is reduced.
7. The in-situ environment simulated wet bulb temperature calibration device of claim 1 or 2, wherein: in the circulating air duct, the straight pipe section rectifying plate adopts a hexagonal section, the hole height is 10mm, and the thickness is 100mm, the section of the rectifying plate is honeycomb-shaped, and the central line of the hole is vertical to the plate surface.
8. The in-situ environment simulated wet bulb temperature calibration device of claim 1 or 2, wherein: in the circulating air duct, the section hexagon of the straight pipe section rectifying plate is a hexagon unit with an opening on the side wall, and the function of balancing the pressure among the units is achieved when airflow just enters the rectifying plate; meanwhile, in order to ensure that the airflow does not form new turbulence in the rectifying plate due to the opening, a steady flow section with a certain length needs to be ensured to ensure that the airflow flowing out of the rectifying plate is uniform and stable, the length of the opening section accounts for 1/3 of the length of the hexagonal unit, namely the thickness of the plate, and the opening ratio (namely the total area of the unit openings/the unit sectional area) is about 40 percent.
9. The humidity calibration method of the in-situ environment simulation wet bulb temperature calibration device of claim 1, characterized by comprising the following steps: the method comprises the following steps:
(1) calculating the difference rho' between the unsaturated water vapor density at the current temperature and the set temperature and humidity according to the result measured by the standard temperature and humidity sensor to obtain how many grams of water vapor are lacked or excess per cubic meter; because the volume V of the air channel of the calibrating device is fixed and the value can be measured, the mass m of the air channel with the lack or the excessive water vapor can be calculated by using the volume V and the density difference rho1；
(2) When the measured value is lower than the set value, because the device is a closed cavity, the saturated steam generator outputs gas with the volume which needs to be sucked from the air duct, and the saturated steam density rho is usedqbSubtracting the unsaturated water vapor density rho under the actual temperature and humidity stateq1To obtain the saturated steam generator per 1m of exchange3Mass m of water vapor added by gas2，m1/m2Obtaining the volume of saturated vapor to be output in the air duct with the volume V;
(3) when the measured value is higher than the set value, because the device is a closed cavity, the drier needs to suck gas with the volume from the air duct according to the output gas with the volume, and the drier exchanges 1m every time3Mass m of water vapor reduced by gas2Is numerically equal to the density rho of unsaturated water vapor in the actual measurement stateq1，m1/m2The volume of the dry air to be output in the air duct with the volume V is obtained.
10. The humidity calibration method of the in-situ environment simulation wet bulb temperature calibration device according to claim 9, wherein: the method comprises the following steps:
the main state parameters of dry air and water vapor, namely the pressure, the temperature, the specific volume and the like, are expressed by using the equation of state of an ideal gas, namely:
PgV＝mgRgt or Pgvg＝RgT
PqV＝mqRqT or Pqvq＝RqT
In the formula:
Pg、Pq-the pressure of dry air and water vapour, Pa;
v-total volume of humid air, m3；
mg、mq-mass of dry air and water vapour, kg;
Rg、Rqthe gas constants of dry air and water vapor, Rg 287J/(kg K), Rq＝461J/(kg·K)；
vgSpecific dry air volume, m3/kg；
vqSpecific volume of water vapor, m3/kg；
T-dry air thermodynamic temperature, (273.15+ T) ° C;
the specific volumes of the dry air and the water vapor are respectively as follows:
the dry air and water vapor densities are equal to the inverse of the specific volume:
in the formula:
ρgdry air density, kg/m3；
ρqWater vapor density, kg/m3；
According to dalton's law, the pressure of the humid air should be equal to the sum of the dry air pressure and the water vapor pressure, i.e.:
B＝Pg+Pq
in the formula:
b-generally referred to as atmospheric pressure, the standard atmospheric pressure at sea level is 101325 Pa.
The density ρ of the humid air is equal to the sum of the dry air density and the water vapor density, i.e.:
in the formula:
rho-wet air density, kg/m3；
Relative humidity
Defined as the ratio of the water vapor pressure of humid air to the water vapor pressure of saturated humid air at the same temperature, i.e.:
in the formula:
Pq·bsaturated water vapour pressure, Pa.
P can be calculated by using Hyland-Wexler empirical formulaq·bAnd when t is (0-200) DEG C:
in the formula:
c1-5800.2206, constant;
c21.3914993, constant;
c3-0.048640239, constant;
c40.000041764768, constant;
c5——-1.4452093×10-8constant;
c66.5459673, constant.
In the formula:
ρq0-setting the state of the unsaturated water vapour density, kg/m3；
Pq1Current state of unsaturated water vapor density, kg/m3；
ρqbSaturated steam density, kg/m3；
the simplified calculation formula can be obtained from the above control operation logic and formula:
the volume calculation formula of the saturated water vapor required to be output when the humidity needs to be increased is as follows:
the volume calculation formula of the required output dry air when the humidity needs to be reduced is as follows:
in the formula:
V′1-volume of saturated water vapour, m, required to be output3；
V′2Required output of volume of dry air, m3；
V-volume in air duct of calibrating device, m3；
m1The mass of saturated steam is required to be increased in the space with the volume of V, kg;
m2-1 m per exchange3The mass of water vapor added to the gas, kg;
m3in the space with the volume V, the mass of saturated steam needs to be reduced, kg;
m4-1 m per exchange3Mass of water vapor reduced by the current gas, kg;
rho' -the density difference of unsaturated water vapor under the current temperature and humidity and the set temperature and humidity, kg/m3。
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