CN113514494B - Air humidity measurement experiment table based on adiabatic evaporation process - Google Patents
Air humidity measurement experiment table based on adiabatic evaporation process Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 64
- 238000005259 measurement Methods 0.000 title claims abstract description 26
- 238000002474 experimental method Methods 0.000 title claims abstract description 24
- 238000001704 evaporation Methods 0.000 title claims abstract description 21
- 230000008020 evaporation Effects 0.000 title claims abstract description 20
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 243
- 238000006243 chemical reaction Methods 0.000 claims abstract description 58
- 229920006395 saturated elastomer Polymers 0.000 claims abstract description 42
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- 238000007599 discharging Methods 0.000 claims description 4
- 238000000889 atomisation Methods 0.000 claims description 3
- 238000010992 reflux Methods 0.000 claims description 3
- 238000009413 insulation Methods 0.000 abstract description 3
- KWGKDLIKAYFUFQ-UHFFFAOYSA-M lithium chloride Chemical compound [Li+].[Cl-] KWGKDLIKAYFUFQ-UHFFFAOYSA-M 0.000 description 13
- 238000000691 measurement method Methods 0.000 description 9
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 8
- 238000005516 engineering process Methods 0.000 description 5
- 239000000243 solution Substances 0.000 description 5
- 238000005868 electrolysis reaction Methods 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- DLYUQMMRRRQYAE-UHFFFAOYSA-N tetraphosphorus decaoxide Chemical compound O1P(O2)(=O)OP3(=O)OP1(=O)OP2(=O)O3 DLYUQMMRRRQYAE-UHFFFAOYSA-N 0.000 description 4
- 241000282414 Homo sapiens Species 0.000 description 3
- 238000011161 development Methods 0.000 description 3
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- 238000004364 calculation method Methods 0.000 description 2
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- 230000007423 decrease Effects 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 238000004134 energy conservation Methods 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000006837 decompression Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- YQCIWBXEVYWRCW-UHFFFAOYSA-N methane;sulfane Chemical compound C.S YQCIWBXEVYWRCW-UHFFFAOYSA-N 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 238000005381 potential energy Methods 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N25/00—Investigating or analyzing materials by the use of thermal means
- G01N25/20—Investigating or analyzing materials by the use of thermal means by investigating the development of heat, i.e. calorimetry, e.g. by measuring specific heat, by measuring thermal conductivity
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N25/00—Investigating or analyzing materials by the use of thermal means
- G01N25/56—Investigating or analyzing materials by the use of thermal means by investigating moisture content
- G01N25/62—Investigating or analyzing materials by the use of thermal means by investigating moisture content by psychrometric means, e.g. wet-and-dry bulb thermometers
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Abstract
The invention relates to an air humidity measurement experiment table based on an adiabatic evaporation process, which comprises an air supply device, a water supply device, a reaction device, a controller, a first temperature sensor, a first pressure sensor and a second temperature sensor. The air supply device continuously provides unsaturated steady flow air for the reaction device in the experimental process, the water supply device continuously provides atomized water for the reaction device in the experimental process, and the reaction device provides a heat insulation environment, so that the unsaturated steady flow air reacts with the atomized water to obtain saturated air. Simultaneously, the first temperature of saturated air, the first pressure of saturated air and the second temperature of unsaturated steady flow air are measured respectively, the controller calculates the humidity of the unsaturated steady flow air according to the first temperature, the first pressure and the second temperature, and then the air humidity of the unsaturated steady flow air at any temperature and any pressure can be measured by taking water and air as media based on the adiabatic evaporation process, so that the measurement result is accurate and the precision is high.
Description
Technical Field
The invention relates to the technical field of humidity detection, in particular to an air humidity measurement experiment table based on an adiabatic evaporation process.
Background
Along with the increasing development of society and technology, human beings have also been deeply aware of humidity, and humidity measurement techniques and measurement methods have also been rapidly developed. Currently, the common humidity measurement method is the telescoping method. The substance will change in length when humidity changes, for example when the relative humidity changes from 0% to 100%, typically the total length of human hair will extend by 2.5%. This change may be amplified by mechanical means and indicated by a pointer, or by mechanical-to-electrical conversion, an electrical signal indicative of the humidity level may be output for measurement and control of humidity.
Hair hygrometers are a typical application of stretch-and-stretch moisture measurement. Compared with various contemporary hygrometers, the device has the advantages of simple structure, convenient use and low cost, but has inherent disadvantages of hysteresis, low precision and the like.
Disclosure of Invention
The invention aims to provide an air humidity measurement experiment table based on an adiabatic evaporation process, which can accurately measure the humidity of air at different temperatures and different pressures.
In order to achieve the above object, the present invention provides the following solutions:
An air humidity measurement experiment table based on an adiabatic evaporation process comprises an air supply device, a water supply device, a reaction device, a controller, a first temperature sensor, a first pressure sensor and a second temperature sensor which are respectively in communication connection with the controller;
the air supply device is connected with the air inlet of the reaction device; the air supply device is used for continuously supplying unsaturated steady flow air to the reaction device in the experimental process;
The water supply device is connected with the reaction device; the water supply device is used for continuously supplying atomized water to the reaction device in the experimental process;
The reaction device is used for providing an adiabatic environment to enable the unsaturated steady flow air and the atomized water to react to obtain saturated air;
The first temperature sensor is used for measuring a first temperature of the saturated air; the first pressure sensor is used for measuring a first pressure of the saturated air; the second temperature sensor is used for measuring a second temperature of the unsaturated steady flow air;
The controller is used for calculating the humidity of the unsaturated steady flow air according to the first temperature, the first pressure and the second temperature.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
The invention provides an air humidity measurement experiment table based on an adiabatic evaporation process, which comprises an air supply device, a water supply device, a reaction device, a controller, a first temperature sensor, a first pressure sensor and a second temperature sensor, wherein the first temperature sensor, the first pressure sensor and the second temperature sensor are respectively in communication connection with the controller. The air supply device continuously provides unsaturated steady flow air for the reaction device in the experimental process, the water supply device continuously provides atomized water for the reaction device in the experimental process, and the reaction device provides a heat insulation environment, so that the unsaturated steady flow air reacts with the atomized water to obtain saturated air. Simultaneously, measure the first temperature of saturated air, the first pressure of saturated air and the second temperature of unsaturated stationary flow air respectively, the humidity of unsaturated stationary flow air is calculated according to first temperature, first pressure and second temperature to the controller, and then can regard water and air as the medium based on adiabatic evaporation process, and the measurement is accurate, the precision is high at arbitrary temperature, arbitrary pressure's air humidity.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic structural diagram of a laboratory bench according to embodiment 1 of the present invention.
Fig. 2 is a control schematic diagram of the laboratory bench according to embodiment 1 of the present invention.
Symbol description:
1: a gas supply device; 2: a water supply device; 3: a reaction device; 4: a controller; 5: a first temperature sensor; 6: a first pressure sensor; 7: a second temperature sensor; 8: a second pressure sensor; 9: an air intake duct; 10: a water return pipe; 11: a water storage tank; 12: a second flow sensor; 13: a drainage pipe; 14: a second shut-off valve; 15: a third stop valve; 16-water inlet; 17: a first water inlet pipe; 18: a second water inlet pipe; 19: a fourth shut-off valve; 20-a reflux port; 1-1: a gas supply part; 1-2: a pressure reducing valve; 2-1: a water inlet pipe; 2-2: a water pump; 2-3: a water distribution pipeline; 2-4: an atomizing nozzle; 2-5: a first stop valve; 2-6: a first flow sensor; 10-1: a first return pipe; 10-2: and a second return pipe.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention aims to provide an air humidity measurement experiment table based on an adiabatic evaporation process, which can accurately measure the humidity of air at different temperatures and different pressures.
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.
Example 1:
Along with the increasing development of society and technology, human beings have also been deeply aware of humidity, and humidity measurement techniques and measurement methods have also been rapidly developed. However, the output parameters to be tested are distinguished from each other, and besides the wet measurement method (telescoping method) using the geometric dimensional change of the substance mentioned in the background art, the following categories are mainly used: wet and dry bulb methods, condensation dew point methods, lithium chloride dew point methods, electro-hygrometry (resistance method, capacitance method), electrolysis (coulomb hygrometer), and the like.
1. The telescoping method comprises the following steps:
The hair hygrometer in the telescopic method is a typical application of the telescopic method for humidity measurement, has the advantages of simple structure, convenient use and low cost compared with various current hygrometers, and even if the humidity sensor such as hair, casing and the like is still used by people in the present situation and the requirement of humidity measurement at the present day with highly developed scientific technology. However, there are also drawbacks inherent in hysteresis, low accuracy, and the like.
2. Dry and wet ball method:
The wet and dry bulb hygrometer consists of two thermometers with identical specifications, one is called a dry bulb thermometer, and the temperature bulb is exposed to air for measuring the ambient temperature. Another known as a wet bulb thermometer, the bulb is wrapped with a special gauze and tries to keep the gauze moist, and the moisture in the gauze continuously evaporates into the surrounding air and takes away heat, causing the wet bulb temperature to drop. The rate of moisture evaporation is related to the moisture content of the surrounding air, with lower air humidity, faster moisture evaporation rates resulting in lower wet bulb temperatures. It can be seen that there is a functional relationship between air humidity and wet and dry bulb temperature difference. The wet and dry bulb hygrometer uses this phenomenon to determine the air humidity by measuring the wet and dry bulb temperatures.
However, this method can only be used over a measurement range of 0℃or more, typically 10 to 40 ℃. In order to ensure that the surface of the wet ball is moist, a water container or a set of water supply system is required to be arranged, and gauze is also kept clean frequently, so that maintenance work is troublesome at ordinary times, otherwise, certain additional errors are brought.
3. Condensation dew point method
The dew point method is an ancient humidity measurement method, and with the development of scientific technology, the dew point technology is perfected. Modern photoelectric dew point meters use thermoelectric refrigeration and can automatically compensate zero points and continuously track and measure dew points. The measurement accuracy of the high-accuracy dew point meter in a general humidity range can reach the dew point temperature of +/-1 ℃.
The principle of dew point hygrometers can be illustrated by a simple experiment. If a clean metal surface is placed in air having a relative humidity of less than 100% and allowed to cool, when the temperature drops to a value at which the relative humidity near the surface reaches 100%, then a surface will develop. Because the water vapor in the air is saturated at this temperature, the water film attached to the cold surface and the water in the air are in dynamic equilibrium, that is, the same number of water molecules leave and return to the surface per unit time. The principle can be described as: when a certain volume of wet air is uniformly cooled under constant total pressure until the water vapor in the air reaches a saturated state, the state is called dew point; during cooling, the partial pressure of both gas and water vapor remains unchanged. If the temperature of the air is Ta and the dew generation temperature is Td, the relative humidity of the humid air can be calculated by: u=saturated water vapor pressure at dew point temperature (Td)/saturated water vapor pressure at original temperature (Ta) ×100%, where the value of saturated water vapor pressure can be obtained by look-up table. When the water vapor reaches saturation below 0 ℃, the water freezes on the mirror surface, and the temperature at the moment is called as frost point.
4. Dew point method of lithium chloride
Dew point lithium chloride hygrometers were first developed by the company Forboro in the united states, after which much research work was done in our country and many countries. The hygrometer is similar to the resistive lithium chloride hygrometer in form, but the working principle is quite different. In short, it works with saturated water vapor pressure of lithium chloride saturated aqueous solution as a function of temperature.
According to Raoult's law, the water vapor pressure curve of lithium chloride solution is located below the saturated water vapor pressure of pure water, and at the same temperature, the water vapor pressure of the former is lower than that of the latter, which is approximately equivalent to 10-12% of that of the latter, namely, the equilibrium relative humidity of the saturated lithium chloride solution is 10-12%, because the water vapor pressure on the surface of the solution decreases as the concentration of the salt solution increases.
5. Electrolytic process
The electrolytic method is one of the methods for measuring trace moisture which are widely used at present. This method was first proposed by Keidel in 1956 and is of interest because it not only allows a very low limit to be reached, but more importantly because it is an absolute measurement method. Such electrolytic hygrometers based on faraday's law are often also known as coulomb hygrometers.
The sensitive element of the coulomb hygrometer is an electrolytic cell, and when the detected gas passes through the electrolytic cell, all water vapor in the gas is absorbed by the phosphoric anhydride film coated on the electrode.
The thermometer is characterized in that the gas continuously passes through the electrolytic cell, and water vapor in the gas is fully absorbed by phosphorus pentoxide and electrolyzed. Within a certain range of moisture concentration and flow rate, the rate of moisture absorption and the rate of electrolysis can be considered to be the same, that is, moisture is continuously absorbed while being continuously electrolyzed, so that the instantaneous electrolysis current can be regarded as an expression of the instantaneous value of the gas moisture content. Since the method requires that the moisture in the gas passing through the cells must be absorbed entirely, it is self-evident that the measured value is influenced by the gas flow rate, and therefore, not only a nominal flow rate is present for a certain cell, but also the flow rate must be kept constant during the measurement and an accurate measurement of the flow rate must be performed. Knowing the gas flow rate and the electrolysis current, the moisture concentration can be calculated.
6. Dynamic method
The double-pressure method and the double-temperature method are based on thermodynamic P, V, T balance principle, the balance time is longer, and the split method is based on accurate mixing of absolute humidity and absolute dry air. Due to the adoption of modern measurement and control means, the devices can be quite precise, but because the devices are complex, expensive, time-consuming and labor-consuming to operate, the device is mainly used for standard measurement, and the measurement precision can reach over +/-2% RH.
7. Electronic humidity sensor method
Electronic humidity sensor products and humidity measurement belong to the industry rising in the 90 s, and in recent years, the research and development fields of the humidity sensor are advanced at home and abroad. The humidity sensor of the carbon-sulfur analyzer is rapidly developed from a simple humidity sensor to an integrated, intelligent and multi-parameter detection direction, and creates favorable conditions for developing a new generation humidity measurement and control system. The humidity measurement technique is also improved to new levels.
The air humidity measurement experiment table for measuring air humidity provided by the embodiment is based on an adiabatic evaporation process (a water evaporation process performed under the condition of no heat and mass exchange with the surrounding environment), and uses water and compressed air as media to measure the air humidity (the dry and wet degree of air) under the conditions of different temperatures and different pressures.
As shown in fig. 1 and 2, the air humidity measurement experiment table based on the adiabatic evaporation process provided in the present embodiment includes an air supply device 1, a water supply device 2, a reaction device 3, a controller 4, and a first temperature sensor 5, a first pressure sensor 6, and a second temperature sensor 7 which are communicatively connected to the controller 4, respectively.
The air supply device 1 is connected with an air inlet of the reaction device 3, and the air supply device 1 is used for continuously providing unsaturated steady flow air for the reaction device 3 in the experimental process. The water supply device 2 is connected with the reaction device 3, and the water supply device 2 is used for continuously supplying atomized water to the reaction device 3 in the experimental process. The reaction device 3 is used for providing a heat insulation environment to enable unsaturated steady flow air and atomized water to react to obtain saturated air. Specifically, the reaction device 3 may be an acrylic tank for performing an adiabatic evaporation process experiment. In the acrylic tank, when unsaturated steady flow air flows through the water surface, atomized water is evaporated and mixed with air flow, in the process, as the heat required by the evaporation of the water is derived from the unsaturated steady flow air, the moisture in the unsaturated steady flow air is increased, the temperature is reduced, and the unsaturated steady flow air and the atomized water continuously react until saturated air is obtained, and the experiment is ended. It should be noted that the unsaturated steady flow air has a low water vapor content, and the saturated air reaches the maximum water vapor content at that temperature. Saturated air refers to a state in which the wet air and the water surface are kept in dynamic balance at a given temperature and pressure, and the water vapor pressure of the wet air is called saturated water vapor pressure at this time, and the wet air is called saturated air.
After obtaining the saturated air, in order to solve the humidity value of the unsaturated steady flow air, a plurality of parameters in the experimental process need to be collected in advance, specifically, the first temperature sensor 5 is used for measuring the first temperature of the saturated air, the first pressure sensor 6 is used for measuring the first pressure of the saturated air, and both the first temperature sensor 5 and the first pressure sensor 6 can be arranged at the air outlet of the reaction device 3. The second temperature sensor 7 is used for measuring a second temperature of the unsaturated steady flow air, and the second temperature sensor 7 can be arranged at the air inlet of the reaction device 3. The controller 4 is configured to calculate the humidity of the unsaturated steady flow air based on the first temperature, the first pressure, and the second temperature.
The experiment table provided by the embodiment can introduce unsaturated steady flow air with different temperatures and different pressures into the reaction device 3 through the air inlet, and obtain saturated air after reacting with atomized water provided by the water supply device 2, so that the humidity value of the unsaturated steady flow air can be calculated based on the second temperature of the unsaturated steady flow air and the first temperature and the first pressure of the saturated air, and then the humidity value of the unsaturated steady flow air under different temperatures and different pressures can be measured.
In order to measure the pressure of the unsaturated steady flow air, the laboratory bench of the present embodiment further comprises a second pressure sensor 8. The second pressure sensor 8 may be disposed at an air inlet of the reaction device 3, where the second pressure sensor 8 is configured to measure a second pressure of the unsaturated steady flow air entering the reaction device 3, so as to record the second pressure of the unsaturated steady flow air in real time. The second pressure sensor 8 may be further communicatively connected to the controller 4, so as to transmit the measured second pressure of the unsaturated steady flow air to the controller 4, and thus the controller 4 can know the second pressure and the second temperature of the unsaturated steady flow air corresponding to the calculated humidity value at this time.
As an alternative embodiment, the air supply device 1 of the present embodiment may include an air supply part 1-1 and a pressure reducing valve 1-2. The air supply part 1-1 is connected with the air inlet of the reaction device 3 through an air inlet pipeline 9, and the pressure reducing valve 1-2 is arranged on the air inlet pipeline 9. The air supply part 1-1 is used for providing initial unsaturated steady flow air, and the pressure reducing valve 1-2 is used for reducing the pressure of the initial unsaturated steady flow air provided by the air supply part 1-1 to obtain unsaturated steady flow air provided to the reaction device 3. The pressure reducing valve 1-2 can also be connected with the controller 4, and the opening degree of the pressure reducing valve 1-2 is controlled by the controller 4 so as to regulate the pressure reducing. The initial unsaturated steady flow air can be compressed air prepared in a laboratory, and the compressed air is properly decompressed by observing the indication number of a pressure gauge on the decompression valve 1-2 before the compressed air in the air inlet pipeline 9 enters the reaction device 3 through the air inlet, so that unsaturated steady flow air with different pressures can be obtained. Of course, the pressure reducing valve 1-2 can be replaced by a pressure regulating valve, so that not only can the compressed air be reduced in pressure, but also the compressed air can be pressurized, and different experimental requirements can be met.
The water supply device 2 of this embodiment may include a water inlet pipe 2-1, one end of the water inlet pipe 2-1 is connected with a water pump 2-2, the other end is connected with a plurality of water distribution pipes 2-3, each water distribution pipe 2-3 passes through the reaction device 3 to be connected with an atomizing nozzle 2-4, and the atomizing nozzle 2-4 is located inside the reaction device 3. The water pump 2-2 is used for pumping water in the water storage device, supplying water to the plurality of water distribution pipes 2-3 through the water inlet pipe 2-1, and pressing water into the atomizing nozzle 2-4. The atomizing nozzle 2-4 is used for atomizing water pressed into the atomizing nozzle 2-4 through the water distribution pipe 2-3 to supply the atomized water to the reaction device 3. A schematic diagram of the use of 4 atomising nozzles 2-4 is schematically shown in fig. 1, but in practice other numbers may be chosen according to practical requirements.
In order to be able to regulate the amount of water pressed into the atomizing nozzle 2-4, the present embodiment is provided with a first shut-off valve 2-5 between the water diversion pipe 2-3 and the atomizing nozzle 2-4. The first shut-off valve 2-5 is located on the water distribution pipe 2-3 outside the reaction device 3, and the first shut-off valve 2-5 is used to regulate the amount of water flowing into the atomizing nozzle 2-4. The first stop valve 2-5 can also be in communication connection with the controller 4, and the opening degree of the first stop valve 2-5 is controlled by the controller 4, so that the water quantity flowing into the atomizing nozzle 2-4 is adjusted. In order to be able to record in real time the amount of water provided by the water supply device 2, the water supply device 2 of the present embodiment further comprises a first flow sensor 2-6. A first flow sensor 2-6 is located on the water intake pipe 2-1, the first flow sensor 2-6 being for measuring the flow of water within the water intake pipe 2-1. The first flow sensor 2-6 may also be communicatively coupled to the controller 4 to communicate the flow of water within the inlet conduit 2-1 to the controller 4.
When experimental operation is carried out, the working process of the water supply device 2 is as follows: firstly, a proper amount of water is injected into the water storage device from a water inlet 16 of the water storage device, a master power supply control switch is turned on, water in the water storage device flows into a water pump 2-2, along with the pressure increase of the water pump 2-2, the water in the water pump 2-2 passes through a water inlet pipeline 2-1, passes through a first flow sensor 2-6 and a plurality of water distribution pipelines 2-3 and then is respectively pressed into an opened first stop valve 2-5, and is atomized by an atomization nozzle 2-4 and then enters a reaction device 3.
Since the final objective of the experiment table of this embodiment is to obtain saturated air, measure the first temperature and the first pressure of the saturated air, and calculate the humidity value of the unsaturated steady flow air by combining the second temperature of the unsaturated steady flow air. Therefore, after saturated air is obtained, the experimental process of the experiment table is finished. In order to accurately determine when the experimental procedure is completed, the return port 20 of the reaction apparatus 3 of the present embodiment is connected to a water storage tank 11 through a return pipe 10. The return water pipe 10 is provided with a second flow sensor 12, and the second flow sensor 12 is in communication connection with the controller 4. The second flow sensor 12 is used for detecting whether water exists in the water return pipeline 10, when water exists in the water return pipeline 10, unsaturated steady flow air in the reaction device 3 is converted into saturated air, and the experimental process is finished.
As another alternative embodiment, the return water pipe 10 includes a first return water pipe 10-1 and a second return water pipe 10-2. One end of the first water return pipe 10-1 is connected with a return port 20 of the reaction device 3, one end of the second water return pipe 10-2 is connected with the water storage tank 11, and the other end of the first water return pipe 10-1 is connected with the other end of the second water return pipe 10-2 through a transparent hose. The presence or absence of water flow in the transparent hose connected between the first water return pipe 10-1 and the second water return pipe 10-2 was observed, and when water flow was present in the transparent hose, it was explained that water in the reaction apparatus 3 began to flow out from the return port 20, and at this time, air was saturated air at the temperature T2, and T2 was called adiabatic saturation temperature, and the experiment was ended.
The controller 4 is also used for controlling the first temperature sensor 5 and the first pressure sensor 6 to start working when water exists in the water return pipeline 10, and respectively measuring the first temperature and the first pressure of saturated air. And then can directly make first temperature sensor 5 and first pressure sensor 6 gather saturated air's first temperature and first pressure, can not gather other useless data, save the resource. The water supply device 2 and the air supply device 1 are both in communication connection with the controller 4, and the controller 4 is also used for respectively controlling the water supply device 2 and the air supply device 1 to stop working when water exists in the water return pipeline 10, so that resources are saved.
The inlet conduit 2-1 may comprise a first inlet conduit 17 and a second inlet conduit 18. One end of the first water inlet pipe 17 is connected with the water pump 2-2, and the other end is connected with the first flow sensor 2-6. The other end of the first flow sensor 2-6 is connected with one end of a second water inlet pipe 18, and the other end of the second water inlet pipe 18 is connected with a plurality of water distribution pipes 2-3. The junction of the first water inlet pipe 17 and the first flow sensor 2-6 is also connected with the water storage tank 11 through the water drainage pipeline 13, the water drainage pipeline 13 is provided with a second stop valve 14, and the second stop valve 14 is in communication connection with the controller 4. The controller 4 is also used for controlling the second stop valve 14 to be opened when water exists in the water return pipeline 10, and discharging the water in the first stop valve 2-5, the water diversion pipeline 2-3 and the second water inlet pipe 18 into the water storage tank 11 through the water discharge pipeline 13. The second stop valve 14 may also be communicatively connected to the controller 4, and the opening of the second stop valve 14 is controlled by the controller 4 to regulate the water flow.
The laboratory bench still includes the third stop valve 15 that installs in the gas outlet department of reaction unit 3, and third stop valve 15 is connected with controller 4 communication. The controller 4 is also used for controlling the third stop valve 15 to open when water exists in the water return pipeline 10, and discharging saturated air in the reaction device 3. The opening degree of the third cutoff valve 15 is controlled by the controller 4 to adjust the air flow.
The return water pipe 10 is also provided with a fourth shut-off valve 19, and the fourth shut-off valve 19 is opened when the experiment is started. When the experiment is completed, the water remaining in the reaction device 3 flows into the water storage tank 11 through the return port 20, the fourth shut-off valve 19, and the return water pipe 10. In order to save components, the water storage device in the water supply device 2 and the water storage tank 11 can be integrated, i.e. the water supply device 2 also adopts the water storage tank 11 as the water storage device. The fourth stop valve 19 may also be communicatively connected to the controller 4, and the opening of the fourth stop valve 19 is controlled by the controller 4 to regulate the water flow rate in the return water pipe 10.
Based on the specific structure of the above-described laboratory bench, the operation process of the laboratory bench will be briefly described herein. When experimental operation is carried out, a proper amount of water is firstly injected into the water storage tank 11 from the water inlet 16, the total power supply control switch is turned on, the water in the water storage tank 11 flows into the water pump 2-2, and along with the pressure increase of the water pump 2-2, the water in the water pump 2-2 is pressed into the opened first stop valve 2-5 after passing through the first flow sensor 2-6, the second water inlet pipe 18 and the plurality of water distribution pipes 2-3 through the first water inlet pipe 17, and is atomized through the atomization nozzle 2-4 and then enters the acrylic tank. Meanwhile, unsaturated steady flow air with the temperature of T 1 and the humidity of w 1 continuously passes through the pressure reducing valve 1-2, the second temperature sensor 7 and the second pressure sensor 8 and then enters the acrylic tank from the air inlet, and w 1 is a parameter to be solved. In the acrylic tank, when the air flows through the water surface, atomized water is evaporated and mixed with the air flow, in the process, the water in the air is increased, the temperature is reduced, the fourth stop valve 19 is opened before the total power supply is switched on, whether the water in the acrylic tank flows out from the reflux port 20 or not is determined by observing whether a transparent hose connected between the first water return pipe 10-1 and the second water return pipe 10-2, the air becomes saturated air at the temperature T 2, and the temperature T 2 is called adiabatic saturation temperature, and the experiment is ended. At this time, the first pressure sensor 6 and the first temperature sensor 5 measure the first pressure and the first temperature of the saturated air in the acrylic tank. The power switch is turned off, and the water remaining in the acrylic tank flows into the water storage tank 11 through the return port 20 and the opened fourth shut-off valve 19 through the return pipe 10. The second stop valve 14 is opened, and the redundant water in the first stop valve 2-5 and the water diversion pipeline 2-3 and the second water inlet pipe 18 respectively connected with the first stop valve passes through the second stop valve 14 and flows into the water storage tank 11. Finally, the water in the water storage tank 11 is discharged through the water discharge port.
The parameters of the experiment table of this example are shown in table 1.
Table 1 table technical parameters
| Parameters (parameters) | Unit (B) | Numerical value |
| Maximum working pressure | MPa | 0.5 |
| Use temperature | ℃ | Normal temperature |
| Maximum working flow rate | L/min | 10 |
| Experimental Medium | / | Water, air |
| Accuracy of pressure | ％ | 0.2 |
| Flow accuracy | ％ | 0.5 |
| Temperature accuracy | ％ | 0.2 |
| Acquisition rate | Hz | ≥1 |
| Power supply | / | 220V±10V |
Since the experimental process performed using the experimental bench of this embodiment has no interaction of heat and work, the change of kinetic energy and gravitational potential energy is negligible. Therefore, the mass energy conservation relationship of the experiment table (the steady flow system with double inlets (air inlet and water inlet, single outlet (air outlet)) used in the embodiment can be simplified.
Since the dry air flow rate is constant, the mass conservation can be obtained:
In the formula 1, the components are mixed, The mass flow rate of the dry air at the inlet; the mass flow of dry air at the outlet; is a specific numerical value.
In the formula 2, the components are mixed,Is the mass flow of water vapor at the inlet; Is the mass flow of the water vapor at the outlet; for evaporating the mass flow of water.
Due to From formulas 1 and 2:
in formula 3, w 1 is the moisture content of the air at the inlet; w 2 is the moisture content of the air at the outlet.
As can be obtained from the method according to 3,
From the opening system energy equation:
In formula 5, h 1 is the specific enthalpy of the air at the inlet; h 2 is the specific enthalpy of the air at the outlet; h f is the specific enthalpy of the liquid water. Specific enthalpy is the enthalpy of a mass of a substance, and the specific enthalpy of an ideal gas is only a function of temperature.
From the formulae (4) and (5):
Due to h 1＝ha1+w1hg1,h2＝ha2+w2hg2, equation 6 is further expanded to:
ha1+w1hg1+(w2-w1)hf＝ha2+w2hg2 (7)
In formula 7, h a1 is the specific enthalpy of the dry air at the inlet; h g1 is the specific enthalpy of saturated steam at the inlet; h a2 is the specific enthalpy of the dry air at the outlet; h g2 is the specific enthalpy of the saturated water vapor at the outlet. The values of the two parameters h g1 and h g2 are obtained by comparing the standard specific enthalpy tables at the corresponding temperatures, namely directly obtained by looking up a table.
Due to h a2-ha1＝cp(T2-T1), according to equation 7:
In the formula 8, c p is the constant pressure specific heat capacity of dry air, the constant pressure specific heat capacity refers to the heat required to be absorbed when the temperature of a certain substance per unit mass is increased by 1K under the condition of unchanged pressure, and the value of the constant pressure specific heat capacity is obtained by looking up a table; t 2 is the temperature at the outlet, i.e., the first temperature of saturated air, and T 1 is the temperature at the inlet, i.e., the second temperature of unsaturated steady flow air.
Wherein w 2 is calculated by the following formula:
In the formula 9, p g2 is the partial pressure of saturated steam at the outlet, and p g2 is obtained by comparing with a standard pressure gauge at a corresponding temperature, namely, is directly obtained by looking up a table; p 2 is the pressure at the outlet, i.e. the first pressure of saturated air.
According to the embodiment, firstly, the mass flow evaporation growth rate of vapor in the air is calculated according to the mass conservation law, and then the vapor is expanded by the energy equation of the opening system, so that an air humidity calculation formula at the adiabatic saturation temperature can be obtained. Based on equation 8, after the first temperature, the first pressure, and the second temperature are acquired, the humidity value of the unsaturated steady flow air can be calculated.
The experimental bench of the embodiment adopts adiabatic evaporation, and the measured air humidity is a process without mass and heat exchange with the surrounding environment, and can measure the air humidity under different temperature and pressure conditions. In this embodiment, when unsaturated air at a certain pressure and temperature flows over the water surface, the temperature of the air decreases as moisture evaporates, and the process is performed under adiabatic conditions, so that the process is a process without heat exchange or mass exchange with the surrounding environment. The air humidity value is obtained according to the mass energy conservation relation of the steady flow system with double inlets and single outlet, and the air humidity value under certain temperature and pressure conditions is obtained in a calculation mode, so that the error is small.
In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other.
The principles and embodiments of the present invention have been described herein with reference to specific examples, the description of which is intended only to assist in understanding the methods of the present invention and the core ideas thereof; also, it is within the scope of the present invention to be modified by those of ordinary skill in the art in light of the present teachings. In view of the foregoing, this description should not be construed as limiting the invention.
Claims (5)
1. An air humidity measurement experiment table based on an adiabatic evaporation process is characterized by comprising an air supply device, a water supply device, a reaction device, a controller, a first temperature sensor, a first pressure sensor and a second temperature sensor which are respectively in communication connection with the controller;
the air supply device is connected with the air inlet of the reaction device; the air supply device is used for continuously supplying unsaturated steady flow air to the reaction device in the experimental process;
The water supply device is connected with the reaction device; the water supply device is used for continuously supplying atomized water to the reaction device in the experimental process;
The reaction device is used for providing an adiabatic environment to enable the unsaturated steady flow air and the atomized water to react to obtain saturated air;
The first temperature sensor is used for measuring a first temperature of the saturated air; the first pressure sensor is used for measuring a first pressure of the saturated air; the second temperature sensor is used for measuring a second temperature of the unsaturated steady flow air;
the controller is used for calculating the humidity of the unsaturated steady flow air according to the first temperature, the first pressure and the second temperature;
The air supply device comprises an air supply component and a pressure regulating valve; the air supply part is connected with the air inlet through an air inlet pipeline; the pressure regulating valve is arranged on the air inlet pipeline; the pressure regulating valve is used for regulating the pressure of the initial unsaturated steady flow air provided by the air supply part to obtain unsaturated steady flow air provided for the reaction device;
The water supply device comprises a water inlet pipeline; one end of the water inlet pipeline is connected with the water pump, and the other end of the water inlet pipeline is connected with a plurality of water distribution pipelines; each water diversion pipeline penetrates through the reaction device and is connected with an atomization nozzle; the atomizing nozzle is positioned in the reaction device;
the water pump is used for providing water for the water diversion pipelines through the water inlet pipeline respectively;
The atomizing nozzle is used for atomizing the water and providing atomized water for the reaction device;
The reflux port of the reaction device is connected with a water storage tank through a water return pipeline; a second flow sensor is arranged on the water return pipeline; the second flow sensor is in communication with the controller; the second flow sensor is used for detecting whether water exists in the water return pipeline or not; when water exists in the water return pipeline, unsaturated steady flow air in the reaction device is converted into saturated air;
the controller is also used for controlling the first temperature sensor and the first pressure sensor to start working when water exists in the water return pipeline, and measuring the first temperature and the first pressure of the saturated air respectively;
The water supply device and the air supply device are both in communication connection with the controller; the controller is also used for respectively controlling the water supply device and the air supply device to stop working when water exists in the water return pipeline;
The water inlet pipeline is also connected with the water storage tank through a drainage pipeline; the drainage pipeline is provided with a second stop valve; the second stop valve is in communication connection with the controller; the controller is also used for controlling the second stop valve to be opened when water exists in the water return pipeline, and discharging the water in the water inlet pipeline into the water storage tank through the water discharge pipeline.
2. The laboratory bench of claim 1, further comprising a second pressure sensor; the second pressure sensor is arranged at the air inlet; the second pressure sensor is used for measuring a second pressure of the unsaturated steady flow air.
3. The laboratory bench according to claim 1, characterized in that a first shut-off valve is arranged between said water distribution pipe and said atomizing nozzle; the first stop valve is positioned on the water distribution pipeline outside the reaction device; the first shut-off valve is used for regulating the water quantity flowing into the atomizing nozzle.
4. The laboratory bench according to claim 1, wherein said water supply further comprises a first flow sensor; the first flow sensor is positioned on the water inlet pipeline; the first flow sensor is used for measuring the flow of water in the water inlet pipeline.
5. The laboratory bench according to claim 1, further comprising a third shut-off valve mounted at an air outlet of said reaction device; the third stop valve is in communication connection with the controller; the controller is also used for controlling the third stop valve to be opened when water exists in the water return pipeline, and discharging saturated air in the reaction device.
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| CS240279B1 (en) * | 1983-07-25 | 1986-02-13 | Lubos Hes | Gas and combustion products moisture measuring device |
| US4559823A (en) * | 1984-05-30 | 1985-12-24 | The United States Of America As Represented By The Secretary Of Agriculture | Device and method for measuring the energy content of hot and humid air streams |
| SU1300366A1 (en) * | 1986-02-12 | 1987-03-30 | Московский технологический институт пищевой промышленности | Psychrometer |
| DE4005744C1 (en) * | 1990-02-23 | 1991-11-21 | Hans-Christian Prof. Dr.-Ing. 4513 Belm De Gudehus | |
| US5343747A (en) * | 1992-06-08 | 1994-09-06 | Jay Rosen | Normalized relative humidity calibration |
| DE10337306A1 (en) * | 2003-08-14 | 2005-03-10 | Il Metronic Sensortechnik Gmbh | Method and arrangement for measuring water activity |
| CN100498316C (en) * | 2004-04-19 | 2009-06-10 | 西北工业大学 | Mixing type method and apparatus for measuring dryness of vapor according to energy conservation |
| CN1269553C (en) * | 2004-06-18 | 2006-08-16 | 清华大学 | Water spray quantity control system and control method for semi-dry process flue gas desulfurization technology |
| CN100573129C (en) * | 2006-05-31 | 2009-12-23 | 西北工业大学 | A kind of coagulating type steam quality measurement device and measuring method |
| CN107975898A (en) * | 2017-11-24 | 2018-05-01 | 四川依米康环境科技股份有限公司 | One kind evaporates cold evaporated water control device and its control method |
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