Apparatus and method for measuring and demonstrating the volume of closed containers for energy dynamics

Abstract

This invention relates to the technical field of experimental teaching equipment for engineering applications in energy and power engineering, and discloses a device and method for measuring and demonstrating the volume of a closed container in energy dynamics. The device includes: a closed container to be tested, on which a temperature sensor and a pressure sensor are installed; the outlet of a working fluid storage tank is connected to the inlet of the closed container to be tested via a pipeline; a refrigerant source is connected to the inlet of the working fluid storage tank via a pipeline; a cooling / heating cold trap is detachably connected to the working fluid storage tank; a vacuum unit is connected to both the working fluid storage tank and the closed container to be tested; and a drying unit is used to remove condensation on the surface of the working fluid storage tank. The device measures the volume of the working fluid storage tank after it is filled with refrigerant. m 1. The second mass of the working fluid storage tank after the refrigerant is filled into the sealed container to be tested m 2. Mass difference and density r Obtaining the actual internal volume of the sealed container under test allows students to systematically observe and understand thermodynamic phenomena throughout the entire process of completing a real engineering measurement.

Description

Technical Field

[0001] This invention relates to the field of experimental teaching equipment for engineering applications in energy and power engineering, and in particular to a device and method for measuring and demonstrating the volume of a closed container used in energy dynamics. Background Technology

[0002] In energy and power engineering education, the measurement of the volume of closed containers is both a typical engineering practice problem and a comprehensive vehicle for teaching thermodynamic principles. However, related technologies have failed to organically integrate industrial measurement needs with teaching demonstration functions, resulting in a long-standing disconnect between engineering training and theoretical teaching.

[0003] In industries such as energy and chemicals, reaction vessels, pressure vessels for storage and transportation, and complex closed containers are widely used. Their internal volume is a key technical parameter for material metering, process calculation, and safe operation and maintenance of equipment. Introducing such engineering measurement problems into experimental teaching can provide students with a real engineering background and cultivate their practical ability to solve complex problems.

[0004] Currently, the most common methods for measuring volume include: (1) Geometric measurement method: It is only applicable to regular cavities and is completely unsuitable for irregular or filled containers. It has a huge error and cannot present any thermodynamic process, so it does not have the function of teaching demonstration.

[0005] (2) Water injection / weighing method: It is simple to operate, but it is only suitable for small containers and cannot be used for containers that are sensitive to water, high temperature, or have complex internal components. At the same time, this process is a static physical operation and is not related to the teaching of thermodynamic principles.

[0006] (3) Gas pressure difference method: It relies on the ideal gas assumption, is significantly affected by temperature fluctuations and gas non-ideality, and has low accuracy; moreover, the measurement process is a single parameter reading, which cannot show the law of thermodynamic state change, and has limited teaching value.

[0007] (4) Acoustic resonance method / ray method: The equipment is expensive, the operation is complicated, and the environmental requirements are high, making it unsuitable for large-scale promotion in teaching scenarios.

[0008] Currently, experimental teaching in energy and power engineering at universities still primarily relies on traditional verification experiments. These experiments have fixed procedures and standardized operations, limiting students' hands-on opportunities. Thermodynamic principles, gas-liquid phase transitions, and the differences in gas-liquid properties are core teaching content for energy and power engineering majors, but existing experimental setups suffer from the following prominent problems:

[0009] (1) Principle demonstration is divorced from engineering context: Most existing devices are single principle demonstrations or simple parameter measurements, making it difficult for students to build a cognitive bridge from abstract theory to industrial application.

[0010] (2) Fragmented presentation of thermodynamic phenomena: Typical thermodynamic phenomena such as expansion and cooling, compression and heating, liquefaction and heat release, and vaporization and heat absorption are scattered in different experimental devices. Students cannot observe the entire chain process of working fluid state change in a single experimental system, making it difficult to form a holistic understanding of thermodynamic cycles.

[0011] (3) The measurement process and the demonstration process are separated: the existing volume measurement experiment only outputs the static volume value, and the existing thermodynamic experiment only shows the state change phenomenon. The two are not integrated at the device level and in the teaching design, so students cannot understand the methodological value of "using thermodynamic principles to solve engineering measurement problems".

[0012] (4) Insufficient student participation and openness: Traditional experimental devices are either highly automated or have closed operation links, making it difficult for students to manually control the working fluid state, observe the phase change process, and analyze measurement data throughout the entire process. This makes it impossible for them to deepen their dual mastery of thermodynamic theory and engineering measurement technology in practice.

[0013] Therefore, there is an urgent need to develop an experimental device and method that deeply integrates the precise measurement of the volume of a closed container with the dynamic demonstration of thermodynamic processes. Summary of the Invention

[0014] To address the aforementioned technical problems, this invention provides a device and method for measuring and demonstrating the volume of a closed container in energy dynamics. Using complex closed-volume measurement as the main engineering task and the thermodynamic state changes of the working fluid as the knowledge carrier, it enables students to systematically observe and understand thermodynamic phenomena throughout the entire process of completing real engineering measurements. This achieves the experimental teaching goal of "measurement as teaching, operation as demonstration," and is of great significance for improving the quality of experimental teaching in energy and power engineering majors and cultivating a comprehensive ability to combine engineering practice with theoretical application.

[0015] The first aspect of this invention provides a closed container volume measurement and demonstration device for energy dynamics, comprising: The sealed container to be tested is equipped with a temperature sensor and a pressure sensor. The volume ratio of the working fluid collection tank to the closed container to be tested is 1 / 100 to 1 / 1000, and the outlet of the working fluid collection tank is connected to the inlet of the closed container to be tested through a pipeline. The refrigerant source is connected to the inlet of the working fluid storage tank via a pipeline; A refrigeration / heating cold trap is detachably connected to a working fluid storage tank. The refrigeration / heating cold trap is used to liquefy the refrigerant in the working fluid storage tank and to thaw the freeze between the refrigeration / heating cold trap and the working fluid storage tank. The vacuum unit is connected to the working fluid storage tank and the sealed container to be tested, respectively. The drying unit is used to remove condensation from the surface of the working fluid storage tank; The working fluid storage tank and the sealed container under test were evacuated using a vacuum unit. Refrigerant was then introduced into the working fluid storage tank through a refrigerant source. The first mass of the working fluid storage tank after surface condensation was eliminated was obtained. m 1. The amount of refrigerant charged is greater than the amount needed to fill the sealed container to be tested. The refrigerant in the working fluid storage tank is slowly vaporized at a predetermined rate and then introduced into the sealed container to be tested until the pressure inside the sealed container reaches atmospheric pressure. The second mass of the working fluid storage tank after surface condensation is eliminated is then obtained. m 2. After the temperature and pressure of the gas inside the sealed container have stabilized, obtain the density of the refrigerant under this condition. r Through the first mass m 1 and the second mass m 2. Mass difference and density r The actual internal volume of the sealed container to be tested is obtained.

[0016] Optionally, a needle valve and a ball valve are installed on the pipeline between the working fluid storage tank and the sealed container to be tested. The needle valve and the ball valve work together to control the opening and closing of the pipeline and the rate at which the refrigerant enters.

[0017] Optionally, the vacuum unit includes: a vacuum pump, a vacuum gauge tube, and a vacuum meter. The vacuum pump is detachably connected to the working fluid storage tank and the sealed container to be tested, respectively. The vacuum gauge tube is installed on the sealed container to be tested, and the vacuum meter is connected to the vacuum gauge tube.

[0018] Optionally, the measuring unit also includes a pressure measuring instrument and a temperature measuring instrument. The pressure measuring instrument is connected to a pressure sensor to display the pressure inside the sealed container under test in real time, and the temperature measuring instrument is connected to a temperature sensor to display the temperature inside the sealed container under test in real time.

[0019] Optionally, the internal net volume of the sealed container to be tested is 5L to 15L, the volume ratio of the working fluid collection tank to the sealed container to be tested is 1:50 to 1:200, and the bottom of the sealed container to be tested is provided with a drain hole for draining water after water filling and calibration.

[0020] Optionally, the refrigerant includes one of difluorochloromethane, 1,1,1,2-tetrafluoroethane, and pentafluoroethane.

[0021] Optionally, the cooling / heating cold trap includes: a cold trap core, a semiconductor plate, a heat sink, and a cooling fan. The cold trap core has a hollow structure, and the working fluid storage tank can be placed inside the cold trap core with a gap of 0.05mm to 0.5mm between them. The semiconductor plate is fixed to two opposite sides of the cold trap core, the heat sink is fixed to the outside of the semiconductor plate, and the cooling fan is installed on the outside of the heat sink.

[0022] Optionally, the cooling / heating cold trap also includes a cold trap panel with four terminals A, B, C and D. Terminals A and B are connected to the cooling fan and to the power supply via wires. Terminals C and D are connected to the semiconductor chip and to terminals A and B via wires.

[0023] A second aspect of the present invention provides a method for measuring and demonstrating the volume of a closed container for energy dynamics, comprising the following steps using the aforementioned apparatus for measuring and demonstrating the volume of a closed container for energy dynamics: Estimate the internal volume of the sealed container to be tested, and calculate the required mass of refrigerant based on the selected refrigerant. m esti ; The working fluid storage tank and the sealed container to be tested were evacuated using a vacuum unit, and the mass of the working fluid storage tank was measured. m 0; Place the working fluid storage tank in the refrigeration / heating cold trap, connect the working fluid storage tank to the refrigerant source to connect the corresponding pipelines, and after purging the residual air in the pipelines, liquefy the refrigerant and collect it in the working fluid storage tank. After the refrigerant is charged, if the working fluid storage tank and the refrigeration / heating cold trap freeze, the freezing can be thawed through the refrigeration / heating cold trap. Weighing the working fluid storage tank m 1. If m 1- m 0<0.8 m esti Repeatedly charge the refrigerant and continue liquefying and collecting the working fluid until it reaches 0.8. m esti <( m 1- m 0)<1.2 m esti ; After filling, the working fluid storage tank is heated to near room temperature using a drying unit. At this point, the total mass of the working fluid storage tank after filling is accurately measured. m 1; Connect the working fluid storage tank and the sealed container to be tested through a pipeline, so that the refrigerant slowly vaporizes and enters the sealed container to be tested until the pressure reaches about 99 kPa~101 kPa. The working fluid storage tank is heated to eliminate condensation on its surface. At this time, the total mass of the working fluid storage tank after filling with working fluid is accurately measured. m 2; Wait for the sealed container to reach thermal equilibrium, then calculate the density of the refrigerant in that state. r ,pass( m 1- m 2) / rThe actual internal volume of the sealed container to be tested is obtained.

[0024] Optionally, the following steps may also be included: Release the remaining working fluid in the working fluid storage tank into the environment; The actual volume is calibrated by filling the sealed container under test with pure water.

[0025] The technical solution provided by the embodiments of the present invention has the following advantages compared with the prior art: This invention provides a device and method for measuring and demonstrating the volume of a closed container in energy dynamics. It overcomes the bottleneck of traditional ideal gas measurement by utilizing the approximately 100-1000 times density difference between the gas and liquid phases. Employing a very small working fluid storage tank (only 1 / 100 to 1 / 1000 of the volume of the closed container to be measured), it achieves accurate measurement of large volumes through gas-liquid phase change and mass conservation. The principle is similar to the story of Cao Chong weighing an elephant, indirectly solving for large volumes with a small volume of known working fluid. This solves the problem that traditional methods such as water injection weighing and ideal gas pressure difference methods still require a large volume of water or gas. It completely solves the problem of measurement failure in the ideal gas law equation of state, achieving high-precision non-destructive measurement of irregular containers. This invention does not require measuring the volume of the working fluid storage tank, only the mass of the working fluid, and the accuracy of mass measurement is very high. Therefore, the accuracy of this invention is significantly higher than that of the traditional ideal gas law equation of state. Simultaneously, this invention deeply integrates industrial needs with experimental teaching, enhancing students' engineering practice abilities. Designed to address real-world engineering challenges such as industrial reactors and irregularly shaped pressure vessels, this device allows students to conduct experiments by solving practical engineering problems. It overcomes the limitations of traditional verification experiments that are detached from industrial settings, significantly enhancing their ability to connect theory with practice and apply engineering technologies, thus seamlessly aligning teaching with industrial needs. Throughout the volume measurement process, it simultaneously and intuitively demonstrates six core thermodynamic phenomena: expansion and cooling, compression and heating, liquefaction and heat release, vaporization and heat absorption, adiabatic throttling and cooling, and vacuum micro-leakage. This transforms abstract gas-liquid phase transition mechanisms and thermodynamic laws into observable, operable, and quantifiable physical processes, resulting in a teaching effect far superior to traditional single-principle demonstration devices. Its structure is adaptable to teaching, easy to operate, and highly stable, making it suitable for mass adoption in universities. Attached Figure Description

[0026] To more clearly illustrate the embodiments and design schemes of the present invention, the accompanying drawings required for this embodiment will be briefly described below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 A structural diagram of the measurement system of a method for measuring the volume of a sealed container and an experimental device for demonstrating thermodynamic phenomena, provided in an embodiment of the present invention; Figure 2 This is a structural diagram of a cooling / heating cold trap provided in an embodiment of the present invention.

[0028] Explanation of reference numerals in the attached figures: 1. Sealed container to be tested; 2. Ball valve; 3. Vacuum gauge; 4. Vacuum gauge tube; 5. Temperature sensor; 6. Pressure sensor; 7. Pressure measuring instrument; 8. Temperature measuring instrument; 9. Computer; 10. Plug; 11. Cold trap cover; 12. Radiator; 13. Semiconductor chip; 14. Cooling fan; 15. Thermocouple; 16. Temperature display; 17. Insulation pad; 18. Base; 19. Cold trap core; 20. Cold trap panel; 21. Power supply; 22. Needle valve; 23. Working fluid storage tank. Detailed Implementation

[0029] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0030] For measuring the volume of a closed container, the most readily conceived method in the art is based on the ideal gas law. This involves filling a reference container with a known internal volume with pressurized gas, then diffusing it into the closed container to be tested (1), and measuring the pressure change before and after. However, this method requires a reference container with a volume close to that of the container being tested, making it difficult to implement when measuring large containers. If a smaller reference container is used, the pressure increase inside the closed container to be tested is minimal due to the significant difference in volume, making accurate detection impossible.

[0031] The technical solutions provided by the various embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0032] Firstly, the first part of the embodiments of the present invention provides a closed container volume measurement and demonstration device for energy dynamics, specifically as follows: Figure 1As shown, the system includes: a sealed container 1 to be tested, a working fluid storage tank 23, a refrigerant source, a cooling / heating cold trap, a vacuum unit, and a drying unit. The sealed container 1 is equipped with a temperature sensor 5 and a pressure sensor 6. The volume ratio of the working fluid storage tank 23 to the sealed container 1 is 1 / 100 to 1 / 1000. The outlet of the working fluid storage tank 23 is connected to the inlet of the sealed container 1 via a pipeline. The refrigerant source is connected to the inlet of the working fluid storage tank 23 via a pipeline. The cooling / heating cold trap is detachably connected to the working fluid storage tank 23. The cooling / heating cold trap is used to liquefy the refrigerant in the working fluid storage tank 23 and to release the freeze between the cooling / heating cold trap and the working fluid storage tank 23. The vacuum unit is connected to both the working fluid storage tank 23 and the sealed container 1 to be tested. The drying unit is used to remove condensation from the surface of the working fluid storage tank 23. The drying unit can be equipped with a blower. The working fluid storage tank 23 and the sealed container 1 to be tested were evacuated using a vacuum unit. Refrigerant was then introduced into the working fluid storage tank 23 through a refrigerant source. The first mass of the working fluid storage tank 23 after surface condensation was eliminated was obtained. m 1. The amount of refrigerant charged is greater than the amount needed to fill the sealed container 1 to be tested. The refrigerant in the working fluid storage tank 23 is slowly vaporized at a predetermined rate and then introduced into the sealed container 1 to be tested until the pressure inside the sealed container 1 reaches atmospheric pressure. The second mass of the working fluid storage tank 23 after surface condensation is eliminated is then obtained. m 2. After the temperature and pressure of the gas inside the sealed container 1 have stabilized, obtain the density of the refrigerant under this state. r Through the first mass m 1 and the second mass m 2. Mass difference and density r The actual internal volume of the sealed container 1 to be tested is obtained. In this embodiment of the invention, the sealed container 1 to be tested is made of aluminum alloy or stainless steel and is filled with metal filler, ceramic filler, glass beads, porous media or complex internal structure, and the effective volume cannot be directly calculated from the geometric dimensions.

[0033] The following thermodynamic phenomena are simultaneously demonstrated during the volume measurement process: (1) During the vacuuming process, the temperature of the air inside the sealed container 1 to be tested decreases, demonstrating the gas expansion and cooling process; (2) During the working fluid vaporization and injection process, the temperature of the gas inside the sealed container 1 to be tested increases, demonstrating the gas compression and heating process; (3) When the refrigerant liquefies in the cold trap, the temperature of the cold trap rises, demonstrating the gas liquefaction and heat release process; (4) When the liquid refrigerant enters the sealed container 1 to be tested and vaporizes, condensation or frost appears on the outer wall of the working fluid storage tank 23, demonstrating the liquid vaporization and heat absorption process; (5) When the remaining refrigerant in the working fluid storage tank 23 is released to the surrounding environment, frost appears at the outlet of the needle valve 22, demonstrating the actual gas adiabatic throttling and cooling phenomenon; (6) After the vacuuming is completed, the ball valve 2 is closed, and then the pressure displayed on the computer is observed in real time, demonstrating the very slow leakage phenomenon under vacuum; Through the above integrated intuitive demonstration of multiple phenomena, the teaching of thermodynamics and phase change principles for energy and power majors is realized.

[0034] This invention provides a device and method for measuring and demonstrating the volume of a closed container in energy dynamics. It overcomes the bottleneck of traditional ideal gas measurement by utilizing the approximately 100-1000 times density difference between the gas and liquid phases. Employing a very small working fluid storage tank (only 1 / 100 to 1 / 1000 of the volume of the closed container to be measured), it achieves accurate measurement of large volumes through gas-liquid phase change and mass conservation. The principle is similar to the story of Cao Chong weighing an elephant, indirectly solving for large volumes with a small volume of known working fluid. This solves the problem that traditional methods such as water injection weighing and ideal gas pressure difference methods still require a large volume of water or gas. It completely solves the problem of measurement failure in the ideal gas law equation of state, achieving high-precision non-destructive measurement of irregular containers. This invention does not require measuring the volume of the working fluid storage tank, only the mass of the working fluid, and the accuracy of mass measurement is very high. Therefore, the accuracy of this invention is significantly higher than that of the traditional ideal gas law equation of state. Simultaneously, this invention deeply integrates industrial needs with experimental teaching, enhancing students' engineering practice abilities. Designed to address real-world engineering challenges such as industrial reactors and irregularly shaped pressure vessels, this device allows students to conduct experiments by solving practical engineering problems. It overcomes the limitations of traditional verification experiments that are detached from industrial settings, significantly enhancing their ability to connect theory with practice and apply engineering technologies, thus seamlessly aligning teaching with industrial needs. Throughout the volume measurement process, it simultaneously and intuitively demonstrates six core thermodynamic phenomena: expansion and cooling, compression and heating, liquefaction and heat release, vaporization and heat absorption, adiabatic throttling and cooling, and vacuum micro-leakage. This transforms abstract gas-liquid phase transition mechanisms and thermodynamic laws into observable, operable, and quantifiable physical processes, resulting in a teaching effect far superior to traditional single-principle demonstration devices. Its structure is adaptable to teaching, easy to operate, and highly stable, making it suitable for mass adoption in universities.

[0035] Optionally, a needle valve 22 and a ball valve 2 are installed on the pipeline between the working fluid storage tank 23 and the sealed container 1 to be tested. The needle valve 22 and the ball valve 2 work together to control the opening and closing of the pipeline and the rate at which the refrigerant enters. The working fluid storage tank 23 is connected to the needle valve 22 via a stainless steel pipe. A quick-connect fitting is provided on the other side of the needle valve 22 to achieve a quick and sealed connection with the hose.

[0036] Optionally, the vacuum unit includes a vacuum pump, a vacuum gauge tube 4, and a vacuum meter 3. The vacuum pump is detachably connected to the working fluid storage tank 23 and the sealed container 1 to be tested, respectively. The vacuum gauge tube 4 is installed on the sealed container 1 to be tested, and the vacuum meter 3 is connected to the vacuum gauge tube 4. The system vacuum level can be reduced to below 100 Pa. The temperature sensor 5 is a thermocouple with a diameter not exceeding 0.5 mm, a chip-type Pt-100 platinum resistance thermometer, or a precision thermistor with a diameter not exceeding 1 mm. The temperature sensor 5 needs to have a fast response speed to reflect the thermodynamic phenomena of the gas inside the sealed container 1 in real time. The outer diameter of the hose used to connect the vacuum pump and the sealed container 1 to be tested is 4 mm to 12 mm. The outer diameter of the hose used to connect the vacuum pump and the working fluid storage tank 23 is 4 mm to 12 mm. The outer diameter of the hose used to connect the working fluid storage tank 23 and the sealed container 1 to be tested is 2 mm to 6 mm. The outer diameter of the hose used to connect the working fluid storage tank 23 and the refrigerant cylinder is 2 mm to 6 mm. The sealed container 1 to be tested has multiple interfaces, on which a pressure sensor 6, a temperature sensor 5, and a vacuum gauge tube 4 are respectively installed. The sealed container 1 to be tested is connected to a ball valve 2, through which vacuum is drawn and samples are injected. A quick-connect fitting is provided on the other side of the ball valve 2 to achieve a quick and sealed connection with the tubing.

[0037] Optionally, the measuring unit also includes a pressure measuring instrument 7 and a temperature measuring instrument 8. The pressure measuring instrument 7 is connected to the pressure sensor 6 to display the pressure inside the sealed container 1 in real time. The temperature measuring instrument 8 is connected to the temperature sensor 5 to display the temperature inside the sealed container 1 in real time. Then, it is connected to a computer 9, which displays the temperature and pressure values ​​of the gas inside the sealed container 1 in real time via software. The weight of the sealed container 1 is measured using an electronic balance with an accuracy better than ±10 mg.

[0038] Optionally, the net internal volume of the sealed container 1 to be tested is 5L to 15L, and the volume ratio of the working fluid collection tank 23 to the sealed container 1 is 1:50 to 1:200. The sealed container 1 to be tested has a drain hole at the bottom for draining water after calibration. The drain hole is sealed by a plug 10. The working fluid collection tank 23 is made of stainless steel, has a cylindrical hollow structure, an outer diameter of 30mm to 50mm, and a volume of 50mL to 150mL. This invention is mainly for teaching purposes and does not require such a wide range of protection. Therefore, the working fluid selected is non-toxic and has a relatively low pressure, and its gas-liquid density ratio is not particularly high. Therefore, the upper limit is set at 200 times. In addition, the small tank cannot be completely filled with liquid, otherwise it will explode immediately. Therefore, some margin needs to be left, so the lower limit is set at 50 times. Both of these values ​​are proportions for teaching experiments.

[0039] The refrigerants used include difluorochloromethane, 1,1,1,2-tetrafluoroethane, pentafluoroethane, sulfur hexafluoride, 1,1,1,3,3-pentafluoropropane, octafluoropropane, tetrafluorochloroethane, tetrafluorochloroethane, pentafluorochloroethane, difluoromethane, and heptafluoropropane. Considering the safety, price, charging pressure, and gas / liquid density ratio of the working fluid, the preferred refrigerant includes one of difluorochloromethane, 1,1,1,2-tetrafluoroethane, and pentafluoroethane.

[0040] refer to Figure 2 The cooling / heating cold trap includes: a cold trap core 19, semiconductor plates 13, a cold trap cover 11, an insulation pad 17, a base 18, a heat sink 12, and a cooling fan 14. The cold trap core 19 has a hollow structure, allowing the working fluid storage tank 23 to be placed inside, with a gap of 0.05mm to 0.5mm between them. A gap smaller would prevent the core from fitting, while a gap larger would result in slow heat transfer and cooling. The cold trap core 19 is made of aluminum alloy, with a hollow cylindrical inner surface and a cuboid outer surface. Four to six semiconductor plates 13 are fixed to opposite sides of the cold trap core 19. One heat sink 12 is fixed to the outside of the semiconductor plates 13 on each side. The cooling fan 14 is installed on the outside of the heat sink 12. The insulation pad 17 is located between the base 18 and the working fluid storage tank 23 to prevent heat loss. A temperature display 16 is mounted on the front panel of the base 18, and a thermocouple 15 connected to the temperature display 16 is installed inside the cold trap core 19. The insulation pad 17, made of insulation material or 3D printed, is cylindrical and has 5-20 small holes with a diameter of 0.5mm-3mm along its axis for draining condensate. The cold trap cover 11 is a hollow structure, made of insulation material or 3D printed, used to cover the inner cavity when the cold trap is unloaded to prevent internal icing. The cold trap cover 11 fits perfectly into the cold trap core 19, with a gap of 0.05mm-1mm between them. The minimum temperature of the cooling / heating cold trap can reach approximately -20℃.

[0041] Specifically, the cooling / heating cold trap also includes a cold trap panel 20, which has four terminals A, B, C, and D. Terminals A and B are connected to the cooling fan 14 and to a power supply 21 via wires. The power supply 21 is a DC power supply. Terminals C and D are connected to the semiconductor chip 13 and to terminals A and B via wires. The cooling fan 14 operates when directly connected to terminals A and B. The semiconductor chip 13 is connected to terminals C and D on the cold trap panel 20, and terminals A and B are connected to terminals C and D via wires. Depending on the connection method, it performs cooling and heating functions respectively.

[0042] The cooling / heating cold trap includes: (1) Cooling mode: Connect terminals A and C, and terminals B and D on the cold trap panel 20 using wires. At this time, the semiconductor chip 13 plays a cooling role to achieve refrigerant liquefaction; (2) Heating and ice melting mode: When the working fluid storage tank 23 and the cold trap are frozen, connect terminals A and D, and terminals B and C on the cold trap panel 20. At this time, the semiconductor chip 13 plays a heating role. The ice can be melted in about 5s to 20s, and the working fluid storage tank 23 can be taken out. The device of this invention adopts quick-connect pipe connection, which is convenient to disassemble and assemble; the cold trap is equipped with a 3D printed heat insulation cover to prevent ice formation under no-load conditions, and the cooling and heating are quickly switched to avoid freezing and sticking; the material and interface layout of the sealed container 1 to be tested are close to the actual industrial situation, the measurement accuracy is high, the calibration method is simple, the overall safety and stability are good, the repeatability is good, and it is suitable for large-scale equipment for experimental teaching in energy and power majors, filling the gap in high-level open engineering experimental equipment.

[0043] The second part of the embodiments of the present invention provides a method for measuring and demonstrating the volume of a closed container for energy dynamics, using the above-described device for measuring and demonstrating the volume of a closed container for energy dynamics, including the following steps: This invention, primarily for teaching purposes, estimates the internal volume of the sealed container 1 to be tested. The volume of the sealed container 1 is not very large; it is estimated based on its dimensions. The density of the selected refrigerant at room temperature and pressure is calculated, and then the approximate mass of refrigerant required for the experiment is calculated by multiplying the density by the internal volume. m esti ; Vacuum was applied to both the working fluid storage tank 23 and the sealed container 1 to be tested using a vacuum unit, and the mass of the working fluid storage tank 23 was measured. m 0; Place the working fluid storage tank 23 in the refrigeration / heating cold trap, connect the working fluid storage tank 23 to the refrigerant source to connect the corresponding pipelines, and after venting the residual air in the pipelines, liquefy the refrigerant and collect it in the working fluid storage tank 23. After the refrigerant is charged, if the working fluid storage tank 23 freezes with the refrigeration / heating cold trap, the freezing is thawed through the refrigeration / heating cold trap. Weigh the working fluid storage tank 23m 1. If m 1- m 0<0.8 m esti Repeatedly charge the refrigerant and continue liquefying and collecting the working fluid until it reaches 0.8. m esti <( m 1- m 0)<1.2 m esti ; After filling, the working medium storage tank 23 is heated to near room temperature by the drying unit. At this time, the total mass of the working medium storage tank 23 after filling is accurately measured. m 1; Connect the working fluid storage tank 23 and the sealed container 1 to be tested through a pipeline, so that the refrigerant slowly vaporizes and enters the sealed container 1 to be tested until the pressure reaches about 99 kPa~101 kPa. The working fluid storage tank 23 is heated to eliminate condensation on its surface. At this time, the total mass of the working fluid storage tank 23 after filling with working fluid is accurately measured. m 2; Wait for the sealed container 1 to reach thermal equilibrium, then calculate the density of the refrigerant in that state. r ,pass( m 1- m 2) / r The actual internal volume of the sealed container 1 to be tested is obtained.

[0044] Optionally, the following steps may also be included: Release the remaining working medium in the working medium storage tank 23 into the environment; The actual volume was calibrated by filling the sealed container 1 under test with pure water.

[0045] This invention provides a method for measuring and demonstrating the volume of a closed container for energy dynamics, comprising the following steps: (1) Estimate the internal volume of the sealed container 1 to be tested. Calculate the density of the refrigerant at room temperature and pressure based on the selected refrigerant. Then, calculate the approximate mass of refrigerant required for the experiment by multiplying the density by the internal volume. m esti ; (2) Connect the working fluid storage tank 23 to the vacuum pump, open the needle valve 22, evacuate for more than 2 minutes, close the needle valve 22, and then remove the working fluid storage tank 23. (3) Connect the sealed container 1 to be tested to the vacuum pump, open the ball valve 2, and evacuate to below 300 Pa. This vacuum level is relatively high, and the influence of residual air can be basically ignored. If it is lower, it will take too long.

[0046] (4) Weigh the working fluid storage tank 23. m 0. Turn on the power supply 21 of the cold trap and cool the cold trap to below -10°C; (5) Connect the working fluid storage tank 23 to the refrigerant cylinder, keep the needle valve 22 closed, open the valve on the refrigerant cylinder, and then release the gas in the pipeline. Repeat this 3 to 5 times to remove the air from the pipeline. (6) Remove the cold trap cover 11 and place the working fluid storage tank 23 in the cold trap. Use the cold trap to liquefy the refrigerant and collect it in the working fluid storage tank 23. Open the valve on the refrigerant cylinder, and then open the needle valve 22. Start timing at the same time. Different refrigerants require different condensation and liquefaction times, approximately 30s to 120s. After timing is complete, close the needle valve 22.

[0047] (7) After the refrigerant is charged, if the working fluid storage tank 23 and the cold trap freeze and cannot be removed, connect terminals A and D and terminals B and C on the cold trap panel 20. At this time, the semiconductor chip will heat up and melt the ice in about 5 to 20 seconds. Then remove the working fluid storage tank 23. Then reconnect the terminals to restore the cooling function of the cold trap.

[0048] (8) Use a balance to roughly weigh the working fluid storage tank 23. m 1. If m 1- m 0<0.8 m esti Repeat steps (5) to (6) to continue liquefying and collecting the working fluid until it reaches 0.8. m esti <( m 1- m 0)<1.2 m esti And the optimal filling volume is m 1- m 0 = 1.05 m esti ; (9) After filling, use a blower to heat the working medium storage tank 23 to near room temperature to completely eliminate condensation on the surface of the working medium storage tank 23. At this time, accurately weigh the total mass of the working medium storage tank 23 after filling with working medium. m 1;

[0049] (10) Connect the working fluid storage tank 23 and the sealed container 1 to be tested via a needle valve 22 and a ball valve 2 using a flexible hose. First open the ball valve 2, and then slowly open the needle valve 22. If the opening of the ball valve 2 is too large, it only serves as a switch. The needle valve 22 can adjust the opening. Therefore, open the ball valve 2 first, and then use the needle valve 22 to control the gas intake speed. Observe the real-time pressure value of the sealed container 1 to be tested. Generally, after adjusting the opening of the needle valve 22 to allow the refrigerant to slowly vaporize, if the gas intake is too fast, the temperature inside the tank will rise rapidly, and the time required for the final temperature and pressure to reach equilibrium will increase. Therefore, slow vaporization is chosen. In addition, if the speed is too fast, the final gas intake pressure may exceed 1 atmosphere. If the pressure is too high, it will also damage the vacuum gauge tube. Enter the sealed container 1 to be tested until the pressure reaches about 99 kPa to 101 kPa. The pressure sensor 6 used in this invention is an absolute pressure type with a range of 100 kPa and an accuracy better than 0.5 class. 100 kPa is atmospheric pressure. When it is basically the same as atmospheric pressure, the gas inside the container will not leak out or the air will leak in. 100 kPa is also the range of the pressure sensor. When the measured pressure is basically the same as atmospheric pressure, the measurement accuracy of the final pressure inside the tank is the highest, and the volume measurement accuracy is also the highest. The whole vaporization process takes about 3 to 10 minutes.

[0050] (11) Remove the working medium storage tank 23 and heat it to near room temperature using a blower to completely eliminate condensation on the surface of the working medium storage tank 23. At this time, accurately weigh the total mass of the working medium storage tank 23 after filling with working medium. m 2;

[0051] (12) Wait for the sealed container 1 to reach thermal equilibrium. When the temperature and pressure of the internal gas remain basically constant, record the temperature and pressure values ​​and calculate the density of the refrigerant under this state. r (The density under this condition is calculated using REFPROP software based on temperature and pressure. The density is calculated after inputting the temperature and pressure into the software.) m 1- m 2) / r The actual internal volume of the sealed container 1 to be tested is obtained;

[0052] (13) Open needle valve 22 to release the remaining working medium in working medium storage tank 23 into the environment; (14) The actual volume is calibrated by filling the sealed container 1 to be tested with pure water. After calibration, the water is drained through the bottom drain hole, and the mass of the water is divided by the density. The accuracy of calibration with water is higher, in order to compare the error of the volume measured by using gas. Then the sealed container 1 to be tested is dried. Detailed Implementation

[0053] Example 1 The working fluid collection tank 23 is made of stainless steel and has a volume of 100 mL. The sealed container to be tested 1 is made of aluminum alloy and has a volume of approximately 10 L, with a volume ratio of approximately 1:100. 1,1,1,2-Tetrafluoroethane is selected as the working fluid. The inner diameter of the cold trap is 40 mm and the depth is 180 mm. The cold trap cover 11 is 3D printed, and temperature measurement is performed using thermocouples. The laboratory temperature in this study is 20℃. Based on 20℃ and 0.1 MPa, the density of 1,1,1,2-tetrafluoroethane is calculated to be 4.2784 g / L. Based on a 10 L volume, approximately 42.78 g of working fluid is required. With a margin of 1.05 to 1.2 times, the working fluid collection tank 23 needs to collect more than 44.92 g of working fluid.

[0054] After turning on power supply 21, the cold trap temperature dropped to -19℃ and remained stable for approximately 5 minutes. The working fluid storage tank 23 was evacuated and its mass was measured to be 246.51 g. The working fluid storage tank 23 was placed in the cold trap, and the refrigerant cylinder was opened while timing was started. After 50 seconds, the needle valve was closed. During the liquefaction process, the cold trap temperature continued to rise, reaching -5℃. The working fluid storage tank 23 was removed and weighed; its mass was 295.64 g, which was sufficient. The working fluid storage tank 23 was heated to near room temperature using a hair dryer to dry the surface moisture, and its mass was re-weighed; it was 295.47 g.

[0055] The sealed container 1 to be tested was evacuated to 180 Pa. The temperature inside the sealed container 1 suddenly dropped from 20℃ to 8℃ the instant the vacuum pump was turned on. The working fluid collection tank 23 was connected to the sealed container 1, and the sample was slowly vaporized and injected. During the injection process, the internal temperature of the sealed container 1 rose to a maximum of 25℃. After about 5 minutes, the pressure inside the sealed container 1 increased to 99.86 kPa, and the temperature was 21.86℃. The valve was closed to stop the injection. At this time, the lower half of the working fluid collection tank 23 was frosted. The working fluid collection tank 23 was heated to near room temperature using a blower, and its mass was measured using a balance to be 253.75 g. Therefore, the mass of 1,1,1,2-tetrafluoroethane injected into the sealed container 1 was 41.72 g. After the temperature inside the sealed container 1 stabilized at 20.08℃, the pressure was measured to be 99.35 kPa. The density of 1,1,1,2-tetrafluoroethane under this condition was calculated to be 4.2487 g / L, and the final volume of the sealed container 1 was determined to be 9.82 L. After the measurement was completed, the remaining working fluid in the working fluid storage tank 23 was released into the environment. Frosting was observed at the outlet of needle valve 22, and condensation was observed at the bottom of the working fluid storage tank 23.

[0056] The volume of the sealed container 1 to be tested was calibrated using pure water. Pure water was poured into a 2L beaker and then into the sealed container 1. The mass difference between the beaker before and after pouring was measured using a balance. This process was repeated 4-5 times until the sealed container 1 was full. The total mass of water poured into the sealed container 1 was accurately obtained as 9773.24g. The water temperature was measured to be 18.27℃, and the current atmospheric pressure was 98.42 kPa. The density of water under these conditions was calculated to be 998.55g / L. The final calibrated volume of the sealed container 1 was 9.79 L. Therefore, the deviation of the volume of the sealed container 1 measured using 1,1,1,2-tetrafluoroethane was 0.30%.

[0057] Example 2 In this embodiment, dichlorofluoromethane was used as the experimental working fluid. The working fluid storage tank 23 was made of stainless steel with a volume of 80 mL. The sealed container 1 to be tested was made of stainless steel with internal packing material and an estimated volume of approximately 12 L. The volume ratio of the two was approximately 1:150. The cold trap had an inner diameter of 45 mm and a depth of 160 mm. Temperature was measured using thermocouples. The experimental ambient temperature was 22 °C. The calculated gaseous density of dichlorofluoromethane at 22 °C and 0.1 MPa was 3.5770 g / L. Based on the estimated working fluid mass of 12 L, approximately 42.92 g was required. With a margin of 1.05, the optimal filling amount was determined to be 45.07 g.

[0058] Turn on the cold trap power supply 21. After about 6 minutes, the cold trap temperature stabilizes at -18℃. Connect the working fluid storage tank 23 to the vacuum pump and evacuate for 3 minutes. After closing the needle valve 22, remove the tank and accurately weigh it; its mass is 196.17 g. Evacuate the sealed container 1 to 120 Pa. The temperature inside the container drops from 22℃ to 12℃ instantly during evacuation, clearly demonstrating the gas expansion and cooling phenomenon. Then, place the working fluid storage tank 23 in the cold trap, connect it to a dichlorofluoromethane cylinder, and purge the air from the pipeline three times. Open the cylinder valve and needle valve, and close the needle valve after 60 seconds. During the liquefaction process, the cold trap temperature continuously rises to -4℃, demonstrating the exothermic process of refrigerant liquefaction.

[0059] The working fluid storage tank 23 and the cold trap experienced slight freezing. The cold trap terminals were switched to heating mode, and the ice melted after 10 seconds. The storage tank was then removed. A blower was used to heat the working fluid storage tank 23 to room temperature and remove surface condensation. The mass of the working fluid after filling was accurately measured to be 245.37 g, meeting the experimental requirements. The working fluid storage tank 23 was connected to the sealed container 1 to be tested. The needle valve 22 was slowly opened to vaporize and inject the difluorochloromethane sample. After approximately 6 minutes, the pressure inside the container rose to 100.64 kPa, and the internal temperature reached a maximum of 27°C, demonstrating the gas compression and heating phenomenon. Simultaneously, frost was clearly formed on the outer wall of the working fluid storage tank 23, visually demonstrating the liquid vaporization and endothermic process.

[0060] After closing the needle valve and ball valve, the working fluid storage tank 23 was removed and decondensed, and accurately weighed to 203.76 g. The calculated mass of difluorochloromethane filled into the container was 41.61 g. The sealed container 1 was allowed to reach thermal equilibrium, with the temperature stabilizing at 22.18 ℃ and the pressure at 99.92 kPa. Under these conditions, the density of difluorochloromethane was 3.5718 g / L, and the calculated container volume was 11.65 L. The needle valve 22 was opened to release the remaining working fluid. Frost rapidly formed at the outlet of the needle valve 22, demonstrating the actual gas adiabatic throttling and cooling phenomenon. Finally, calibration with pure water yielded an actual container volume of 11.54 L. The relative deviation of this measurement in this embodiment was approximately 0.95%.

[0061] The above inventions are merely a few specific embodiments of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A closed container volume measurement and demonstration device for energy dynamics, characterized in that, include: The sealed container to be tested (1) is equipped with a temperature sensor (5) and a pressure sensor (6). The volume ratio of the working fluid storage tank (23) to the sealed container (1) to be tested is 1 / 100 to 1 / 1000, and the outlet of the working fluid storage tank (23) is connected to the inlet of the sealed container (1) to be tested through a pipeline. The refrigerant source is connected to the inlet of the working fluid storage tank (23) via a pipeline; A cooling / heating cold trap is detachably connected to a working fluid storage tank (23). The cooling / heating cold trap is used to liquefy the refrigerant in the working fluid storage tank (23) and to release the freeze between the cooling / heating cold trap and the working fluid storage tank (23). The vacuum unit is connected to the working fluid storage tank (23) and the sealed container to be tested (1), respectively; A drying unit is used to remove condensation from the surface of the working fluid storage tank (23); The working fluid storage tank (23) and the sealed container (1) to be tested were evacuated using a vacuum unit. Refrigerant was then introduced into the working fluid storage tank (23) through a refrigerant source to obtain the first mass of the working fluid storage tank (23) after surface condensation was eliminated. m 1. The amount of refrigerant charged is greater than the amount required to fill the sealed container (1) to be tested. The refrigerant in the working fluid storage tank (23) is slowly vaporized at a predetermined rate and then introduced into the sealed container (1) to be tested until the pressure in the sealed container (1) to be tested reaches atmospheric pressure. The second mass of the working fluid storage tank (23) after surface condensation is eliminated is obtained again. m 2. After the temperature and pressure of the gas inside the sealed container (1) have stabilized, obtain the density of the refrigerant in that state. ρ Through the first mass m 1 and the second mass m 2. Mass difference and density ρ The actual internal volume of the sealed container (1) to be tested is obtained.

2. The closed container volume measurement and demonstration device for energy dynamics as described in claim 1, characterized in that, A needle valve (22) and a ball valve (2) are installed on the pipeline between the working fluid storage tank (23) and the sealed container (1) to be tested. The opening and closing of the pipeline and the speed at which the refrigerant enters are controlled by the cooperation of the needle valve (22) and the ball valve (2).

3. The closed container volume measurement and demonstration device for energy dynamics as described in claim 1, characterized in that, The vacuum unit includes a vacuum pump, a vacuum gauge tube (4) and a vacuum meter (3). The vacuum pump is detachably connected to the working fluid storage tank (23) and the sealed container (1) to be tested. The vacuum gauge tube (4) is installed on the sealed container (1) to be tested. The vacuum meter (3) is connected to the vacuum gauge tube (4).

4. The closed container volume measurement and demonstration device for energy dynamics as described in claim 1, characterized in that, The measuring unit also includes a pressure measuring instrument (7) and a temperature measuring instrument (8). The pressure measuring instrument (7) is connected to the pressure sensor (6) and is used to display the pressure inside the sealed container (1) under test in real time. The temperature measuring instrument (8) is connected to the temperature sensor (5) and is used to display the temperature inside the sealed container (1) under test in real time.

5. The closed container volume measurement and demonstration device for energy dynamics as described in claim 1, characterized in that, The internal net volume of the sealed container (1) to be tested is 5L to 15L. The volume ratio of the working medium storage tank (23) to the sealed container (1) to be tested is 1:50 to 1:

200. The sealed container (1) to be tested is provided with a drain hole at the bottom for draining water after water filling and calibration.

6. The closed container volume measurement and demonstration device for energy dynamics as described in claim 1, characterized in that, The refrigerant includes one of difluorochloromethane, 1,1,1,2-tetrafluoroethane, and pentafluoroethane.

7. The closed container volume measurement and demonstration device for energy dynamics as described in claim 1, characterized in that, The cooling / heating cold trap includes: a cold trap core (19), a semiconductor chip (13), a heat sink (12), and a cooling fan (14). The cold trap core (19) is a hollow structure. The working fluid storage tank (23) can be placed inside the cold trap core (19), and the gap between the two is 0.05mm~0.5mm. The semiconductor chip (13) is fixed to two opposite sides of the cold trap core (19). The heat sink (12) is fixed to the outside of the semiconductor chip (13). The cooling fan (14) is installed on the outside of the heat sink (12).

8. The closed container volume measurement and demonstration device for energy dynamics as described in claim 7, characterized in that, The cooling / heating cold trap also includes a cold trap panel (20), which is provided with four terminals A, B, C and D. Terminals A and B are connected to a cooling fan (14) and connected to a power supply (21) via wires. Terminals C and D are connected to a semiconductor chip (13) and connected to terminals A and B via wires.

9. A method for measuring and demonstrating the volume of a closed container for energy dynamics, using the device for measuring and demonstrating the volume of a closed container for energy dynamics as described in any one of claims 1 to 8, characterized in that, Includes the following steps: Estimate the internal volume of the sealed container (1) to be tested, and calculate the required mass of refrigerant for the experiment based on the selected refrigerant. m esti ; The working fluid storage tank (23) and the sealed container to be tested (1) were evacuated using a vacuum unit, and the mass of the working fluid storage tank (23) was measured. m 0; Place the working fluid storage tank (23) in the refrigeration / heating cold trap, connect the working fluid storage tank (23) to the refrigerant source to make the corresponding pipeline connected, after the residual air in the pipeline is discharged, the refrigerant is liquefied and collected in the working fluid storage tank (23); After the refrigerant is charged, if the working fluid storage tank (23) freezes with the refrigeration / heating cold trap, the freezing is thawed through the refrigeration / heating cold trap. Weigh the working fluid storage tank (23) m 1. If m 1- m 0<0.8 m esti Repeatedly charge the refrigerant and continue liquefying and collecting the working fluid until it reaches 0.

8. m esti <( m 1- m 0)<1.2 m esti ; After filling, the working medium storage tank (23) is heated to near room temperature through the drying unit. At this time, the total mass of the working medium storage tank (23) after filling is accurately measured. m 1; Connect the working fluid storage tank (23) and the sealed container (1) to be tested through a pipeline, so that the refrigerant slowly vaporizes and enters the sealed container (1) to be tested until the pressure reaches about 99 kPa~101 kPa; The working medium storage tank (23) is heated to eliminate condensation on its surface. At this time, the total mass of the working medium storage tank (23) after filling with working medium is accurately measured. m 2; Wait for the sealed container (1) to reach thermal equilibrium, and calculate the density of the refrigerant in this state. ρ ,pass( m 1- m 2) / ρ The actual internal volume of the sealed container (1) to be tested is obtained.

10. A method for measuring and demonstrating the volume of a closed container for energy dynamics as described in claim 9, characterized in that, It also includes the following steps: Release the remaining working medium in the working medium storage tank (23) into the environment; The actual volume is calibrated by filling the sealed container (1) under test with pure water.

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