Dynamic pressure variable temperature liquid surface tension testing device and testing method

Abstract

The invention belongs to the field of surface tension testing, and particularly discloses a dynamic pressure variable temperature liquid surface tension testing device and method, and the device comprises a vacuum box, a temperature adjusting module and a testing platform module; the vacuum box is divided into a vacuum box upper part and a vacuum box lower part; the temperature adjusting module comprises a condenser, a compressor, a fan, a heating resistance wire, a filter, a cold-heat exchanger, a capillary tube and an evaporator. The temperature adjusting module is arranged on the upper portion of the vacuum box and can exchange heat with the lower portion of the vacuum box. According to the device and the method, the surface tension of the liquid can be measured under different pressures and different temperatures, the physical and chemical properties of the liquid can be understood by measuring the surface tension under different temperatures and pressures, the related industrial process can be optimized, the performance of a fire extinguishing material can be improved, and the thermodynamic behavior of the liquid can be predicted and understood; and the method has far-reaching influence on scientific research and industrial application.

Description

Technical Field

[0001] The present invention relates to the technical field of measuring the surface tension of a dynamically pressurized and temperature-variable liquid, and particularly relates to a device and method for measuring the surface tension of a dynamically pressurized and temperature-variable liquid. Background Art

[0002] There are many types of fire extinguishing agent materials with different performances. Among them, the surfactant, which is the core component of the foam fire extinguishing agent, has the effect of reducing the surface tension of the aqueous solution. It can generate a condensed foam floating layer on the surface of the burning liquid to isolate air and reduce the temperature in the combustion zone, and is the main fire extinguishing material for extinguishing fuel fires. It is widely used in petrochemical enterprises, solvent factories, oil fields, oil depots, garages, airports and other fields. However, China has a vast territory and complex geographical environment. There are significant pressure differences between high plateaus and plains, and obvious temperature differences between winter and summer in the north and south. This will inevitably affect the surface tension performance of the surfactant, and further affect the fire extinguishing performance of the foam fire extinguishing agent. Therefore, it is of great significance to detect the surface tension of different foam fire extinguishing agents under different pressures and temperatures for the fire extinguishing effectiveness of the foam fire extinguishing agent.

[0003] Surface tension is a force acting on the liquid surface to reduce the surface area of the liquid. Since there is a thin layer at the surface where the liquid contacts the gas, called the surface layer, the molecules in the surface layer are sparser than those inside the liquid, the distance between molecules is larger than that inside the liquid, and the interaction between molecules shows an attractive force, which is the surface tension. The main surface tension measurement methods include the platinum plate method, the platinum ring method, the pendant drop method, the bubble pressure method, the drop weight method, the capillary rise method, the maximum bubble pressure method, etc. When using the platinum ring method for testing, first immerse the platinum ring 2-3 mm below the liquid surface (or the interface between two immiscible liquids), and then slowly lift the platinum ring upward. A film will be formed between the ring and the liquid surface. Measure the maximum force value exerted by the film on the ring during the entire process of lifting the platinum ring, and then convert it into the true surface (interface) tension value.

[0004] In the prior art, a variable-temperature liquid surface tension coefficient measuring instrument is disclosed in a Chinese utility model patent with the publication number CN202320634193. A variable-temperature liquid surface tension coefficient measuring experimental device is designed, providing a measuring device with clear principle, simple structure and convenient use. The device adjusts the liquid temperature through a heating water tank and measures the surface tension coefficient at different temperatures using the pulling-off method. At the same time, an optoelectronic door assembly and a single-chip microcomputer control system are used to accurately detect the liquid film height and the change in pulling force, realizing high-precision measurement. With this device, the liquid surface tension coefficient can be obtained at different temperatures, and at the same time, the liquid level can be conveniently and smoothly adjusted, improving the measurement accuracy and repeatability. A vacuum high-temperature surface tension meter is disclosed in a Chinese utility model patent with the publication number CN215004844U. A vacuum high-temperature surface tension meter is designed, solving the problem of graphite sheet oxidation, making the test data accurate and effective, and providing feasibility for the surface tension test of easily oxidized samples. The device extracts air inside the vacuum chamber, and inert gas is filled into the vacuum chamber to assist in exhausting the air, enabling the test substrate to be tested under the protection of non-oxidizing gas and inert gas, solving the oxidation problem of the surface tension test substrate. The temperature outside the heating furnace body is reduced by water cooling to prevent the equipment from accelerating aging or damage, and at the same time, protecting the operator from scalding. The provided photographing window has the function of replaceable transparent quartz glass, facilitating subsequent maintenance and replacement.

[0005] However, the device of CN215004844U can only measure the surface tension in a vacuum condition and does not have the function of measuring the surface tension under different pressure conditions. Moreover, this device is used to measure the surface tension of materials under high-temperature (above 1000 °C) conditions in a vacuum, which is not applicable to most research. The device of CN215004844U is only applicable to a certain range of temperature changes. This kind of test device is placed in the air and the temperature is controlled by a water tank, which is not applicable to the measurement of low-temperature liquids and cannot be used for the measurement of surface tension in a variable-pressure environment. Moreover, there is no relevant report on the dynamic pressure variable-temperature liquid surface tension test device and method in China at present. Summary of the Invention

[0006] To solve the shortcomings in the prior art that the existing devices cannot measure the liquid surface tension under different pressures and at low temperatures and do not separate the measuring device from the external environment, the present invention provides a dynamic pressure variable-temperature liquid surface tension test device and a test method. The surface tension test device of the present invention is placed in a vacuum chamber, and the pressure inside the vacuum chamber can be adjusted by a vacuum pump, realizing isolation from the external environment. There is a heating resistance wire inside the vacuum chamber, and there is also an electric heating device on the lifting platform. A small compressor for adjusting the temperature inside the chamber is also provided on the vacuum chamber, enabling temperature adjustment from low temperature to high temperature. In addition, this device can be connected to a computer to view the various states of the device in real time, solving the problems mentioned in the above background technology.

[0007] To achieve the above object, the present invention provides the following technical solutions: A dynamic pressure variable temperature liquid surface tension testing device, characterized in that the device includes a vacuum chamber, a temperature adjustment module, and a test platform module;

[0008] The vacuum chamber is divided into two parts: the upper part of the vacuum chamber and the lower part of the vacuum chamber; the temperature adjustment module includes: a condenser, a compressor, a fan, a heating resistance wire, a filter, a cold and heat exchanger, a capillary tube, and an evaporator; the whole composed of the condenser, the compressor, the fan, the filter, the cold and heat exchanger, the capillary tube, and the evaporator is placed in a metal protection shell and set in the upper part of the vacuum chamber, and can perform heat exchange with the lower part of the vacuum chamber.

[0009] Preferably, the compressor is connected to the fan, and the fan dissipates heat for the compressor; the compressor is respectively connected to the condenser and the evaporator, the evaporator is connected to the cold and heat exchanger, the cold and heat exchanger is connected to the capillary tube, the capillary tube is connected to the dry filter, and the dry filter is connected to the condenser.

[0010] Preferably, a heating resistance wire is provided on the inner wall of the lower part of the vacuum chamber, a vacuum pump is provided outside the vacuum chamber, the vacuum pump is connected to the air extraction hole, and the vacuum chamber can be evacuated by controlling the vacuum valve and the air release hole located on the outer wall of the vacuum chamber.

[0011] Preferably, a vacuum gauge capable of reading the pressure inside the chamber at any time is also provided on the outer wall of the vacuum chamber.

[0012] Preferably, the test platform module includes: an electromagnetic force balance sensor, a hook, a balancer, a platinum ring, a temperature sensor, a petri dish, a lifting platform, a level, and a motor.

[0013] Preferably, the electromagnetic force balance sensor is connected to the hook through a balancer; the platinum ring is placed on the hook, and a temperature sensor is installed behind the hook; the petri dish is placed on the electrically heated lifting platform, and a level is installed outside and below the electrically heated lifting platform, and the lifting platform is connected to the motor.

[0014] On the other hand, to achieve the above object, the present invention also provides the following technical solutions: A dynamic pressure variable temperature liquid surface tension testing method, including the following steps:

[0015] Step 1: Open the cabinet door, adjust the device to be on a horizontal plane, check the level, observe whether the instrument is in a horizontal state, remove the platinum ring, wash it three times with deionized water, then burn the platinum ring with an alcohol lamp until it is glowing red, and install it on the hook after cooling; take out the watch glass, wash it three times with deionized water, wipe it clean, place the solution to be measured in the watch glass, then place the watch glass on the lifting platform, turn on the power of the device, open the surface tension test system software in the computer, and check whether the working status of each component of the device is normal through the computer;

[0016] Step 2: Close the air vent, open the vacuum valve, start the vacuum pump, adjust the environmental pressure in the cabinet, and at the same time control the heating resistance wire or the compressor to enter the working state through the computer to adjust the temperature in the cabinet;

[0017] Wait until the temperature of the temperature sensor and the pressure of the pressure gauge reach the test conditions, close the vacuum valve, turn off the vacuum pump, and control the test device to start through the computer;

[0018] Step 3: After the test is completed, control the heating resistance wire or the compressor to exit the working state through the computer, open the air vent, wait until the temperature and pressure return to the external environment state, take out the platinum ring and the watch glass for cleaning for the next test.

[0019] The beneficial effects of the present invention are:

[0020] 1) The test environment of the device of the present invention is placed in a vacuum chamber to achieve isolation from the external environment. This design effectively avoids the interference of air flow and other environmental factors on the measurement results, and improves the accuracy and stability of the measurement. There is a heating resistance wire and a small compressor capable of adjusting the temperature in the vacuum chamber, which can achieve a wide range of temperature adjustment from low temperature to high temperature, and can adapt to the test requirements of liquids under more environmental conditions, especially the surface tension test at low temperatures. The device can measure the surface tension of liquids under different pressure conditions, which is particularly important for scenarios that require testing the surface tension of liquids in a specific pressure environment in scientific research and industrial applications.

[0021] 2) The device of the present invention can be connected to a computer to achieve real-time viewing of various states of the device, including parameters such as temperature, pressure, and surface tension. This not only improves the timeliness of data but also facilitates data recording and analysis. The operation process of the device has been optimized, the steps are simple and clear, and it is easy for operators to conduct experiments according to the steps, reducing operation errors and improving experimental efficiency. Due to the design of the device considering environmental control and precise temperature and pressure adjustment, the repeatability and accuracy of the experiment have been significantly improved, which is crucial for the reliability requirements in scientific research. The device can reduce experimental failures and repeated experiments caused by environmental factors, thereby saving experimental costs and improving experimental efficiency, and having good economic benefits.

[0022] 3) The device of the present invention can provide more accurate data support for the research on the physical and chemical properties of liquids, which helps to optimize relevant industrial processes, improve material properties, predict and understand the thermodynamic behavior of liquids, etc., and has important scientific research and industrial application values. Brief Description of the Drawings

[0023] Figure 1 It is a schematic structural diagram of a dynamic pressure variable-temperature liquid surface tension test device;

[0024] In the figure, 1 - condenser, 2 - compressor, 3 - fan, 4 - heating resistance wire, 5 - electromagnetic force balance sensor, 6 - air extraction hole, 7 - vacuum pump, 8 - drying filter, 9 - cold and heat exchanger, 10 - capillary tube, 11 - evaporator, 12 - air release hole, 13 - pressure gauge, 14 - cabinet door, 15 - lifting platform, 16 - spirit level, 17 - motor, 18 - vacuum valve, 19 - computer, 20 - hook, 21 - balancer, 22 - temperature sensor, 23 - platinum ring, 24 - watch glass. Detailed Embodiments

[0025] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0026] It should be noted that, without conflict, the embodiments and features in the embodiments of the present invention can be combined with each other. It should be noted that similar reference numerals and letters indicate similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0027] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship when the product of the present invention is normally placed, or the orientation or positional relationship commonly understood by those skilled in the art. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0028] In the description of the present invention, it should also be noted that unless otherwise clearly specified and defined, the terms "set", "installed", "connected", and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] Please refer to Figure 1 , the present invention provides a technical solution: a dynamic pressure variable temperature liquid surface tension testing device, which includes a vacuum chamber, a temperature adjustment module, and a test platform module;

[0030] The vacuum chamber is divided into two parts: the upper part of the vacuum chamber and the lower part of the vacuum chamber; the temperature adjustment module includes: a condenser 1, a compressor 2, a fan 3, a heating resistance wire 4, a filter 8, a heat exchanger 9, a capillary tube 10, and an evaporator 11; the whole composed of the condenser 1, the compressor 2, the fan 3, the filter 8, the heat exchanger 9, the capillary tube 10, and the evaporator 11 is placed in a metal protective shell and set in the upper part of the vacuum chamber, and can exchange heat with the lower part of the vacuum chamber.

[0031] In the device structure, the vacuum chamber is used to isolate the external environment and ensure the stability of the test environment. A heating resistance wire and a temperature adjustment device are provided inside the vacuum chamber to achieve high-temperature adjustment. The lifting platform is used to place the petri dish containing the liquid to be tested, and accurate surface tension data can be obtained by the slow rise and fall of the lifting platform during the test. The platinum ring for measuring the liquid surface tension is installed on the hook and contacts the liquid surface by the movement of the lifting platform. It is used in cooperation with the heating resistance wire to quickly adjust the temperature of the solution in the petri dish. The small compressor is used to adjust the temperature inside the chamber to achieve low-temperature adjustment. The vacuum pump is used to adjust the pressure inside the vacuum chamber to achieve surface tension testing under different pressure conditions. The computer interface is used to connect to the computer to monitor and record parameters such as temperature, pressure, and surface tension during the test in real time.

[0032] Further, the compressor 2 is connected to the fan 3, and the fan 3 is used to dissipate heat for the compressor 2; the compressor 2 is respectively connected to the condenser 1 and the evaporator 11, the evaporator 11 is connected to the heat exchanger 9, the heat exchanger 9 is connected to the capillary tube 10, the capillary tube 10 is connected to the drying filter 8, and the drying filter 8 is connected to the condenser.

[0033] Further, a heating resistance wire 4 is provided on the inner wall of the lower part of the vacuum chamber, and a vacuum pump 7 is provided outside the vacuum chamber. The vacuum pump 7 is connected to the air extraction hole 6, and the vacuum chamber can be evacuated by controlling the vacuum valve 18 and the air release hole 12 located on the outer wall of the vacuum chamber.

[0034] A vacuum gauge 13 for reading the pressure inside the box at any time is also provided on the outer wall of the vacuum box.

[0035] Further, the test platform module includes: an electromagnetic force balance sensor 5, a hook 20, a balancer 21, a platinum ring 23, a temperature sensor 22, a petri dish 24, a lifting platform 15, a spirit level 16, and a motor 17.

[0036] The electromagnetic force balance sensor 5 is connected to the hook 20 through the balancer 21; the platinum ring 23 is placed on the hook 20, and a temperature sensor 22 is installed behind the hook 20; the petri dish 24 is placed on the electrically heated lifting platform 15, and a spirit level 16 is installed outside and below the electrically heated lifting platform 15, and the lifting platform 15 is connected to the motor 17.

[0037] The entire device is connected to a computer 19, and the device can be controlled through software.

[0038] When testing with the above dynamic pressure variable temperature liquid surface tension testing device, that is, a testing method based on the dynamic pressure variable temperature liquid surface tension testing device, includes the following steps:

[0039] Step 1: Open the box door 14, adjust the equipment to be on a horizontal plane, check the spirit level 16 to observe whether the instrument is in a horizontal state, remove the platinum ring 23, wash it three times with deionized water, then burn the platinum ring 23 with an alcohol lamp until it is in a red-hot state, and install it on the hook 20 after cooling; take out the petri dish 24, wash it three times with deionized water, wipe it clean, place the test solution (pure water) in the petri dish 24, the injection volume of the solution is about 1 / 2 - 2 / 3 of the volume of the petri dish 24, then place the petri dish 24 on the lifting platform 15, turn on the power supply of the equipment, open the surface tension testing system software in the computer 19, and check whether the working states of all components of the equipment are normal through the computer 19;

[0040] Step 2: Close the air vent 12, open the vacuum valve 18, start the vacuum pump 7, and adjust the environmental pressure inside the box, such as adjusting the environmental pressure inside the box to 100 kPa; at the same time, control the heating resistance wire 4 or the compressor to enter the working state through the computer 19 to adjust the temperature inside the box; such as setting the temperature to 30 °C;

[0041] Wait until the temperature of the temperature sensor 22 and the pressure of the pressure gauge 13 reach the test conditions, close the vacuum valve 18, turn off the vacuum pump 7, and control the test device to start through the computer 19; at the same time, check that the temperature of the computer 19 reaches the set temperature. Finally, click the test button in the surface tension testing system, the test platform automatically lifts to complete the test, and the test result is displayed as 71.31 mN / m on the software interface.

[0042] Step 3: After the test is completed, control the heating resistance wire 4 or the compressor to exit the working state through the computer 19, open the air vent 12, wait for the temperature and pressure to return to the external environment state, take out the platinum ring 23 and the petri dish 24 for cleaning, so as to conduct the next test.

[0043] The test environment of the device of the present invention is placed in a vacuum chamber to achieve isolation from the external environment. This design effectively avoids the interference of air flow and other environmental factors on the measurement results, and improves the accuracy and stability of the measurement. There is a heating resistance wire and a small compressor capable of adjusting the temperature in the vacuum chamber, which can achieve a wide range of temperature adjustments from low temperature to high temperature, and can meet the test requirements of liquids under more environmental conditions, especially the surface tension test under low temperature conditions. The device can measure the surface tension of liquids under different pressure conditions, which is particularly important for scenarios that require testing the surface tension of liquids in a specific pressure environment in scientific research and industrial applications.

[0044] Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A dynamic pressure variable temperature liquid surface tension testing device, characterized in that: The device includes a vacuum box, a temperature regulating module, and a test platform module; The vacuum box is divided into two parts: an upper part of the vacuum box and a lower part of the vacuum box; the temperature adjustment module comprises: a condenser (1), a compressor (2), a fan (3), a heating resistor (4), a filter (8), a cold and heat exchanger (9), a capillary tube (10) and an evaporator (11); the condenser (1), the compressor (2), the fan (3), the filter (8), the cold and heat exchanger (9), the capillary tube (10) and the evaporator (11) are placed in a metal protective shell and arranged on the upper part of the vacuum box, and can exchange heat with the lower part of the vacuum box.

2. The dynamic pressure and temperature-varying liquid surface tension testing device according to claim 1, characterized in that: The compressor (2) is connected to a fan (3), and the fan (3) is used to dissipate heat for the compressor (2); the compressor (2) is connected to a condenser (1) and an evaporator (11) respectively, the evaporator (11) is connected to a cold and heat exchanger (9), the cold and heat exchanger (9) is connected to a capillary tube (10), the capillary tube (10) is connected to a drying filter (8), and the drying filter (8) is connected to the condenser.

3. The dynamic pressure and temperature-varying liquid surface tension testing device according to claim 1, characterized in that: A heating resistance wire (4) is arranged on the inner wall of the lower part of the vacuum box, and a vacuum pump (7) is arranged outside the vacuum box. The vacuum pump (7) is connected to the air extraction hole (6). By controlling the vacuum valve (18) and the air release hole (12) located on the outer wall of the vacuum box, the vacuum box can be evacuated.

4. The dynamic pressure and temperature-varying liquid surface tension testing device according to claim 1, characterized in that: The outer wall of the vacuum box is also provided with a vacuum gauge (13) which can read the pressure inside the box at any time.

5. The dynamic pressure and temperature-varying liquid surface tension testing device according to claim 1, characterized in that: The test platform module comprises: an electromagnetic force balance sensor (5), a hook (20), a balancer (21), a platinum ring (23), a temperature sensor (22), a watch glass (24), a lifting platform (15), a level (16), and a motor (17).

6. The dynamic pressure and temperature-varying liquid surface tension testing device according to claim 1, characterized in that: The electromagnetic force balance sensor (5) is connected to the hook (20) via a balancer (21); the platinum ring (23) is placed on the hook (20), and a temperature sensor (22) is installed behind the hook (20); the watch glass (24) is placed on an electrically heated lifting platform (15), and a level (16) is installed outside the lower part of the electrically heated lifting platform (15), and the lifting platform (15) is connected to a motor (17).

7. A testing method based on the dynamic pressure variable temperature liquid surface tension testing device according to any one of claims 1 to 6, characterized in that: The steps include: Step 1: Open the box door (14), adjust the equipment to a horizontal plane, check the level (16), observe whether the instrument is in a horizontal state, remove the platinum ring (23), wash it three times with deionized water, and then burn the platinum ring (23) with an alcohol lamp until it is red, and install it on the hook (20) after cooling; take out the watch glass (24), wash it three times with deionized water, wipe it clean and place the solution to be tested in the watch glass (24), and then place the watch glass (24) on the lifting platform (15), turn on the power of the equipment, open the surface tension test system software in the computer (19), and check whether the working status of each component of the equipment is normal through the computer (19); Step 2: close the vent hole (12), open the vacuum valve (18), start the vacuum pump (7), adjust the ambient pressure in the box, and at the same time control the heating resistor (4) or the compressor to enter the working state through the computer (19) to adjust the temperature in the box; When the temperature of the temperature sensor (22) and the pressure of the pressure gauge (13) reach the test conditions, the vacuum valve (18) is closed, the vacuum pump (7) is turned off, and the test device is started by controlling the computer (19); Step 3: After the test is completed, the computer (19) controls the heating resistor (4) or the compressor to exit the working state, opens the vent hole (12), waits for the temperature and pressure to return to the external environment state, takes out the platinum ring (23) and the watch glass (24) for cleaning, so as to carry out the next test.

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