Fluorescent visualization device and method for soil displacement-phase change microfluidic simulation

Abstract

The application provides a fluorescence visualization device and method for soil displacement-phase change microfluidic simulation, which simulates soil pore structure through internal channels of a microfluidic chip, controls fluid pressure and flow through a microfluidic control system, changes the temperature of the microfluidic chip through a heating temperature control system, marks and observes the seepage characteristics of non-aqueous phase organic matter through a fluorescence visualization system, and collects drainage and matrix suction data through a matrix suction test module, so as to derive and obtain the soil water characteristic curve of the microfluidic chip simulated non-saturated soil, store and process the collected images and data through a data collection and image analysis system, and obtain pressure-temperature-flow interrelationship, image fluorescence area percentage and other data. Meanwhile, the microfluidic simulation of non-saturated seepage of soil, the ultraviolet fluorescence marking of non-aqueous phase organic matter, and the provision of devices and methods for the study of high-temperature phase change behavior and seepage characteristics of multi-phase fluid in soil are realized.

Description

Technical Field

[0001] This invention belongs to the field of environmental geotechnical engineering technology, and specifically relates to a fluorescent visualization device and method for soil displacement-phase change microfluidic simulation, which is suitable for the visualization study of phase change behavior and unsaturated seepage characteristics of pore fluids inside soil under high temperature conditions. Background Technology

[0002] Microfluidic technology can simulate the pore structure inside soil by precisely etching channels. Furthermore, microfluidic chips are often made of transparent materials, and combined with visualization devices, they can monitor the seepage characteristics and phase evolution of fluids within the pores in real time. Therefore, microfluidic technology has the fundamental conditions for simulating physical processes in non-uniform porous media.

[0003] Currently, most microfluidic seepage characterization of non-aqueous organic matter relies on pigment labeling. However, the addition of pigments can affect the viscosity and homogeneity of the non-aqueous organic matter. Ultraviolet fluorescence labeling effectively avoids this effect, achieving a more realistic characterization of non-aqueous organic matter seepage. For steady-state methods of determining the relative permeability of oil-water two-phase fluids, accurate determination of the steady state and water saturation is crucial. Traditional steady-state methods typically determine the steady state by measuring inlet and outlet pressures and flow rates. However, the flow rates can often only be calculated by weighing, and this method requires separation of the mixed fluids, making it complex and less accurate. Using fluorescent labeling and image processing to determine the steady state and water saturation effectively avoids these drawbacks. Regarding the determination of matrix suction in unsaturated soils, various methods exist, such as the pressure plate method, filter paper method, and centrifuge method. These methods can only determine the numerical values ​​of matrix suction and water content, but cannot directly observe the seepage movement characteristics and distribution of liquid held by solid particles in the pores. Therefore, visualizing the unsaturated seepage process in soil and linking it with existing unsaturated seepage theories is of great scientific value for constructing and verifying existing unsaturated soil theories. Summary of the Invention

[0004] The present invention provides a fluorescent visualization device and method for soil displacement-phase change microfluidic simulation to solve the above-mentioned technical problems;

[0005] This invention provides a fluorescent visualization device and method for microfluidic simulation of soil displacement-phase change. It simulates the pore structure of soil by utilizing the internal pore topology of a microfluidic chip, controls fluid pressure and flow rate through a microfluidic control system, modulates the temperature of the microfluidic chip through a heating and temperature control system, marks and observes microfluidic seepage characteristics through a fluorescent visualization system, collects data such as drainage volume and matrix suction through a matrix suction test module, and derives the soil-water characteristic curve of unsaturated soil using the microfluidic chip through theoretical derivation. A data acquisition and image analysis system stores and processes the acquired images and data, yielding a series of data such as the pressure-temperature-flow relationship, matrix suction curve, and percentage of fluorescent area in the image. The advantages of this invention are that it provides a device and method that realizes microfluidic simulation of unsaturated soil seepage and fluorescent visualization of non-aqueous organic matter. The microfluidic chip temperature can be adjusted through a heating and temperature control device, providing a device for studying the high-temperature phase change behavior and seepage characteristics of multiphase fluids within soil. Furthermore, the matrix suction test module and theoretical methods reveal the relationship between the soil-water characteristic curve of unsaturated soil and the internal fluid seepage characteristics.

[0006] A fluorescent visualization device for soil displacement-phase change microfluidic simulation is provided, characterized in that the device includes: a microfluidic control system (1), a heating and temperature control system (2), a fluorescent visualization system (3), a matrix suction auxiliary testing system (4), a data acquisition and image analysis system (5), and a microfluidic chip (6).

[0007] The microfluidic control system (1) consists of an air compressor (11), a microfluidic pressure pump (12), a high-precision fluid flow meter (13), a liquid storage tank (14), an air guide tube (15), and a capillary tube (16). The air compressor (11), microfluidic pressure pump (12), and liquid storage tank (14) are connected via the air guide tube (15); the liquid storage tank (14) is connected to the high-precision fluid flow meter (13) and the microfluidic chip (6) via the capillary tube (16); the air compressor (11), microfluidic pressure pump (12), and liquid storage tank (14) are connected via the air guide tube (15); the liquid storage tank (14), high-precision fluid flow meter (13), and microfluidic chip (6) are connected via the capillary tube (16); the air compressor (11), microfluidic pressure pump (12), and high-precision fluid flow meter (13) ... microfluidic pressure pump (12), high-precision fluid flow meter (13), and microfluidic chip (6) are connected via the capillary tube (16); the microfluidic pressure pump (12), high-precision fluid flow meter (13), and microfluidic chip (6) are connected via the capillary tube (16); the 11) It can provide a gas pressure range of 0-800kPa; the microfluidic pressure pump (12) can realize pressure regulation in the range of 0-7000mbar, can regulate the microfluidic pressure filled into the microfluidic chip (6), and can control the microfluidic through two different adjustment modes: constant flow mode and constant pressure mode; the high-precision fluid flow meter (13) can monitor the volumetric flow rate of the fluid passing through the capillary in real time, with a measurement range of 0-80ul / min and an accuracy of 0.001ul / min;

[0008] The liquid storage tank (14) is in the shape of a closed test tube and is not connected to the air. It is used to store the liquid to be tested. A gas guide tube (15) and a capillary guide tube (16) can be connected to it. The gas guide tube (15) is inserted into the upper 1 / 3 height of the liquid storage tank (14) through the top port, and the capillary guide tube (16) is inserted into the lower 1 / 3 height of the liquid storage tank (14) after passing through the top port.

[0009] The heating and temperature control system (2) consists of an asbestos insulation layer (21), a sample chamber (22), a heating element (23), an electric temperature controller (24), and a heat-insulating glass window (25). The system is a double-layered box. The heating element is placed between the inner layer of the asbestos insulation layer (21) and the sample chamber (22). The heat-insulating glass window (25) is connected to the sample chamber (22) through a reserved slot (221). The asbestos insulation layer (21) is made of malleable asbestos profile with a thermal conductivity of 0.03 W / (m*k). Two symmetrical holes (211) are reserved on the side wall for the passage of capillary tubes (16) and electric temperature controller wires. The sample chamber (22) is made of aluminum with a thermal conductivity of 237. W / (m*k), the inner bottom surface is provided with four protruding chip fixing posts (222), and the two symmetrical positions on the side wall are reserved with reserved round holes through which the capillary guide tube (16) and the electric temperature controller (24) wires can pass. All the reserved round holes in the sample chamber (22) are connected to the round holes (211) of the asbestos insulation layer (21); the heating plate (23) is a rectangular alumina ceramic heating plate, which can be temperature-regulated by the electric temperature controller (24), thereby regulating and maintaining the temperature in the sample chamber (22) within the temperature range of room temperature to 180℃; the heat-insulating glass window (25) is a square JGS1 deep ultraviolet glass sheet, with a ring of anti-fog heating wire (251) attached around the top surface of the glass sheet, which can be temperature-regulated by the electric temperature controller (24); the heat-insulating glass window (25) is placed in the reserved slot (221) of the sample chamber (22), forming a sealed cavity with the sample chamber (22);

[0010] The fluorescence visualization system (3) consists of a heat-resistant background light source (31), a CMOS camera (32), a photoelectric controller (33), and a black flexible light shield (34). The heat-resistant background light source (31) is set on the bottom surface inside the sample chamber (22), and the CMOS camera (32) is mounted directly above the heat-insulating glass window (25) of the sample chamber (22). The CMOS camera (32) and the heat-insulating glass window of the sample chamber (22) are connected by the black flexible light shield (34).

[0011] The heat-resistant background light source (31) has visible light LEDs (311) and ultraviolet LEDs (312) distributed at intervals inside. The ultraviolet LEDs can emit ultraviolet light of three wavelengths: 254 / 275 / 308nm, with a total radiant flux of 3mW. The on or off states of different LEDs can be controlled by the photoelectric controller (33). The visible light LEDs (311) are used to observe conventional fluids, and the ultraviolet LEDs (312) can induce light non-aqueous organic matter to produce fluorescence in the wavelength range of 390nm-780nm, which is used to observe the pore seepage characteristics of non-aqueous organic matter. The CMOS camera (32) can adjust the acquisition frequency and imaging range, has 60 million pixels, and a frame rate of 70 frames per second. The acquired images can be recorded by a computer.

[0012] The matrix suction auxiliary testing system (4) consists of a matrix suction control component (41), a high-precision fluid flow meter (13), and a collection bottle (42). The matrix suction control component (41) has a layer of water-permeable but air-permeable clay plate (411) inside, and capillary connectors (412) are on both sides of the clay plate. The high-precision fluid flow meter (13) is connected to one side of the clay plate (411). The end of the capillary guide tube (16) is connected to the collection bottle (42), and the top of the collection bottle (42) has a 1mm diameter vent hole for balancing gas pressure.

[0013] The data acquisition and image analysis system (5) is connected to the microfluidic pressure pump (12), CMOS camera (32), high-precision fluid flow meter (13), and photoelectric controller (33) via data cables;

[0014] Connect the microfluidic pressure pump (12) of the microfluidic control system (1) to the data acquisition and image analysis system (5), and connect the high-precision fluid flow meter (13) of the microfluidic control system (1) to the microfluidic chip (6) through the round hole (211) of the heating and temperature control system (2) via the capillary tube (16); connect both ends of the matrix suction auxiliary test system (4) to the microfluidic chip (6) and the high-precision fluid flow meter (13) respectively via the capillary tube (16); connect the fluorescence visualization system (3) to the data acquisition and image analysis system (5) to form the fluorescence visualization device for soil displacement-phase change microfluidic simulation described in this invention.

[0015] Simultaneously, a method for implementing a fluorescent visualization device for soil displacement-phase change microfluidic simulation is provided.

[0016] Beneficial effects: The present invention provides an apparatus and method that realizes microfluidic simulation of unsaturated seepage in soil and fluorescence visualization of non-aqueous organic matter. It determines the steady state of seepage through a fluorescent labeling system and area parameters after image processing, providing a new approach for the steady-state method to determine the relative permeability of oil-water two-phase fluids. The temperature of the microfluidic chip can be adjusted by a heating and temperature control device, providing an apparatus for studying the high-temperature phase transition behavior and seepage characteristics of multiphase fluids inside soil. Furthermore, it reveals the relationship between the soil-water characteristic curve of unsaturated soil and the pore fluid seepage characteristics during the change of matrix suction through a matrix suction-assisted testing system and related theoretical methods. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this specification or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, 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.

[0018] Figure 1 This is a schematic diagram of the working operation of the fluorescent visualization device for soil displacement-phase change microfluidic simulation of the present invention.

[0019] Figure 2 This is a schematic diagram illustrating the fluorescent labeling effect during the non-aqueous organic matter percolation process of the present invention;

[0020] Figure 3 This is a schematic diagram of the soil-water characteristic curve of the microfluidic chip of the present invention simulating unsaturated soil.

[0021] Explanation of reference numerals in the attached figures:

[0022] 1. Microfluidic control system;

[0023] 11. Air compressor;

[0024] 12. Microfluidic pressure pump;

[0025] 13. High-precision fluid flow meter;

[0026] 14. Liquid reservoir;

[0027] 15. Air delivery tube;

[0028] 16. Capillary tube;

[0029] 2. Heating and temperature control system;

[0030] 21. Asbestos insulation layer;

[0031] 211. Wire hole;

[0032] 22. Sample chamber;

[0033] 221. Reserved card slot;

[0034] 222. Chip fixing post;

[0035] 23. Heating element;

[0036] 24. Electric temperature controller;

[0037] 25. Insulated glass window;

[0038] 251. Anti-fog heating wire;

[0039] 3. Fluorescence visualization system;

[0040] 31. Temperature-resistant background light source;

[0041] 311. Visible light LED;

[0042] 312. Ultraviolet LED;

[0043] 32. CMOS camera;

[0044] 33. Photoelectric controller;

[0045] 34. Black flexible sunshade;

[0046] 4. Matrix suction-assisted testing system;

[0047] 41. Matrix suction control components;

[0048] 411. Terracotta slab;

[0049] 412. Capillary connector;

[0050] 42. Collection bottle;

[0051] 5. Data acquisition and image analysis system;

[0052] 6. Microfluidic chip. Detailed Implementation

[0053] The technical solutions of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0054] The technical solutions of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0055] The present invention provides a fluorescent visualization device for soil displacement-phase change microfluidic simulation, the device comprising: a microfluidic control system (1), a heating and temperature control system (2), a fluorescent visualization system (3), a matrix suction auxiliary testing system (4), a data acquisition and image analysis system (5), and a microfluidic chip (6).

[0056] The microfluidic control system (1) consists of an air compressor (11), a microfluidic pressure pump (12), a high-precision fluid flow meter (13), a liquid storage tank (14), an air guide tube (15), and a capillary tube (16). The air compressor (11), microfluidic pressure pump (12), and liquid storage tank (14) are connected via the air guide tube (15); the liquid storage tank (14) is connected to the high-precision fluid flow meter (13) and the microfluidic chip (6) via the capillary tube (16); the air compressor (11), microfluidic pressure pump (12), and liquid storage tank (14) are connected via the air guide tube (15); the liquid storage tank (14), high-precision fluid flow meter (13), and microfluidic chip (6) are connected via the capillary tube (16); the air compressor (11), microfluidic pressure pump (12), and high-precision fluid flow meter (13) ... microfluidic pressure pump (12), high-precision fluid flow meter (13), and microfluidic chip (6) are connected via the capillary tube (16); the microfluidic pressure pump (12), high-precision fluid flow meter (13), and microfluidic chip (6) are connected via the capillary tube (16); the 11) It can provide a gas pressure range of 0-800kPa; the microfluidic pressure pump (12) can realize pressure regulation in the range of 0-7000mbar, can regulate the microfluidic pressure filled into the microfluidic chip (6), and can control the microfluidic through two different adjustment modes: constant flow mode and constant pressure mode; the high-precision fluid flow meter (13) can monitor the volumetric flow rate of the fluid passing through the capillary in real time, with a measurement range of 0-80ul / min and an accuracy of 0.001ul / min;

[0057] The liquid storage tank (14) is in the shape of a closed test tube and is not connected to the air. It is used to store the liquid to be tested. A gas guide tube (15) and a capillary guide tube (16) can be connected to it. The gas guide tube (15) is inserted into the upper 1 / 3 height of the liquid storage tank (14) through the top port, and the capillary guide tube (16) is inserted into the lower 1 / 3 height of the liquid storage tank (14) after passing through the top port.

[0058] The heating and temperature control system (2) consists of an asbestos insulation layer (21), a sample chamber (22), a heating element (23), an electric temperature controller (24), and a heat-insulating glass window (25). The system is a double-layered box. The heating element is placed between the inner layer of the asbestos insulation layer (21) and the sample chamber (22). The heat-insulating glass window (25) is connected to the sample chamber (22) through a reserved slot (221). The asbestos insulation layer (21) is made of malleable asbestos profile with a thermal conductivity of 0.03 W / (m*k). Two symmetrical holes (211) are reserved on the side wall for the passage of capillary tubes (16) and electric temperature controller wires. The sample chamber (22) is made of aluminum with a thermal conductivity of 237. W / (m*k), the inner bottom surface is provided with four protruding chip fixing posts (222), and the two symmetrical positions on the side wall are reserved with reserved round holes through which the capillary guide tube (16) and the electric temperature controller (24) wires can pass. All the reserved round holes in the sample chamber (22) are connected to the round holes (211) of the asbestos insulation layer (21); the heating plate (23) is a rectangular alumina ceramic heating plate, which can be temperature-regulated by the electric temperature controller (24), thereby regulating and maintaining the temperature in the sample chamber (22) within the temperature range of room temperature to 180℃; the heat-insulating glass window (25) is a square JGS1 deep ultraviolet glass sheet, with a ring of anti-fog heating wire (251) attached around the top surface of the glass sheet, which can be temperature-regulated by the electric temperature controller (24); the heat-insulating glass window (25) is placed in the reserved slot (221) of the sample chamber (22), forming a sealed cavity with the sample chamber (22);

[0059] The fluorescence visualization system (3) consists of a heat-resistant background light source (31), a CMOS camera (32), a photoelectric controller (33), and a black flexible light shield (34). The heat-resistant background light source (31) is set on the bottom surface inside the sample chamber (22), and the CMOS camera (32) is mounted directly above the heat-insulating glass window (25) of the sample chamber (22). The CMOS camera (32) and the heat-insulating glass window of the sample chamber (22) are connected by the black flexible light shield (34).

[0060] The heat-resistant background light source (31) has visible light LEDs (311) and ultraviolet LEDs (312) distributed at intervals inside. The ultraviolet LEDs can emit ultraviolet light of three wavelengths: 254 / 275 / 308nm, with a total radiant flux of 3mW. The on or off states of different LEDs can be controlled by the photoelectric controller (33). The visible light LEDs (311) are used to observe conventional fluids, and the ultraviolet LEDs (312) can induce light non-aqueous organic matter to produce fluorescence in the wavelength range of 390nm-780nm, which is used to observe the pore seepage characteristics of non-aqueous organic matter. The CMOS camera (32) can adjust the acquisition frequency and imaging range, has 60 million pixels, and a frame rate of 70 frames per second. The acquired images can be recorded by a computer.

[0061] The matrix suction auxiliary testing system (4) consists of a matrix suction control component (41), a high-precision fluid flow meter (13), and a collection bottle (42). The matrix suction control component (41) has a layer of water-permeable but air-permeable clay plate (411) inside, and capillary connectors (412) are on both sides of the clay plate. The high-precision fluid flow meter (13) is connected to one side of the clay plate (411). The end of the capillary guide tube (16) is connected to the collection bottle (42), and the top of the collection bottle (42) has a 1mm diameter vent hole for balancing gas pressure.

[0062] The data acquisition and image analysis system (5) is connected to the microfluidic pressure pump (12), CMOS camera (32), high-precision fluid flow meter (13), and photoelectric controller (33) via data cables;

[0063] Connect the microfluidic pressure pump (12) of the microfluidic control system (1) to the data acquisition and image analysis system (5), and connect the high-precision fluid flow meter (13) of the microfluidic control system (1) to the microfluidic chip (6) through the round hole (211) of the heating and temperature control system (2) via the capillary tube (16); connect both ends of the matrix suction auxiliary test system (4) to the microfluidic chip (6) and the high-precision fluid flow meter (13) respectively via the capillary tube (16); connect the fluorescence visualization system (3) to the data acquisition and image analysis system (5) to form the fluorescence visualization device for soil displacement-phase change microfluidic simulation described in this invention.

[0064] This invention also provides a method for implementing a fluorescence visualization device for soil displacement-phase change microfluidic simulation, including the following three implementation sub-methods:

[0065] Sub-method 1: Microfluidic chip (6) simulation of soil-water characteristic curve test method for unsaturated soil

[0066] Step 1: Saturate the microfluidic chip (6) and the matrix suction control device (41), and connect the microfluidic chip (6) to the matrix suction control device (41) and the high-precision fluid flow meter (13) connected to its rear end through the capillary tube (16) and saturate them;

[0067] Step 2: Drain the liquid in the storage tank (14) and add a desiccant;

[0068] Step 3: Assemble the above-mentioned fluorescent visualization device for soil displacement-phase change microfluidic simulation;

[0069] Step 4: Camera imaging adjustment, turn on the power of the heat-resistant background light source (31) and turn on the LED light, then turn on the CMOS camera (32) and adjust the acquisition frequency and imaging range;

[0070] Step 5: Start the electric temperature controller (24) and adjust the heating temperature and heating rate to make the temperature of the sample chamber (22) reach the set value T and remain stable;

[0071] Step 6: Turn on the high-precision fluid flow meter (13) and start monitoring the real-time flow rate Q(t) of the fluid passing through the matrix suction control unit (41);

[0072] Step 7: After the sample chamber temperature and CMOS camera imaging are adjusted, turn on the data acquisition and image analysis system (5) to start recording and storing relevant data and images;

[0073] Step 8: Start the air compressor (11) and connect the power supply to the microfluidic pressure pump (12), select the constant pressure mode, and set the intake pressure P. t The saturated fluid in the microfluidic chip (6) is driven into the collection bottle (42). When the instantaneous flow rate Q(t) measured by the high-precision fluid flow meter (13) is 0, the next stage of inlet pressure P is applied. t The intake pressures for each stage are 10 kPa, 20 kPa, 30 kPa, 40 kPa, 50 kPa, 100 kPa, 200 kPa, 400 kPa, 600 kPa, 800 kPa, and 1000 kPa, respectively.

[0074] Step 9: Calculate the soil-water characteristic curves of the microfluidic chip simulating unsaturated soil according to the following procedure:

[0075] ① Air pressure value P t The fluid volume V passing through the high-precision fluid flow meter (13) under certain conditions x It can be calculated using formula (1), which is:

[0076] (1)

[0077] In equation (1), V x Let t1 be the fluid volume passing through the high-precision fluid flow meter (13) during the time period (t1, t2); t1 and t2 are the start of the time period (when the applied air pressure value P is applied). t The start time and end time (the moment when the instantaneous flow rate Q(t) is 0); Q(t) is the instantaneous flow rate through the high-precision fluid flow meter (13);

[0078] ②The total volume V of the microfluidic chip (6) c for:

[0079] (2)

[0080] In equation (2), A is the bottom area of ​​the microfluidic chip (6); h is the thickness of the microfluidic chip (6); L0 is the length of the microfluidic chip (6); and W is the width of the microfluidic chip (6).

[0081] ③ Equivalent porosity of microfluidic chip (6) for:

[0082] (3)

[0083] In equation (3), V c V represents the total volume of the microfluidic chip (6); H The equivalent total pore volume of the microfluidic chip (6) can be calculated using equation (4), which is:

[0084] (4)

[0085] In equation (4), V H is the equivalent total pore volume of the microfluidic chip (6); n is the number of channels in the microfluidic chip (6); π is pi. L is the equivalent average radius of the channels in the microfluidic chip (6); t The average length of the axis of the n channels in the microfluidic chip (6);

[0086] ④ The internal water potential h of the microfluidic chip (6) at any given time t With air pressure value P t The relationship is shown in formula (5), which is:

[0087] (5)

[0088] In equation (5), h t P represents the water potential in the microfluidic chip (6) at time t; t Let be the gas pressure applied at time t;

[0089] ⑤ Chip saturation S r It can be calculated using formula (6), which is:

[0090] (6)

[0091] In equation (6): S r V represents chip saturation. x V is the volume of fluid passing through the high-precision fluid flow meter (13) during the time interval (0, t); H The equivalent total pore volume of the microfluidic chip (6);

[0092] ⑥ Calculate the air pressure value P respectively tThe chip saturation S at 10kPa, 20kPa, 30kPa, 40kPa, 50kPa, 100kPa, 200kPa, 400kPa, 600kPa, 800kPa, and 1000kPa. r and with air pressure value P t The horizontal axis represents the pressure value P at each pressure level. t The corresponding chip saturation S r Plot a curve on the vertical axis to represent the saturation S. r The microfluidic chip (6) with parameters simulates the soil-water characteristic curves of unsaturated soil.

[0093] ⑦ Determine the volumetric water content θ using formula (7) t The microfluidic chip (6) with parameters simulates the soil-water characteristic curve of unsaturated soil, and the formula (7) is:

[0094] (7)

[0095] In equation (7): θ t The volumetric water content of the microfluidic chip (6) at time t can be calculated using equation (8); θ s The saturated volumetric water content of the microfluidic chip (6) can be calculated using equation (9); θ r The residual volumetric water content of the microfluidic chip (6) can be calculated using equation (10); h t The internal water potential of the microfluidic chip (6) at time t can be calculated using equation (5); α, m, and N are all fitting parameters, where m = 1 - 1 / N; where equations (8), (9), and (10) are respectively:

[0096] (8)

[0097] (9)

[0098] (10)

[0099] In formulas (8), (9), and (10), V H The equivalent total pore volume of the microfluidic chip (6) is calculated using formula (4); V t The volume of water discharged through the high-precision fluid flow meter (13) during the time period (0, t) can be calculated using formula (1); V c The total volume of the microfluidic chip (6) is calculated using formula (2); m s The mass of the microfluidic chip (6) was absolutely dry before the experiment; m r The quality of the microfluidic chip (6) after the experiment was completed and dried; The density of the fluid used for saturation in step 1 (the fluid is water, diesel, gasoline, or pure contaminated liquid).

[0100] ⑧ Substituting the results of formulas (5), (8), (9), and (10) into formula (7) yields the fitting parameters α, m, and N. Finally, α, m, N, and θ are used to obtain the fitting parameters. s θ r Substituting into equation (7), we can obtain the volumetric water content θ in the soil simulated by the microfluidic chip (6). t With water potential h t Expression of the soil-water characteristic curve of the relationship;

[0101] Sub-method 2: A method for testing the relative permeability of water-oil two-phase fluids based on a microfluidic chip (6) and a non-aqueous organic fluorescence visualization device;

[0102] Step A1: Assemble the above-mentioned fluorescent visualization device for soil displacement-phase change microfluidic simulation;

[0103] Step A2: Turn on the power of the heat-resistant background light source (31) and adjust the wavelength of the ultraviolet LED (312) to induce the non-aqueous organic matter in the microfluidic chip (6) to produce fluorescence in the wavelength range of 390nm-780nm; then turn on the CMOS camera (32) and set the acquisition frequency and imaging range.

[0104] Step A3: Start the electric temperature controller (24) and adjust the heating temperature and heating rate to adjust the temperature of the sample chamber (22) to T. x And stabilized for 1 hour;

[0105] Step A4: Data acquisition, adjust the imaging area of ​​the CMOS camera (32), open the computer acquisition software, record and save the image;

[0106] Step A5: Image processing, binarize the image, extract t x The fluorescent area A of the image of the microfluidic chip (6) at any given time ntx and the area A of the non-fluorescent portion wtx The percentage of the fluorescent area α in the image can be calculated using formula (11), which is:

[0107] (11)

[0108] In equation (11), α is the percentage of the fluorescent portion of the image area; A is the bottom area of ​​the microfluidic chip (6); A ntx For the binarized microfluidic chip (6)t x Area of ​​the fluorescent portion in the time-lapse image;

[0109] Step A6: Saturate the microfluidic chip (6) with water, then introduce oil to drive the water out. Adjust the microfluidic pressure pump (12) to gradually increase the volumetric flow rate of the introduced oil within the range of 0.1 μl / min-10 μl / min until the microfluidic chip (6) no longer drains water. Calculate the bound water saturation according to formula (12), which is:

[0110] (12)

[0111] In equation (12): S ws For the microfluidic chip (6) bound water saturation; V H V represents the equivalent total pore volume of the microfluidic chip (6); w The volume of water discharged from the microfluidic chip (6) can be calculated using formula (13), which is:

[0112] (13)

[0113] In equation (13): V w V is the volume of water discharged from the microfluidic chip (6); H A1 is the equivalent total pore volume of the microfluidic chip (6); A1 is the area of ​​the fluorescent part of the microfluidic chip (6) when it stops draining; A is the bottom area of ​​the microfluidic chip (6);

[0114] Step A7: Fill the storage tank (14) with oil and turn on the microfluidic pressure pump (12) to drive the oil through the microfluidic chip (6) at a volumetric flow rate of 1 μl / min, and collect the discharge flow rate q through the high-precision fluid flow meter (13). n When t S The oil filling volume reaches 10 times that of the microfluidic chip (6) at any time, with an equivalent total pore volume V. H Then, record the discharge flow rate at this time as q. nS The effective permeability K of the oil phase under bound water saturation is calculated according to formula (14). nS Formula (14) is:

[0115] (14)

[0116] In equation (14): K nS q represents the effective permeability of the oil phase under bound water saturation. nS For t S The oil filling volume reaches 10 times that of the microfluidic chip (6) at any time, with an equivalent total pore volume V. H The discharge flow rate value recorded later; μ n For temperature T x The viscosity of the lower oil phase; L0 is the length of the microfluidic chip (6); S is the cross-sectional area of ​​the microfluidic chip (6); P t This refers to the gas pressure at the inlet.

[0117] Step A8: Calculate the water-oil ratio β based on the binarized image analysis results from Step A5. x The calculation process for the water saturation and oil saturation of the microfluidic chip (6) is as follows:

[0118] At the initial time t1, according to the initial water-oil ratio β x =w x :n x The water-oil mixture is filled into the storage tank (14), and the microfluidic pressure pump (12) is adjusted to drive the water-oil mixture into the microfluidic chip (6) at a volume flow rate of 1 μl / min. The inlet and outlet pressures of the microfluidic chip (6) and the flow rate of the water-oil mixture are recorded by the microfluidic pressure pump (12) and the high-precision fluid flow meter (13).

[0119] When t2, the microfluidic chip (6) discharges oil volume V. n (out) and the volume of water discharged V w (out) All are greater than 3 times the equivalent total pore volume V of the microfluidic chip (6) H And the percentage of fluorescent area in the image within 1 minute after time t2. If the fluctuation range does not exceed ±3%, it can be determined that the two-phase fluid seepage under this water-oil ratio has reached a stable state; at this time, the inlet pressure is recorded as P. in ;

[0120] The volume of the oil-water two-phase fluid at each location in the system when it reaches a steady state is calculated; the volume of the oil-water two-phase fluid at the outlet at time t2 can be calculated by formulas (15) and (16) respectively:

[0121] (15)

[0122] (16)

[0123] In formulas (15) and (16), V n (out) V is the volume of oil discharged by the microfluidic chip (6) at time t2; w (out) V represents the volume of water discharged by the microfluidic chip (6) at time t2; n (in) The volume of oil injected into the microfluidic chip (6) at time t2 can be calculated using formula (17); V w (in) The volume of oil injected into the microfluidic chip (6) at time t2 can be calculated using formula (18); V nt1 V nt2 V represents the oil phase volume in the microfluidic chip (6) at times t1 and t2, respectively, which can be calculated using formula (19); wt1 Vwt2 The water phase volumes in the microfluidic chip (6) at times t1 and t2 are respectively, and can be calculated using formula (20); t1 is the initial time; t2 is the time when the steady state is reached; where formulas (17), (18), (19), and (20) are respectively:

[0124] (17)

[0125] (18)

[0126] (19)

[0127] (20)

[0128] In equations (17), (18), (19), and (20), V n (in) V is the volume of oil injected into the microfluidic chip (6) at time t2; w (in) V is the volume of oil injected into the microfluidic chip (6) at time t2; in The total volume of the oil-water mixture injected into the microfluidic chip (6) at time t2; w x For the xth level water-oil ratio β x =w x :n x Water phase ratio coefficient; n x For the xth level water-oil ratio β x =w x :n x Oil phase ratio coefficient; V ntx For t x The volume of the oil phase in the microfluidic chip (6) at any given time; V H The equivalent total pore volume of the microfluidic chip (6); A ntx For the binarized microfluidic chip (6)t x The area of ​​the fluorescent portion in the time-lapse image; A is the bottom area of ​​the microfluidic chip; V wtx For t x The volume of the aqueous phase in the microfluidic chip (6) at any given time; A wtx For the binarized microfluidic chip (6)t x Area of ​​non-fluorescent portion in time-lapse image;

[0129] The water saturation and oil saturation of the microfluidic chip (6) are calculated according to the following formulas (21) and (22):

[0130] (twenty one)

[0131] (twenty two)

[0132] In formulas (21) and (22), S ntx For microfluidic chips (6)t x Oil saturation at time; S wtx For microfluidic chips (6)t x Water saturation at time V; ntx For t x The volume of the oil phase in the microfluidic chip (6) at any given time; V wtx For t x The volume of the aqueous phase in the microfluidic chip (6) at any given time; V H The equivalent total pore volume of the microfluidic chip (6); A ntx For the binarized microfluidic chip (6)t x Area of ​​the fluorescent portion of the time-lapse image; A wtx For the binarized microfluidic chip (6)t x Area of ​​the non-fluorescent portion of the image at any given time; A is the bottom area of ​​the microfluidic chip.

[0133] Step A9: The relative permeability of the water-oil two-phase fluid based on the microfluidic chip (6) and the non-aqueous organic fluorescence visualization device is calculated according to formulas (23), (24), (25), and (26):

[0134] (twenty three)

[0135] (twenty four)

[0136] (25)

[0137] (26)

[0138] In formulas (23), (24), (25), and (26), K n The water-oil ratio is β x Effective permeability of oil phase; K w The water-oil ratio is β x Effective permeability of aqueous phase at time; K rn The water-oil ratio is β x relative permeability of oil phase; K rw The water-oil ratio is β x relative permeability of water phase at time; K nS For bound water saturation S ws Effective permeability of the oil phase below; q n The oil flow rate through the high-precision fluid flow meter (13); q w For the water flow rate passing through the high-precision fluid flow meter (13); μ n To measure temperature T x Viscosity of the lower oil phase; μw To measure temperature T x Viscosity of the water phase; V n (out) V is the volume of oil discharged by the microfluidic chip (6) at time t2; w (out) L0 is the volume of water discharged by the microfluidic chip (6) at time t2; L0 is the length of the microfluidic chip (6); S is the cross-sectional area of ​​the microfluidic chip (6); P in P represents the inlet gas pressure at time t2. out Let P be the outlet pressure value at time t2. out =0;

[0139] Sub-method 3: Temperature phase transition test method for non-aqueous organic compounds;

[0140] Step S1: Connect the microfluidic chip (6) and the high-precision fluid flow meter (13) in advance through the capillary tube (16) and fill it with non-aqueous organic matter to saturate it;

[0141] Step S2: Seal the injection port of the microfluidic chip (6) after it has been filled with non-aqueous organic matter and place it into the sample chamber (22);

[0142] Step S3: Assemble the above-mentioned heating and temperature control system (2), fluorescence visualization system (3), data acquisition and image analysis system (5), and microfluidic chip (6);

[0143] Step S4: Turn on the power of the heat-resistant background light source (31) and adjust the wavelength of the ultraviolet LED (312) to induce the non-aqueous organic matter in the channel of the microfluidic chip (6) to produce fluorescence in the wavelength range of 390nm-780nm. Then turn on the CMOS camera (32) and set the acquisition frequency and imaging range.

[0144] Step S5: Activate the electric temperature controller (24) and adjust the heating temperature to maintain the temperature of the sample chamber (22) at T. x ;

[0145] Step S6: Data analysis is performed according to the following process to obtain the phase change V of the non-aqueous organic matter in the microfluidic chip (6). x With temperature T x Relationship:

[0146] ①When t0 is the start time of the test, T0 is the initial temperature, and t is the temperature of the sample chamber (22) when it rises to T x And when the temperature remains stable, since the injection port of the microfluidic chip (6) is closed, the non-aqueous organic matter inside the microfluidic chip (6) will rise to T due to the temperature. x The resulting phase transition volume V Tx That is, the fluid volume V passing through the high-precision fluid flow meter (13) at the discharge end. x As shown in the following formula:

[0147] (27)

[0148] In formula (27), V Tx Non-aqueous organic matter, due to the temperature increasing from T0 to T x The resulting phase transition volume; V t The fluid volume passing through the high-precision fluid flow meter (13) during the time interval Δt = t - t0;

[0149] ② The non-aqueous organic matter in the microfluidic chip (6) at temperature T x Phase transition ratio λ Tx for:

[0150] (28)

[0151] In formula (28), V Tx Non-aqueous organic matter, due to the temperature increasing from T0 to T x The resulting phase transition volume; V n The total volume of non-aqueous organic matter is equal to the equivalent total pore volume V of the microfluidic chip (6) when the microfluidic chip (6) is in a saturated state. H ;

[0152] ③ By adjusting the temperature of the sample chamber (22) at i different temperature levels through the electric temperature controller (24) and testing, the appropriate temperature T can be obtained. x =T1, T2, T3...T i Phase transition volume V at a series of temperature levels Tx =V T1 V T2 V T3 ......V Ti The phase transition ratio λ of the corresponding level is calculated using formula (28). Tx Then, based on temperature T x The horizontal axis represents the phase transition ratio λ. Tx Plot the temperature-phase transition ratio (T) on the vertical axis. x -λ Tx The relationship curve was finally obtained by fitting a function to obtain the non-aqueous organic phase transition ratio λ in the microfluidic chip (6). Tx With temperature T x The relationship is as follows:

[0153] (29)

[0154] In formula (29), T x Let λ be the temperature at time t; Tx For non-aqueous organic matter in the microfluidic chip (6) at temperature Tx The phase transition ratio below.

[0155] The technical features of this invention are: (1) Microfluidic technology and ultraviolet fluorescent labeling technology are used to realize the microfluidic simulation of unsaturated seepage in soil and the fluorescence visualization of non-aqueous organic matter; (2) Image processing is used to realize the purpose of determining the steady state of seepage through image area parameters, providing a new technology for the steady-state method to determine the relative permeability of oil-water two-phase fluids; (3) A heating and temperature control device is used to adjust the temperature of the microfluidic chip, providing a device for the study of high-temperature phase change behavior and seepage characteristics of multiphase fluids inside soil; (4) The matrix suction-assisted testing method is used to reveal the soil-water characteristic curve of unsaturated soil and the pore fluid transport characteristics during the matrix suction change process.

[0156] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the scope of the technology disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention. All should be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

[0157] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A fluorescent visualization device for soil displacement-phase change microfluidic simulation, characterized in that, The device includes: a microfluidic control system (1), a heating and temperature control system (2), a fluorescence visualization system (3), a matrix suction auxiliary testing system (4), a data acquisition and image analysis system (5), and a microfluidic chip (6). The microfluidic control system (1) consists of an air compressor (11), a microfluidic pressure pump (12), a high-precision fluid flow meter (13), a liquid storage tank (14), an air guide tube (15), and a capillary guide tube (16). The air compressor (11), microfluidic pressure pump (12), and liquid storage tank (14) are connected via the air guide tube (15); the liquid storage tank (14) is connected to the high-precision fluid flow meter (13) and the microfluidic chip (6) via the capillary guide tube (16). The gas compressor (11) can provide a gas pressure range of 0-800 kPa; the microfluidic pressure pump (12) can achieve pressure regulation in the range of 0-7000 mbar, can regulate the microfluidic pressure filled into the microfluidic chip (6), and can control the microfluidic through constant flow mode and constant pressure mode; the high-precision fluid flow meter (13) can monitor the volumetric flow rate of the fluid passing through the capillary in real time, with a measurement range of 0-80 ul / min and an accuracy of 0.001 ul / min; The liquid storage tank (14) is in the shape of a closed test tube and is not connected to the air. It is used to store the liquid to be tested. A gas guide tube (15) and a capillary guide tube (16) can be connected to it. The gas guide tube (15) is inserted into the upper 1 / 3 height of the liquid storage tank (14) through the top port, and the capillary guide tube (16) is inserted into the lower 1 / 3 height of the liquid storage tank (14) after passing through the top port. The heating and temperature control system (2) consists of an asbestos insulation layer (21), a sample chamber (22), a heating element (23), an electric temperature controller (24), and a heat-insulating glass window (25). The system is a double-layered box. The heating element is placed between the inner layer of the asbestos insulation layer (21) and the sample chamber (22). The heat-insulating glass window (25) is connected to the sample chamber (22) through a reserved slot (221). The asbestos insulation layer (21) is made of malleable asbestos profile with a thermal conductivity of 0.03 W / (m*k). Two symmetrical holes (211) are reserved on the side wall for the passage of capillary tubes (16) and electric temperature controller wires. The sample chamber (22) is made of aluminum with a thermal conductivity of 237. W / (m*k), the inner bottom surface is provided with four protruding chip fixing posts (222), and the two symmetrical positions on the side wall are reserved with reserved round holes through which the capillary guide tube (16) and the electric temperature controller (24) wires can pass. All the reserved round holes in the sample chamber (22) are connected to the round holes (211) of the asbestos insulation layer (21); the heating plate (23) is a rectangular alumina ceramic heating plate, which can be temperature-regulated by the electric temperature controller (24), thereby regulating and maintaining the temperature in the sample chamber (22) within the temperature range of room temperature to 180℃; the heat-insulating glass window (25) is a square JGS1 deep ultraviolet glass sheet, with a ring of anti-fog heating wire (251) attached around the top surface of the glass sheet, which can be temperature-regulated by the electric temperature controller (24); the heat-insulating glass window (25) is placed in the reserved slot (221) of the sample chamber (22), forming a sealed cavity with the sample chamber (22); The fluorescence visualization system (3) consists of a heat-resistant background light source (31), a CMOS camera (32), a photoelectric controller (33), and a black flexible light shield (34). The heat-resistant background light source (31) is set on the bottom surface inside the sample chamber (22), and the CMOS camera (32) is mounted directly above the heat-insulating glass window (25) of the sample chamber (22). The CMOS camera (32) and the heat-insulating glass window of the sample chamber (22) are connected by the black flexible light shield (34). The heat-resistant background light source (31) has visible light LEDs (311) and ultraviolet LEDs (312) distributed at intervals inside. The ultraviolet LEDs can emit ultraviolet light of three wavelengths: 254 / 275 / 308nm, with a total radiant flux of 3mW. The on or off states of different LEDs can be controlled by the photoelectric controller (33). The visible light LEDs (311) are used to observe conventional fluids, and the ultraviolet LEDs (312) can induce light non-aqueous organic matter to produce fluorescence in the wavelength range of 390nm-780nm, which is used to observe the pore seepage characteristics of non-aqueous organic matter. The CMOS camera (32) can adjust the acquisition frequency and imaging range, has 60 million pixels, and a frame rate of 70 frames per second. The acquired images can be recorded by a computer. The matrix suction auxiliary testing system (4) consists of a matrix suction control component (41), a high-precision fluid flow meter (13), and a collection bottle (42). The matrix suction control component (41) has a layer of water-permeable but air-permeable clay plate (411) inside, and capillary connectors (412) are on both sides of the clay plate. The high-precision fluid flow meter (13) is connected to one side of the clay plate (411). The end of the capillary guide tube (16) is connected to the collection bottle (42), and the top of the collection bottle (42) has a 1mm diameter vent hole for balancing gas pressure. The data acquisition and image analysis system (5) is connected to the microfluidic pressure pump (12), CMOS camera (32), high-precision fluid flow meter (13), and photoelectric controller (33) via data cables; Connect the microfluidic pressure pump (12) of the microfluidic control system (1) to the data acquisition and image analysis system (5), and connect the high-precision fluid flow meter (13) of the microfluidic control system (1) to the microfluidic chip (6) through the round hole (211) of the heating and temperature control system (2) via the capillary tube (16); connect the two ends of the matrix suction auxiliary test system (4) to the microfluidic chip (6) and the high-precision fluid flow meter (13) respectively via the capillary tube (16); connect the fluorescence visualization system (3) to the data acquisition and image analysis system (5) to form the fluorescence visualization device for soil displacement-phase change microfluidic simulation.

2. An experimental method for a fluorescence visualization device based on soil displacement-phase change microfluidic simulation, characterized in that, Includes the following three sub-methods: Sub-method 1: Microfluidic chip (6) simulation of soil-water characteristic curve test of unsaturated soil; Step 1: Saturate the microfluidic chip (6) and the matrix suction control device (41), and connect the microfluidic chip (6) to the matrix suction control device (41) and the high-precision fluid flow meter (13) connected to its rear end through the capillary tube (16) and saturate them; Step 2: Drain the liquid in the storage tank (14) and add a desiccant; Step 3: Assemble the fluorescence visualization device for soil displacement-phase change microfluidic simulation as described in claim 1; Step 4: Camera imaging adjustment, turn on the power of the heat-resistant background light source (31) and turn on the LED light, then turn on the CMOS camera (32) and adjust the acquisition frequency and imaging range; Step 5: Start the electric temperature controller (24) and adjust the heating temperature and heating rate to bring the temperature of the sample chamber (22) to the set value. T And remain stable; Step 6: Turn on the high-precision fluid flow meter (13) and start monitoring the real-time flow rate of the fluid passing through the matrix suction control unit (41). Q ( t ); Step 7: After the sample chamber temperature and CMOS camera imaging are adjusted, turn on the data acquisition and image analysis system (5) to start recording and storing relevant data and images; Step 8: Start the air compressor (11) and connect the power supply to the microfluidic pressure pump (12), select the constant pressure mode, and set the intake pressure. P t The saturated fluid in the microfluidic chip (6) is driven into the collection bottle (42), and the instantaneous flow rate measured by the high-precision fluid flow meter (13) is... Q ( t When the pressure is 0, apply the next stage intake pressure. P t The intake pressures for each stage are 10 kPa, 20 kPa, 30 kPa, 40 kPa, 50 kPa, 100 kPa, 200 kPa, 400 kPa, 600 kPa, 800 kPa, and 1000 kPa, respectively. Step 9: Calculate the soil-water characteristic curves of the microfluidic chip simulating unsaturated soil according to the following procedure: ① Air pressure value P t The fluid volume passing through the high-precision fluid flow meter (13) under certain conditions V x It can be calculated using formula (1), which is: (1) In equation (1), V x for( t 1, t 2) The volume of fluid passing through the high-precision fluid flow meter (13) over a period of time; t 1. t 2 represents the start and end times of the time period, with the start time being the applied air pressure value. P t The start and end times are the instantaneous flow values. Q ( t () is time 0; Q ( t The instantaneous flow rate value passing through the high-precision fluid flow meter (13) is the value of the flow rate. ②The total volume of the microfluidic chip (6) V c for: (2) In equation (2), A The bottom area of ​​the microfluidic chip (6); h The thickness of the microfluidic chip (6); L 0 represents the length of the microfluidic chip (6); W The width of the microfluidic chip (6); ③ Equivalent porosity of microfluidic chip (6) ξ for: (3) In equation (3), V c The total volume of the microfluidic chip (6); V H The equivalent total pore volume of the microfluidic chip (6) can be calculated using equation (4), which is: (4) In equation (4), V H The equivalent total pore volume of the microfluidic chip (6); n π represents the number of channels in the microfluidic chip (6); π represents pi. The equivalent average radius of the channels in the microfluidic chip (6); L t For microfluidic chips (6) n Average length of the axis of the root channel; ④ The internal water potential of the microfluidic chip (6) at any given time h t With air pressure value P t The relationship is shown in formula (5), which is: （5） In equation (5), h t for t The water potential in the microfluidic chip (6) at any given moment; P t for t The applied gas pressure value at any given time; ⑤ Chip saturation S r It can be calculated using formula (6), which is: （6） In formula (6): S r Chip saturation; V x for( 0 , t The volume of fluid passing through the high-precision fluid flow meter (13) within a time period; V H The equivalent total pore volume of the microfluidic chip (6); ⑥ Calculate the air pressure values ​​respectively P t Chip saturation at 10kPa, 20kPa, 30kPa, 40kPa, 50kPa, 100kPa, 200kPa, 400kPa, 600kPa, 800kPa, and 1000kPa. S r and based on air pressure value P t The horizontal axis represents the pressure value at each level. P t Corresponding chip saturation S r Plot a curve on the vertical axis to represent saturation. S r The microfluidic chip (6) with parameters simulates the soil-water characteristic curves of unsaturated soil. ⑦ Determine the volumetric moisture content using formula (7) θ t The microfluidic chip (6) with parameters simulates the soil-water characteristic curve of unsaturated soil, and the formula (7) is: （7） In equation (7): θ t for t The volumetric water content of the microfluidic chip (6) at any given time can be calculated using equation (8); θ s The saturated volumetric water content of the microfluidic chip (6) can be calculated using equation (9); θ r The residual volumetric water content of the microfluidic chip (6) can be calculated using equation (10); h t for t The water potential inside the microfluidic chip (6) at any given time can be calculated using equation (5); α, m, N All are fitted parameters. m =1-1 / N Among them, formulas (8), (9), and (10) are respectively: （8） （9） （10） In formulas (8), (9), and (10), V H The equivalent total pore volume of the microfluidic chip (6) is calculated using formula (4); V t for( 0 , t The volume of water discharged through the high-precision fluid flow meter (13) within a time period can be calculated using formula (1); V c The total volume of the microfluidic chip (6) is calculated using formula (2); m s The mass of the microfluidic chip (6) was absolutely dry before the experiment; m r The quality of the microfluidic chip (6) after the experiment was completed and dried; ρ w The density of the fluid used for saturation in step 1, wherein the fluid is water, diesel, gasoline, or pure contaminated liquid; ⑧ Substituting the results of formulas (5), (8), (9), and (10) into formula (7) yields the fitting parameters. α, m, N Finally α, m, N, θ s , θ r Substituting into equation (7), the volumetric water content in the soil simulated by the microfluidic chip (6) can be obtained. θ t With water force h t Expression of the soil-water characteristic curve of the relationship; Sub-method 2: Sub-method for testing the relative permeability of water-oil two-phase fluids based on microfluidic chip (6) and non-aqueous organic fluorescence visualization device; Step A1: Assemble the fluorescence visualization device for soil displacement-phase change microfluidic simulation as described in claim 1; Step A2: Turn on the power of the heat-resistant background light source (31) and adjust the wavelength of the ultraviolet LED (312) to induce the non-aqueous organic matter in the microfluidic chip (6) to produce fluorescence in the wavelength range of 390nm-780nm; then turn on the CMOS camera (32) and set the acquisition frequency and imaging range. Step A3: Start the electric temperature controller (24) and adjust the heating temperature and heating rate to adjust the temperature of the sample chamber (22) to the specified value. T x And stabilized for 1 hour; Step A4: Data acquisition, adjust the imaging area of ​​the CMOS camera (32), open the computer acquisition software, record and save the image; Step A5: Image processing, binarize the image, extract... t x Area of ​​fluorescent portion in image of microfluidic chip (6) at any given time A ntx and the area of ​​the non-fluorescent portion A wtx Percentage of fluorescent area in the image α Formula (11) can be used for calculation. Formula (11) is as follows: （11） In equation (11), α The percentage of the fluorescent area in the image; A The bottom area of ​​the microfluidic chip (6); A ntx For the binarized microfluidic chip (6) t x Area of ​​the fluorescent portion in the time-lapse image; Step A6: Saturate the microfluidic chip (6) with water, then introduce oil to drive the water out. Adjust the microfluidic pressure pump (12) to gradually increase the volumetric flow rate of the introduced oil within the range of 0.1 μl / min-10 μl / min until the microfluidic chip (6) no longer drains water. Calculate the bound water saturation according to formula (12), which is: （12） In equation (12): S ws For microfluidic chip (6) bound water saturation; V H The equivalent total pore volume of the microfluidic chip (6); V w The volume of water discharged from the microfluidic chip (6) can be calculated using formula (13), which is: （13） In equation (13): V w The volume of water discharged from the microfluidic chip (6); V H The equivalent total pore volume of the microfluidic chip (6); A 1 represents the area of ​​the fluorescent portion of the microfluidic chip (6) when it is no longer draining water; A The bottom area of ​​the microfluidic chip (6); Step A7: Fill the storage tank (14) with oil and turn on the microfluidic pressure pump (12) to drive the oil through the microfluidic chip (6) at a volumetric flow rate of 1 μl / min, and collect the discharge flow rate value through the high-precision fluid flow meter (13). q n ;when t S The oil filling volume reaches 10 times that of the microfluidic chip (6) with equivalent total pore volume. V H Then, record the discharge flow rate at this time as... q nS The effective permeability of the oil phase under bound water saturation is calculated according to formula (14). K nS Formula (14) is: （14） In equation (14): K nS The effective permeability of the oil phase under bound water saturation; q nS for t S The oil filling volume reaches 10 times that of the microfluidic chip (6) with equivalent total pore volume. V H The discharge flow rate value recorded afterward; μ n For temperature T x Viscosity of the lower oil phase; L 0 The length of the microfluidic chip (6); S The cross-sectional area of ​​the microfluidic chip (6); P t This refers to the gas pressure at the inlet. Step A8: Calculate the water-oil ratio based on the binarized image analysis results from step A5. β x The calculation process for the water saturation and oil saturation of the microfluidic chip (6) is as follows: At the initial moment t At time 1, based on the initial water-oil ratio β x =w x :n x The water-oil mixture is filled into the storage tank (14), and the microfluidic pressure pump (12) is adjusted to drive the water-oil mixture into the microfluidic chip (6) at a volume flow rate of 1 μl / min. The inlet and outlet pressures of the microfluidic chip (6) and the flow rate of the water-oil mixture are recorded by the microfluidic pressure pump (12) and the high-precision fluid flow meter (13). when t At time 2, the microfluidic chip (6) discharges oil volume V n (out) and the volume of discharged water V w (out) All are greater than 3 times the equivalent total pore volume of the microfluidic chip (6) V H ,and t Percentage of fluorescent area in the image within 1 minute after time 2 If the fluctuation range does not exceed ±3%, it can be determined that the two-phase fluid seepage at this water-oil ratio has reached a stable state; at this time, the inlet pressure is recorded as follows. P in ; Calculation of the volume of oil-water two-phase fluid at each location in the system when it reaches a steady state; t The volume of the oil-water two-phase fluid at the outlet at time 2 can be calculated using formulas (15) and (16), respectively: （15） （16） In formulas (15) and (16), V n (out) for t The volume of oil discharged by the microfluidic chip (6) at time 2; V w (out) for t The volume of water discharged by the microfluidic chip (6) at time 2; V n (in) for t The volume of oil filled into the microfluidic chip (6) at time 2 can be calculated using formula (17); V w (in) for t The volume of oil filled into the microfluidic chip (6) at time 2 can be calculated using formula (18); V nt1 , V nt2 They are respectively t 1. t The volume of the oil phase in the microfluidic chip (6) at time 2 can be calculated using formula (19); V wt1 , V wt2 They are respectively t 1. t The volume of the aqueous phase in the microfluidic chip (6) at time 2 can be calculated using formula (20); t 1 represents the initial time. t 2 is the time when a steady state is reached; where formulas (17), (18), (19), and (20) are respectively: （17） （18） （19） （20） In equations (17), (18), (19), and (20), V n (in) for t The volume of oil injected into the microfluidic chip (6) at time 2; V w (in) for t The volume of oil injected into the microfluidic chip (6) at time 2; V in for t The total volume of the oil-water mixture filled into the microfluidic chip (6) at time 2; w x For the first x Grade water-oil ratio β x =w x :n x The water phase ratio coefficient; n x For the first x Grade water-oil ratio β x =w x :n x The oil phase ratio coefficient; V ntx for t x The volume of the oil phase in the microfluidic chip (6) at any given time; V H The equivalent total pore volume of the microfluidic chip (6); A ntx For the binarized microfluidic chip (6) t x Area of ​​the fluorescent portion in the time-lapse image; A This represents the bottom area of ​​the microfluidic chip. V wtx for t x The volume of the aqueous phase in the microfluidic chip (6) at any given time; A wtx For the binarized microfluidic chip (6) t x Area of ​​non-fluorescent portion in time-lapse image; The water saturation and oil saturation of the microfluidic chip (6) are calculated according to the following formulas (21) and (22): （21） （22） In formulas (21) and (22), S ntx For microfluidic chips (6) t x Oil saturation at any given time; S wtx For microfluidic chips (6) t x Water saturation at any given time; V ntx for t x The volume of the oil phase in the microfluidic chip (6) at any given time; V wtx for t x The volume of the aqueous phase in the microfluidic chip (6) at any given time; V H The equivalent total pore volume of the microfluidic chip (6); A ntx For the binarized microfluidic chip (6) t x Area of ​​the fluorescent portion in the time-lapse image; A wtx For the binarized microfluidic chip (6) t x Area of ​​non-fluorescent portion in time-lapse image; A This represents the bottom area of ​​the microfluidic chip. Step A9: The relative permeability of the water-oil two-phase fluid based on the microfluidic chip (6) and the non-aqueous organic fluorescence visualization device is calculated according to formulas (23), (24), (25), and (26): （23） （24） （25） （26） In formulas (23), (24), (25), (26), K n The water-oil ratio is β x Effective permeability of oil phase; K w The water-oil ratio is β x Effective permeability of aqueous phase at time; K rn The water-oil ratio is β x Relative permeability of oil phase; K rw The water-oil ratio is β x Relative permeability of water phase at time; K nS For bound water saturation S ws Effective permeability of the oil phase below; q n For the oil flow rate through the high-precision fluid flow meter (13); q w The water flow rate is measured by a high-precision fluid flow meter (13); μ n In order to measure temperature T x Viscosity of the lower oil phase; μ w In order to measure temperature T x Viscosity of the water phase; V n (out) for t The volume of oil discharged by the microfluidic chip (6) at time 2; V w (out) for t The volume of water discharged by the microfluidic chip (6) at time 2; L 0 The length of the microfluidic chip (6); S The cross-sectional area of ​​the microfluidic chip (6); P in for t 2 The inlet gas pressure value at any given time; P out for t 2 Constant pressure value at the export end. P out =0; Sub-method 3: Temperature phase transition test method for non-aqueous organic compounds; Step S1: Connect the microfluidic chip (6) and the high-precision fluid flow meter (13) in advance through the capillary tube (16) and fill it with non-aqueous organic matter to saturate it; Step S2: Seal the injection port of the microfluidic chip (6) after it has been filled with non-aqueous organic matter and place it into the sample chamber (22); Step S3: Assemble the heating and temperature control system (2), fluorescence visualization system (3), data acquisition and image analysis system (5), and microfluidic chip (6) as described in claim 1. Step S4: Turn on the power of the heat-resistant background light source (31) and adjust the wavelength of the ultraviolet LED (312) to induce the non-aqueous organic matter in the channel of the microfluidic chip (6) to produce fluorescence in the wavelength range of 390nm-780nm. Then turn on the CMOS camera (32) and set the acquisition frequency and imaging range. Step S5: Activate the electric temperature controller (24) and adjust the heating temperature to maintain the temperature of the sample chamber (22) at a constant level. T x ; Step S6: Data analysis is performed according to the following process to obtain the phase change of non-aqueous organic matter in the microfluidic chip (6). V x With temperature T x Relationship: ① When t0 is the start time of the experiment, T 0 is the starting temperature. t The temperature of the sample chamber (22) was increased to T x And when the temperature remains stable, since the injection port of the microfluidic chip (6) is closed, the non-aqueous organic matter inside the microfluidic chip (6) will rise to a certain temperature. T x The resulting phase transition volume V Tx That is, the volume of fluid passing through the high-precision fluid flow meter (13) at the discharge end. V x As shown in the following formula: （27） In formula (27), V Tx Non-aqueous organic matter due to temperature self T 0 rises to T x The resulting phase transition volume; V t for Δt = t - t The fluid volume passing through the high-precision fluid flow meter (13) during the 0-period time period; ② The non-aqueous organic matter in the microfluidic chip (6) at temperature T x Phase transition ratio below λ Tx for: （28） In formula (28), V Tx Non-aqueous organic matter due to temperature self T 0 rises to T x The resulting phase transition volume; V n The total volume of non-aqueous organic matter is equal to the equivalent total pore volume of the microfluidic chip (6) when the microfluidic chip (6) is in a saturated state. V H ; ③ Adjust the temperature of the sample chamber (22) using the electric temperature controller (24) to maintain the temperature within the specified range. i By gradually varying and testing different temperature levels, appropriate results can be obtained. T x = T 1 、T 2 、T 3 ...... T i Phase transition volumes at a series of temperature levels V Tx = V T1 、V T2 、V T3 ...... V Ti The phase transition ratio of the corresponding level is calculated using formula (28). λ Tx Then by temperature T x The horizontal axis represents the phase transition ratio. λ Tx Plot the temperature-phase transition ratio curve with the vertical axis as the ordinate, denoted as . T x - λ Tx Finally, the phase transition ratio of non-aqueous organic matter in the microfluidic chip (6) was obtained by function fitting. λ Tx With temperature T x The relationship is as follows: （29） In formula (29), T x for t Temperature at any given time; λ Tx For non-aqueous organic matter in the microfluidic chip (6) at temperature T x The phase transition ratio below.

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