An acoustic characterization apparatus for detecting structural properties of phase change material

Abstract

The application relates to the technical field of phase change material research, and discloses an acoustic characterization equipment for detecting structural characteristics of phase change materials, which comprises a sample, a test reaction kettle, an acoustic test assembly, a temperature control assembly, a pressure control assembly and a data acquisition assembly; wherein the sample is in a cylindrical structure, the outer side of which is wrapped with three layers of latex film and one layer of tin paper; the test reaction kettle comprises a reaction kettle shell and a reaction kettle base; the acoustic test assembly is provided with two groups, which are installed at the upper and lower ends of the sample and used for emitting acoustic waves with different frequencies so as to obtain the attenuation characteristics and internal structural characteristics of the test material. The application realizes the preparation and acoustic test of phase change materials with different structures under different temperature and pressure conditions. Compared with other equipment, the equipment can not only realize the acoustic test of the phase change process of the phase change material under high net confining pressure, but also can carry out acoustic tests with frequency changes and different waveforms without replacing the acoustic probe.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of phase change material research, and particularly relates to an acoustic characterization equipment for detecting structural characteristics of phase change materials. BACKGROUND

[0002] Phase change refers to the process of a material transforming from one phase to another phase under certain temperature and pressure conditions, such as water turning into ice and ice sublimating into gas. Phase change materials have been widely used in many fields, but in the field of engineering geology, phase change materials often pose a threat to engineering safety, such as ground frost heaving and thaw subsidence in winter in northern regions, and exploitation of natural gas hydrates in marine strata.

[0003] Water is a common phase change material. Under normal pressure and at or below 0°C, water changes from a liquid state to a solid state, and at the same time, the volume expands. Frozen soil refers to a special soil in which liquid water in the soil changes into solid water under low-temperature conditions in northern or plateau regions, which causes the volume of the soil to expand. When the weather warms up, the solid water in the frozen soil changes into liquid water, and the volume decreases. Under the long-term action of freezing and thawing, the engineering buildings are easily damaged. Natural gas hydrate, also known as combustible ice, is a solid product generated by liquid water and methane under low-temperature and high-pressure conditions. Natural gas hydrate is present in deep-sea sediments, and the sediments are usually silty sand. In the process of exploitation of natural gas hydrate, the hydrate decomposes into liquid water and methane, and the strength of the sediments greatly decreases, which easily induces seabed geological disasters.

[0004] Currently, the internal microstructure of phase change materials is mainly detected by scanning electron microscopy (SEM), computerized tomography (CT), nuclear magnetic resonance (NMR), and ultrasonic detection. The main problems of the current testing methods are as follows: (1) The SEM method measures the structure at the nanoscale, and cannot reflect the structure of the material at the strata scale. In addition, it is difficult to realize the preparation and observation of the phase change material on the SEM testing platform. (2) Although the CT test can obtain the overall pore structure of the sample and reconstruct the sample in three dimensions, the testing accuracy of the CT decreases sharply with the increase of the size of the test sample. In addition, the operation of the equipment is complex, the testing cost is too high, and it is difficult to popularize and apply. (3) Although the NMR testing technology can carry out the structure test of a large-size phase change material under temperature control conditions, the test results are very sensitive to the setting of the test parameters and the operation of the instrument. In addition, the material composition (paramagnetic substance) affecting the NMR signal is widely present in real geological materials, which becomes a bottleneck problem for the use of the technology for the detection of phase change structures in geological bodies. (4) The ultrasonic detection uses a high-frequency band of acoustic waves, which is quite different from the wave frequency band of seismic exploration, and cannot be associated with the results of the commonly used seismic exploration on site. In addition, the ultrasonic wave uses a high-frequency band with a short wavelength and fast attenuation, and the detection range is limited.

[0005] At present, the acoustic detection technology has a relatively in-depth study on the structure evolution law in liquid water phase change. The main means for on-site exploration of special structures is still the geophysical exploration technology mainly based on seismic wave technology with an excitation frequency in the order of Hz-kHz. The detection of the structure of the phase change material (frozen soil, natural gas hydrate) in the laboratory mainly focuses on the high frequency range (MHz order), and in addition, usually one frequency is excited for the structure detection of the phase change material. The acoustic characteristics of hydrates under different frequencies need to replace the corresponding frequency probe, and the frequent replacement of the probe is easy to cause irreversible damage to the durability of the equipment. Therefore, the current acoustic detection results of the laboratory test cannot be associated with the test results on site, and cannot be applied to the structure interpretation of the phase change material on site.

[0006] Based on the above deficiencies of the existing acoustic detection technology, the present application provides a set of acoustic response test equipment and method for detecting the internal structure of the phase change material under different stresses and initial water content. The equipment adopts a variable frequency acoustic probe which can not only excite low frequency waves but also adjust the excitation waveform such as sine wave and square wave. Through the equipment, the attenuation characteristics and internal structure characteristics of the test material can be obtained, and then the evolution law of the internal structure of the material can be analyzed. SUMMARY

[0007] To solve the technical problems proposed in the background art, the present application provides an acoustic characterization equipment for detecting the structure characteristics of the phase change material.

[0008] The present application adopts the following technical scheme: an acoustic characterization equipment for detecting the structure characteristics of the phase change material, comprising a sample, a test reaction kettle, an acoustic test assembly, a temperature control assembly, a pressure control assembly and a data acquisition assembly.

[0009] Among them:

[0010] The sample is a cylindrical structure wrapped with three layers of latex film and one layer of tin paper.

[0011] The test reaction kettle comprises a reaction kettle shell and a reaction kettle base.

[0012] The acoustic test assembly is provided with two groups, which are installed at the upper and lower ends of the sample, and is used to emit acoustic waves of different frequencies to obtain the attenuation characteristics and internal structure characteristics of the test material.

[0013] The temperature control assembly is used to create a constant temperature experimental environment.

[0014] The pressure control assembly is used to change the stress environment of the sample. The pressure control assembly comprises a confining pressure control unit and a pore pressure control unit. The confining pressure control unit is used to control the peripheral pressure of the sample, and the pore pressure control unit is used to control the internal pore pressure of the sample.

[0015] The data acquisition assembly is electrically connected with the acoustic test assembly, the temperature control assembly and the pressure control assembly to synchronously collect data of the acoustic test assembly, the pressure control assembly and the temperature control assembly.

[0016] Further to the above-mentioned scheme, the acoustic test assembly comprises an acoustic probe and an acoustic probe holder, the acoustic probe holder is fixed to one end of the sample, and the acoustic probe is installed in the acoustic probe holder, and a detection end of the acoustic probe is in contact with the surface of the sample.

[0017] Further to the above-mentioned scheme, the temperature control assembly comprises a constant-temperature water bath, a water bath barrel and a temperature sensor, the water bath barrel is used for placing the test reaction kettle, water is stored in the water bath barrel, the constant-temperature water bath is used for controlling the temperature of the water in the water bath barrel, and the temperature sensor is installed on the reaction kettle shell and is used for detecting the temperature in the reaction kettle.

[0018] Further to the above-mentioned scheme, the acoustic probe comprises a probe one and a probe two, both of which comprise a Peek insulating material, a piezoelectric ceramic sheet (a stretching element, a bending element), a shielding layer and an insulating layer, the difference between the probe one and the probe two lies in that the bending element piezoelectric ceramic sheet is arranged in the Peek insulating material in the probe one, the stretching element piezoelectric ceramic sheet is arranged in the Peek insulating material in the probe two, and the epoxy resin insulating layer, the shielding layer and the Peek insulating material are sequentially arranged outside the piezoelectric ceramic sheet, and the probe one and the probe two both comprise a coaxial line connected with the stretching element piezoelectric ceramic sheet or the bending element piezoelectric ceramic sheet.

[0019] Further to the above-mentioned scheme, the acoustic probe holder is fixed to both ends of the sample through a fixing support, two mounting hole positions are arranged in the acoustic probe holder and are used for mounting the probe one and the probe two respectively, the mounting hole positions are in a stepped hole shape and both comprise a first section, a middle section and a tail section, a wire storage area is further arranged in the acoustic probe holder and is connected with the two mounting hole positions, the Peek insulating material in the probe one and the probe two is mounted in the first section of the corresponding mounting hole position, a Peek cover plate is further arranged on the acoustic probe holder, a sealing joint is mounted at the tail section of the mounting hole position, a gas guide hole is further arranged in the acoustic probe holder, and the gas guide holes in the two acoustic probe holders are respectively connected with the confining pressure control unit and the pore pressure control unit.

[0020] Further to the above-mentioned scheme, the confining pressure control unit comprises a confining pressure tracking pump, a confining pressure control valve and a confining pressure pipeline connected in series, and one end of the confining pressure pipeline is located in the reaction kettle.

[0021] The pore pressure control unit comprises an air outlet module and an air inlet module, and the air outlet module and the air inlet module are respectively connected with the gas guide holes in the acoustic probe holder.

[0022] As a further of the above-mentioned scheme, the air inlet module comprises a pore pressure air valve, a pore pressure air pressure sensor, a buffer container, a gas supply device and a pore pressure air pipeline connected in series with the above-mentioned structure, and the air outlet end of the pore pressure air pipeline is connected with the acoustic probe holder below the sample

[0023] The air outlet module comprises a pore pressure air valve, a pore pressure air pressure sensor, a buffer container, a gas supply device and a pore pressure air pipeline connected in series with the above-mentioned structure, and the air outlet end of the pore pressure air pipeline is connected with the acoustic probe holder below the sample

[0024] As a further of the above-mentioned scheme, the top of the sample is further provided with a displacement sensor, the displacement sensor is electrically connected with the acquisition computer, and the displacement sensor is fixedly installed through a fixing support.

[0025] As a further of the above-mentioned scheme, the data acquisition assembly comprises an oscilloscope, a filter, an acoustic wave emitter, a data acquisition card and an acquisition computer, the data acquisition card can synchronously acquire data of the pressure control assembly and the temperature control assembly, and the data acquisition card sends the acquired data to the acquisition computer.

[0026] Compared with the prior art, the present application has the beneficial effects that:

[0027] 1、The present application can realize the preparation and acoustic testing of different structure phase change materials under different temperature and pressure conditions, wherein the temperature range is-10℃~40℃, the confining pressure range is 0~20MPa, and the pore pressure range is 0~15MPa. Compared with other devices, the present application can realize acoustic testing of phase change materials in the phase transition process under high net confining pressure (0~15MPa).

[0028] 2、Compared with other acoustic testing devices, the present application can not only carry out compression wave and shear wave testing, but also carry out acoustic testing of frequency change (low frequency band 50Hz-100kHz) and different waveforms (square wave and sine wave) without replacing the acoustic probe.

[0029] 3、The present application carries out indoor phase change material testing and analysis in the frequency range close to the frequency range of waves used in seismic exploration, and the test results are seamlessly connected with field testing.

[0030] 4、The present application obtains acoustic signals of different frequencies to interpret the internal structure of the phase change material, so as to obtain the optimal frequency reflecting the optimal result. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 The present application is an acoustic characterization equipment, and the overall structure schematic diagram of the present application is shown in the figure.

[0032] Figure 2 The present application is a reaction kettle, and the schematic diagram of the internal structure of the present application is shown in the figure.

[0033] Figure 3 A front view of the acoustic probe holder according to the present application;

[0034] Figure 4 A top view of the acoustic probe holder according to the present application;

[0035] Figure 5 A schematic diagram of the evolution of the confining pressure hole pressure under different effective confining pressures using the acoustic characterization equipment according to the present application;

[0036] Figure 6 A waveform diagram of the acoustic signal measured by the acoustic characterization equipment according to the present application before phase change of the material;

[0037] Figure 7 A waveform diagram of the acoustic signal measured by the acoustic characterization equipment according to the present application after phase change of the material.

[0038] Main symbol explanation:

[0039] Water bath circulating barrel 1, displacement sensor 2, reaction kettle shell 3, acoustic probe holder 4, acoustic probe 5, sample 6, reaction kettle base 7, constant temperature water bath 8, acoustic wave emitter 9, filter 10, oscilloscope 11, fixed support 12, sealing joint 13, temperature sensor 14, hole pressure inlet pressure sensor 15, hole pressure inlet valve 16, buffer container 17, gas supply equipment 18, confining pressure tracking pump 19, confining pressure inlet pressure sensor 20, confining pressure control valve 21, data acquisition card 22, hole pressure outlet pressure sensor 23, acquisition computer 24, hole pressure outlet valve 25, hole pressure inlet pipeline 26, confining pressure pipeline 27, hole pressure outlet pipeline 28, confining pressure liquid inlet and outlet 29, pressure-resistant coaxial cable 30, rubber membrane 31, first section 401, middle section 402, tail section 403, air guide hole 405, connection port 406, wire storage area 407, probe one 51, probe two 52, Peek cover plate 53. DETAILED DESCRIPTION

[0040] Hereinafter, the present application will be further described in conjunction with the drawings and specific embodiments, and it should be noted that the following described embodiments or technical features can be combined in any manner to form new embodiments without conflict.

[0041] Embodiment 1

[0042] Reference Figures 1-4 According to the present application, an acoustic characterization equipment for detecting the structural characteristics of phase change materials is provided, which comprises a sample 6, a test reaction kettle, an acoustic test assembly, a temperature control assembly, a data acquisition assembly, and a pressure control assembly.

[0043] Among them:

[0044] Sample 6 is a cylindrical structure, and its outer side is wrapped with three layers of latex film and one layer of tin paper;

[0045] The test reactor includes a reactor shell 3 and a reactor base 7;

[0046] The acoustic test assembly is provided with two groups and is installed on the upper and lower sides of the sample 6, and the acoustic test assembly includes an acoustic probe 5 and an acoustic probe 5 holder 4, the acoustic probe 5 holder 4 is fixed at one end of the sample 6, and the acoustic probe 5 is installed in the acoustic probe 5 holder 4; the detection end of the acoustic probe 5 is in contact with the surface of the sample 6;

[0047] The temperature control assembly includes a constant temperature water bath 8, a water bath barrel and a temperature sensor, the water bath barrel is used to place the test reactor, the water bath barrel stores water, the constant temperature water bath 8 is used to control the temperature of the water in the water bath barrel, and the temperature sensor 14 is installed on the reactor shell 3 and is used to detect the temperature in the reactor;

[0048] The pressure control assembly includes a confining pressure control unit and a pore pressure control unit, and the confining pressure control unit is used to control the peripheral pressure of the sample 6, and the pore pressure control unit is used to control the internal pore pressure of the sample 6;

[0049] The data acquisition assembly includes an oscilloscope 11, a filter 10, an acoustic wave emitter 9, a data acquisition card 22 and an acquisition computer 24, the data acquisition card 22 can synchronously acquire the data of the pressure control assembly and the temperature sensor, so as to monitor the test process through the pressure-temperature-time data;

[0050] The acoustic probe 5 includes a probe one 51 and a probe two 52, and both of them include a Peek insulating material, a piezoelectric ceramic sheet (stretching element, bending element), a shielding layer and an insulating layer, the difference between the probe one 51 and the probe two 52 lies in that the bending element piezoelectric ceramic sheet is arranged in the Peek insulating material in the probe one 51, the stretching element piezoelectric ceramic sheet is arranged in the Peek insulating material in the probe two 52, and an epoxy resin insulating layer, a shielding layer and a Peek insulating material are sequentially arranged in the periphery of the piezoelectric ceramic sheet;

[0051] The specific manufacturing process is that the piezoelectric ceramic sheet is welded with a wire, is insulated by using epoxy optical glue, is shielded by using conductive silver paint, and finally is filled in the Peek insulating material after being insulated;

[0052] More specifically: first, the coaxial shield line is welded with the positive and negative electrodes of the piezoelectric ceramic sheet, and then epoxy glue is applied to the outer surface for insulation treatment after the welding is completed; second, after the insulation treatment is completed, a layer of conductive glue is evenly applied for signal shielding, and then the negative electrode of the coaxial shield line is connected with the shielding layer; finally, the above-mentioned parts are installed in the Peek insulation material, and epoxy resin is used for sealing, and after the glue is cured, the acoustic probe is completed.

[0053] When the acoustic probe is completed, the acoustic probe holder is installed, the coaxial shield line of the acoustic probe is connected with the sealing connector, the sealing connector is fixed in the holder by threads, in order to facilitate the installation of the acoustic probe, a wire storage area is designed in the acoustic probe holder, which is used to store the coaxial shield line. After the acoustic probe is installed in the mounting hole, the acoustic probe is fixed with the Peek cover plate.

[0054] In this scheme, the reaction kettle shell, the reaction kettle base and the acoustic probe holder are made of 316L stainless steel, which can withstand a pressure of 30MPa after processing. The two acoustic probe holders in the reaction kettle are located above and below the sample, and the acoustic probe contacts the sample.

[0055] In order to avoid the communication between the hole pressure and the confining pressure, the rubber membrane is used to fix the sample and the acoustic probe holder. In order to ensure the stability of signal transmission and the insulation of wire, the pressure-resistant coaxial line is used to connect the sealing connector of the acoustic probe holder and the sealing connector in the reaction kettle base.

[0056] In this scheme, the oscilloscope, filter and acoustic wave generator are purchased from market manufacturers. The acoustic wave generator is used to excite the waveform and frequency parameters of the device, the filter is used to filter the noise in the acoustic wave, and the oscilloscope is used to visualize the acoustic wave signal. The main process of acoustic wave test is that the acoustic wave generator excites the signal to make the acoustic probe vibrate, the other acoustic probe receives the vibration signal, which is transmitted to the filter, and finally the signal is transmitted to the oscilloscope after filtering. The acoustic wave generator is connected with the acoustic probe in the acoustic probe holder through the sealing connector (10) in the reaction kettle base and the pressure-resistant coaxial line, and the other acoustic probe is connected with the filter through the pressure-resistant coaxial line and the reaction kettle base. Figure 2

[0057] ​The acoustic probe 5 holder 4 is fixed at both ends of the sample 6 by the fixing support 12, two mounting hole positions are arranged in the acoustic probe 5 holder 4, which are respectively used for mounting the probe one 51 and the probe two 52, the mounting hole positions are in the form of stepped holes, and each includes a first section 401, a middle section 402 and a tail section 403, wherein the acoustic probe 5 holder 4 is further provided with a wire storage area 407 communicating with the two mounting hole positions, the probe one 51 and the probe two 52 are both mounted in the first section 401 of the corresponding mounting hole position by the Peek insulating material, the acoustic probe 5 holder 4 is further provided with a Peek cover plate 53, coaxial lines connecting the straight element piezoelectric ceramic sheet and the bending element piezoelectric ceramic sheet are arranged in the probe one 51 and the probe two 52, the tail section 403 of the mounting hole position is provided with a sealing joint 13, and the acoustic probe 5 holder 4 is further provided with a gas guide hole 405, which is used for connecting the pore pressure inlet gas pipeline 26 or the pore pressure outlet gas pipeline 28.

[0058] The wires connected with the acoustic probe 5 pass through the coaxial wire storage area 407 and the wire joint, and are connected with the oscilloscope 11, the filter 10 and the acoustic wave transmitter;

[0059] The displacement sensor 2 is further arranged at the top of the sample 6, and is electrically connected with the acquisition computer 24, and is arranged by the fixing support 12.

[0060] The confining pressure control unit comprises a confining pressure tracking pump 19, a confining pressure control valve 21 and a confining pressure pipeline 27 connected in series, one end of the confining pressure pipeline 27 is located in the reaction kettle, and a confining pressure liquid inlet and outlet 29 is arranged on the corresponding reaction kettle shell.

[0061] The pore pressure control unit comprises an outlet gas module and an inlet gas module, the outlet gas module and the inlet gas module are connected with the acoustic probe 5 holder 4, the inlet gas module comprises a pore pressure inlet valve 16, a pore pressure inlet pressure sensor 15, a buffer container 17, a gas supply device 18 and a pore pressure inlet pipeline 26 connected in series, and the outlet end of the pore pressure inlet pipeline 26 is connected with the acoustic probe 5 holder 4 below the sample 6.

[0062] The outlet gas module comprises a pore pressure outlet pressure sensor 23, a pore pressure outlet valve 25 and a pore pressure outlet pipeline 28 connected in series, and one end of the pore pressure outlet pipeline 28 is connected with the acoustic probe 5 holder 4 above the sample 6.

[0063] In the scheme, the data acquisition card 22 is electrically connected with the temperature sensor, the pore pressure outlet pressure sensor 23, the pore pressure inlet pressure sensor 15, the confining pressure inlet pressure sensor 20 and the displacement sensor 2, and the data acquisition card 22 transmits the collected information to the acquisition computer 24 for storage.

[0064] Example 2

[0065] The application provides a method for using an acoustic characterization equipment for detecting structure characteristics of a phase change material, which comprises the following steps.

[0066] Step 1: sample 6 preparation and installation

[0067] A suitable soil body is selected as a phase change material storage medium, a sample in the shape of a cylinder with a certain compaction degree and initial water content is prepared, the sample 6 has variable diameter (0-50 mm) and variable height (0-100 mm), after the preparation, the sample 6 is embedded into the lower acoustic probe 5 holder 4, is wrapped from inside to outside with three layers of latex film and one layer of tin paper (to protect the sample 6 from being damaged), then the upper acoustic probe 5 holder 4 is installed on the top of the sample 6, and the upper end and the lower end are fixed by three rubber bands respectively.

[0068] Step 2: equipment installation

[0069] After the installation of the sample 6, the acoustic probe 5 holder 4 is fixed by using a support, the displacement sensor 2 is installed, the sealed shield cable, the sealed joint 13 and the hole pressure inlet and outlet pipeline in the reaction kettle are connected, then the reaction kettle shell 3 is installed and the fixing screws are tightened, the confining pressure pipeline 27 and the hole pressure inlet and outlet pipeline are connected with the external joints of the reaction kettle, then the confining pressure liquid is injected into the reaction kettle through the confining pressure pipeline 27, after the injection is completed, the confining pressure tracking pump 19 is opened, the tracking confining pressure is set to 0.3-0.5 MPa, finally the reaction kettle is put into the water bath circulating barrel 1, the constant temperature water bath 8 is opened, and the temperature value is set to the normal temperature.

[0070] The acoustic test assembly, the temperature control assembly, the data acquisition assembly and the pressure control assembly are opened, and the temperature, the hole pressure, the confining pressure and the displacement change curves with time in the reaction kettle are monitored.

[0071] Step 3: acoustic test of the non-phase change material

[0072] After the temperature, the displacement and the pressure are stable, the initial acoustic characteristics of the material before phase change are tested, including shear wave and compression wave tests under different frequencies and waveforms.

[0073] Step 4: acoustic test of the material in the phase change process

[0074] After the test is completed, according to the selected gas medium and pressure, the hole pressure value is set, the gas is injected into the buffer container 17 and the reaction kettle, the hole pressure is gradually increased until the pressure is stable, finally the hole pressure gas valve is closed. The temperature value set by the constant temperature water bath 8 is adjusted to the phase change reaction temperature value of the material, after the water bath temperature is stable, the acoustic test is carried out once every certain time, and the acoustic characteristic evolution law in the phase change process of the material is monitored.

[0075] The judgment standard for the completion of the phase change of the material is that the temperature, the pressure and the displacement do not change basically for more than 12 hours.

[0076] Step 5, acoustic test of phase change material under different confining pressures

[0077] The net confining pressure value is adjusted by setting different tracking pressure values through the confining pressure tracking pump 19, so as to obtain the stress-strain state of the phase change material under different consolidation stress states, and the acoustic test is carried out after the temperature, pressure and displacement are stable.

[0078] Step 6, acoustic test of phase change material in pressure reduction / temperature rising process

[0079] In the process of recovering the phase change material from a high-pressure low-temperature environment to a normal temperature and pressure, a step-by-step pressure reduction or temperature rising method is usually used. If a step-by-step pressure reduction method is used to carry out the test, the pore pressure can be reduced by opening the pore pressure outlet valve, and the exhaust gas needs to be harmlessly treated. After each pressure balance, the acoustic characteristics are tested, and then the pressure reduction and acoustic test are continued until the pore pressure is reduced to 0, and the test is ended.

[0080] Step 7, interpretation of acoustic wave signal

[0081] The low-frequency acoustic wave signals of different frequencies are analyzed, the acoustic method is used to interpret the signals, the wave speed and attenuation signal of the phase change material during the phase change process are obtained, and then the internal structure and evolution of the phase change material are quantitatively characterized.

[0082] With reference to the drawings Figure 5 which is the curve of confining pressure and pore pressure changing with time during the test process. During the cooling process, the phase change material changes from liquid to solid, and the phase change occurs. Figures 6-7 which is the acoustic test signal of the material before and after the phase change. According to the acoustic test signal, the acoustic characteristics of the material after the phase change can be analyzed.

[0083] The above embodiments are only preferred embodiments of the present application, and cannot be used to limit the scope of protection of the present application. Any non-essential changes and substitutions made by those skilled in the art on the basis of the present application are within the scope of protection of the present application.

Claims

1. An acoustic characterization equipment for detecting structure characteristics of a phase change material, comprising a sample, a test reactor, an acoustic test assembly, a temperature control assembly, a pressure control assembly and a data acquisition assembly; wherein: the sample is in a cylindrical structure, and is wrapped with three layers of latex film and one layer of tin paper on the outside; the test reactor comprises a reactor shell and a reactor base; the acoustic test assembly is provided with two groups, which are installed at the upper and lower ends of the sample, and are used to emit acoustic waves of different frequencies to obtain the attenuation characteristics and internal structure characteristics of the test material; the temperature control assembly is used to create a constant temperature experimental environment; the pressure control assembly is used to change the stress environment of the sample, and comprises a confining pressure control unit and a pore pressure control unit, wherein the confining pressure control unit is used to control the peripheral pressure of the sample, and the pore pressure control unit is used to control the pore pressure of the sample; the data acquisition assembly is electrically connected with the acoustic test assembly, the temperature control assembly and the pressure control assembly, so as to synchronously acquire data of the acoustic test assembly, the pressure control assembly and the temperature control assembly; the acoustic test assembly comprises an acoustic probe and an acoustic probe holder, the acoustic probe holder is fixed at one end of the sample, the acoustic probe is installed in the acoustic probe holder, and the detection end of the acoustic probe is in contact with the surface of the sample; the acoustic probe comprises a probe one and a probe two, both of which comprise a Peek insulating material, a piezoelectric ceramic sheet, a shielding layer and an insulating layer, the difference between the probe one and the probe two lies in that the piezoelectric ceramic sheet in the Peek insulating material of the probe one is a bending element, the piezoelectric ceramic sheet in the Peek insulating material of the probe two is a stretching element, and an epoxy resin insulating layer, a shielding layer and a Peek insulating material are sequentially arranged on the periphery of the piezoelectric ceramic sheet, and the probe one and the probe two both comprise a coaxial line connected with the stretching element or the bending element; the acoustic probe holder is fixed at both ends of the sample through a fixing support, and is provided with two mounting hole positions in the acoustic probe holder, which are respectively used to mount the probe one and the probe two, the mounting hole positions are in a stepped hole shape, and each of the mounting hole positions comprises a first section, a middle section and a tail section, the acoustic probe holder is further provided with a wire storage area communicating with the two mounting hole positions, the Peek insulating material in the probe one and the probe two is mounted in the first section of the corresponding mounting hole position, a Peek cover plate is further arranged on the acoustic probe holder, a sealing joint is mounted at the tail section of the mounting hole position, a gas guide hole is further formed in the acoustic probe holder, and the gas guide holes in the two acoustic probe holders are respectively connected with the confining pressure control unit and the pore pressure control unit.

2. An acoustic characterization apparatus for investigating the properties of a phase change material structure as claimed in claim 1, characterized in that the temperature control assembly comprises a constant temperature water bath, a water bath barrel and a temperature sensor, the water bath barrel is used to place the test reactor, water is stored in the water bath barrel, the constant temperature water bath is used to control the temperature of the water in the water bath barrel, and the temperature sensor is installed on the reactor shell and is used to detect the temperature in the reactor.

3. An acoustic characterization apparatus for investigating the properties of a phase change material structure as claimed in claim 1, characterized in that, the confining pressure control unit comprises a confining pressure tracking pump, a confining pressure control valve and a confining pressure pipeline connected in series, and one end of the confining pressure pipeline is located in the reactor; the pore pressure control unit comprises an air outlet module and an air inlet module, and the air outlet module and the air inlet module are respectively connected with the gas guide holes in the acoustic probe holder.

4. An acoustic characterisation apparatus for investigating the properties of a phase change material structure as claimed in claim 3, wherein, The air inlet module comprises a pore pressure air inlet valve, a pore pressure air inlet pressure sensor, a buffer container, a gas supply device and a pore pressure air inlet pipeline connected in series, and the air outlet end of the pore pressure air inlet pipeline is connected with the acoustic probe holder below the sample; The air outlet module comprises a pore pressure air outlet pressure sensor, a pore pressure air outlet valve and a pore pressure air outlet pipeline connected in series, and one end of the pore pressure air outlet pipeline is connected with the acoustic probe holder above the sample.

5. An acoustic characterization apparatus for investigating the properties of a phase change material structure as claimed in claim 1, characterized in that, The top of the sample is also provided with a displacement sensor, which is electrically connected with the acquisition computer and is fixed by a fixing support.

6. An acoustic characterization apparatus for investigating the properties of a phase change material structure as claimed in claim 1, characterized in that, The data acquisition assembly comprises an oscilloscope, a filter, an acoustic wave emitter, a data acquisition card and an acquisition computer, the data acquisition card can synchronously acquire the data of the pressure control assembly and the temperature control assembly, and the data acquisition card transmits the acquired data to the acquisition computer.

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