A test system for multi-frequency ultrasonic coupling reinforced falling film generation process

Abstract

The application discloses a kind of test systems of multi-frequency ultrasonic coupling reinforced falling film generation process, the test system includes falling film generator body (3), ultrasonic atomization controller (23), ultrasonic atomization controller (24), concentrated solution configuration system, heating water system, working condition control system, ammonia recovery system, experimental support system, high-precision parameter measurement system;Ultrasonic atomization controller (23) and ultrasonic atomization controller (24) control the power, frequency and phase of annular ultrasonic atomizer (7) and annular ultrasonic oscillator (6) respectively;According to the control and record corresponding parameters of set parameter.This application quantitatively analyzes the synergistic promotion effect of multi-frequency ultrasonic oscillation atomization coupling on heat and mass transfer of generation process by testing the generation characteristics of different working parameters under the condition of ultrasonic strengthening or not, and the core purpose is to maximize the generation performance by analyzing the change of mass transfer driving potential of different falling film heights, and to actively control by using ultrasonic parameters. This method has important significance for promoting the heat and mass transfer of generator, and has universality for generator performance test.

Description

Technical Field

[0001] This invention belongs to the technical field of enhancing the heat and mass transfer performance of the generator process, and specifically relates to a test system and test method that uses multi-frequency ultrasonic oscillation atomization coupling technology to synergistically optimize the heat and mass transfer performance of the generator. Background Technology

[0002] Ammonia absorption cooling / heat pump cycles can efficiently recover and utilize low-grade heat energy, representing a crucial technological path for promoting the green transformation of the energy structure. However, the large size of the equipment, low coefficient of performance (COP), and high cost are major obstacles to its development. Ammonia generation is the most critical heat and mass transfer process affecting the COP and miniaturization of ammonia absorption cooling / heat pumps. Therefore, optimizing generator technology is essential, with experimental testing being a key component. Current optimization technologies often involve improving the structure of internal components. Control experiments require frequent shutdowns and component replacements before measuring and comparing the generator's mass transfer and the purity of the outlet ammonia vapor. This testing method necessitates readjusting operating conditions during component replacements, increasing experimental errors and costs. Furthermore, observing the changes in mass transfer capacity within the generator is crucial for improving performance; therefore, improvements to existing generation methods and the development of supporting testing systems and methods are necessary. Summary of the Invention

[0003] Technical Problem: To further improve generator performance and solve the problems existing in current generator measurement technologies, this invention proposes a testing system and method for multi-frequency ultrasonic coupling-enhanced falling film generation. This significantly reduces human and random errors, improves testing accuracy, simplifies experimental operations, and saves time. Sampling points are set at different heights within the falling film generator, enabling the measurement of ammonia component concentrations in ultrasonically atomized droplets and vapors at different locations within the generator. This quantitatively reflects the gas-liquid mass transfer driving potential, and the generation performance can be actively adjusted by regulating the parameters of the annular ultrasonic atomizer and annular ultrasonic oscillator.

[0004] Technical solution: In order to achieve the above objectives, the present invention proposes a test system for the multi-frequency ultrasonic coupling enhanced falling film generation process. The test system includes a falling film generator body, an ultrasonic parameter control system, a concentrated solution preparation system, a heating water system, an operating condition control system, an ammonia recovery system, an experimental support system, and a high-precision parameter measurement system.

[0005] The falling film generator body includes a liquid distribution plate, two inclined falling film tubes, a droplet sampler, and a solution distributor; each inclined falling film tube is equipped with multiple annular ultrasonic atomizers and annular ultrasonic oscillators.

[0006] The top of the falling film generator body is connected to the concentrated solution tank via a flow meter M1, and the concentrated solution tank is connected to a constant temperature water bath.

[0007] The falling film generator body is connected to a nitrogen cylinder, a tap water pipe, and a bubble absorber on its side, and the bubble absorber is connected to a constant temperature water bath and a tap water pipe.

[0008] The bottom of the falling film generator body is connected to a dilute solution tank and a constant temperature heater, respectively.

[0009] The ultrasonic parameter control system includes a first ultrasonic atomization controller, a second ultrasonic atomization controller, a ring ultrasonic atomizer, and a ring ultrasonic oscillator. The first and second ultrasonic atomization controllers control the power, frequency, and phase of the ring ultrasonic atomizer and the ring ultrasonic oscillator, respectively. The phase difference is controlled by setting the start-up time using a microcontroller. The ring ultrasonic atomizer has an annular overflow protrusion on its edge to ensure that the overflow solution forms a stable liquid film on the falling film tube below. The ring ultrasonic atomizer support is also machined into a smooth curved surface to maintain uniform and stable flow of the falling film solution. The cable entering the falling film generator body is sealed and protected with epoxy resin.

[0010] The concentrated solution preparation system includes a concentrated solution tank, an ammonia tank, a distilled water tank, a first precision electronic balance, a constant temperature water bath, a vacuum pump, a bubbling tube, and a regulating valve. The distilled water tank and the ammonia tank are directly connected to the concentrated solution tank. The first precision electronic balance measures the mass of distilled water and ammonia entering the concentrated solution tank to prepare the solution. After preparation, the connecting valve is shut off. According to the required mass fraction of the solution under experimental conditions, a quantitative amount of distilled water is first injected into the concentrated solution tank. Then, a quantitative amount of ammonia gas is slowly injected from the bottom of the generator using a bubbling absorption method, and the constant temperature water bath is used to cool the solution to ensure that the ammonia gas is fully absorbed by the water to complete the preparation of the required solution.

[0011] The heating water system includes a constant temperature heater, a flow meter M3, a regulating valve, and water pipes. The regulating valve adjusts the heating water flow rate, and the constant temperature heater controls the heating water inlet temperature.

[0012] The operating condition control system includes a generator body, a concentrated solution preparation system, a heating water system, and connecting pipes, used for operating condition regulation. The concentration of the inlet solution is controlled by adjusting the solution temperature and concentration in the concentrated solution preparation system. The inlet solution flow rate is controlled by a regulating valve and flows through flow meter M1 into the generator. The generator pressure is regulated by adjusting the cooling water temperature and flow rate in the bubbling absorber. The heating water temperature and flow rate are controlled by adjusting the power of the constant temperature heater and a regulating valve, respectively, and measured by flow meter M3, thus regulating the heating output. The concentrated solution flows through a falling film tube and is heated by countercurrent hot water inside the tube to complete the generation process. The resulting dilute solution flows out from the bottom of the generator and enters a dilute solution tank via flow meter M2. Samplers collect samples from the solution inlet and outlet, as well as from droplet samplers at different heights within the generator. The sampled solution is vaporized using a vaporization container and analyzed by gas chromatography to obtain the mass fractions of ammonia and water in each sample.

[0013] The ammonia recovery system includes a bubble absorber, a constant temperature cooling water bath, and a regulating valve. Ammonia is recovered to the bubble absorber by bubbling absorption so that it can be reused when preparing ammonia solution. The heat of ammonia absorption is carried away by the constant temperature cooling water bath.

[0014] The experimental support system includes a flushing water system, a nitrogen cylinder, and a vacuum pump. The flushing water system and nitrogen are used to flush and purge the system before and after testing to ensure that there is no residual ammonia solution on the experimental body before each experiment, and to ensure that the generator body is in a consistent state before the experiment. The vacuum pump is used to evacuate the concentrated solution tank before preparing the solution and to evacuate the experimental system after flushing and purging before each experiment.

[0015] The high-precision parameter measurement system includes a temperature sensor, a pressure sensor, a first precision electronic balance, a second precision electronic balance, a gas chromatograph, a mass flow meter sensor, an electrical parameter instrument, a data acquisition unit, and a computer. The temperature sensor measures the temperature of the falling film solution, droplets, vapor, and the inlet and outlet temperatures of the heating water within the generator. The flow meter sensor transmits the flow rate signals of the cold and hot water. The pressure sensor measures the pressure at different heights within the generator and the vapor outlet pressure. The gas chromatograph measures and analyzes the mass fraction of the solutions at the generator inlet and outlet, as well as the mass fraction of droplets at different heights within the tower. The precision electronic balance weighs the required mass of distilled water and ammonia to prepare the solution, determining the mass fraction of the prepared solution. When measuring the weight of the dilute and concentrated solution tanks after the generation process, the connected pipelines must be disconnected to ensure weighing accuracy. The electrical parameter instrument measures the power and frequency of the constant-temperature heater and the ultrasonic unit. The computer records, analyzes, and processes the temperature, pressure, flow rate, and electrical parameter data acquired by the data acquisition unit.

[0016] Beneficial effects: Compared with existing generator enhancement technologies and testing systems, this invention does not require shutdown to replace internal generator components during the experiment, making operation convenient and reducing human and random errors, thus improving testing accuracy; it uses mass flow meters and weighing methods to measure the mass of solutions at the generator inlet and outlet, respectively, and can perform self-calibration of single sets of data; sampling points are set at different heights within the falling film generator, enabling the measurement of ammonia component concentration in ultrasonically atomized droplets and vapor at different locations within the generator, quantitatively reflecting the driving potential of gas-liquid mass transfer, and actively adjusting ultrasonic parameters to find the optimal operating conditions for generator performance. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the test system for improving the heat and mass transfer effect of a multi-frequency ultrasonic coupling enhanced falling film generator proposed in this invention.

[0018] Figure 2 for Figure 1 Schematic diagram of the installation structure of the annular ultrasonic atomizer on a single inclined tube;

[0019] Figure 3 for Figure 1 Schematic diagram of the installation structure of the annular ultrasonic oscillator on a single inclined tube;

[0020] Figure 4 This is a three-dimensional design drawing of a test system for improving the heat and mass transfer effect of a multi-frequency ultrasonic coupling enhanced falling film generator proposed in this invention.

[0021] The diagram includes: 1. Distilled water tank; 2. Nitrogen cylinder; 3. Falling film generator; 4. Liquid distribution tray; 5. Falling film tube; 6. Circular ultrasonic oscillator; 7. Circular ultrasonic nebulizer; 8. Droplet sampler; 901. Flowmeter M1; 902. Flowmeter M2; 903. Flowmeter M3; 10. Concentrated solution tank; 11. Vacuum pump; 12. Constant temperature water bath; 13. Sampling and delivery port; 14. Bubble tube; 1501. First precision electronic balance; 1502. Second precision electronic balance; 16. Constant pressure valve; 17. Ammonia tank; 18. Vaporization container; 19. Gas chromatograph; 20. Computer; 21. Data acquisition instrument; 22. Dilute solution tank; 23. Nebulizing ultrasonic controller; 24. Oscillating ultrasonic controller; 25. Bubble absorber; 26. Constant temperature heater; 27. Regulating valve; 28. Solution distributor; 29. ​​Support. Detailed Implementation

[0022] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the invention. After reading this invention, any modifications of the invention in various equivalent forms by those skilled in the art will fall within the scope defined by the appended claims.

[0023] like Figure 1As shown, the present invention proposes a test system for improving the heat and mass transfer effect of a multi-frequency ultrasonic coupling enhanced falling film generator, comprising a falling film generator body 3, an ultrasonic parameter control system, a concentrated solution preparation system, a heating water system, an operating condition control system, an ammonia recovery system, an experimental support system, and a high-precision parameter measurement system;

[0024] The falling film generator body 3 contains two inclined falling film tubes 5, a droplet sampler 8, and a solution distributor 28. The tube ends are machined with straight sections at a certain angle, the angle between which is the inclination angle and the main tube section. Multiple annular ultrasonic atomizers 7 and annular ultrasonic oscillators 6 are installed on each falling film tube. Multiple distribution plates 4 with different opening diameters are installed inside the falling film generator body 3 to conduct experiments on different falling film solution thicknesses. Three concentricity adjustment screws are installed on the distribution plates 4 to ensure the consistency of the radial falling film thickness of the falling film tubes. The top of the falling film generator body 3 is connected to a concentrated solution tank 10 via a flow meter M1, and the concentrated solution tank 10 is connected to a constant temperature water bath 12. The sides of the falling film generator body 3 are connected to a nitrogen cylinder 2, a tap water pipe, and a bubbling absorber 25, respectively. The bubbling absorber 25 is connected to the constant temperature water bath 12 and the tap water pipe, respectively. The bottom of the falling film generator body 3 is connected to a dilute solution tank 22 and a constant temperature heater 26, respectively.

[0025] The ultrasonic parameter control system includes an ultrasonic atomizing controller 23, an ultrasonic atomizing controller 24, a ring ultrasonic atomizer 7, and a ring ultrasonic oscillator 6. The ultrasonic atomizing controller 23 and the ultrasonic atomizing controller 24 respectively control the parameters (power, frequency, and phase) of the ring ultrasonic atomizer 7 and the ring ultrasonic oscillator 6. The phase difference is controlled by setting the start-up time through a microcontroller. The edge of the ultrasonic atomizing oscillator is machined with an annular overflow protrusion to ensure that the overflow solution forms a stable liquid film on the falling film tube below. The support of the ultrasonic oscillator is also machined into a smooth curved surface to maintain the uniform and stable flow of the falling film solution. The cable entering the falling film generator body 3 is sealed and protected with epoxy resin.

[0026] The operating condition control system includes a concentrated solution tank 10, an ammonia tank 17, a distilled water tank 1, a first precision electronic balance 1501, a constant temperature water bath 12, a vacuum pump 11, a bubbling tube 14, and a regulating valve 27, etc. The distilled water tank 1 and the ammonia tank 17 are directly connected to the concentrated solution tank 10. The first precision electronic balance 1501 measures the mass of distilled water and ammonia entering the concentrated solution tank 10 to prepare the solution. After preparation, the connecting valve is disconnected. According to the mass fraction of the solution required for the experimental conditions, a quantitative amount of distilled water is first injected into the concentrated solution tank 10. Then, a quantitative amount of ammonia gas is slowly injected from the bottom of the generator using a bubbling absorption method, and the constant temperature water bath 12 is used to cool the solution to ensure that the ammonia gas is fully absorbed by the water to complete the preparation of the required solution.

[0027] The superheated water system includes a thermostatic heater 26, a flow meter 9, a regulating valve 27 and a water pipe. The regulating valve 27 adjusts the flow rate of the heated water, and the thermostatic heater (26) controls the inlet temperature of the heated water.

[0028] The ultra-concentrated solution preparation system includes a generator body 3, a concentrated solution preparation system, a heating water system, and connecting pipes for operating condition control. The concentration of the inlet solution of the generator is controlled by adjusting the solution temperature and concentration in the concentrated solution preparation system; the inlet solution flow rate is controlled by regulating valve 27, flowing through flow meter M1 into the generator; the generator pressure is adjusted by regulating the cooling water temperature and flow rate in the bubbling absorber 25; the heating water temperature and flow rate (measured by flow meter M3) are controlled by adjusting the power of the constant temperature heater 26 and regulating valve 27 respectively, thus controlling the amount of heating generated; the concentrated solution flows through the falling film tube 5, is heated by the countercurrent hot water inside the tube to complete the generation process, and the resulting dilute solution flows out from the bottom of the generator, passing through flow meter M2 into the dilute solution tank 29. Sampler 13 samples the solution at the inlet and outlet, as well as droplet samplers 8 at different heights within the generator. The sampled solution is vaporized through vaporization container 18 and analyzed by gas chromatograph 19 to obtain the mass fractions of ammonia and water in each sample.

[0029] The ammonia recovery system includes a bubble absorber 25, a constant temperature cooling water bath 12, a flow meter 9, a regulating valve 27, etc. Ammonia is recovered to the bubble absorber 25 by bubbling absorption so that it can be reused when preparing ammonia solution. The heat of ammonia absorption is carried away by the constant temperature cooling water bath.

[0030] The experimental support system includes a flushing water system, a nitrogen cylinder 2, and a vacuum pump 11. The flushing water system and nitrogen are used to flush and purge the system before and after testing to ensure that there is no residual ammonia solution on the experimental body before each experiment, and to ensure that the generator body 3 is in a consistent state before the experiment. The vacuum pump 11 is used to evacuate the concentrated solution tank 10 before preparing the solution and to evacuate the experimental system after flushing and purging before each experiment.

[0031] The high-precision parameter measurement system includes a temperature sensor 33, a pressure sensor 31, a first precision electronic balance 1501, a second precision electronic balance 1502, a gas chromatograph 19, a mass flow meter sensor 30, an electrical parameter instrument 32, a data acquisition unit 21, and a computer 20. The temperature sensor 33 measures the temperature of the falling film solution, droplets, vapor, and the inlet and outlet temperatures of the generator heating water; the flow meter sensor 30 transmits the flow signals of the cold and hot water; the pressure sensor 31 measures the pressure at different heights within the generator and the vapor outlet pressure; the gas chromatograph 19 measures and analyzes the mass fraction of the solutions at the generator inlet and outlet, as well as the droplets at different heights within the tower; the first precision electronic balance 1501 and the second precision electronic balance 1502 weigh the required mass of distilled water and ammonia to prepare the solution, determining the mass fraction of the prepared solution; when measuring the weight of the dilute solution tank 22 and the concentrated solution tank 10 after the generation process, the connected pipelines must be disconnected to ensure weighing accuracy; the electrical parameter instrument 32 measures the power and frequency of the constant temperature heater 26 and the ultrasonic unit. The electronic computer 20 records, analyzes, and processes the data (temperature, pressure, flow rate, electrical parameters, etc.) collected by the data acquisition instrument 21;

[0032] like Figure 2 and Figure 3 As shown, in one embodiment, the annular ultrasonic atomizer and the annular ultrasonic oscillator are respectively fixed to the outer wall of the inclined tube 5 by their own bottom clamps;

[0033] like Figure 4 As shown, as one implementation method, the actual installation of the experimental system only needs to meet the requirement of consistent connection between the components in the 3D design drawing;

[0034] The test methods of the test system based on the enhanced heat and mass transfer effect of the multi-frequency ultrasonic coupling enhanced falling film generator of the present invention include: a method for testing the mass transfer per unit time of ammonia and water components, and a method for testing the mass transfer driving potential at different heights within the generator.

[0035] The method for testing the mass transfer per unit time of the ammonia and water components is as follows:

[0036] Because measuring the mass transfer of ammonia on the vapor side is difficult, the solution side is measured instead. The mass transfer of ammonia and water components per unit time on the solution side is calculated using the inlet and outlet flow rates and mass fractions of the generator. Taking the mass transfer of ammonia as an example:

[0037] ;

[0038] In the formula, (kg·s -1 This indicates the mass transfer of ammonia components on the vapor side per unit time. , (%) represents the mass fraction of ammonia component in the solutions at the inlet and outlet of the generator, determined by gas chromatography sampling and analysis. M1 m M2 (kg·s) -1 The values ​​(M1, M2, and M2) represent the mass flow rates of the solutions at the inlet and outlet of the generator under stable flow conditions, measured by mass flow meters M1 and M2, respectively. To ensure experimental accuracy, a precision balance was used to determine the mass and concentration of the concentrated and dilute solutions in the tanks before and after the integrated generator-distillation process. The mass transfer per unit time was calculated by the ratio of mass change to experimental time, which was used to verify the measurement results of the flow meters and perform mutual calibration.

[0039] The method for testing the mass transfer driving potential at different heights within the generator is as follows:

[0040] Simultaneously, the parameters of droplets and vapor at different falling film heights were measured. The mass fractions of ammonia and water on the droplet and vapor sides were determined by gas chromatography and converted into mole fractions. Droplets at different falling film heights were collected using a droplet sampler, and the droplet temperature was measured by a temperature sensor, while the pressure at the corresponding position was measured by a pressure sensor.

[0041] The pressure difference mass transfer driving potential of the ammonia component is calculated. For example:

[0042] ,

[0043] In the formula This represents the saturated pressure of pure ammonia corresponding to the measured droplet temperature, which is calculated using the thermodynamic properties of pure ammonia. The mole fraction of ammonia in the saturated solution at the corresponding temperature and pressure of the droplet is calculated from the thermodynamic properties of the solution; P represents the pressure measured at different falling film heights. This represents the mole fraction of ammonia on the vapor side at different falling film heights.

[0044] Characteristic tests were conducted under different operating parameters:

[0045] 1) Keep the inlet solution parameters constant, change the ultrasonic parameters to conduct experiments, obtain data on the influence of ultrasonic oscillation and atomization parameters on generation characteristics, and the mass transfer driving potential of ammonia and water at different heights in the tower.

[0046] 2) Keeping the total ultrasonic power constant, conduct experiments by changing the ultrasonic power, frequency and other parameters at different falling film heights to obtain the optimal combination of ultrasonic parameters for improving generator performance.

[0047] 3) Experiments were conducted by changing the heating conditions (hot water temperature, flow rate) to obtain data on the influence of ultrasonic parameters on the generation characteristics under different heating conditions.

[0048] 4) Experiments were conducted by changing the generator's operating pressure to obtain data on the influence of ultrasonic parameters on the generation characteristics under different generation pressure conditions.

[0049] 5) Experiments were conducted by changing the concentration of the inlet solution. The valve connecting the concentrated solution preparation system to the generator was closed, and then an appropriate amount of ammonia or distilled water was injected into the concentrated solution tank to adjust the solution concentration; keeping other parameters constant, data on the effect of different inlet solution concentrations on the characteristics of ultrasonic-enhanced distillation were obtained.

[0050] Compared with the prior art, the technical effects of the present invention include:

[0051] 1) Simplified experimental operation and significantly reduced test error, improving test accuracy: Compared with the existing technology, which requires shutdown to replace internal components of the generator for control experiments and the problem that readjusting the operating conditions can easily introduce a large number of errors, this invention does not require shutdown to replace components. The generation characteristics test under different enhancement conditions can be completed by adjusting the ultrasonic parameters, which greatly simplifies the experimental operation process; at the same time, the mass flow meter and the weighing method are used to measure the mass of the solution at the inlet and outlet of the generator to achieve data self-calibration, effectively reducing human error and random error, and improving the accuracy of test results.

[0052] 2) Achieving refined quantitative characterization of the mass transfer process within the generator, providing data support for performance regulation: This invention sets sampling points and droplet samplers at different heights within the falling film generator, enabling precise measurement of key parameters such as ammonia concentration, temperature, and pressure of ultrasonically atomized droplets and vapor at different falling film heights. This quantitatively reflects the distribution and variation of the gas-liquid mass transfer driving potential within the generator, overcoming the limitations of existing technologies that struggle to accurately observe changes in the mass transfer capacity within the generator. This provides crucial quantitative data support for subsequent optimization of ultrasonic parameters and enhancement of the mass transfer process.

[0053] This invention enables proactive and precise control of generation performance and rapid optimization of optimal operating conditions. Through an independent ultrasonic parameter control system, it can flexibly adjust the power, frequency, phase, and other parameters of the annular ultrasonic atomizer and oscillator at different falling film heights. Based on test data of mass transfer driving potential at different heights, it can proactively control the ultrasonic parameters of the generation process, specifically strengthen weak mass transfer areas, and quickly find and determine the optimal combination of operating parameters for generation performance. Compared with existing technologies that can only passively improve generation performance by modifying component structures, this invention offers more flexible and efficient control, and the optimization effect is more targeted.

[0054] The descriptions of the orientation and relative positional relationships of the structures in this invention, such as front, back, left, right, up, and down, do not constitute a limitation of this invention, but are merely for the convenience of description.

[0055] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A testing system for the multi-frequency ultrasonic coupling enhanced falling film generation process, characterized in that: The testing system includes a falling film generator body (3), an ultrasonic parameter control system, a concentrated solution preparation system, a heating water system, an operating condition control system, an ammonia recovery system, an experimental support system, and a high-precision parameter measurement system. The falling film generator body (3) includes a liquid distribution plate (4), two inclined falling film tubes (5), a droplet sampler (8), and a solution distributor (28); each inclined falling film tube (5) is equipped with multiple annular ultrasonic atomizers (7) and annular ultrasonic oscillators (6). The top of the falling film generator body (3) is connected to the concentrated solution tank (10) via a flow meter M1 (901), and the concentrated solution tank (10) is connected to a constant temperature water bath (12); The falling film generator body (3) is connected to the nitrogen cylinder (2), the tap water pipe, and the bubble absorber (25) on its side, respectively. The bubble absorber (25) is connected to the constant temperature water bath (12) and the tap water pipe, respectively. The bottom of the falling film generator body (3) is connected to the dilute solution tank (22) and the constant temperature heater (26) respectively.

2. The testing system for the multi-frequency ultrasonic coupling enhanced falling film generation process according to claim 1, characterized in that, The ultrasonic parameter control system includes a first ultrasonic atomizing controller (23), a second ultrasonic atomizing controller (24), an annular ultrasonic atomizer (7), and an annular ultrasonic oscillator (6). The power, frequency, and phase of the annular ultrasonic atomizer (7) and the annular ultrasonic oscillator (6) are controlled by the first ultrasonic atomizing controller (23) and the second ultrasonic atomizing controller (24), respectively. The phase difference is controlled by setting the start-up time through a microcontroller. The edge of the annular ultrasonic atomizer (7) is machined with annular overflow protrusions to ensure that the overflow solution forms a stable liquid film on the falling film tube below. The support of the annular ultrasonic atomizer (7) is also machined into a smooth curved surface to keep the flow of the falling film solution uniform and stable. The cable entering the falling film generator body (3) is sealed and protected with epoxy resin.

3. The testing system for the multi-frequency ultrasonic coupling enhanced falling film generation process according to claim 1, characterized in that, The concentrated solution preparation system includes a concentrated solution tank (10), an ammonia tank (17), a distilled water tank (1), a first precision electronic balance (1501), a constant temperature water bath (12), a vacuum pump (11), a bubbling tube (14), and a regulating valve (27). The distilled water tank (1) and the ammonia tank (17) are directly connected to the concentrated solution tank (10). The mass of distilled water and ammonia entering the concentrated solution tank (10) is measured by the first precision electronic balance (1501) to prepare the solution. After preparation, the connecting valve is cut off. According to the mass fraction of the solution required by the experimental conditions, a quantitative amount of distilled water is first injected into the concentrated solution tank (10). Then, a quantitative amount of ammonia is slowly injected from the bottom of the generator by bubbling absorption. The constant temperature water bath (12) is used to cool the solution to ensure that the ammonia is fully absorbed by the water to complete the preparation of the required solution.

4. The testing system for the multi-frequency ultrasonic coupling enhanced falling film generation process according to claim 1, characterized in that, The heating water system includes a constant temperature heater (26), a flow meter M3 (903), a regulating valve (27) and a water pipe. The regulating valve (27) adjusts the flow rate of the heating water, and the constant temperature heater (26) controls the inlet temperature of the heating water.

5. The testing system for the multi-frequency ultrasonic coupling enhanced falling film generation process according to claim 1, characterized in that, The operating condition control system includes a generator body (3), a concentrated solution preparation system, a heating water system, and connecting pipes, used for operating condition regulation; the concentration of the inlet solution of the generator is controlled by adjusting the solution temperature and concentration in the concentrated solution preparation system; the inlet solution flow rate is controlled by the regulating valve (27) and flows through the flow meter M1 (901) into the generator; the generator pressure is regulated by adjusting the cooling water temperature and flow rate in the bubbling absorber (25); the heating water temperature and flow rate are controlled by adjusting the power of the constant temperature heater (26) and the regulating valve (27), respectively, and are measured by the flow meter M3 (903), thereby realizing the regulation of the heating amount generated; The concentrated solution flows through the falling film tube (5) and is heated by the countercurrent hot water inside the tube to complete the generation process. The dilute solution after generation flows out from the bottom of the generator and enters the dilute solution tank (29) through the flow meter M2 (902). The sampler (13) takes samples from the solution inlet and outlet and the droplet sampler (8) at different heights inside the generator. The sampled solution is vaporized through the vaporization container (18) and analyzed by the gas chromatograph (19) to obtain the mass fraction of ammonia and water in each sample.

6. The testing system for the multi-frequency ultrasonic coupling enhanced falling film generation process according to claim 1, characterized in that, The ammonia recovery system includes a bubble absorber (25), a constant temperature cooling water bath (12), and a regulating valve (27). Ammonia is recovered to the bubble absorber (25) by bubble absorption so that it can be reused when preparing ammonia solution. The heat absorbed by ammonia is carried away by the constant temperature cooling water bath.

7. The testing system for the multi-frequency ultrasonic coupling enhanced falling film generation process according to claim 1, characterized in that, The experimental support system includes a flushing water path, a nitrogen cylinder (2), and a vacuum pump (11). The flushing water path and nitrogen are used to flush and purge the system before and after the test to ensure that there is no residual ammonia solution on the experimental body before each experiment, and to ensure that the generator body (3) is in the same state before the experiment. The vacuum pump (11) is used to evacuate the concentrated solution tank (10) before preparing the solution and to evacuate the experimental system after flushing and purging before each experiment.

8. The testing system for the multi-frequency ultrasonic coupling enhanced falling film generation process according to claim 1, characterized in that, The high-precision parameter measurement system includes a temperature sensor (33), a pressure sensor (31), a first precision electronic balance (1501), a second precision electronic balance (1502), a gas chromatograph (19), a mass flow meter sensor (30), an electrical parameter instrument (32), a data acquisition instrument (21), and a computer (20). The temperature sensor (33) is used to measure the temperature of the falling film solution, droplets, steam, and the inlet and outlet temperatures of the heating water in the generator. The flow meter sensor (30) transmits the flow signals of the cold and hot water. The pressure sensor (31) measures the pressure at different heights in the generator and the steam outlet pressure. The gas chromatograph (19) is used to measure the mass fraction of the solutions at the inlet and outlet of the generator and the droplets at different heights in the tower; the precision electronic balance (15) is used to weigh the mass of distilled water and ammonia required for the preparation of the solution and determine the mass fraction of the preparation solution; when measuring the weight of the dilute solution tank (22) and the concentrated solution tank (10) after the generation process is completed, the pipeline connected to them must be disconnected to ensure the accuracy of the weighing; the electrical parameter instrument (32) measures the power and frequency of the constant temperature heater (26) and the ultrasonic group; the electronic computer (20) records, analyzes and processes the temperature, pressure, flow rate and electrical parameter data collected by the data acquisition instrument (21).

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