An inclined falling film generator with ultrasonic oscillation atomization coupling to enhance the heat and mass transfer of ammonia water.

Abstract

This invention discloses an inclined falling film generator that enhances the heat and mass transfer of ammonia water through ultrasonic oscillation atomization coupling. The generator includes a housing containing several inclined falling film tubes. A downward-flowing falling film solution flows outside the tubes, while an upward-flowing heat source flows inside. The falling film solution is heated by the heat source, generating rising vapor that exits at the top of the generator. Multiple sets of ultrasonic atomizers and ultrasonic oscillators are spaced apart on the outside of each falling film tube. The high-frequency ultrasonic atomizers atomize the falling film solution into fine droplets, which exchange heat and mass with the rising vapor whose temperature decreases progressively along the falling film height, thus improving the purity of the generator outlet and reducing irreversible losses. The medium- and low-frequency ultrasonic oscillators enhance internal disturbances in the solution, strengthening heat and mass transfer. This invention effectively utilizes the stepped heat distribution of the rising vapor within the generator, improving the purity and quality of the generator outlet, enabling miniaturization of the generator equipment and improving system performance.

Description

Technical Field

[0001] This invention relates to an inclined falling film generator that enhances the heat and mass transfer of ammonia water through ultrasonic oscillation atomization coupling, belonging to the technical field of efficient recovery and utilization of low-grade heat energy. Background Technology

[0002] Ammonia absorption refrigeration / heat pump cycle can efficiently recover and utilize low-grade heat energy (such as solar energy, industrial waste heat / exhaust heat, etc.) to drive the production of cooling capacity. It also uses an environmentally friendly working fluid pair (refrigerant ammonia-absorbent water), which can effectively solve the industry pain points of low utilization rate of low-grade energy and excessive consumption of fossil energy. It is one of the important technical paths to support the implementation of my country's "carbon peaking and carbon neutrality" strategic goals and promote the green transformation of energy structure.

[0003] Ammonia generation is the most critical heat and mass transfer process affecting the coefficient of performance (COP) and miniaturization of ammonia absorption refrigeration / heat pumps. The final ammonia vapor concentration has a significant impact on distillation efficiency; higher concentrations result in lower distillation energy consumption and smaller equipment size. Existing generation methods struggle to effectively increase the final ammonia vapor concentration, and overcoming this limitation has become a key technical challenge urgently needing to be addressed in generator optimization research.

[0004] A significant temperature difference exists between the vapor at the bottom and outlet of the vertical falling film generator, with the vapor temperature exhibiting a stepped distribution along the column height; that is, the vapor produced by the vertical falling film generator decreases as the column height increases. Vapors from different locations mix and enter the distillation column from the top of the generator. Due to the stepped temperature distribution, irreversible losses occur during the vapor mixing process. Inspired by the distillation process, if a portion of the falling film solution from different locations is distributed into the vapor zone, the stepped heat of the high-temperature vapor can be fully utilized through the distillation effect, reducing irreversible heat losses caused by vapor mixing, increasing the final ammonia vapor concentration, thereby reducing distillation energy consumption and decreasing equipment size. Summary of the Invention

[0005] Technical Problem: This invention proposes an inclined falling film generator that enhances the heat and mass transfer of ammonia water through ultrasonic oscillation and atomization coupling. An ultrasonic atomizer is used to atomize droplets that contact vapor for water absorption and ammonia removal, improving vapor purity. An ultrasonic oscillator is used to disturb the liquid film, increasing the liquid film mass transfer coefficient. The synergistic enhancement of generation performance through ultrasonic oscillation and atomization coupling improves the coefficient of performance of the ammonia water absorption refrigeration / heat pump system and enables miniaturization of the distillation equipment.

[0006] Technical solution: In order to achieve the above objectives, the present invention proposes an inclined falling film generator for enhancing the heat and mass transfer of ammonia water through ultrasonic oscillation atomization coupling, which is used to generate high-purity refrigerant vapor in an ammonia water absorption refrigeration / heat pump system. The falling film generator is provided with an upper end cap, a shell, and a lower end cap in sequence from top to bottom. The top of the upper end cap is provided with a heating water outlet, which is connected to the heating water pipeline through a threaded hole; the bottom is provided with a falling film pipe connection hole; the upper end cap is connected to the shell through the upper end cap threaded hole; The side of the housing is provided with a concentrated solution inlet, a vapor outlet and a pressure sensor interface. The concentrated solution inlet is connected to the solution pipeline through a concentrated solution pipe connection threaded hole. Inside the housing are a liquid distribution plate, an inclined tube, a solution distributor, and an annular ultrasonic atomizer and an annular ultrasonic oscillator, both of which are fixed on the inclined tube. The bottom is connected to the lower end cap through a lower end cap threaded hole. The lower end cap has a dilute solution outlet on its side, which is connected to a solution pipeline through a threaded hole in the dilute solution outlet; and a heating water inlet is provided at the bottom, which is connected to a heating water pipeline through a threaded hole in the heating water inlet.

[0007] The inclined tube is located between the liquid distribution plate and the solution distributor inside the shell. Both ends of the inclined tube are machined with straight pipe sections at a certain angle. The bending angle is the inclination angle. The upper straight pipe section of the inclined tube passes through the through hole in the liquid distribution plate, and the lower straight pipe section of the inclined tube is connected to the heating water through hole of the solution distributor.

[0008] In the annular ultrasonic atomizer, the ultrasonic atomizer vibrator is fixed to the outer wall of the upper half of the inclined tube by a clamp, the annular baffle is horn-shaped, its lower end is fixed to the outer wall of the upper half of the inclined tube by a clamp, and the upper end of the annular baffle surrounds the outer periphery of the ultrasonic atomizer vibrator.

[0009] The ultrasonic oscillator is fixed to the outer wall of the lower half of the inclined tube by a clamp.

[0010] The liquid distribution plate is provided with multiple through holes for each inclined tube to pass through, and a gap is formed between the inner wall of the through hole and the outer wall of the inclined tube to allow the concentrated solution to flow through.

[0011] The solution distributor is equipped with a falling film solution through-hole and a heating water through-hole. The falling film solution through-hole is connected to the dilute solution outlet, and the inclined tube is connected to the heating water through-hole, so that the heating water is evenly distributed to each inclined tube.

[0012] The installation positions of the annular ultrasonic atomizer and the annular ultrasonic oscillator are adjusted according to the operating conditions, and the inclined tubes are evenly distributed on the circumference with the central axis of the generator as the center.

[0013] The operating principle of the inclined falling film generator with ultrasonic oscillation atomization coupling to enhance the heat and mass transfer of ammonia water proposed in this invention is as follows: Heated water enters the inner chamber of the lower head through the heated water inlet at the bottom of the generator, and is evenly distributed to each inclined tube by the solution distributor to provide a heat source for the falling film solution; the heated water flows upward along the falling film tube, converges in the upper head chamber, and flows out from the heated water outlet at the top of the upper head; the concentrated ammonia solution flows into the generator through the concentrated solution inlet, and after being evenly distributed by the liquid distribution plate, forms a downward flowing liquid film on the inclined tube. The liquid film is heated by the countercurrent heated water in the tube to generate steam, and the steam flows upward along the gap between the inclined tubes and finally flows out from the steam outlet; the liquid film flows through the ultrasonic atomizer, and part of the solution is atomized into droplets and comes into contact with the rising steam to absorb water and remove ammonia, thereby increasing the purity of the rising steam; after the droplets exchange heat and mass with the steam, their own concentration decreases, and being captured by the liquid film will cause a decrease in the mass transfer driving potential of the liquid film surface; the ultrasonic oscillator acts on the inside of the liquid film, increasing the heat and mass transfer coefficient inside the liquid film, overcoming the negative effects caused by the atomized droplets, and increasing the amount of steam generated.

[0014] Beneficial effects: Compared with the prior art, the present invention has the following advantages: 1. The annular ultrasonic atomizer of this invention emits ultrasonic waves in the kilohertz frequency range, which can promote surface renewal effects, generate local eddies, and cause interfacial turbulence. The solution on the atomizer surface gains energy to form millimeter-sized droplets. The atomized droplets are dispersed in the gaps between the inclined tubes, come into contact with the vapor to absorb water and remove ammonia, increase the vapor concentration at the generator outlet, and make efficient use of the generator space, which can significantly reduce the volume of the generator and distillation equipment.

[0015] 2. The annular ultrasonic oscillator in this invention can induce internal fluid disturbances through cavitation and mechanical effects, reducing the boundary layer thickness and promoting heat transfer within the liquid film, between the liquid film and the heat source, and between the liquid film and vapor. It also promotes heat and mass transfer between gas and liquid, thereby increasing generation efficiency.

[0016] 3. This invention proposes fixing a ring-shaped ultrasonic oscillator and a ring-shaped ultrasonic atomizer to the outer wall of an inclined tube using clamps. An ultrasonic controller group controls the oscillator parameters (power, frequency, and phase of the ultrasonic oscillator and atomizer). The phase difference is controlled by setting the start-up time using a microcontroller. The cable entering the generator is sealed and protected with epoxy resin. Based on the spatiotemporal variation characteristics of the solution parameters along the falling film height direction within the generator, the installation positions of the ultrasonic oscillator and atomizer, as well as the oscillator parameters, can be specifically adjusted to achieve synergistic enhancement of heat and mass transfer through ultrasonic oscillation and atomization coupling, thereby more efficiently improving generator performance. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of an inclined falling film generator for enhancing the heat and mass transfer of ammonia water by ultrasonic oscillation atomization coupling proposed in this invention. Figure 2 for Figure 1 Top view of the medium solution dispenser; Figure 3 for Figure 1 Schematic diagram of the installation structure of the annular ultrasonic atomizer on a single inclined tube; Figure 4 for Figure 1 Schematic diagram of the installation structure of the annular ultrasonic oscillator on a single inclined tube; Figure 5 for Figure 3 A sectional view of section A1-A1; Figure 6 This is a schematic diagram of the droplet capture process by the liquid film between two adjacent tubes; The diagram shows: 1. Upper head, 101 heating water outlet, 102 threaded hole for heating water pipe connection, 103 falling film pipe connection hole, 104 threaded hole for upper head; 2. Shell, 201 concentrated solution inlet, 202 threaded hole for concentrated solution pipe connection, 203 steam outlet, 204 threaded hole for shell, 205 pressure sensor interface; 3. Lower head, 301 dilute solution outlet, 302 threaded hole for dilute solution outlet, 303 heating water inlet, 304 threaded hole for lower head; 4. Liquid distribution plate; 5. Annular ultrasonic oscillator, 501 annular baffle, 502 ultrasonic atomizer vibrator; 6. Inclined tube; 7. Annular ultrasonic oscillator; 8. Solution distributor, 801 falling film solution through hole, 802 heating water through hole; 9. Support; 10. Clamp. Detailed Implementation

[0018] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto: This invention utilizes multi-frequency ultrasonic oscillation atomization coupling to enhance the heat and mass transfer utilization space and internal heat and mass transfer coefficient within the generator, thereby achieving more efficient generation performance.

[0019] like Figure 1 As shown, an inclined falling film generator for enhanced heat and mass transfer of ammonia water by ultrasonic oscillation atomization coupling includes an upper end cap 1, a heating water outlet 101, a heating water pipe connection threaded hole 102, a falling film pipe connection hole 103, an upper end cap threaded hole 104, a shell 2, a concentrated solution inlet 201, a concentrated solution pipe connection threaded hole 202, a steam outlet 203, a pressure sensor interface 205, a lower end cap 3, a dilute solution outlet 301, a dilute solution outlet threaded hole 302, a heating water inlet 303, a lower end cap threaded hole 304, a liquid distribution plate 4, a ring ultrasonic oscillator 5, an inclined tube 6, a ring ultrasonic oscillator 7, a solution distributor 8, and a support 9. The top of the upper end cap 1 is provided with a heating water outlet 101, which is connected to the heating water pipeline through a heating water pipe connection threaded hole 102; the bottom is provided with a falling film pipe connection hole 103; the upper end cap 1 is connected to the shell 2 through the upper end cap threaded hole 104; the side of the shell 2 is provided with a concentrated solution inlet 201, a steam outlet 203 and a pressure sensor interface 205, wherein the concentrated solution inlet 201 is connected to the solution pipeline through the concentrated solution pipe connection threaded hole 202; the interior is equipped with a liquid distribution plate 4, an inclined pipe 6, a solution distributor 8, an annular ultrasonic atomizer 5 and an annular ultrasonic oscillator. All 7 devices are fixed on the inclined tubes 6; the liquid distribution plate 4 is provided with multiple through holes for each inclined tube 6 to pass through, and the inner wall of the through hole and the outer wall of the inclined tube form a gap for the concentrated solution to flow through; the two ends of the inclined tube are machined with straight pipe sections at a certain angle, and the angle between them and the main pipe section is the inclination angle; the two ends of the inclined tube are welded to the solution distributor; the lower end cap 3 is connected to the bottom of the shell 2 through the lower end cap threaded hole 304; the side of the lower end cap 3 is provided with a dilute solution outlet 301, which is connected to the solution pipeline through the dilute solution outlet threaded hole 302; a heating water inlet 303 is provided at the bottom; Heating water enters the lower head 3 chamber through heating water inlet 303, and is then evenly distributed into the inclined tubes 6 by solution distributor 8 to heat the falling film solution outside the tubes. Finally, it converges and enters the upper head 3 chamber and flows out from the water outlet 101. Concentrated solution enters through concentrated solution inlet 201 and is evenly distributed to each inclined tube 6 by liquid distribution plate 4. A downward-flowing liquid film is formed on the outer wall of the inclined tubes 6. The liquid film generates mixed vapor when heated. The liquid film is partially atomized into droplets by the annular ultrasonic atomizer 5 and comes into contact with the vapor to absorb water and remove ammonia, thereby improving the purity of the vapor. Finally, the vapor flows upward layer by layer and is discharged from the vapor outlet 203. The mechanical and acoustic effects of the annular ultrasonic oscillator can increase the disturbance inside the liquid film, thereby improving the heat and mass transfer coefficient of the liquid film. like Figure 2 As shown, the solution distributor 8 is provided with a falling film solution through hole 801 and a heating water through hole 802, which are respectively connected to the dilute solution outlet and the inclined tube, so as to evenly distribute the heating water to each inclined tube; like Figure 3 and Figure 5 As shown, in one embodiment, the annular ultrasonic atomizer transducer 502 and the annular baffle 501 are both fixed to the outer wall of the inclined tube 6 by clamps 10. like Figure 4 As shown, in one embodiment, the annular ultrasonic oscillator 7 is fixed to the outer wall of the inclined tube 6 by a clamp 10; like Figure 6 As shown, in one embodiment, the purpose of tilting the inclined tube 6 is to increase the amount of droplets captured by the liquid film by reducing the horizontal distance of the droplet movement between two adjacent inclined tubes, so that the droplets can continue to be heated to generate vapor and realize the secondary utilization of the droplets. In one implementation, the installation positions of the annular ultrasonic atomizer 5 and the annular ultrasonic oscillator 7 can be adjusted according to the operating conditions. The inclined tubes 8 are distributed circumferentially around the central axis of the generator. The frequency of the annular ultrasonic atomizer is 30-80 kHz, which can atomize droplets with a particle size of 100 micrometers or larger. The frequency of the annular ultrasonic oscillator is 20-100 kHz. The power, frequency, and phase of the annular ultrasonic oscillator and the annular ultrasonic atomizer are controlled by an ultrasonic controller group.

[0020] This invention proposes a novel approach to actively enhance the performance of ammonia generators based on ultrasonic technology. By adjusting ultrasonic parameters, the performance and operating range of absorption cooling / heat pump systems can be improved. The heat and mass transfer performance during ammonia generation is enhanced through the synergistic coupling of ultrasonic atomization and oscillation: on one hand, high-frequency ultrasound atomizes the solution into millimeter-sized droplets, which are dispersed in the gaps between inclined tubes. The droplets contact the vapor, absorbing water and expelling ammonia, effectively utilizing the heat gradient of the rising vapor and improving vapor purity. On the other hand, low- and medium-frequency ultrasound directly acts on the falling film solution, generating cavitation and mechanical effects within the liquid film, causing internal fluid disturbance and reducing the boundary layer thickness. This overcomes the problem of reduced mass transfer driving potential on the liquid film surface caused by the atomized droplets being captured by the liquid film, thereby improving heat and mass transfer efficiency. Based on the spatiotemporal variation characteristics of solution parameters during generation, the oscillator parameters (power, frequency, and phase of the annular ultrasonic atomizer 5 and oscillator 7) can be specifically adjusted using an ultrasonic controller to achieve synergistic enhancement of heat and mass transfer through ultrasonic oscillation and atomization coupling, thus improving generation performance more efficiently.

[0021] 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.

[0022] 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 tilting falling film generator for enhancing ammonia heat and mass transfer through ultrasonic oscillation atomization coupling, used to generate high-purity refrigerant vapor in an ammonia absorption refrigeration / heat pump system, characterized in that: The falling film generator is provided with an upper end cap (1), a housing (2), and a lower end cap (3) in sequence from top to bottom. The top of the upper end cap (1) is provided with a heating water outlet (101), which is connected to the heating water pipeline through a heating water pipe connection threaded hole (102); the bottom is provided with a falling film pipe connection hole (103); the upper end cap (1) is connected to the shell (2) through the upper end cap threaded hole (104); The side of the housing (2) is provided with a concentrated solution inlet (201), a vapor outlet (203) and a pressure sensor interface (205). The concentrated solution inlet (201) is connected to the solution pipeline through a concentrated solution pipe connection threaded hole (202). Inside the housing (2) are installed a liquid distribution plate (4), an inclined pipe (6), a solution distributor (8), an annular ultrasonic atomizer (5) and an annular ultrasonic oscillator (7) fixed on the inclined pipe (6). The bottom is connected to the lower end cap (3) through a lower end cap threaded hole (304). The lower end cap (3) is provided with a dilute solution outlet (301) on its side, which is connected to the solution pipeline through the dilute solution outlet threaded hole (302); and a heating water inlet (303) is provided at the bottom, which is connected to the heating water pipeline through the heating water inlet threaded hole.

2. The tilting falling film generator for enhanced ammonia heat and mass transfer via ultrasonic oscillation atomization coupling as described in claim 1, characterized in that, The inclined tube (6) is located between the liquid distribution plate (4) and the solution distributor (8) inside the housing (2). The inclined tube (6) has straight pipe sections with a certain angle at both ends. The bending angle is the inclination angle. The upper straight pipe section of the inclined tube (6) passes through the through hole in the liquid distribution plate (4), and the lower straight pipe section of the inclined tube (6) is connected to the heating water through hole (802) of the solution distributor (8).

3. The tilting falling film generator for enhanced ammonia heat and mass transfer via ultrasonic oscillation atomization coupling as described in claim 1, characterized in that, In the annular ultrasonic atomizer (5), the ultrasonic atomizer vibrator (502) is fixed to the outer wall of the upper half of the inclined tube (6) by a clamp (10), and the annular baffle (501) is horn-shaped, with its lower end fixed to the outer wall of the upper half of the inclined tube (6) by a clamp (10), and the upper end of the annular baffle (501) surrounds the outer periphery of the ultrasonic atomizer vibrator (502).

4. The tilting falling film generator for enhanced ammonia heat and mass transfer via ultrasonic oscillation atomization coupling as described in claim 1, characterized in that, The ultrasonic oscillator (7) is fixed to the outer wall of the lower half of the inclined tube (6) by a clamp (10).

5. The tilting falling film generator for enhanced ammonia-water heat and mass transfer via ultrasonic oscillation atomization coupling as described in claim 1, characterized in that, The liquid distribution plate (4) is provided with a plurality of through holes for each inclined tube (6) to pass through, and a gap is formed between the inner wall of the through hole and the outer wall of the inclined tube (6) for the concentrated solution to flow through.

6. The tilting falling film generator for enhanced ammonia heat and mass transfer via ultrasonic oscillation atomization coupling according to claim 1, characterized in that, The solution distributor (8) is provided with a falling film solution through hole (801) and a heating water through hole (802). The falling film solution through hole (801) is connected to the dilute solution outlet (301), and the inclined tube (6) is connected to the heating water through hole (802) to evenly distribute the heating water to each inclined tube (6).

7. The tilting falling film generator for enhanced ammonia heat and mass transfer via ultrasonic oscillation atomization coupling according to claim 3, characterized in that, The installation positions of the annular ultrasonic atomizer (5) and the annular ultrasonic oscillator (7) are adjusted according to the operating conditions, and the inclined tubes (6) are evenly distributed on the circumference with the generator's central axis as the center.

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