CN114857971B - Multistage frequency ultrasonic vibration pulsating heat pipe device and operation process thereof - Google Patents

Multistage frequency ultrasonic vibration pulsating heat pipe device and operation process thereof Download PDF

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Publication number
CN114857971B
CN114857971B CN202210472825.8A CN202210472825A CN114857971B CN 114857971 B CN114857971 B CN 114857971B CN 202210472825 A CN202210472825 A CN 202210472825A CN 114857971 B CN114857971 B CN 114857971B
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ultrasonic vibrator
ultrasonic
heat pipe
pulsating heat
primary
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CN114857971A (en
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钱宁
姜帆
傅玉灿
张靖周
徐九华
赵彪
丁文锋
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Nanjing University of Aeronautics and Astronautics
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Nanjing University of Aeronautics and Astronautics
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D15/00—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies
    • F28D15/02—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes
    • F28D15/06—Control arrangements therefor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F13/00—Arrangements for modifying heat-transfer, e.g. increasing, decreasing
    • F28F13/06—Arrangements for modifying heat-transfer, e.g. increasing, decreasing by affecting the pattern of flow of the heat-exchange media
    • F28F13/10—Arrangements for modifying heat-transfer, e.g. increasing, decreasing by affecting the pattern of flow of the heat-exchange media by imparting a pulsating motion to the flow, e.g. by sonic vibration

Abstract

The invention relates to a multi-stage frequency ultrasonic vibration pulsating heat pipe device and an operation process thereof, wherein the device mainly comprises a pulsating heat pipe, a secondary ultrasonic vibrator and a support frame part, wherein the pulsating heat pipe is arranged on the secondary ultrasonic vibrator, and the secondary ultrasonic vibrator is fixed on the support frame; the secondary ultrasonic vibrator mainly comprises a primary ultrasonic vibrator and an ultrasonic assembly, and the overall structural size meets the design requirement of full-wavelength resonance. The primary ultrasonic vibrator and the ultrasonic assembly are both provided with ultrasonic piezoelectric ceramic transducers, but the resonant frequencies of the primary ultrasonic vibrator and the ultrasonic assembly are different. The whole length of the first-level ultrasonic vibrator meets the design principle of half-wavelength resonance. The evaporation end of the pulsating heat pipe is provided with a base which is connected with the ultrasonic vibrator through a stud. The device provided by the invention can adjust the frequency change of the ultrasonic vibration device, realize the stable work of the pulsating heat pipe under the condition of multi-stage frequency ultrasonic, and ensure the matching of the ultrasonic transmission direction and the flow direction of the working medium in the pulsating heat pipe.

Description

Multistage frequency ultrasonic vibration pulsating heat pipe device and operation process thereof
Technical Field
The invention relates to a multistage frequency ultrasonic vibration pulsating heat pipe device and an operation process thereof. The device can realize the stable and reliable loading and transfer of the ultrasonic energy field with multi-level frequency on the pulsating heat pipe, and provides an experimental basis for the application of the pulsating heat pipe in the field of ultrasonic vibration processing.
Background
The pulsating heat pipe is used as a passive heat transfer element and has the characteristics of simple structure and high heat transfer capacity. The method is already applied to mechanical processing such as turning, grinding and the like, and plays roles in reducing the processing temperature and slowing down the grinding of tools. Therefore, the pulsating heat pipe has wide application prospect in ultrasonic processing. The influence of ultrasound on the heat transfer performance of the pulsating heat pipe is explored, and how to realize stable and reliable loading and transfer of ultrasound on the pulsating heat pipe needs to be solved. The ultrasonic wave is loaded with the directional requirement on the pulsating heat pipe, and the ultrasonic wave transmission direction is required to be consistent with the flow direction of the working medium in the pulsating heat pipe.
From the current research, there is a research that a ceramic piezoelectric sheet is directly placed at the evaporation end of the pulsating heat pipe or is contacted with an ultrasonic sensor to vibrate.
For example, the patent application with publication number CN110726317A discloses an ultrasonic pulsating heat pipe radiator with thermoelectric generation drive and temperature warning, which comprises a pulsating heat pipe, a piezoelectric ceramic piece and an ultrasonic generator, wherein the piezoelectric ceramic piece is arranged on the surface of the pulsating heat pipe; the temperature difference power generation device comprises a temperature difference power generation sheet and a DC-DC converter, wherein a heat conduction plate and an indicator light circuit temperature difference power generation sheet are electrically connected with an ultrasonic generator through the DC-DC converter; the evaporation section of the pulsating heat pipe is embedded into a heat conducting plate, one surface of the heat conducting plate is attached to a component to be radiated, the other surface of the heat conducting plate is attached with a thermoelectric generation piece, and the other surface of the thermoelectric generation piece is in contact with air; the electromagnetic relay of the indicating lamp circuit is electrically connected with the thermoelectric generation piece and can be used for early warning the junction temperature of the components so as to protect the components. The invention utilizes the pulsating heat pipe to generate temperature difference power to drive the piezoelectric ceramic piece to work, and the cavitation effect generated by the ultrasonic wave emitted by the piezoelectric ceramic piece can strengthen the heat transfer performance of the pulsating heat pipe. Because the thermoelectric generation is self-supplied, the thermoelectric generator can be flexibly applied to the occasions of heat dissipation of various semiconductor components.
The invention patent application with publication number CN102607305A relates to a plate type pulsating heat pipe heat transfer system with an electric control piezoelectric ceramic block fixed on the side surface, which comprises a plate with a bent pore passage arranged inside, and working media are filled in the bent pore passage. The bent duct is divided into an evaporation zone, a heat insulation zone and a condensation zone from bottom to top in sequence. It is characterized in that: an electrically controlled piezoelectric ceramic block is fixed on the side surface of the plate. The voltage applied to the electric control piezoelectric ceramic block is adjustable in size and frequency. The heat transfer system has the advantages that: the size and frequency of the voltage loaded on the piezoelectric ceramic are controlled, so that the piezoelectric ceramic generates ultrasonic waves with different frequencies and intensities, and the heat transfer performance of the pulsating heat pipe during starting and normal working is controlled. The starting power of the pulsating heat pipe is reduced, and the application limit of the pulsating heat pipe under the low-power condition is relieved. The cavitation principle is adopted to reduce the heat transfer resistance of the pulsating heat pipe and strengthen the heat transfer performance of the pulsating heat pipe during normal operation. The material used is common, the cost is low, the manufacture is convenient, the use is simple, and the operability and the application prospect are stronger.
The utility model with publication number CN202582301U discloses a pulsating heat pipe heat transfer system sleeved with an electric control piezoelectric ceramic block, which comprises a pulsating heat pipe 1 filled with working medium 2. The pulsating heat pipe 1 is divided into an evaporation area I, a heat insulation area II and a condensation area III from bottom to top in sequence. It is characterized in that: an electric control piezoelectric ceramic block 3 is sleeved on the pulsating heat pipe 1. The voltage applied to the electric control piezoelectric ceramic block 3 is adjustable in size and frequency. The pulsating heat pipe heat transfer system has the following advantages: the size and frequency of the voltage loaded on the piezoelectric ceramic are controlled, so that the piezoelectric ceramic generates ultrasonic waves with different frequencies and intensities, and the heat transfer performance of the pulsating heat pipe during starting and normal working is controlled. The starting power of the pulsating heat pipe is reduced, and the application limit of the pulsating heat pipe under the low-power condition is relieved. The cavitation principle is adopted to reduce the heat transfer resistance of the pulsating heat pipe and strengthen the heat transfer performance of the pulsating heat pipe during normal operation. The used materials are common and have low cost. The manufacturing is convenient, the use is simple, and the practical operability and the application prospect are stronger.
The apparatus or method of the above-mentioned publication does not control the true frequency and amplitude of the ultrasound acting on the pulsating heat pipe. Meanwhile, the matching of the ultrasonic transmission direction and the flow direction of the working medium in the pulsating heat pipe is not ensured. Meanwhile, the method and the device can only maintain the ultrasound to work under the specific frequency and amplitude conditions.
Research literature at home and abroad shows that the ULTRASONIC wave with multiple frequencies or large frequencies has obvious EFFECT ON improving the Heat Transfer performance OF the pulsating Heat pipe (Proceedings OF the ASME 2016 5th International Conference ON Micro/Nanoscale Heat and Mass Transfer January 4-6, 2016, biopolis, singapore, EXPERIMENTAL INVESTRATION OF ULTRASONIC FREQUENCY EFFECT ANOSCILLATION HEAT PIP). The conventional ultrasonic vibration platform or ultrasonic vibration knife handle cannot realize frequency adjustment, and the test condition for exploring the heat transfer performance of the ultrasonic frequency to the pulsating heat pipe is limited.
Meanwhile, most of the current ultrasonic vibration devices are mainly studied on how to realize large-amplitude ultrasonic processing. For example, patent publication No. CN 113601279A discloses a large-amplitude ultrasonic vibration device applied to ultrasonic-assisted grinding. But it is rarely reported about ultrasonic vibration devices of multistage frequencies. Therefore, a device for realizing stable and reliable loading and transmission of the ultrasonic energy field with multi-stage frequency on the pulsating heat pipe is needed.
The influence of the ultrasound on the heat transfer performance of the pulsating heat pipe is also researched, and the adaptability of the structure of the pulsating heat pipe and the ultrasonic vibration device is also considered. In the structural design of the pulsating heat pipe, due to the structural complexity, the problems of clamping and temperature measurement need to be considered by adopting an ultrasonic vibration device. The design of the connection structure of the evaporation end of the pulsating heat pipe and the ultrasonic vibration device needs to ensure the transmission of the ultrasound on the pulsating heat pipe and reduce the stress concentration at the connection position of the evaporation end. Meanwhile, the temperature measurement mode also needs to be improved. The traditional pulsating heat pipe temperature measurement mode mostly adopts external temperature measurement, namely, a thermocouple is stuck on the outer wall surface of the pulsating heat pipe by using special glue. But this approach cannot be used under ultrasonic conditions. The ultrasonic vibration causes friction on the thermocouple and the outer wall surface, thereby affecting the accuracy of the temperature measurement. Therefore, the structure of the pulsating heat pipe needs to be improved, so that the pulsating heat pipe is suitable for the multistage frequency ultrasonic vibration device disclosed by the invention to form a complete multistage frequency ultrasonic vibration pulsating heat pipe device.
Disclosure of Invention
The purpose of the invention is as follows: in order to solve the technical defects, the invention aims to provide a multi-frequency ultrasonic vibration pulsating heat pipe device and an operation process thereof.
The technical scheme is as follows: in order to realize the purpose of the invention, the invention adopts the following technical scheme:
a multi-stage frequency ultrasonic vibration pulsating heat pipe device mainly comprises a pulsating heat pipe, a two-stage ultrasonic vibrator and a support frame; the secondary ultrasonic vibrator mainly comprises a primary ultrasonic vibrator and an ultrasonic vibration assembly.
The primary ultrasonic vibrator mainly comprises an ultrasonic amplitude transformer, a piezoelectric ceramic transducer and a rear end cover. The ultrasonic amplitude transformer is an integrated composite conical amplitude transformer with an input end connected with a cylindrical structure. The front section of the amplitude transformer is designed with a boss structure which can play a role in fixing. The rear section of the cylinder is provided with a thread design. The rear end cover is a cone, and the size of the upper end face is the same as that of the piezoelectric ceramic piece. The lower end face has the same size as the front end cap of the ultrasonic vibration assembly. Both end surfaces are provided with threaded holes. Meanwhile, the length of the rear end cover is consistent with the length of the conical section of the amplitude transformer, and the conicity is the same, so that the primary ultrasonic vibrator can be used as the amplitude transformer structure of the secondary ultrasonic vibrator. The integral length size of the first-level ultrasonic vibrator meets the design requirement of half-wavelength resonance.
The ultrasonic vibration assembly comprises a front end cover, a piezoelectric ceramic transducer, a rear end cover and a bolt. Both end faces of the front end cover are provided with threaded holes. The bolt rod part penetrates through the rear cover plate, the piezoelectric ceramic piece and the electrode plate and is screwed into the threaded hole on the rear end face of the front end cover.
The primary ultrasonic vibrator and the ultrasonic vibration assembly are both piezoelectric ceramic pieces, and the excitation frequencies of the piezoelectric ceramic pieces in the two parts are different. The piezoelectric ceramic pieces in the first-stage ultrasonic vibrator and the second-stage ultrasonic vibrator are selected to meet the requirement that the difference between the outer diameters of the two piezoelectric pieces is equal to the difference between the diameters of the input end and the output end of the amplitude transformer of the first-stage ultrasonic vibrator.
The primary ultrasonic vibrator and the ultrasonic assembly are connected and combined into a secondary ultrasonic vibrator by adopting a double-end stud. In order to ensure the stable transmission of the ultrasonic surface, the two connecting surfaces need to be polished or coated with a small amount of silicone grease to reduce the surface roughness. The whole secondary ultrasonic vibrator meets the design principle of full-wavelength resonance.
The primary ultrasonic vibrator can be used as an independent ultrasonic vibration device to work at the self resonant frequency and can be used as an amplitude transformer structure of the secondary ultrasonic vibrator. The secondary ultrasonic vibrator uses a piezoelectric ceramic transducer of an ultrasonic assembly, and the resonant frequency is different from that of the primary ultrasonic vibrator.
In the application, the whole pulsating heat pipe is of an integrated structure with a base. The base is in a round table structure, the upper end face of the base is one side with a small diameter, and the upper end face of the base is connected with the bottom of the evaporation end of the pulsating heat pipe. The diameter of the lower end face of the base is the same as that of the output end of the amplitude transformer of the primary ultrasonic vibrator, a threaded hole is formed in the base, and the base can be connected with the ultrasonic vibrator through a double-end stud. The integral taper of the circular truncated cone is the same as the taper of the amplitude transformer of the primary ultrasonic vibrator. Meanwhile, the circular truncated cone is provided with a groove, so that the circular truncated cone can be clamped and screwed conveniently by using a wrench. In order to ensure the stability of the pulsating heat pipe structure under the ultrasonic vibration condition, the vacuumizing liquid injection port is arranged on the central axis of the condensation end of the pulsating heat pipe and is vertically upward. The temperature measuring points are distributed at the junction positions of the condensation end, the evaporation end and the heat insulation section, and the thermocouples are inserted into the pulsating heat pipe to adopt an internal temperature measuring mode. The pulsating heat pipe with the structure can ensure the reliable transmission of ultrasound and the accuracy of a temperature measurement result.
An operation process of a multistage frequency ultrasonic vibration pulsation heat pipe device comprises the following steps:
(1) The primary ultrasonic vibrator is fixed on a bracket, and the pulsating heat pipe is arranged at the output end of the composite conical deformation amplitude rod of the primary ultrasonic vibrator. The ultrasonic power supply is connected with the primary ultrasonic vibrator transducer;
(2) And starting the ultrasonic power supply, wherein the working frequency of the pulsating heat pipe is the resonant frequency f1 of the primary ultrasonic vibrator.
(3) The way of realizing the frequency conversion work of the ultrasonic vibration device is to combine the primary ultrasonic vibrator and the ultrasonic assembly into a secondary ultrasonic vibrator. The ultrasonic power supply is connected with the electrode plate of the ultrasonic assembly, and the primary ultrasonic vibrator is used as an amplitude transformer structure of the secondary ultrasonic vibrator. The working frequency of the pulsating heat pipe is the resonant frequency f2 of the secondary ultrasonic vibrator.
Wherein the vibration magnitude depends on the power of the piezoelectric ultrasonic transducer and the amplification factor of the ultrasonic horn. The piezoelectric ceramic pieces in the first-stage ultrasonic vibrator and the second-stage ultrasonic vibrator are different, and the difference value of the outer diameters of the two piezoelectric pieces is equal to the difference value of the diameters of the input end and the output end of the amplitude transformer of the first-stage ultrasonic vibrator.
Has the advantages that:
(1) The invention has simple structure and convenient installation, and the primary ultrasonic vibrator can be used as an independent ultrasonic vibration device to work at the self resonant frequency and can be used as an amplitude transformer structure of the secondary ultrasonic vibrator. The working frequency of the pulsating heat pipe can be the resonant frequency of the primary ultrasonic vibrator or the resonant frequency of the ultrasonic assembly, the frequency adjustment of the ultrasonic vibration device is completed through the combined structure of the primary ultrasonic vibrator and the secondary ultrasonic vibrator, and the stable work of the pulsating heat pipe under the condition of multi-stage frequency ultrasonic is realized.
(2) In the ultrasonic vibration device realized by the invention, the selection of the piezoelectric ceramic piece can be adjusted according to the processing requirement. And various combination modes of the ultrasonic vibration device under different working conditions can be realized.
(3) The invention realizes the controllability of the real frequency and amplitude of the ultrasound applied to the pulsating heat pipe. Meanwhile, the matching performance of the ultrasonic transmission direction and the flow direction of the working medium in the pulsating heat pipe can be ensured.
Drawings
FIG. 1 is a schematic view of the overall structure of a multi-stage frequency ultrasonic vibration pulsating heat pipe apparatus according to the present invention;
FIG. 2 is an exploded view of the structure of the multi-stage frequency ultrasonic vibration pulsating heat pipe apparatus according to the present invention;
fig. 3 is a schematic structural diagram of the primary ultrasonic vibrator 4;
FIG. 4 is a schematic structural view of the rear end cap 4-3 of FIG. 3;
FIG. 5 is a schematic structural view of the composite conical horn 4-1 of FIG. 3;
FIG. 6 is a schematic structural view of the ultrasonic assembly 5;
fig. 7 is a schematic structural diagram of the two-stage ultrasonic vibrator 2;
fig. 8 is a schematic structural diagram of the pulsating heat pipe 1;
fig. 9 is a schematic structural view of the support frame 3;
FIG. 10 is a diagram showing the results of modal analysis of the primary ultrasonic vibrator and the pulsating heat pipe in example 1;
fig. 11 is a diagram showing the result of modal analysis of the two-stage ultrasonic vibrator and the pulsating heat pipe in example 1.
Description of the main reference symbols in the drawings: 1-pulsating heat pipes; 2-a secondary ultrasonic vibrator; 3-a support frame; 4-a primary ultrasonic vibrator; 4-1-a composite conical deformation amplitude transformer, 4-2-a piezoelectric ceramic transducer and 4-3-a rear end cover; 5-ultrasonic assembly, 5-1-piezoelectric ceramic transducer, 5-2-rear end cover, 5-3-front end cover, 5-4 bolt, 6-ultrasonic power supply, 7-boss and 8-cylindrical structure.
Detailed Description
In order to make the technical solutions in the present patent application better understood by those skilled in the art, the technical solutions in the present application will be clearly and completely described below with reference to the accompanying drawings in the present application. It should be apparent that the described embodiments are only some embodiments of the present application, and not all embodiments. All other embodiments obtained by a person of ordinary skill in the art without any inventive work based on the embodiments in the present application shall fall within the protection scope of the present application.
The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.
Example 1
Fig. 1 is a schematic view of the overall structure of a multistage frequency ultrasonic vibration pulsating heat pipe device according to the present invention, and fig. 2 is an exploded view of the structure. Referring to fig. 1 and 2, the multistage frequency ultrasonic vibration pulsating heat pipe device sequentially comprises a pulsating heat pipe 1, a two-stage ultrasonic vibrator 2, a support frame 3 and an ultrasonic power supply 6 from top to bottom. The secondary ultrasonic vibrator comprises a primary ultrasonic vibrator 4 and an ultrasonic assembly 5, the primary ultrasonic vibrator is fixed on the support frame through a flange arranged at a half-wavelength node, and the working frequency of the ultrasonic power supply can be selected by connecting the primary ultrasonic vibrator 4 or the secondary ultrasonic vibrator 2.
Fig. 3 is a schematic structural diagram of a primary ultrasonic vibrator 4, fig. 4 is a schematic structural diagram of a rear end cover in fig. 3, and fig. 5 is a schematic structural diagram of a composite conical deformation horn 4-1 in fig. 3. Referring to fig. 3-5, the primary ultrasonic vibrator 4 has an overall length that meets the design requirements of the secondary ultrasonic vibrator 2 for a conical deformation amplitude rodL 1 The design principle of half-wavelength resonance is satisfied. The piezoelectric ceramic composite material mainly comprises a composite conical amplitude transformer 4-1, a piezoelectric ceramic transducer 4-2 and a rear end cover 4-3. The output end of the composite conical deformation amplitude rod 4-1 is connected with the pulsating heat pipe, and the working frequency is the resonant frequency of the primary ultrasonic vibrator 4. Rear end cap 4-3 front end face diameterl 1 =35mm, diameter of rear end facel 2 =50mm，l 2 - l 1 =15mm. And the front end surface and the rear end surface are both provided with penetrating threaded holes. Rear end face entersPolishing treatment is carried out to ensure that the connection is tight and no energy is lost. Wherein the piezoelectric ceramic transducer 4-2 has an outer diameter of 35mm and an inner diameter of 20mm.
Fig. 5 is a schematic structural view of the composite conical amplitude transformer 4-1 in fig. 3, the front end cover 5-3 and the ultrasonic amplitude transformer are designed to be integrated in a stable working mode, and a boss 7 and a cylindrical structure 8 are arranged at the input end of the composite conical amplitude transformer 4-1 and are used for installing and positioning the piezoelectric ceramic transducer 4-2 and the rear end cover 4-3. Boss 7 (diameter)l 4 ) Can be connected with the bracket to play a role in fixing. In order to ensure that the first-stage ultrasonic vibrator can be used as a horn structure of the second-stage ultrasonic vibrator, the conical section of the horn of the first-stage ultrasonic vibrator is consistent with the conical section of the rear end cover in length and has the same taper. In this embodiment, the diameter of the horn output endl 3 =20mm. Length of conic segmentL 2 And the rear end cap 4-3. The diameter of the cylindrical structure 8 meets the inner diameter of a ceramic wafer of the piezoelectric transducer, and the rear section is designed by external threads and is connected with a threaded hole on the front end face of the rear end cover 4-3.
Fig. 6 is a schematic structural diagram of the ultrasonic assembly 5, and the ultrasonic assembly 5 mainly includes a front end cap 5-1, a piezoelectric ceramic transducer 5-2, a rear end cap 5-3, and a bolt 5-4. The secondary ultrasonic vibrator uses the excitation frequency of the piezoelectric ceramic transducer 5-2 of the ultrasonic assembly to be different from that of the piezoelectric ceramic transducer 4-2 in the primary ultrasonic vibrator 4. Wherein the outer diameter of the piezoelectric ceramic piece of the piezoelectric ceramic transducer is selected to be 50mm. The piezoelectric ceramic pieces in the first-stage ultrasonic vibrator and the second-stage ultrasonic vibrator are selected so that the difference between the outer diameters of the two piezoelectric pieces is equal to the difference between the diameters of the input end and the output end of the amplitude transformer of the first-stage ultrasonic vibrator (in the embodiment, the difference is 15 mm).
Fig. 7 is a schematic structural diagram of the secondary ultrasonic vibrator 2, and the secondary ultrasonic vibrator 2 mainly comprises a primary ultrasonic vibrator 4 and an ultrasonic assembly 5. And the rear end cover 4-3 of the primary ultrasonic vibrator 4 is connected with the ultrasonic assembly 5 by adopting a stud. It is necessary to ensure no gap after connection. The two connecting surfaces need to be polished, and a small amount of silicone grease can be coated to reduce the surface roughness. The whole length of the secondary ultrasonic vibrator 2 is based on the full-wavelength resonance design principle, a flange supporting structure is placed at a half-wavelength node position, and through holes are circumferentially arranged on the flange and fixed on the supporting frame 3 through bolts. The ultrasonic power supply can be connected with the primary ultrasonic vibrator 4 or the secondary ultrasonic vibrator 2 to select the working frequency.
The pulsating heat pipe 1 (see fig. 8) is an integrated structure with a base. The bottom of the evaporation end is provided with a round table-shaped base. The upper end surface is a side with a small diameter and is connected with the bottom of the evaporation end of the pulsating heat pipe, and the diameter of the lower end surface is consistent with the output end of the composite conical deformation amplitude transformer 4-1 of the primary ultrasonic vibrator 4. The lower end face of the base is provided with a threaded hole which can be connected with the secondary ultrasonic vibrator through a double-end stud. The vacuumizing liquid injection port is arranged on the axis of the condensation end of the pulsating heat pipe, and the direction of the vacuumizing liquid injection port is vertical upwards.
Threaded holes are circumferentially arranged on the round edge of the support frame 3 (shown in figure 9) and are connected with the flange of the secondary ultrasonic vibrator through bolts.
The operation process of the multistage frequency ultrasonic vibration pulsation heat pipe device comprises the following steps:
(1) The pulsating heat pipe 1 is connected with the output end of a composite conical deformation amplitude rod 4-1 of the primary ultrasonic vibrator 4 through a stud. The ultrasonic power supply 6 is connected with the ultrasonic transducer 4-2 of the primary ultrasonic vibrator 4, the ultrasonic power supply 6 is started, and the working frequency of the pulsating heat pipe 1 is the resonant frequency f1=14899Hz of the primary ultrasonic vibrator 4.
(2) When the frequency needs to be changed, the primary ultrasonic vibrator 4 is connected with the ultrasonic assembly 5 through the stud, and the combined secondary ultrasonic vibrator 2 is fixed on the support frame 3.
(3) The ultrasonic power supply is connected with an ultrasonic transducer 5-2 in the secondary ultrasonic vibrator 2, the power supply 6 is turned on, and the frequency of the pulsating heat pipe 1 is the resonant frequency f2=23014Hz of the secondary ultrasonic vibrator 2.
FIG. 10 is a diagram showing the results of modal analysis of the primary ultrasonic vibrator and the pulsating heat pipe in example 1; fig. 11 is a diagram showing the result of modal analysis of the two-stage ultrasonic vibrator and the pulsating heat pipe in example 1. It can be seen that the true frequency and amplitude of the ultrasound applied to the pulsating heat pipe is controllable. Meanwhile, the matching performance of the ultrasonic transmission direction and the flow direction of the working medium in the pulsating heat pipe can be ensured.
Therefore, the frequency adjustment of the ultrasonic vibration device is realized through the combined structure. The working frequency of the pulsating heat pipe can be the resonant frequency of the primary ultrasonic vibrator or the resonant frequency of the ultrasonic assembly, and the pulsating heat pipe is simple in structure and convenient to install.
The foregoing description of various embodiments of the present application is provided to those skilled in the art for the purpose of illustration. It is not intended to be exhaustive or to limit the invention to a single disclosed embodiment. As described above, various alternatives or modifications of the present application will be apparent to those skilled in the art to which the above-described technology pertains. Thus, while some alternative embodiments have been discussed in detail, other embodiments will be apparent or relatively easy to derive by those of ordinary skill in the art. This application is intended to cover all alternatives, modifications, and variations of the invention that have been discussed herein, as well as other embodiments that fall within the spirit and scope of the above-described application.
Although the present application has been described in terms of embodiments, those of ordinary skill in the art will recognize that there are numerous variations and permutations of the present application without departing from the spirit of the application, and it is intended that the appended claims encompass such variations and permutations without departing from the spirit of the application.

Claims (3)

1. A multi-stage frequency ultrasonic vibration pulsating heat pipe device is characterized by sequentially comprising a pulsating heat pipe (1), a secondary ultrasonic vibrator (2), a support frame (3) and an ultrasonic power supply (6) from top to bottom; the secondary ultrasonic vibrator comprises a primary ultrasonic vibrator (4) and an ultrasonic assembly (5), the pulsating heat pipe (1) is arranged on the secondary ultrasonic vibrator, the secondary ultrasonic vibrator is fixed on the support frame, the ultrasonic power supply selects the working frequency by connecting the primary ultrasonic vibrator (4) or the secondary ultrasonic vibrator (2), and stable work of the pulsating heat pipe under the condition of multi-frequency ultrasound is realized;
the integral length of the primary ultrasonic vibrator meets the design principle of half-wavelength resonance; the ultrasonic vibrator can be used as an independent ultrasonic vibration device and works at the self resonant frequency, or can be used as an amplitude transformer structure of a secondary ultrasonic vibrator; the primary ultrasonic vibrator comprises a composite conical deformation amplitude transformer (4-1), a piezoelectric ceramic transducer (4-2) and a rear end cover (4-3) which are connected in sequence;
the composite conical amplitude transformer is designed in an integrated manner, the output end of the composite conical amplitude transformer is connected with the pulsating heat pipe, and the input end of the composite conical amplitude transformer is provided with a boss (7) and a cylindrical structure (8) which are used for installing and positioning the piezoelectric ceramic transducer (4-2) and the rear end cover (4-3); the working frequency is the resonance frequency of the first-stage ultrasonic vibrator, and in order to ensure that the first-stage ultrasonic vibrator can be used as the amplitude transformer structure of the second-stage ultrasonic vibrator, the conical section of the composite conical deformation amplitude transformer is consistent with the conical degree of the rear end cover;
the whole length of the secondary ultrasonic vibrator is based on the full-wavelength resonance design principle; the secondary ultrasonic vibrator (2) comprises a primary ultrasonic vibrator (4) and an ultrasonic assembly (5), and a rear end cover of the primary ultrasonic vibrator is connected with the ultrasonic assembly by adopting a stud, so that no gap exists after connection; a flange supporting structure is placed at the position of the half-wavelength node of the secondary ultrasonic vibrator, and through holes are circumferentially arranged on the flange and fixed on the supporting frame through bolts;
the piezoelectric ceramic pieces in the first-stage ultrasonic vibrator and the second-stage ultrasonic vibrator are selected so that the difference between the outer diameters of the two piezoelectric pieces is equal to the difference between the diameters of the input end and the output end of the amplitude transformer of the first-stage ultrasonic vibrator;
the ultrasonic assembly (5) comprises a front end cover (5-1), a piezoelectric ceramic transducer (5-2), a rear end cover (5-3) and a bolt (5-4); the excitation frequency of the piezoelectric ceramic transducer (5-2) of the ultrasonic assembly is different from that of the piezoelectric ceramic transducer (4-2) in the primary ultrasonic vibrator (4).
2. The multi-stage frequency ultrasonic vibration pulsating heat pipe device as claimed in claim 1, wherein the pulsating heat pipe is of an integrated structure, a truncated cone-shaped base is arranged at the bottom of an evaporation end, and a vacuumizing liquid injection port is arranged on a central axis of a condensation end of the pulsating heat pipe and is directed vertically upwards; the whole body is small at the top and big at the bottom, and the diameter of the lower end surface is the same as that of the output end of the composite conical amplitude of the primary ultrasonic vibrator; the integral taper of the truncated cone-shaped base is the same as the taper of the amplitude transformer of the primary ultrasonic vibrator; meanwhile, the base in the shape of a truncated cone is provided with a groove, so that the base can be clamped and screwed conveniently by a wrench; the lower end face of the round table-shaped base is provided with a threaded hole and is connected with the secondary ultrasonic vibrator through a stud, temperature measuring points are distributed at junction positions of a condensation end, an evaporation end and a heat insulation section, a thermocouple is inserted into the pulsating heat pipe, and an internal temperature measuring mode is adopted.
3. The operation process of the multi-stage frequency ultrasonic vibration pulsating heat pipe device as claimed in claim 1, wherein the steps are as follows:
(1) Fixing the primary ultrasonic vibrator on a support frame, and connecting the pulsating heat pipe with the output end of the composite conical deformation amplitude rod of the primary ultrasonic vibrator through a stud; the ultrasonic power supply is connected with the piezoelectric ceramic transducer of the primary ultrasonic vibrator, the ultrasonic power supply is started, and the working frequency of the pulsating heat pipe is the resonant frequency f1 of the primary ultrasonic vibrator;
(2) When the frequency needs to be changed, the primary ultrasonic vibrator is connected with the ultrasonic assembly through the stud, and the combined secondary ultrasonic vibrator is fixed on the support frame by virtue of the flange;
(3) The ultrasonic power supply is connected with the piezoelectric ceramic transducer in the secondary ultrasonic vibrator, the power supply is started, and the frequency of the pulsating heat pipe is the resonant frequency f2 of the secondary ultrasonic vibrator.
CN202210472825.8A 2022-04-29 2022-04-29 Multistage frequency ultrasonic vibration pulsating heat pipe device and operation process thereof Active CN114857971B (en)

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US7002283B2 (en) * 2003-06-03 2006-02-21 Asm Assembly Automation Ltd. Ultrasonic transducer assembly
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