Ultrasonic wave-nanofluid coupled light condensation and heat collection device

Abstract

The invention discloses an ultrasonic wave-nanofluid coupled light condensation and heat collection device, and belongs to the technical field of solar heat utilization equipment. The device comprises a heat collecting pipe, the heat collecting pipe is composed of a glass outer pipe and a metal inner pipe, and the space between the glass outer pipe and the metal inner pipe is in a vacuum state. And an embedded ultrasonic plate is arranged on the inner wall of the metal inner pipe and consists of a temperature-resistant substrate and ultrasonic transducers which are uniformly arranged in a dot matrix manner. An external circuit is connected with the transducer electrode through a lead to provide an abrupt change electric field, so that the piezoelectric / magnetostrictive element generates high-frequency mechanical vibration to form ultrasonic waves. The ultrasonic waves act on the nano-fluid flowing through the heat collecting pipe, deposition of nano-particles is effectively prevented, the stability of the nano-fluid is enhanced, and the photo-thermal conversion efficiency is improved. Meanwhile, fluid mixing and heat exchange are enhanced through ultrasonic waves, and pipe wall temperature distribution and heat loss are reduced. The device is simple in structure, is suitable for various nanofluids and condenser types, and is suitable for a solar heat utilization system.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of solar heat utilization equipment, and particularly relates to a light-concentrating and heat-collecting device coupled with ultrasonic waves and nanofluids. BACKGROUND

[0002] At present, traditional fossil energy is increasingly depleted worldwide, and its use brings serious environmental problems, so it is urgent to reduce the dependence on fossil energy and promote the green and low-carbon transformation of energy. As a kind of energy with abundant reserves and clean and renewable, solar energy is regarded as an important part of future energy structure, and its utilization technology is increasingly valued.

[0003] Solar energy utilization technology mainly includes photothermal utilization, photoelectric utilization and photochemical conversion. Among them, the solar heat utilization technology converts solar energy into heat energy, the process is direct and the efficiency is relatively high, and the application forms are various, such as trough system, tower system and the like. The core component of this kind of system is the heat collecting tube, which is usually composed of a glass outer tube and a metal inner tube, and a vacuum is maintained between the two tubes to insulate heat, and a selective absorption layer is coated on the outer surface of the metal tube to efficiently capture solar energy.

[0004] However, the heat collecting performance is largely limited by the heat conduction ability of the heat transfer working medium. Traditional working medium such as heat conducting oil, water or molten salt has low thermal conductivity, which restricts the efficiency improvement of the whole heat collecting system. Therefore, nanofluid, i.e. a suspension formed by dispersing solid particles of nanometer scale in traditional base fluid, is introduced into this field. Nanofluid can significantly improve the heat conduction performance and photo-thermal conversion efficiency of the working medium, and is an ideal heat collecting medium.

[0005] However, nanofluid faces a key challenge in actual operation: nanoparticles are easy to deposit at the bottom or wall of the flow channel due to aggregation, sedimentation and the like. This deposition phenomenon not only blocks the flow channel, but also destroys the stability of nanofluid, so that its superior thermal properties are gradually lost, eventually leading to a decrease in photo-thermal conversion efficiency, which limits the long-term stable application of nanofluid in solar heat collection.

[0006] Therefore, a technical solution is urgently needed to effectively inhibit the deposition of nanoparticles and maintain the stability of nanofluid, so as to fully exert the performance advantages of nanofluid in solar heat collecting system. SUMMARY

[0007] To address the aforementioned technical problems, this invention provides an ultrasonic-nanofluid coupled solar thermal collector, which combines ultrasonic vibration technology with a solar collector tube. Ultrasonic vibration controls the movement of nanoparticles, causing the nanoparticles deposited at the bottom of the collector tube to float in the working fluid, thus maintaining the stability of the nanofluid. Simultaneously, the ultrasonic vibration increases the mixing degree of the fluid within the collector tube, enhancing heat exchange and increasing the heat absorbed by the fluid. This reduces the circumferential temperature distribution of the collector tube and minimizes heat loss radiated outwards from the metal tube.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] An ultrasonic-nanofluid coupled solar thermal collector includes a heat collection tube comprising a glass outer tube, a metal inner tube, and an embedded ultrasonic plate arranged on the inner wall of the metal inner tube.

[0010] The metal inner tube is filled with nanofluid, which is used to quickly convert the solar energy absorbed by the heat collection tube into heat energy.

[0011] The embedded ultrasonic plate includes a heat-resistant ultrasonic device embedded substrate and a plurality of ultrasonic transducers arranged in a uniform dot matrix inside the substrate. An electrical signal is applied to the plurality of ultrasonic transducers to generate ultrasonic waves, which are used to maintain the long-term stability of the nanofluid.

[0012] Furthermore, the outer glass tube and the inner metal tube are nested together, with a vacuum between them.

[0013] Furthermore, the heat-resistant ultrasonic device has several leads arranged inside its embedded substrate for applying electrical signals to several ultrasonic transducers.

[0014] Furthermore, the outer wall of the glass outer tube is provided with a flange interface, the flange interface is connected to the upper end of the heat collection tube support, and the lower end of the heat collection tube support is connected to the condenser lens.

[0015] Furthermore, the condenser lens consists of two pieces spaced at a predetermined distance, which combine to form a parabolic structure.

[0016] Furthermore, the two condenser lenses are fixed on the support frame, and a tracking device is connected below the support frame. The tracking device tracks the sun's position to ensure that the incident sunlight rays are parallel to the normal direction of the condenser lenses.

[0017] Furthermore, the ultrasonic transducer includes a piezoelectric / magnetostrictive element, a backing block, and electrodes. One end of the lead wire is connected to an external circuit, and the other end is connected to the electrodes to realize the input of electrical signals. The electrodes are fixed to the metal layer of the piezoelectric / magnetostrictive element and are used to receive electrical signals to apply a sudden electric field to the piezoelectric / magnetostrictive element.

[0018] Furthermore, the backing block is tightly attached to the end face of the non-metallic layer of the piezoelectric / magnetostrictive element, and is made of a high-density material.

[0019] Furthermore, a wear-resistant material layer is provided between the piezoelectric or magnetostrictive element and the nanofluid inside the metal inner tube, the wear-resistant material layer being made of epoxy resin or aluminum oxide.

[0020] Furthermore, the nanofluid comprises a base liquid and solid nanoparticles dispersed in the base liquid, wherein the base liquid is any one of water, heat transfer oil or molten salt, and the solid nanoparticles are any one of metal nanoparticles or metal oxide nanoparticles.

[0021] The beneficial effects of this invention are as follows:

[0022] This effectively solves the problem of nanoparticle deposition. The high-frequency mechanical vibration generated by the ultrasonic transducer creates an ultrasonic field in the nanofluid, which can resuspend the nanoparticles deposited at the bottom of the heat collector tube and uniformly disperse them in the base liquid, thereby maintaining the stability of the nanofluid in the long term and ensuring that its superior thermophysical properties can be continuously exerted.

[0023] It significantly improves the photothermal conversion efficiency. The ultrasonic action not only prevents particle deposition, but also enhances the disturbance and mixing of the fluid inside the heat collection tube, promotes heat exchange between the high-temperature fluid near the wall and the main fluid, and enables the nanofluid to absorb and carry away more heat, while reducing the uneven circumferential temperature distribution of the heat collection tube and the heat loss due to outward radiation.

[0024] The system boasts strong compatibility and low modification costs. This invention can be directly embedded into the inner wall of existing heat collection tubes and is suitable for various nanofluids (the base fluid can be water, heat transfer oil, or molten salt, and the nanoparticles include various metals and their oxides) and condenser lens types (such as trough parabolic mirrors, Fresnel lenses, etc.). It requires minimal structural modifications to the original system, is easy to implement, and has low investment costs.

[0025] Stable and reliable operation. The ultrasonic transducer adopts a design with a heat-resistant substrate, backing block, and wear-resistant protective layer to ensure long-term stable operation and efficient energy transfer in the high-temperature working environment of the heat collection tube. Attached Figure Description

[0026] Figure 1 This is a structural diagram of a concentrated solar collector device with ultrasonic-nanofluid coupling according to the present invention;

[0027] Figure 2 This is a partially enlarged schematic diagram of the heat collection tube;

[0028] Figure 3 This is a schematic diagram of an embedded ultrasonic plate structure.

[0029] Figure 4 This is a side view schematic diagram of an ultrasonic transducer;

[0030] Figure 5 This is a schematic diagram of the overall structure of an ultrasonic transducer.

[0031] Figure label:

[0032] 1-Heat collector tube, 2-Heat collector tube support, 3-Embedded ultrasonic plate, 4-Condenser lens, 5-Condenser lens support frame, 6-Support frame, 7-Tracking shaft, 8-Ground fixed bracket, 9-Ultrasonic transducer, 10-Flange interface, 11-Glass outer tube, 12-Metal inner tube, 31-Temperature resistant ultrasonic device embedded substrate, 32-Lead wire, 91-Backing block, 92-Piezoelectric / magnetostrictive element, 93-Electrode, 94-Fixing structure, 95-Outer shell. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0034] like Figure 1 , Figure 2 , Figure 3 As shown, this invention provides a concentrated solar collector device with ultrasonic-nanofluid coupling. Ultrasonic waves are applied to the solar collector tube to enhance the stability of the nanofluid inside the tube. The concentrated solar collector device includes a solar collector tube 1, which comprises a glass outer tube 11, a metal inner tube 12, and an embedded ultrasonic plate 3 arranged on the inner wall of the metal inner tube 12. The glass outer tube 11 and the metal inner tube 12 are stacked, with a vacuum between them. Nanofluid flows inside the metal inner tube 12. The embedded ultrasonic plate 3 consists of a plurality of ultrasonic transducers 9 and a heat-resistant ultrasonic device embedded substrate 31. The plurality of ultrasonic transducers 9 are arranged in a uniform array inside the heat-resistant ultrasonic device embedded substrate 31. At the same time, a plurality of leads 32 are arranged inside the substrate for applying electrical signals to the plurality of ultrasonic transducers 9.

[0035] Preferably, the outer wall of the glass outer tube 11 of the trough-type solar collector is provided with flange interfaces 10 at both ends. Each flange interface 10 is connected to the upper end of the solar collector tube support 2 supporting the solar collector tube 1, and the lower end of the solar collector tube support 2 is connected to the condenser lens 4. The condenser lens 4 and the tracking shaft 7 are connected by a support frame 6. The condenser lens 4 has a parabolic structure. Specifically, there are two condenser lenses 4, spaced at a predetermined distance, which combine to form a parabolic structure. The two condenser lenses 4 are fixed on the support frame 6. The tracking device 7 tracks the sun's position to ensure that the incident sunlight is parallel to the normal direction of the condenser lens 4. The condenser lens 4 can be any one of a trough-type parabolic condenser lens, a Fresnel lens, or a refractive condenser lens.

[0036] The ultrasonic transducer 9 realizes the process of converting electrical energy into ultrasonic energy. The conversion process is achieved by inputting a sudden electric field into the ultrasonic transducer 9. The material will generate mechanical vibration as the electric field changes. When the vibration frequency exceeds 20kHz, it will drive the surrounding medium (air, water, metal, etc.) to vibrate together, forming ultrasonic waves that propagate outward. The magnitude and direction of the voltage can be changed as needed to adjust the electric field and adjust the effect of ultrasonic vibration.

[0037] like Figures 4-5 As shown, preferably, the ultrasonic transducer 9 consists of core functional components and auxiliary structures, with each part having a clear division of labor to jointly achieve efficient energy conversion and signal transmission. The core functional components include a piezoelectric / magnetostrictive element 92, which is the core component for converting electrical energy into mechanical vibration energy. The auxiliary structures include a backing block 91, an electrode 93 and a lead wire 32, a housing 95, and a fixing structure 94 between the electrode 93 and the lead wire 32.

[0038] One end of the lead 32 is connected to an external circuit, and the other end is connected to an electrode 93 to input an electrical signal. The electrode 93 is fixed to the metal layer of the piezoelectric / magnetostrictive element 92 and is used to receive the electrical signal to apply a sudden electric field to the piezoelectric / magnetostrictive element 92. The piezoelectric / magnetostrictive element 92 will generate mechanical vibration as the electric field changes. The electrode 93 and the lead 32 are made of conductive materials, including but not limited to aluminum and copper.

[0039] Preferably, the backing block 91 is an element that ensures the stability of the ultrasonic signal, and is closely attached to the back side (i.e. the reverse side of the metal layer) of the piezoelectric / magnetostrictive element 92, and is made of a high-density material.

[0040] Preferably, there is a layer of wear-resistant material (such as epoxy resin or alumina) of a specific thickness between the piezoelectric / magnetostrictive element 92 and the working fluid inside the metal inner tube 12 of the heat collection tube 1. This reduces the reflection loss of ultrasound at the "piezoelectric / magnetostrictive element-working fluid" interface, allowing more ultrasound energy to be transferred into the medium, while protecting the core component from wear.

[0041] Preferably, the working fluid in the inner metal tube 12 of the heat collector tube 1 is a nanofluid, which is a fluid working medium composed of nanoscale solid particles and a base liquid. Preferably, the base liquid is any one of water, heat transfer oil, and molten salt, and the nanoscale solid particles are any one of metal nanoparticles and metal oxide nanoparticles. Preferably, the molten salt is any one of solar salt and Hitec salt, the metal nanoparticles are any one of Al, Cu, and Fe, and the metal oxide nanoparticles are any one of CuO and Al2O3.

[0042] Example

[0043] According to Figure 1 The device structure shown is arranged such that sunlight parallel to the normal of the condenser lens shines on the condenser lens, is reflected by the condenser lens and focused onto the heat collection tube at the focal line of the condenser lens. The heat collection tube is the core component for converting light energy into heat energy. The conversion of light energy into heat energy is completed inside the heat collection tube. The heat collection tube consists of a glass outer tube and a metal inner tube. The space between the glass outer tube and the metal inner tube is a vacuum state, which effectively reduces heat loss during the heat collection process.

[0044] Nanofluids flow through the inner wall of the metal tube of the heat collector, converting the absorbed light energy into heat energy.

[0045] Ultrasonic vibration affects the movement of nanoparticles. The deposited nanoparticles are refloated in the base fluid by the action of ultrasonic energy, and the stability of the nanofluid is maintained within a certain range. At the same time, ultrasonic vibration increases the mixing degree between the fluid near the wall of the heat collection tube and the mainstream, and the nanofluid absorbs and carries away more heat, thereby improving the photothermal conversion rate of the system.

[0046] Nanofluids (base fluids include heat transfer oil, water, ethylene glycol, and molten salt; nanoparticles include, but are not limited to, various metal nanoparticles, metal oxide nanoparticles, carbide nanoparticles, and nitride nanoparticles, such as Au, Ag, Cu, Fe, Au-Cu, SiC, Si3N4, SiO2, and Al2O3)

[0047] Electrodes include, but are not limited to, circular, rectangular / square, ring-shaped, and strip-shaped electrodes. Lead materials include, but are not limited to, silver-plated copper wire, copper wire, and copper alloy wire. The external circuit drive power is 2000W, and the circuit carrying power is 4000W. The external circuit provides an electrical signal whose direction and magnitude change over time and can be modified as needed. High-temperature nanofluids can be applied in power generation, industrial heating, and building heating.

[0048] This invention is based on the background of using nanofluid as the heat transfer medium in the heat collection tube. During the flow of the nanofluid, solid particles will be deposited in the heat collection tube. By using a sudden electric field to control the vibration of the ultrasonic plate, the deposited solid particles are made to float again in the base fluid, maintaining a certain stability of the nanofluid. At the same time, due to the effect of ultrasonic vibration, the mixing degree between fluids is enhanced, and more nanoparticles participate in the heat exchange process, thus improving efficiency.

[0049] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A concentrated solar collector device with ultrasonic-nanofluid coupling, characterized in that, The system includes a heat collection tube, which comprises a glass outer tube, a metal inner tube, and an embedded ultrasonic plate arranged on the inner wall of the metal inner tube. The metal inner tube is filled with nanofluid, which is used to quickly convert the solar energy absorbed by the heat collection tube into heat energy. The embedded ultrasonic plate includes a heat-resistant ultrasonic device embedded substrate and a plurality of ultrasonic transducers arranged in a uniform dot matrix inside the substrate. An electrical signal is applied to the plurality of ultrasonic transducers to generate ultrasonic waves, which are used to maintain the long-term stability of the nanofluid.

2. The ultrasonic-nanofluid coupled concentrating solar collector according to claim 1, characterized in that, The outer glass tube and the inner metal tube are nested together, with a vacuum between them.

3. The ultrasonic-nanofluid coupled concentrating solar collector according to claim 1, characterized in that, The heat-resistant ultrasonic device also has several leads arranged inside the embedded substrate for applying electrical signals to several ultrasonic transducers.

4. The ultrasonic-nanofluid coupled concentrating solar collector according to claim 1, characterized in that, The outer wall of the glass outer tube is provided with a flange interface, which is connected to the upper end of the heat collection tube support, and the lower end of the heat collection tube support is connected to the condenser lens.

5. The ultrasonic-nanofluid coupled concentrating solar collector according to claim 4, characterized in that, The condenser lens consists of two pieces, spaced at a preset distance, which combine to form a parabolic structure.

6. The ultrasonic-nanofluid coupled concentrating solar collector according to claim 5, characterized in that, The two condenser lenses are fixed on the support frame, and a tracking device is connected to the bottom of the support frame. The tracking device tracks the position of the sun to ensure that the incident sunlight is parallel to the normal direction of the condenser lens.

7. The ultrasonic-nanofluid coupled concentrating solar collector according to claim 3, characterized in that, The ultrasonic transducer includes a piezoelectric / magnetostrictive element, a backing block, and electrodes. One end of the lead wire is connected to an external circuit, and the other end is connected to the electrodes to realize the input of electrical signals. The electrodes are fixed to the metal layer of the piezoelectric / magnetostrictive element and are used to receive electrical signals to apply a sudden electric field to the piezoelectric / magnetostrictive element.

8. The ultrasonic-nanofluid coupled concentrating solar collector according to claim 7, characterized in that, The backing block is tightly attached to the end face of the non-metallic layer of the piezoelectric / magnetostrictive element and is made of a high-density material.

9. The ultrasonic-nanofluid coupled concentrating solar collector according to claim 7, characterized in that, A wear-resistant material layer is provided between the piezoelectric or magnetostrictive element and the nanofluid inside the metal inner tube. The wear-resistant material layer is made of epoxy resin or aluminum oxide.

10. The ultrasonic-nanofluid coupled concentrating solar collector according to claim 1, characterized in that, The nanofluid comprises a base liquid and solid nanoparticles dispersed in the base liquid. The base liquid is any one of water, heat transfer oil, or molten salt, and the solid nanoparticles are any one of metal nanoparticles or metal oxide nanoparticles.

Images