Carbon-based metamaterial for synergistically absorbing noise and waste gas

Abstract

The invention discloses a carbon-based metamaterial capable of cooperatively absorbing noise and waste gas. The carbon-based metamaterial comprises a gradient particle size porous carbon base layer, a micro-perforated film, a micro-perforated plate and a back cavity which are sequentially arranged in the sound wave injection direction; the gradient particle size porous carbon-based layer comprises a conical groove laid on the surface of the micro-perforated membrane and a gradient particle size porous carbon-based material laid in a layered manner along the height direction of the conical groove. The carbon-based metamaterial provided by the invention not only has broadband and efficient sound absorption performance, but also can adsorb volatile organic compounds in air, so that efficient cooperative control of noise and air pollution is realized.

Description

Technical Field

[0001] This invention belongs to the field of environmental protection materials technology, and in particular relates to a carbon-based metamaterial that synergistically absorbs noise and exhaust gases. Background Technology

[0002] Traditional porous sound-absorbing materials (such as foam and fiber cotton) have good absorption effects on mid-to-high frequency noise, but poor absorption performance on low-frequency noise. Increasing the thickness of the porous material can improve the low-frequency absorption coefficient, but the effect is not ideal. Micro-perforated plates, through the Helmholtz resonance sound-absorbing structure formed by the micropores on the plate and the cavity behind it, can effectively absorb mid-to-low frequency noise. They have a high absorption coefficient in the frequency band where the resonance absorption peak is located, but are difficult to adapt to wide-band noise environments. To effectively broaden the sound absorption bandwidth, the traditional technique is to fill the cavity behind the micro-perforations with porous sound-absorbing material. At the same time, in order to increase the acoustic impedance of the micro-perforated plate and thus improve its absorption coefficient within the sound absorption bandwidth, the perforation diameter of the micro-perforated plate is required to be less than 1 mm, or even ultra-micro-perforated plates with a perforation diameter of 0.3 mm or less, and its perforation rate is less than 2%. This affects the incidence of high-frequency sound, and thus affects the absorption effect of the porous sound-absorbing material in the resonance cavity on high-frequency sound. Low-frequency sound is basically unaffected due to its excellent diffraction properties. Metamaterials have become a hot research topic in the field of acoustics in recent years. By designing artificial structures to manipulate sound waves and thus regulate their acoustic properties, they overcome acoustic characteristics that natural materials do not possess. How to optimize the combination and parameters of acoustic materials and structures to improve broadband sound absorption performance remains a key challenge for those skilled in the art.

[0003] Patent document CN112497858B discloses a polymeric sponge sound-absorbing composite material and its preparation method. A graphene oxide film is partially applied to the pores of a polymeric sponge matrix to form a semi-open network structure, increasing flow resistance and dissipating sound wave energy. While this material exhibits improved sound absorption performance compared to traditional porous materials, its fundamental nature still relies primarily on the viscous dissipation mechanism of porous materials. It has limited absorption capacity for low-frequency sound, low mechanical strength, and complex processing technology.

[0004] Patent document CN117577084A discloses a multi-level metastructure acoustic liner, which constructs a multi-level structure by connecting multiple resonant cavity units in series and then in parallel. Compared with the traditional acoustic liner structure of perforated plate plus honeycomb back cavity, its acoustic liner structure is thinner and lighter, and has a wider sound absorption bandwidth. However, such structures usually rely entirely on resonant sound absorption. Due to the limitations of sound absorption causality, the structure is relatively thick, and the processing precision and results of the multi-layer resonant cavity series structure are both high. Its sound absorption performance in the mid-to-high frequency range drops sharply.

[0005] Patent document CN107573633A discloses a bio-based porous carbon sound-absorbing composite material, which uses bamboo-based porous carbon blended with polymers. It has certain adsorption properties for air pollutants, but its sound absorption mechanism is simple and not effectively coupled with the resonant structure, resulting in insignificant low-frequency sound absorption effect.

[0006] In summary, existing technologies have certain shortcomings. Materials designed to improve sound absorption (such as porous materials) typically lack efficient adsorption capabilities for volatile organic compounds (VOCs) such as formaldehyde; while adsorption materials focused on air purification (such as various activated carbon products) lack sound absorption performance for broadband, especially low-frequency, sound waves. Therefore, there is an urgent need in this field for a new material capable of achieving efficient and synergistic control of indoor noise and VOCs. Summary of the Invention

[0007] The purpose of this invention is to provide a carbon-based metamaterial that synergistically absorbs noise and exhaust gases. This carbon-based metamaterial not only has wide-band and high-efficiency sound absorption performance, but can also adsorb volatile organic compounds in the air, thereby achieving efficient synergistic control of noise and air pollution.

[0008] To achieve the objective of this invention, the following technical solution is provided: a carbon-based metamaterial for synergistic absorption of noise and exhaust gas, comprising: a gradient-size porous carbon substrate, a microperforated membrane, a microperforated plate, and a back cavity arranged sequentially along the direction of sound wave injection; The gradient particle size porous carbon base layer includes a conical groove laid on the surface of a microperforated membrane, and a gradient particle size porous carbon-based material laid in layers along the height direction of the conical groove.

[0009] This invention achieves air purification and low-frequency sound absorption effects through a specific filter structure layer and a gradient particle size porous carbon base layer composed of porous carbon-based materials of different diameters.

[0010] Specifically, the gradient particle size porous carbon base layer is laid with five layers of gradient particle size porous carbon-based materials of different diameters along the direction of sound wave injection.

[0011] The five-layer gradient particle size porous carbon-based material is defined sequentially as the first layer, the second layer, the third layer, the fourth layer, and the fifth layer along the direction of sound wave injection. The diameter of the gradient-size porous carbon-based material in the first layer is greater than 3 mm. The diameter of the gradient-size porous carbon-based material in the second layer ranges from 1 to 2 mm. The diameter of the gradient-size porous carbon-based material in the third layer ranges from 0.5 to 1 mm. The diameter of the gradient-size porous carbon-based material in the fourth layer ranges from 1 to 2 mm. The fifth layer has a gradient particle size porous carbon-based material with a particle diameter range of 0.5~1mm.

[0012] Specifically, the conical groove includes upright and inverted types. The groove opening of the upright type faces the direction of sound wave injection, while the groove opening of the inverted type faces the microperforated membrane.

[0013] Specifically, the conical groove includes upright and inverted types. The groove opening of the upright type faces the direction of sound wave injection, while the groove opening of the inverted type faces the microperforated membrane.

[0014] Specifically, there are multiple conical grooves, and the multiple conical grooves are arranged in an array.

[0015] Specifically, the perforations in the microperforated membrane are located within the perforation projection range of the microperforated plate.

[0016] Specifically, the pore size of the microperforated membrane is smaller than that of the microperforated plate.

[0017] Specifically, the gradient particle size porous carbon base layer has a waterproof and breathable membrane on the side facing the direction of sound wave injection.

[0018] Specifically, the working principle of the carbon-based metamaterial is as follows: When sound waves are incident on this material, they first enter the layer of porous carbon-based material with gradient particle size. This material is composed of porous carbon-based materials of different particle sizes arranged layer by layer along the direction of sound wave propagation, forming a structure with gradually changing acoustic impedance. At the same time, the material has conical grooves inside, so that the acoustic impedance experienced by the sound waves when passing through the interface between different particle size layers can achieve a relatively smooth transition, thereby minimizing the sound wave reflection caused by abrupt changes in interface impedance and achieving efficient absorption of sound waves.

[0019] After passing through a layer of porous carbon-based material with a gradient particle size, the sound waves that are not completely dissipated (mainly low-frequency sound waves) continue to propagate to the microperforated membrane, microperforated plate, and back cavity. This structure utilizes the microperforated membrane, microperforated plate, and back cavity to form a Helmholtz resonance sound absorption structure, generating a resonant sound absorption effect to absorb mid-to-low frequency sound waves. The perforation diameter of the microperforated membrane is significantly smaller than that of the microperforated plate, resulting in a greater acoustic impedance, which compensates for the insufficient broadband sound absorption effect of the larger-diameter microperforated plate.

[0020] Meanwhile, gradient-size porous carbon-based materials have a high specific surface area and abundant microporous structure, which can physically adsorb air pollutants, thereby achieving synergistic control of noise and exhaust gas.

[0021] Compared with existing technologies, the beneficial effects of the present invention are: (1) Combining a layer of porous carbon-based material with a gradient particle size and a micro-perforated plate resonant structure not only has wide-band and high-efficiency sound absorption performance, but also can simultaneously adsorb volatile organic compounds in the air, thus achieving efficient synergistic control of noise and air pollution.

[0022] (2) A conical groove is opened inside the porous material with gradient particle size so that the acoustic impedance experienced by the sound wave when passing through the interface between carbon substrates of different particle sizes can be smoothly transitioned, thereby avoiding sound wave reflection caused by sudden change in interface impedance to the greatest extent and achieving efficient absorption of sound waves.

[0023] (3) The material contains a micro-perforated membrane. The perforation diameter of the micro-perforated membrane is significantly smaller than that of the micro-perforated plate. By stacking the micro-perforated membrane and the micro-perforated plate, the acoustic impedance of the resonant sound absorption structure can be improved, and the sound absorption effect of the micro-perforated plate with a larger pore size can be enhanced. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of Embodiment 1; Figure 2 This is a top view of the microperforated membrane provided in this embodiment; Figure 3 This is a top view of the micro-perforated plate provided in this embodiment; Figure 4 This is a schematic diagram of the structure of Embodiment 2; Figure 5 This is a comparison diagram of the sound absorption effects of the carbon-based metamaterial, microperforated plate, and activated carbon provided in this embodiment; Figure 6 The graph shows the change in formaldehyde adsorption capacity over time for carbon-based materials with different particle sizes.

[0025] In the diagram: 1. Gradient particle size porous carbon base layer; 2. Conical groove; 3. Microperforated membrane; 4. Microperforated plate; 5. Back cavity; 6. Waterproof and breathable membrane. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0027] Example 1 like Figure 1As shown, this embodiment provides a carbon-based metamaterial for synergistically absorbing noise and exhaust gas, comprising a gradient-size porous carbon base layer 1, a micro-perforated membrane 3, a micro-perforated plate 4, and a back cavity 5 arranged sequentially along the incident direction of the sound wave. The micro-perforated membrane 3 is placed between the gradient-size porous carbon base material 1 and the micro-perforated plate 4, and the back cavity 5 is located below the micro-perforated plate 4.

[0028] In Example 1, the gradient particle size porous carbon substrate 1 has 5 layers. Along the direction of sound wave incident, the average particle size of the 5 layers of porous carbon-based material is as follows: the first layer has a particle size of 3.5 mm, the second layer has a particle size of 1 mm, the third layer has a particle size of 0.5 mm, the fourth layer has a particle size of 1 mm, and the fifth layer has a particle size of 0.5 mm. The thickness of each layer is 10 mm.

[0029] like Figure 2 and Figure 3 As shown, in this embodiment 1, the perforations of the microperforated membrane 3 are located within the perforation projection range of the microperforated plate 4.

[0030] In this embodiment 1, the microperforated membrane 3 has a pore diameter of 0.2 mm and a thickness of 0.1 mm, and the microperforated plate 4 has a pore diameter of 0.8 mm and a thickness of 0.9 mm.

[0031] In this embodiment, a waterproof and breathable membrane 6 is provided on the surface of the gradient particle size porous carbon-based material 1.

[0032] In this embodiment 1, the conical groove is placed upright with its opening facing the direction of sound wave injection. This design can reduce the contact area between the gradient particle size porous carbon-based material and the microperforated membrane, avoid clogging the perforations of the microperforated membrane, and reduce reflected sound. However, the change in acoustic impedance is not as smooth as that of the "V" shaped groove.

[0033] Example 2 like Figure 4 As shown, this embodiment provides a second type of carbon-based metamaterial, which includes a gradient-size porous carbon substrate 1, a micro-perforated membrane 3, a micro-perforated plate 4, and a back cavity 5 arranged sequentially along the direction of sound wave incident. The micro-perforated membrane 3 is placed between the gradient-size porous carbon substrate 1 and the micro-perforated plate 4, and the back cavity 5 is located below the micro-perforated plate 4.

[0034] As another embodiment, its basic structure is the same as that of embodiment 1. The main difference is that the inner conical groove in this embodiment is inverted, so that the groove opening faces the microperforated membrane. This design can increase the sound absorption area, realize the continuous change of sound impedance, avoid sound wave reflection caused by sudden change in interface impedance, and achieve better sound absorption effect. However, the contact area between the gradient particle size porous carbon-based material and the microperforated membrane is large, which will cause some of the microperforated membrane to be blocked, affecting the overall sound absorption performance of the material.

[0035] The sound absorption performance of the carbon-based metamaterial provided in this embodiment is as follows: Figure 5As shown, its measured average sound absorption coefficient is 0.77, which is higher than that of a single micro-perforated plate and activated carbon, and its sound absorption bandwidth is wider. The static adsorption effect of the carbon-based metamaterial for formaldehyde provided in this embodiment is as follows: Figure 6 As shown, the adsorption of formaldehyde reached equilibrium after 168 h, with an adsorption capacity of 114.1 mg·g⁻¹. -1 .

[0036] Furthermore, the terms "upper," "lower," "inner," "outer," "front," and "rear" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Unless otherwise specifically stated, the relative steps, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention.

[0037] Of course, the above description is only a specific embodiment of the present invention and is not intended to limit the scope of the present invention. All equivalent changes or modifications made to the structure, features and principles described in the claims of the present invention should be included in the scope of the claims of the present invention.

[0038] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A carbon-based metamaterial for synergistic absorption of noise and exhaust gases, characterized in that, include: A gradient-size porous carbon substrate, a microperforated membrane, a microperforated plate, and a back cavity are sequentially arranged along the direction of sound wave injection. The gradient particle size porous carbon base layer includes a conical groove laid on the surface of a microperforated membrane, and a gradient particle size porous carbon-based material laid in layers along the height direction of the conical groove.

2. The carbon-based metamaterial for synergistic absorption of noise and exhaust gas according to claim 1, characterized in that, The gradient particle size porous carbon base layer is composed of five layers of gradient particle size porous carbon-based materials with different diameters laid sequentially along the direction of sound wave injection.

3. The carbon-based metamaterial for synergistic absorption of noise and exhaust gas according to claim 2, characterized in that, The five-layer gradient particle size porous carbon-based material is defined sequentially as the first layer, the second layer, the third layer, the fourth layer, and the fifth layer along the direction of sound wave injection. The diameter of the gradient-size porous carbon-based material in the first layer is greater than 3 mm. The diameter of the gradient-size porous carbon-based material in the second layer ranges from 1 to 2 mm. The diameter of the gradient-size porous carbon-based material in the third layer ranges from 0.5 to 1 mm. The diameter of the gradient-size porous carbon-based material in the fourth layer ranges from 1 to 2 mm. The fifth layer has a gradient particle size porous carbon-based material with a particle diameter range of 0.5~1mm.

4. The carbon-based metamaterial for synergistic absorption of noise and exhaust gas according to claim 1, characterized in that, The conical groove includes upright and inverted types. The groove opening of the upright type faces the direction of sound wave injection, while the groove opening of the inverted type faces the microperforated membrane.

5. The carbon-based metamaterial for synergistic absorption of noise and exhaust gas according to claim 1, characterized in that, There are multiple conical grooves, and the multiple conical grooves are arranged in an array.

6. The carbon-based metamaterial for synergistic absorption of noise and exhaust gases according to claim 1, characterized in that, The perforations in the microperforated membrane are located within the perforation projection range of the microperforated plate.

7. The carbon-based metamaterial for synergistic absorption of noise and exhaust gas according to claim 1, characterized in that, The pore size of the microperforated membrane is smaller than that of the microperforated plate.

8. The carbon-based metamaterial for synergistic absorption of noise and exhaust gas according to claim 1, characterized in that, The gradient particle size porous carbon base layer has a waterproof and breathable membrane on the side facing the direction of sound wave injection.

Images