Filter and filtering device

Abstract

The application relates to the technical field of filtration, and provides a filter and a filtering device. The filter comprises a structural body, the structural body is divided into multiple compartments penetrating the height direction of the structural body by a partition wall; in two adjacent compartments, the air inlet end of one compartment is blocked, the air outlet end of the other compartment is blocked, and the partition wall is in a porous structure; the structural body satisfies Z=H*Y*T*E*X / (P*Dv50*D), and 3<=Z<=25. The filter provided by the application has good filtering effect and low back pressure.

Description

Technical Field

[0001] This application relates to the field of filtration technology, and in particular to a filter and a filtration device. Background Technology

[0002] To reduce exhaust and particulate matter emissions during vehicle use, honeycomb ceramics are widely used in vehicle exhaust purification. Wall-flow particulate filters, in particular, rely on blocking the inlet and outlet of the carrier pores to force airflow through the pores, thus preventing particle capture. Reducing the pore size of the filter wall helps improve filtration efficiency; however, smaller pore sizes lead to a significant increase in exhaust back pressure, resulting in increased fuel consumption and reduced power. Therefore, how to reduce the exhaust back pressure of the honeycomb ceramic diesel filter without affecting its filtration efficiency has become a pressing technical problem that needs to be solved. Summary of the Invention

[0003] Based on this, one embodiment of this application provides a filter and a filter device with low exhaust back pressure and high filtration efficiency.

[0004] In a first aspect, this application provides a filter, the filter comprising a structural body, the structural body being divided into a plurality of compartments extending through the height of the structural body by partition walls; in two adjacent compartments, the air inlet of one compartment is blocked and the air outlet of the other compartment is blocked, the partition walls having a porous structure;

[0005] The main structure satisfies: Z = H × Y × T × E × X / (P × Dv50 × D), 3 ≤ Z ≤ 25;

[0006] Wherein, H is the height of the main structure, in inches; Y is the tortuosity of the main structure; T is the thickness of the partition wall, in mils; E is the density of the compartments contained in the cross section of the main structure perpendicular to the height direction, in cpsi; X is the difference between the average diameter of the unblocked compartments at the air inlet end of the filter and the average diameter of the unblocked compartments at the air outlet end of the filter, in mm; P is the porosity of the partition wall, in %; Dv50 is the median pore size of the pore structure in the partition wall, in μm; and D is the average diameter of the main structure, in inches.

[0007] In some embodiments, the tortuosity Y of the main structure satisfies: 5≤Y≤20.

[0008] In some embodiments, the density E of the compartments in the cross-section of the main structure perpendicular to the height direction satisfies: 200cpsi≤E≤400cpsi.

[0009] In some implementations, the thickness T of the partition wall satisfies: 6mil ≤ T ≤ 10mil.

[0010] In some embodiments, the porosity P of the partition wall satisfies: 50% ≤ P ≤ 70%.

[0011] In some embodiments, the median pore size Dv50 of the partition wall pore structure satisfies 7μm≤Dv50≤15μm.

[0012] In some implementations, the height H of the main structure satisfies: 5 inch ≤ H ≤ 10 inch.

[0013] In some embodiments, the average diameter D of the main body of the structure satisfies: 7.5 inch ≤ D ≤ 12 inches.

[0014] In some embodiments, the difference X between the average diameter of the unblocked compartment at the air inlet end of the filter and the average diameter of the unblocked compartment at the air outlet end of the filter satisfies: 0 < X ​​≤ 0.4 mm.

[0015] In some embodiments, the material of the main body of the structure includes at least one of cordierite ceramic, silicon carbide, and alumina.

[0016] Secondly, this application provides a filtration device comprising a filter as described in the first aspect.

[0017] Compared with traditional technologies, this application has at least the following beneficial effects:

[0018] This application performs calculations on the structural dimensions, tortuosity, wall thickness, number of compartments per unit area, porosity, median pore size, and inlet / outlet diameter difference of the filter to obtain a filter with a Z value in the range of 3 to 25. This filter has both high capture efficiency and low back pressure, which can effectively improve filtration efficiency and thus reduce vehicle energy consumption. Attached Figure Description

[0019] Figure 1 This is a cross-sectional schematic diagram of a filter provided in one embodiment of this application, where T refers to the thickness of the partition wall;

[0020] Figure 2 This is a side view of a filter provided in one embodiment of this application. D refers to the average diameter of the main body of the structure, and H refers to the height of the main body of the structure.

[0021] Among them, 10-filter; 11-main structure; 12-partition; 13-compartment. Detailed Implementation

[0022] The present application will be further described in detail below with reference to the embodiments and examples. These embodiments and examples are only for illustrating the present application and are not intended to limit the scope of the present application. The purpose of providing these embodiments and examples is to make the disclosure of the present application more thorough and comprehensive. It should also be understood that the present application can be implemented in many different forms and is not limited to the embodiments and examples described herein. Those skilled in the art can make various modifications or alterations without departing from the spirit of the present application, and the equivalent forms obtained also fall within the protection scope of the present application. In addition, numerous specific details are set forth in the following description to provide a fuller understanding of the present application. It should be understood that the present application can be implemented without one or more of these details.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0024] In this application, "optionally," "optionally," and "optional" mean that something is optional, that is, it means that it is selected from either "with" or "without." If there are multiple "optional" entries in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, each "optional" entry shall be independent.

[0025] In this application, the terms "first aspect," "second aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first aspect," "second aspect," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on quantity.

[0026] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0027] In this application, when numerical intervals (i.e., numerical ranges) are involved, unless otherwise specified, the distribution of selectable numerical values ​​within the numerical interval is considered continuous, and includes the two endpoints of the numerical interval (i.e., the minimum and maximum values), as well as every numerical value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that numerical interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints, which is equivalent to directly listing every integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical ranges disclosed in this application should be understood to include any and all subranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, percentage, ratio, etc. The term "numerical interval" can be broadly included to include percentage intervals, ratio intervals, proportion intervals, etc.

[0028] All references to this application are incorporated herein by reference as if each document were individually incorporated herein by reference. Unless they conflict with the purpose and / or technical solution of this application, all cited references are incorporated herein by reference in their entirety and for all purposes. When references are cited in this application, the definitions of relevant technical features, terms, nouns, phrases, etc., are also incorporated herein by reference. Examples and preferred embodiments of the cited technical features may also be incorporated herein by reference, but only to the extent that they enable the implementation of this application. It should be understood that when the cited content conflicts with the description in this application, this application shall prevail or modifications shall be made adaptably to the description in this application.

[0029] In traditional technologies, automotive exhaust purification uses honeycomb ceramic products for filtration. However, the high filtration efficiency and low exhaust back pressure of honeycomb ceramic structures are contradictory, making it difficult to achieve both simultaneously. Although increasing the porosity of honeycomb ceramic products or thinning their walls can reduce back pressure, the capture effect will significantly deteriorate.

[0030] The first aspect of this application provides a filter, such as Figure 1 and Figure 2 As shown, the filter 10 includes a main body 11, which is divided into multiple compartments 13 extending through the height of the main body 11 by partition walls 12; in two adjacent compartments 13, the air inlet of one compartment 13 is blocked and the air outlet of the other compartment 13 is blocked, and the partition walls 12 have a porous structure.

[0031] The main structure satisfies: Z = H × Y × T × E × X / (P × Dv50 × D), 3 ≤ Z ≤ 25;

[0032] Wherein, H is the height of the main structure, in inches; Y is the tortuosity of the main structure; T is the thickness of the partition wall, in mils; E is the density of the compartments contained in the cross section of the main structure perpendicular to the height direction, in cpsi; X is the difference between the average diameter of the unblocked compartments at the air inlet end of the filter and the average diameter of the unblocked compartments at the air outlet end of the filter, in mm; P is the porosity of the partition wall, in %; Dv50 is the median pore size of the pore structure in the partition wall, in μm; and D is the average diameter of the main structure, in inches.

[0033] This application performs calculations on the structural dimensions, tortuosity, wall thickness, number of compartments per unit area, porosity, median pore size, and inlet / outlet diameter difference of the filter to obtain a filter with a Z value in the range of 3 to 25. This filter has both high capture efficiency and low back pressure, which can effectively improve filtration efficiency and thus reduce vehicle energy consumption.

[0034] Wherein, Z includes, but is not limited to: 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24 or 25. It can be selected from 3 to 20.

[0035] Understandably, tortuosity Y is defined as the ratio of the actual length of the seepage channel to the straight length of the path through the seepage medium; that is, the true length of the trajectory of a fluid particle within the channel when it travels a unit distance through the medium. Tortuosity can be obtained through mercury intrusion porosimetry.

[0036] It is understandable that the density E of cells within a cross-section perpendicular to the height of the structural body is also called porosity, which refers to the number of cells per unit area on a cross-section perpendicular to the height of the structural body. Its unit, cpsi (channels per square inch), refers to the number of cells per square inch of cross-section.

[0037] It is understood that the structures of the compartments in this application may be the same or different. Optionally, the structures of all compartments in this application may be the same. It is understood that in the filter, the total diameter of the inlet end of the compartment is greater than the total diameter of the outlet end of the compartment.

[0038] If the structures and dimensions of each compartment are different, the average diameter X1 of the air intake end is calculated based on the diameters of all unblocked compartments at the intake end. X1 = (sum of diameters of all unblocked and intact compartments at the intake end) / (number of unblocked and intact compartments at the intake end). Similarly, the average diameter X2 of the air outlet end is calculated. X2 = (sum of diameters of all unblocked and intact compartments at the outlet end) / (number of unblocked and intact compartments at the outlet end), so X = X1 - X2. Furthermore, if the compartment structures are identical, X is the difference between the inlet diameter and the outlet diameter of a single compartment. It should be noted that if the cross-section of the compartment is not circular, the cross-sections of the intake and outlet ends can be converted to equivalent diameters of a circular cross-section.

[0039] It is understood that in this application, "the partition wall has a porous structure" means that the partition wall is made of porous material.

[0040] In some embodiments, the tortuosity Y of the main structure satisfies: 5≤Y≤20. Wherein, Y includes, but is not limited to: 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20.

[0041] In some embodiments, the density E of the compartments in the cross section of the main structure perpendicular to the height direction satisfies: 200cpsi≤E≤400cpsi, for example, it can be 200cpsi, 220cpsi, 240cpsi, 260cpsi, 280cpsi, 300cpsi, 320cpsi, 340cpsi, 360cpsi, 380cpsi or 400cpsi.

[0042] In some embodiments, the thickness T of the partition wall satisfies: 6mil≤T≤10mil, for example, it can be 6.0mil, 6.5mil, 7.0mil, 7.5mil, 8.0mil, 8.5mil, 9.0mil, 9.5mil or 10.0mil.

[0043] In some embodiments, the porosity P of the partition wall satisfies: 50% ≤ P ≤ 70%, for example, it can be 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%, 68%, or 70%.

[0044] In some embodiments, the median pore size Dv50 of the partition wall pore structure satisfies 7μm≤Dv50≤15μm, for example, it can be 7.0μm, 7.5μm, 8.0μm, 8.5μm, 9.0μm, 9.5μm, 10.0μm, 10.5μm, 11.0μm, 11.5μm, 12.0μm, 12.5μm, 13.0μm, 13.5μm, 14.0μm, 14.5μm or 15.0μm.

[0045] In some embodiments, the height H of the main body of the structure satisfies: 5 inch ≤ H ≤ 10 inch, for example, it can be 5.0 inch, 5.5 inch, 6.0 inch, 6.5 inch, 7.0 inch, 7.5 inch, 8.0 inch, 8.5 inch, 9.0 inch, 9.5 inch or 10.0 inch.

[0046] In some embodiments, the average diameter D of the main body of the structure satisfies: 7.5 inch ≤ D ≤ 12 inch, for example, it can be 7.5 inch, 8.0 inch, 8.5 inch, 9.0 inch, 9.5 inch, 10.0 inch, 10.5 inch, 11.0 inch, 11.5 inch or 12.0 inch.

[0047] In some embodiments, the difference X between the average diameter of the unblocked compartment at the air inlet end of the filter and the average diameter of the unblocked compartment at the air outlet end of the filter satisfies: 0 < X ​​≤ 0.4 mm, for example, it can be 0.04 mm, 0.08 mm, 0.12 mm, 0.16 mm, 0.20 mm, 0.24 mm, 0.28 mm, 0.32 mm, 0.36 mm or 0.40 mm.

[0048] In some embodiments, the material of the main body of the structure includes at least one of cordierite ceramic, silicon carbide, and alumina.

[0049] In some embodiments, the cross-sectional shape of the compartment can be at least one of polygon and circle. Optionally, the cross-sectional shape of the compartment is square or rectangular. The apex corner of the square can be rounded, right-angled, or beveled, etc.

[0050] In some embodiments, the main body of the structure is columnar. For example, it may be cylindrical.

[0051] In some embodiments, the filter satisfies:

[0052] δ = [Back pressure × (Standard PN value - Test PN value) / Standard PN value] / (H / D) 2 ), 0≤δ≤25. Where, back pressure refers to the outlet gas pressure after filtration, kPa; H is the height of the main structure, inch; D is the average diameter of the main structure, inch; the test PN value is the PN value ≥10nm measured using the World Harmonized Transient Cycle (WHTC), # / kWh; the standard PN value refers to the filtration standard that the filter can achieve, for example, standard PN value = 2.5 × 10 11# / kWh.

[0053] This application evaluates the back pressure and collection efficiency of the filter by setting a δ value, so that the filter has both collection efficiency that meets the filtration standards and low back pressure.

[0054] Exemplarily, a method for preparing the above-mentioned filter is provided, taking cordierite ceramic as the main structural component as an example, including the following steps:

[0055] S1. Mix flaky talc, flaky kaolin, spherical silica, alumina, aluminum hydroxide, organic binder and pore-forming agent to obtain a mixed powder;

[0056] S2. Add lubricant and water to the mixed powder in step S1, knead and knead the mixture, and then extrude, microwave dry and cut it to prepare the blank of the required structural body. The mold used for extrusion molding has slits that correspond to the shape of the compartments in the structural body.

[0057] S3. The blank from step S2 is sintered to obtain a main body with compartments, and the filter is obtained after the compartments are plugged.

[0058] It is understandable that during the preparation of the preform, the porosity, median pore size, and tortuosity of the filter are adjusted by adjusting the particle size of the raw materials and the amount of pore-forming agent; and the pore density, height, average diameter, wall thickness, inflow diameter, and outflow diameter of the filter are adjusted by adjusting the size of the preform and the size of the mold.

[0059] In some embodiments, the organic adhesive includes at least one of hydroxymethyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, and ethyl cellulose.

[0060] In some embodiments, the pore-forming agent includes an organic pore-forming agent. For example, the pore-forming agent includes at least one of starch, PMMA microspheres, foamed microspheres, and superabsorbent polymer.

[0061] In some embodiments, the lubricant includes at least one selected from alkyl polyether, fatty alcohol polyoxyethylene ether, xanthan gum, potassium arginine, and glycerol.

[0062] In some embodiments, the particle size D50 of the flaky talc is 15 μm to 35 μm.

[0063] In some embodiments, the particle size D50 of kaolin is 3 μm to 15 μm.

[0064] In some embodiments, the particle size D50 of silicon oxide is 2 μm to 10 μm.

[0065] In some embodiments, the particle size D50 of alumina is 1 μm to 10 μm.

[0066] In some embodiments, the particle size D50 of aluminum hydroxide is 1 μm to 13 μm.

[0067] A second aspect of this application provides a filtration device comprising a filter as described in the first aspect.

[0068] In some embodiments, the filtration device is used to purify vehicle exhaust. Optionally, the filtration device includes a main body and a filter disposed within the main body.

[0069] The embodiments of this application will be described in detail below with reference to examples. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of this application. For experimental methods in the following embodiments where specific conditions are not specified, please refer to the guidelines given in this application, or follow experimental manuals or conventional conditions in the art, or follow the conditions recommended by the manufacturer, or refer to experimental methods known in the art.

[0070] Example 1

[0071] The raw materials were weighed according to the following percentages by mass: 41.5% flaky talc; 11.5% flaky kaolin; 16.7% spherical silica; 17.8% alumina; 12.5% ​​aluminum hydroxide; 5.2% organic binder; 6% pore-forming agent; 0.7% lubricant; and 36.5% water. The organic binder was hydroxymethyl cellulose, the organic pore-forming agent was starch with a particle size D50 of 15 μm, the lubricant was glycerol, and the particle size D50 of the flaky talc was 25 μm, the flaky kaolin was 9 μm, the spherical silica was 6 μm, the alumina was 5 μm, and the aluminum hydroxide was 7 μm.

[0072] First, the flake talc, flake kaolin, spherical silica, alumina, aluminum hydroxide, organic binder and organic pore-forming material are mixed evenly to obtain a mixed powder.

[0073] The mixed powder, lubricant and water are then kneaded and pounded into mud. The mud is then extruded under vacuum, dried by microwave and cut to prepare the blank of the required structural body. The blank is first heated at 280°C for 7 hours to remove the glue, and then fired at 1420°C for 6 hours. After the holes are plugged, the filter is obtained, wherein the cross-sectional shape of the compartment in the filter is rectangular.

[0074] In other embodiments and comparative examples, filters were prepared according to the method of Example 1. The porosity, median pore size, tortuosity, pore density, height, average diameter, wall thickness, inlet diameter, and outlet diameter of the filters were adjusted by changing the blank size, raw material particle size, pore-forming agent dosage, and mold size. Filters of Examples 2-15 and Comparative Examples 1-7 were obtained. The test results for tortuosity Y, wall thickness T, number of compartments per unit area E in the cross-section of the main structure E, porosity P, median pore size Dv50, average diameter D, height H, and the difference X between the inlet diameter and outlet diameter of the main structure are shown in Table 1.

[0075] The median aperture Dv50 and tortuosity Y were obtained using mercury porosimetry.

[0076] The average diameter D and height H of the main structure were obtained using a measuring ruler.

[0077] The difference X between the average diameter of the air inlet end and the average diameter of the air outlet end of the compartment is obtained by measuring the diameter of the unblocked inlet end and the unblocked outlet end of the main structure using an imaging tester.

[0078] Porosity test: A 25mm×25mm×25mm sample block was prepared according to the methods of the above embodiments and comparative examples, with an allowable error of ±0.5mm. The dry weight of the sample block was measured as m0.

[0079] Place the sample block in a 1000mL beaker with the compartment facing upwards so that the sample is completely submerged in water. Use a vacuum pump to evacuate for 10 minutes, then boil it in a microwave oven and let it stand for 30 minutes.

[0080] Then place it at room temperature, use an air gun at a low wind speed (0.2MPa) to blow away the moisture adhering to the surface and the inner wall of the sample channel, place it on an analytical balance and weigh it, and record the weight as m1;

[0081] Place a beaker filled with water on the analytical balance, insert the small strainer, zero the analytical balance, and slowly place the product sample into the small strainer with tweezers so that it is completely submerged (the small strainer should not contact the inner wall of the beaker or the bottom of the beaker). Read the balance reading and record it as m2. The porosity P = (m1-m0) / m2 × 100%.

[0082] Table 1

[0083]

[0084]

[0085] The Z-value of the filter is calculated according to Z = H × Y × T × E × X / (P × Dv50 × D), and the filter is then subjected to back pressure and PN10 tests. The test methods include:

[0086] Back pressure test method: Use a Superflow back pressure tester at room temperature (25℃) and a flow rate of 1020 m³ / h. 3 The back pressure of the above filter was tested under the condition of / h.

[0087] PN10 test method: The PN value of PN≥10nm is measured using the World Harmonized Transient Cycle (WHTC).

[0088] Where δ = [back pressure × (standard PN value - test PN value) / standard PN value] / (H / D) 2 The standard PN value is 2.5 × 10⁻⁶. 11 # / kWh.

[0089] The test results are shown in Table 2.

[0090] Table 2

[0091]

[0092]

[0093] As can be seen from the table above:

[0094] In embodiments 1-15 of this application, the calculated Z value is between 3 and 25, and the δ value is between 0 and 25. That is to say, the filter in this application meets the capture efficiency requirements and has low back pressure.

[0095] Specifically, compared with Comparative Examples 1, 2, and 5, Example 1 shows changes in the wall thickness, porosity, and pore density of the main structure. Although Comparative Examples 1 and 2 have lower back pressures, their filtration effects are poor. Comparative Example 5 meets the filtration requirements, but its back pressure is high. Compared with Comparative Examples 3, 4, and 7, Example 6 shows changes in the wall thickness, porosity, and median pore size of the main structure. In Example 6, the average diameter of the main structure is larger. At this average diameter, Comparative Examples 3 and 4 have relatively high back pressures, and the filtration efficiency of Comparative Example 7 does not meet the usage requirements. Compared with Comparative Example 6, Example 11 shows changes in the wall thickness, porosity, and median pore size of the main structure, resulting in a significant decrease in back pressure.

[0096] Therefore, this application limits the structural dimensions, tortuosity, wall thickness, number of compartments per unit area, porosity, median pore size, and inlet / outlet diameter difference of the filter, and calculates a filter with a Z value in the range of 3 to 25. This filter has both high capture efficiency and low back pressure, which can effectively improve filtration efficiency and thus reduce vehicle energy consumption.

[0097] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0098] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the appended claims.

Claims

1. A filter, characterized in that, The filter includes a main body, which is divided into multiple compartments extending through the height of the main body by partition walls; in two adjacent compartments, the air inlet of one compartment is blocked and the air outlet of the other compartment is blocked, and the partition walls have a porous structure. The main structure satisfies: Z = H × Y × T × E × X / (P × Dv50 × D), 3 ≤ Z ≤ 25, where Z is a dimensionless parameter used to comprehensively evaluate the filter's collection efficiency and back pressure based on the main structure parameters. Wherein, H is the height of the main structure, in inches; Y is the tortuosity of the main structure; T is the thickness of the partition wall, in mils; E is the density of the compartments contained in the cross section of the main structure perpendicular to the height direction, in cpsi; X is the difference between the average diameter of the unblocked compartments at the air inlet end of the filter and the average diameter of the unblocked compartments at the air outlet end of the filter, in mm; P is the porosity of the partition wall, in %; Dv50 is the median pore size of the pore structure in the partition wall, in μm; and D is the average diameter of the main structure, in inches. The tortuosity Y of the main structure satisfies: 5≤Y≤20; the density E of the compartments in the cross-section of the main structure perpendicular to the height direction satisfies: 200cpsi≤E≤400cpsi; the thickness T of the partition wall satisfies: 6mil≤T≤10mil; the porosity P of the partition wall satisfies: 50%≤P≤70%; the median pore size Dv50 of the pore structure in the partition wall satisfies: 7μm≤Dv50≤15μm. The filter satisfies: δ=[back pressure×(standard PN value-test PN value) / standard PN value] / (H / D) 2 The δ value ranges from 0 to 25; where δ is a dimensionless parameter used to comprehensively evaluate the back pressure and collection efficiency of the filter based on the results of the globally unified transient cycle test; back pressure refers to the outlet gas pressure after filtration, in kPa; and the standard PN value refers to the filtration standard that the filter can achieve, with a standard PN value of 2.5 × 10⁻⁶. 11 # / kWh; The test PN value is the PN value of the filter with PN≥10nm measured using the world-standard transient cycling method, # / kWh.

2. The filter as claimed in claim 1, characterized in that, The main structure satisfies at least one of the following conditions: (1) The height H of the main structure satisfies: 5 inch ≤ H ≤ 10 inch; (2) The average diameter D of the main body of the structure satisfies: 7.5 inch ≤ D ≤ 12 inch.

3. The filter as described in claim 1, characterized in that, The difference X between the average diameter of the unblocked compartment at the air inlet of the filter and the average diameter of the unblocked compartment at the air outlet of the filter satisfies: 0 < X ​​≤ 0.4 mm.

4. The filter according to any one of claims 1-3, characterized in that, The main material of the structure includes at least one of cordierite ceramic, silicon carbide, and alumina.

5. A filtration device, characterized in that, The filtration device includes the filter according to any one of claims 1-4.

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