A method for predicting the filtration resistance of a pleated fibrous filter

Abstract

A kind of pleated fiber filter filtration resistance prediction method, including the steps of: based on the geometric parameters of pleated fiber filter, establish the non-uniform surface velocity field distribution model along its contour variation;Pleated fiber filter is dispersed into multiple micro-element along its contour, the relationship model between micro-element body arc length and the unfolded length of pleated fiber filter is constructed;The calculation model of local filtration resistance of pleated fiber filter and the calculation model of dynamic dust layer filtration resistance of pleated fiber filter are constructed;Based on the liquid saturation degree generated in dust layer, the calculation model for quantifying additional capillary resistance is constructed;According to the flow continuity principle, the filtration resistance of pleated fiber filter at time t is obtained by integrating and summing all micro-element bodies.The invention comprehensively considers the influence of pleated macroscopic geometric structure, dust layer dynamic evolution and inter-particle microcosmic liquid phase force on filtration resistance, improves the accuracy and practicability of pleated fiber filter filtration resistance prediction.

Description

Technical Field

[0001] This invention relates to a method for predicting the filtration resistance of pleated fiber filter media, belonging to the field of dust pollution control technology. Background Technology

[0002] With the acceleration of industrial production and urbanization, atmospheric particulate matter pollution has become increasingly prominent, hindering sustainable economic, environmental, and health development. Pleated fiber filter materials, due to their large filtration area and compact structure, are widely used in industrial particulate matter removal. Fiber filtration resistance, as one of the core performance indicators for pleated fiber filter dust removal equipment, directly affects the equipment's energy consumption and operational stability.

[0003] Existing filtration resistance models, such as Darcy's law and models based on single-fiber filtration theory, have certain limitations in predicting the dynamic filtration resistance of pleated filter media. These limitations are mainly manifested in the following ways: Firstly, they simplify the geometry of the filter media, treating it as a flat plate and ignoring the uneven local velocity distribution caused by the pleated structure. This makes it impossible to accurately describe the differentiated behavior of airflow at the peaks and valleys of the pleats, thus failing to accurately predict the filtration resistance of pleated fiber filter media. Secondly, they neglect interparticle liquid phase interactions. When filtering high-humidity or sticky particles, the liquid bridging force and capillary force between particles are key factors leading to a dense dust layer structure and abnormally high resistance; existing models generally lack a quantitative description of this microscopic force. Thirdly, they are limited to static models. Traditional models often ignore the dynamic evolution of the porosity and permeability of the dust cake over time during filtration, causing their prediction accuracy to gradually decrease with filtration time. Fourthly, they lack correction for the actual particle morphology. Traditional models often assume particles are ideal spheres, ignoring the influence of the irregular morphology and surface roughness of real particles on flow and adhesion characteristics. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a method for predicting the filtration resistance of pleated fiber filter media. This method can comprehensively consider the influence of the macroscopic geometry of the pleats, the dynamic evolution of the dust layer, and the microscopic liquid phase interaction between particles on the filtration resistance, thereby improving the accuracy and practicality of predicting the filtration resistance of pleated fiber filter media.

[0005] To achieve the above objectives, the present invention provides a method for predicting the filtration resistance of pleated fiber filter media, comprising the following steps: S1. Based on the geometric parameters of the pleated fiber filter media, a non-uniform surface velocity field distribution model that varies along its contour is established. S2. Discretize the pleated fiber filter media into multiple micro-elements along its contour, and construct a model relating the arc length of the micro-element to the unfolded length of the pleated fiber filter media. S3. Consider the local filtration resistance as the sum of clean filter media, dynamically evolving dust layer, and additional capillary resistance, and construct a calculation model for the local filtration resistance of pleated fiber filter media; based on the dynamically changing dust layer thickness and dust layer porosity, and combined with the particle true surface morphology correction factor, construct a calculation model for the dynamic dust layer filtration resistance of pleated fiber filter media. S4. Based on the liquid phase saturation generated by the liquid in the dust layer, construct a calculation model for quantifying the additional capillary resistance; S5. Based on steps S1-S4, according to the principle of flow continuity, the filtration resistance of the pleated fiber filter media at time t is obtained by integrating and summing all the micro-elements.

[0006] Furthermore, the specific process of S1 is as follows: Due to the contraction and expansion phenomena at the pleats during dust-laden airflow filtration, the normal filtration velocity distribution on the surface of the pleated fiber filter media is uneven. Based on the principle of fluid continuity, assuming the inlet velocity of the pleated fiber filter media is... A dimensionless geometric distribution function is constructed to describe the velocity distribution. Combining geometric parameters such as the radius of curvature and spacing of the folds, the non-uniform surface velocity field distribution model that varies along the fold contour is expressed as: (1) in, The normal filtration velocity is the surface velocity of the pleated fiber filter media. It is a dimensionless geometrical distribution function. The location of the fold arc length. Let be the radius of curvature of the fold. The spacing between folds; Dimensionless geometric distribution function The maximum value is taken at the peak of the fold and the minimum value is taken at the bottom of the fold. To simplify, the dimensionless geometric distribution function describing the velocity distribution can be approximated as a function that is inversely proportional to the width of the local channel of the dust-laden airflow.

[0007] Furthermore, the specific process of S2 is as follows: Assuming the pleats on the filter media are regularly and periodically distributed, for a single pleat unit, we define it as the distance from one pleat bottom to the next. Constructing a two-dimensional coordinate system based on the pleated fiber filter media, we use arc length coordinates to describe the pleat profile. Discretizing the filter media along the pleat profile into multiple micro-elements, the arc length of each micro-element is then expressed as: (2); in, Let the arc length of each infinitesimal element be... This is the total unfolded length along the fold contour. The number of discrete elements along the fold contour.

[0008] Furthermore, the specific process of S3 is as follows: S3.1, in arc length Consider a filter media micro-element. Express the total filtration resistance generated by the dust-laden airflow passing through this micro-element as the sum of the clean filter media filtration resistance, the dynamically evolving dust layer filtration resistance, and the additional capillary resistance. At time t, the local filtration resistance of this infinitesimal element is expressed as: (3); in, Arc length The local filtration resistance of the filter media micro-elements arc length The filtration resistance of micro-element filter media in a clean state Arc length The filtration resistance of dust layer in the dynamic evolution of micro-element filter media Arc length Additional capillary resistance of the filter media micro-elements; S3.2, the aforementioned With the arc length The velocity of the dust-laden airflow is directly proportional to the velocity of the airflow at the location. Based on Darcy's law, the calculation formula is as follows: (4); in, The aerodynamic viscosity of the dust-laden airflow. arc length The thickness of the filter media micro-elements arc length The permeability of filter media micro-elements in a clean state. The normal filtration velocity is the surface velocity of the pleated fiber filter media. S3.3 The dynamic evolution of dust layer filtration resistance is essentially the additional flow resistance generated by the dust-laden airflow passing through the dust layer. The dust layer is essentially a porous medium. It can be calculated using Darcy's law, the dust particle deposition flux, filtration velocity, and dust layer permeability. (5); in, Arc length Local deposition flux of filter media micro-elements The permeability of the dust layer; S3.4 As filtration proceeds, dust accumulates on the surface of the filter media, and the filtration resistance of the dynamically evolving dust layer increases. The filtration resistance is mainly determined by the dynamically changing dust layer over time. Both the thickness and permeability of the dust layer affect the filtration resistance. The thickness of the dust layer is related to the local deposition flux of dust particles, as shown below: (6); in, The inlet dust concentration of the filter media micro-elements. Arc length The local capture efficiency of the filter media micro-elements. To load the true density of dust particles The varying average porosity of the dust layer; S3.5. Considering that the loaded dust particles are not smooth and homogeneous spherical particles, a particle true surface morphology correction factor is introduced. To correct the impact of irregular particle shape on the filtration resistance of dust layer, by means of Kozeny-Carman The equation for calculating the permeability of the dust layer is expressed as: (7); in, The average particle diameter; S3.6, Combining equations (5) to (7), the formula for calculating the dynamic evolution of dust layer filtration resistance is obtained as follows: (8).

[0009] Furthermore, the specific process of S4 is as follows: S4.1 In humid environments, liquid bridging forces are generated between dust particles and between dust particles and fibers, affecting the structural evolution of the dust layer and consequently altering its porosity and permeability. Since liquid bridging forces are difficult to calculate directly, this step establishes a filtration resistance model from the perspective of energy dissipation and changes in flow channels. When liquid bridging forces exist, the resulting liquid bridges fill the pores between dust particles, reducing the effective gas flow cross-sectional area and increasing shear dissipation at the gas-liquid interface. The liquid bridging effect is equivalent to a decrease in the permeability of the dust layer. The ratio of the liquid phase volume to the pore volume of the dust layer is defined as the liquid phase saturation of the dust layer, which is also related to the relative humidity of the environment and the hydrophilicity of the loaded dust particles. Furthermore, a dust layer permeability reduction function based on liquid phase saturation is introduced. Therefore, the effective permeability of the dust layer considering the influence of the liquid phase is: (9); in, Effective permeability of dust layer The liquid phase saturation of the dust layer. This is a dust layer permeability reduction function based on liquid phase saturation; S4.2 Using multiphase flow theory, the dust layer permeability reduction function based on liquid phase saturation is expressed as: (10); Among them, the index It is related to the pore structure and its value is greater than 2; S4.3. The surface roughness of particles affects the critical humidity for capillary agglomeration and the stable morphology of liquid bridges, thus affecting the liquid saturation of the dust layer. A rougher surface can adsorb more liquid at the same humidity. By introducing a surface roughness correction factor, the liquid saturation of the dust layer can be expressed as a function of relative humidity and the surface roughness correction factor. (11); in, For ambient relative humidity, This is a correction factor based on liquid phase saturation; S4.4 Additional capillary resistance is the extra filtration resistance caused by the presence of the liquid phase, i.e., liquid bridges. It is considered to be caused by the difference between the effective permeability of the dust layer and the dust layer permeability. Therefore, it is calculated using the effective permeability of the dust layer, the dust layer permeability, the dust particle deposition flux, and the filtration velocity. (12); S4.5, combining equations (5), (9) to (12), the formula for calculating the additional capillary resistance is obtained as follows: (13).

[0010] Furthermore, the specific process of S5 is as follows: S5.1, at any time The total flow rate through the entire pleated fiber filter media can be expressed as the product of the macroscopic filtration velocity and the airward area of ​​the filter media. Simultaneously, the total flow rate through the entire pleated fiber filter media can also be considered as the sum of the flow rates of all micro-channels. Using the integral form of the flow rate of each micro-channel, the equation for the total flow rate through the entire pleated fiber filter media is obtained as follows: (14); in, The total flow rate through the entire pleated fiber filter media. To filter air velocity, The projected area of ​​the filter media's windward side. The depth of the folds; S5.2 For parallel flow channels in pleated fiber filter media, if the pressure drop of each channel is equal, then the local filtration resistance of the micro-element is a function that is proportional to the arc length. An irrelevant constant, which is also equal to the overall filtration resistance of the pleated fiber filter media, can be expressed by the combined equations (3), (4), (8), and (13): (15); Because in formula (14) Since the function to be solved is implicit, it is an implicit integral equation. use Other terms are represented as: (16); in, The local specific drag of the infinitesimal element; S5.3, Combining equations (15) to (16), the prediction model for the filtration resistance of the pleated fiber filter media at time t is obtained as follows: (17).

[0011] This invention discretizes the pleated filter media into multiple micro-elements along its contour, and establishes a local resistance model for each micro-element considering time evolution and liquid bridge effects. The local filtration resistance is considered as the sum of the filtration resistance of the clean filter media, the filtration resistance of the dynamically evolving dust layer, and the additional capillary resistance. Finally, the overall filtration resistance of the pleated fiber filter media is obtained through integral calculation along the entire pleated contour. This invention couples the macroscopic geometry of the pleats, the dynamic evolution of the dust layer, and the microscopic liquid bridge force within a unified theoretical framework, significantly improving the accuracy of predicting the filtration resistance of moist, sticky dust. By introducing a time variable, it can predict the resistance change curve throughout the entire process from the initial filtration stage to the stable stage and even the dust removal cycle, providing a theoretical basis for optimizing dust removal strategies. By introducing a correction factor, adjustments can be made according to the physicochemical properties of different dusts, resulting in wider applicability. It clearly distinguishes and quantifies the resistance of the dry dust layer and the additional resistance caused by the liquid phase, contributing to a deeper understanding of the underlying mechanism of abnormally high filtration resistance under high humidity environments. This invention comprehensively considers the influence of the macroscopic geometric structure of the pleats, the dynamic evolution of the dust layer, and the microscopic liquid phase interaction between particles on the filtration resistance, thereby improving the accuracy and practicality of predicting the filtration resistance of pleated fiber filter media. It also has the advantages of strong dynamism and wide adaptability. Attached Figure Description

[0012] Figure 1 This is a flowchart of the method of the present invention; Figure 2 This is a schematic diagram of the relational model in S1 of this invention; Figure 3 This is a comparison chart of the actual measured values ​​and the calculated values ​​from the model in an embodiment of the present invention. Detailed Implementation

[0013] The invention will now be further described with reference to the accompanying drawings.

[0014] like Figure 1 and Figure 2 As shown, a method for predicting the filtration resistance of pleated fiber filter media includes the following steps: S1. Based on the geometric parameters of the pleated fiber filter media, a non-uniform surface velocity field distribution model that varies along its contour is established. S2. Discretize the pleated fiber filter media into multiple micro-elements along its contour, and construct a model relating the arc length of the micro-element to the unfolded length of the pleated fiber filter media. S3. Consider the local filtration resistance as the sum of clean filter media, dynamically evolving dust layer, and additional capillary resistance, and construct a calculation model for the local filtration resistance of pleated fiber filter media; based on the dynamically changing dust layer thickness and dust layer porosity, and combined with the particle true surface morphology correction factor, construct a calculation model for the dynamic dust layer filtration resistance of pleated fiber filter media. S4. Based on the liquid phase saturation generated by the liquid in the dust layer, construct a calculation model for quantifying the additional capillary resistance; S5. Based on steps S1-S4, according to the principle of flow continuity, the filtration resistance of the pleated fiber filter media at time t is obtained by integrating and summing all the micro-elements.

[0015] An embodiment of the present invention is a dry filtration and dust removal system in a vertical shaft hoisting tower of a coal mine. By comparing the measured value and the calculated value of the filtration resistance of the dust removal system, the filtration resistance prediction method of the pleated fiber filter media of the present invention was verified.

[0016] In this embodiment, the median particle size of the loaded dust was 75.16 μm. A differential pressure gauge (model DP-CALC5825, range -3735 to 3735 Pa, accuracy 0.1 Pa, TSI Inc., USA) was used to measure the pressure difference between the filter chamber and the clean chamber in the dry filtration dust removal system to characterize the filtration resistance of the dust removal system.

[0017] The dust removal system requires continuous cleaning during normal operation. In this embodiment, only the filtration resistance data of the first two consecutive cycles of the positive sequence cleaning were selected to verify the filtration resistance prediction method of the pleated fiber filter media. The initial filtration resistances of the first two filtration cycles were 471.1 Pa and 675.3 Pa, respectively.

[0018] The basic parameters such as the radius of curvature, number of pleats, pleat spacing, particle size of loaded dust, and filtration velocity of the pleated fiber filter media are substituted into the above-mentioned filtration resistance prediction model for pleated fiber filter media for calculation. The calculated values ​​of the filtration resistance prediction model for pleated fiber filter media are compared with the actual measured values ​​on site to verify the accuracy of the filtration resistance prediction method for pleated fiber filter media provided by this invention.

[0019] A comparison between the calculated values ​​and the actual measured values ​​of the filtration resistance prediction model for the pleated fiber filter media in the above dry filtration dust removal system. Figure 3 As shown. From Figure 3It can be seen that the measured values ​​of the filtration resistance of the pleated fiber filter media and the calculated values ​​by the prediction method maintained a good consistency in the two positive-sequence cleaning cycles, and the model and test data matched well.

[0020] In addition, measured and calculated data of 8 and 6 sets of filter resistance were selected at the same time interval in two positive sequence cleaning cycles, respectively, and compared, as shown in Table 1: Table 1 Comparison of Measured and Calculated Data on Fiber Filter Resistance of Pleated Fiber Filter Media

[0021] As shown in Table 1, in the eight sets of verification data for the first filtration cycle, the maximum relative error between the calculated value of the filtration resistance prediction model and the actual measured value was -3.62%, the minimum relative error was 0.40%, and the average deviation between the calculated value and the actual measured value was 2.25%. In the six sets of verification data for the second filtration cycle, the maximum relative error between the calculated value of the filtration resistance prediction model and the actual measured value was 2.41%, the minimum relative error was 0.83%, and the average deviation between the calculated value and the actual measured value was 1.48%.

[0022] The comparison results of the above filtration resistance data show that the filtration resistance prediction method of the pleated fiber filter media provided by the present invention can accurately predict the filtration resistance of the fiber filter media in the actual operation process of the dry filtration dust removal system.

Claims

1. A method for predicting the filtration resistance of pleated fiber filter media, characterized in that, Includes the following steps: S1. Based on the geometric parameters of the pleated fiber filter media, a non-uniform surface velocity field distribution model that varies along its contour is established. S2. Discretize the pleated fiber filter media into multiple micro-elements along its contour, and construct a model relating the arc length of the micro-element to the unfolded length of the pleated fiber filter media. S3. Consider the local filtration resistance as the sum of clean filter media, dynamically evolving dust layer, and additional capillary resistance, and construct a calculation model for the local filtration resistance of pleated fiber filter media; based on the dynamically changing dust layer thickness and dust layer porosity, and combined with the particle true surface morphology correction factor, construct a calculation model for the dynamic dust layer filtration resistance of pleated fiber filter media. The specific process includes: S3.1, in arc length Consider a filter media micro-element. Express the total filtration resistance generated by the dust-laden airflow passing through this micro-element as the sum of the clean filter media filtration resistance, the dynamically evolving dust layer filtration resistance, and the additional capillary resistance. At time t, the local filtration resistance of this infinitesimal element is expressed as: (3); in, Arc length The local filtration resistance of the filter media micro-elements arc length The filtration resistance of micro-element filter media in a clean state Arc length The filtration resistance of dust layer in the dynamic evolution of micro-element filter media Arc length Additional capillary resistance of the filter media micro-elements; S3.2, the aforementioned With the arc length The velocity of the dust-laden airflow is directly proportional to the velocity of the airflow at the location. Based on Darcy's law, the calculation formula is as follows: (4)； in, The aerodynamic viscosity of the dust-laden airflow. arc length The thickness of the filter media micro-elements arc length The permeability of filter media micro-elements in a clean state. The normal filtration velocity is the surface velocity of the pleated fiber filter media. S3.

3. Using Darcy's law, the following calculations are performed using dust particle deposition flux, filtration velocity, and dust layer permeability: (5)； in, Arc length Local deposition flux of filter media micro-elements The permeability of the dust layer; S3.4 As filtration proceeds, dust accumulates on the surface of the filter media, and the filtration resistance of the dynamically evolving dust layer increases. The filtration resistance is mainly determined by the dynamically changing dust layer over time. Both the thickness and permeability of the dust layer affect the filtration resistance. The thickness of the dust layer is related to the local deposition flux of dust particles, as shown below: (6)； in, The inlet dust concentration of the filter media micro-elements. Arc length The local capture efficiency of the filter media micro-elements. To load the true density of dust particles The varying average porosity of the dust layer; S4. Based on the liquid phase saturation generated by the liquid in the dust layer, construct a calculation model for quantifying the additional capillary resistance; The specific process is as follows: S4.1 In humid environments, liquid bridging forces are generated between dust particles and between dust particles and fibers, affecting the structural evolution of the dust layer and consequently altering its porosity and permeability. Since liquid bridging forces are difficult to calculate directly, this step establishes a filtration resistance model from the perspective of energy dissipation and changes in flow channels. When liquid bridging forces exist, the resulting liquid bridges fill the pores between dust particles, reducing the effective gas flow cross-sectional area and increasing shear dissipation at the gas-liquid interface. The liquid bridging effect is equivalent to a decrease in the permeability of the dust layer. The ratio of the liquid phase volume to the pore volume of the dust layer is defined as the liquid phase saturation of the dust layer, which is also related to the relative humidity of the environment and the hydrophilicity of the loaded dust particles. Furthermore, a dust layer permeability reduction function based on liquid phase saturation is introduced. Therefore, the effective permeability of the dust layer considering the influence of the liquid phase is: (9)； in, Effective permeability of dust layer The liquid phase saturation of the dust layer. This is a dust layer permeability reduction function based on liquid phase saturation; S4.2 Using multiphase flow theory, the dust layer permeability reduction function based on liquid phase saturation is expressed as: (10)； Among them, the index It is related to the pore structure and its value is greater than 2; S4.

3. The surface roughness of particles affects the critical humidity for capillary agglomeration and the stable morphology of liquid bridges, thus affecting the liquid saturation of the dust layer. A rougher surface can adsorb more liquid at the same humidity. By introducing a surface roughness correction factor, the liquid saturation of the dust layer can be expressed as a function of relative humidity and the surface roughness correction factor. (11)； in, For ambient relative humidity, This is a surface roughness correction factor; S4.4 Additional capillary resistance is the extra filtration resistance caused by the presence of the liquid phase, i.e., liquid bridges. It is considered to be caused by the difference between the effective permeability of the dust layer and the dust layer permeability. Therefore, it is calculated using the effective permeability of the dust layer, the dust layer permeability, the dust particle deposition flux, and the filtration velocity. (12)； S4.5, combining equations (5), (9) to (12), the formula for calculating the additional capillary resistance is obtained as follows: (13)； S5. Based on steps S1-S4, according to the principle of flow continuity, the filtration resistance of the pleated fiber filter media at time t is obtained by integrating and summing all the micro-elements.

2. The method for predicting filtration resistance of pleated fiber filter media according to claim 1, characterized in that, The specific process of S1 is as follows: Based on the principle of fluid continuity, assuming the inlet velocity of the pleated fiber filter media is... A dimensionless geometric distribution function is constructed to describe the velocity distribution. Combining the radius of curvature and spacing of the folds, the non-uniform surface velocity field distribution model that varies along the fold contour is expressed as: (1)； in, The normal filtration velocity is the surface velocity of the pleated fiber filter media. It is a dimensionless geometrical distribution function. The location of the fold arc length. Let be the radius of curvature of the fold. The spacing between folds; Dimensionless geometric distribution function The maximum value is taken at the peak of the fold and the minimum value is taken at the bottom of the fold. To simplify, the dimensionless geometric distribution function describing the velocity distribution can be approximated as a function that is inversely proportional to the width of the local channel of the dust-laden airflow.

3. The method for predicting filtration resistance of pleated fiber filter media according to claim 2, characterized in that, The specific process of S2 is as follows: Assuming the pleats on the filter media are regularly and periodically distributed, for a single pleat unit, we define it as the distance from one pleat bottom to the next. Constructing a two-dimensional coordinate system based on the pleated fiber filter media, we use arc length coordinates to describe the pleat profile. Discretizing the filter media along the pleat profile into multiple micro-elements, the arc length of each micro-element is then expressed as: (2)； in, Let the arc length of each infinitesimal element be... This is the total unfolded length along the fold contour. The number of discrete elements along the fold contour.

4. The method for predicting filtration resistance of pleated fiber filter media according to claim 3, characterized in that, The specific process of S3 also includes: S3.

5. Considering that the loaded dust particles are not smooth and homogeneous spherical particles, a particle true surface morphology correction factor is introduced. To correct the impact of irregular particle shape on the filtration resistance of dust layer, by means of Kozeny-Carman The equation for calculating the permeability of the dust layer is expressed as: (7)； in, The average particle diameter; S3.6, Combining equations (5) to (7), the formula for calculating the dynamic evolution of dust layer filtration resistance is obtained as follows: (8)。 5. The method for predicting filtration resistance of pleated fiber filter media according to claim 1, characterized in that, The specific process of S5 is as follows: S5.1, at any time The total flow rate through the entire pleated fiber filter media can be expressed as the product of the macroscopic filtration velocity and the airward area of ​​the filter media. Simultaneously, the total flow rate through the entire pleated fiber filter media can also be considered as the sum of the flow rates of all micro-channels. Using the integral form of the flow rate of each micro-channel, the equation for the total flow rate through the entire pleated fiber filter media is obtained as follows: (14)； in, The total flow rate through the entire pleated fiber filter media. To filter air velocity, The projected area of ​​the filter media's windward side. The depth of the folds; S5.2 For parallel flow channels in pleated fiber filter media, if the pressure drop of each channel is equal, then the local filtration resistance of the micro-element is a function that is proportional to the arc length. An irrelevant constant, which is also equal to the overall filtration resistance of the pleated fiber filter media, can be expressed by the combined equations (3), (4), (8), and (13): (15)； Because in formula (14) Since the function to be solved is implicit, it is an implicit integral equation. use Other terms are represented as: (16)； in, The local specific drag of the infinitesimal element; S5.3, Combining equations (14) to (16), the prediction model for the filtration resistance of the pleated fiber filter media at time t is obtained as follows: (17)。

Images