A method for modeling heterogeneous coating of a dpf porous media catalyst

Abstract

The application provides a DPF porous medium catalyst heterogeneous coating modeling method, first, a binary image is scanned to obtain all solid phase coordinates, and a matrix is constructed to store the coordinates; boundary grabbing is performed according to the obtained storage matrix to obtain a solid phase boundary matrix; a required catalyst loading area is determined, the solid phase coordinates required to be loaded are screened out in the solid phase boundary matrix to form a new catalyst loading boundary storage matrix; a weight factor p is introduced to change the randomly selected solid phase boundary into a catalyst loading phase, and the required simulation coating times are repeated; until all the screened solid phase boundaries complete catalyst coating simulation, a two-dimensional CDPF model with catalyst heterogeneous coating is finally obtained. Compared with the prior art, the application simulates the catalyst heterogeneous coating mode on the basis of the two-dimensional porous medium white carrier model structure, is more in line with the actual carrier structure, and provides theoretical guidance for the improvement of the DPF performance.

Description

Technical Field

[0001] This invention belongs to the field of DPF support model construction and optimization technology, and relates to a method for modeling heterogeneous coating of DPF porous media catalysts. Background Technology

[0002] To meet increasingly stringent emission requirements, diesel particulate filters (DPFs) have been developed to capture particulate matter in exhaust gases. Although current DPFs achieve a capture efficiency of over 90%, blockage can occur within the DPF channels after a period of operation, leading to high back pressure. If the deposited particles are not cleaned promptly, engine fuel consumption will increase and effective torque will decrease. Therefore, studying the movement and deposition characteristics of particles in DPFs is crucial for developing DPFs with low back pressure and high capture efficiency. Consequently, modeling research on DPF carriers is also fundamental and important work.

[0003] Porous media are a major component of the DPF wall, and their microstructure significantly impacts DPF capture efficiency, pressure drop characteristics, and regeneration mechanisms. The pore shape and size of the DPF carrier, as well as the internal structure and thickness of the porous media, play a decisive role in DPF flowability, thus affecting engine economy and power. Particles in diesel engine exhaust enter the DPF and are subjected to Brownian diffusion, interception, and inertial mechanisms, colliding with the filter walls. Wall-flow filters are excellent carriers for catalyst coatings; the catalyst material helps burn accumulated soot and catalyzes the conversion of gaseous pollutants, contributing to improved DPF performance. At the microscale, to further investigate the impact of catalyst coating within the CDPF on its performance, it is necessary to construct a catalyst coating method, laying the foundation for a final, analytically applicable porous media model of the CDPF.

[0004] Patent CN101994547A discloses a method for partially coating a filter with platinum group metals to improve the quality limit of coal ash and reduce costs. A diesel particulate filter (DPF) has a thin strip of carrier-coated filter material on the upstream inlet or downstream outlet. This carrier coating has a surface added to the DPF and a porous structure of platinum group metals (PGMs). Patent CN111939917A discloses a DPF catalyst with good sulfur resistance, comprising a support and a bottom layer and a top layer coated on the support. The active component of the bottom layer is a noble metal; the active component of the top layer includes a first metal and a second metal; the active components of both the bottom and top layers are loaded on a coating material and sequentially coated onto the support. The coating material includes a first metal oxide and a second metal oxide. Patent CN114547838A discloses a method for optimizing the two-phase boundary of a DPF porous media model. It proposes the concept of boundary coefficient and performs pixel cell transformation based on the boundary coefficient, thereby removing the burr-like boundary of the two-dimensional porous media model, widening the average flow pore size, increasing the inherent permeability of the DPF support, improving flowability, and optimizing the two-phase boundary of the DPF porous media model. However, it does not optimize the coating of the porous media catalyst. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the existing technology by providing a heterogeneous coating modeling method for DPF porous media catalysts. By simulating the heterogeneous coating mode of catalysts on the solid surface of DPF porous media, the method more closely matches the actual support structure, thereby providing a model basis for the study of CDPF performance and providing theoretical guidance for improving DPF performance.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] This invention provides a method for modeling heterogeneous coating of DPF porous media catalysts, comprising the following steps:

[0008] S1: A two-dimensional porous medium image is generated using the four-parameter random generation method (QSGS), and then binarized. All obtained pixels are divided into pore phase lattices and solid phase lattices, and a storage matrix is ​​constructed to store the coordinates of all solid phase lattices.

[0009] S2: Perform boundary extraction on the storage matrix constructed in S1 to obtain the solid-phase boundary matrix;

[0010] S3: Determine the required catalyst simulation loading region, and select all solid phase boundary lattice coordinates that conform to the simulation loading region from the solid phase boundary matrix obtained in S2 to form a new catalyst loading boundary storage matrix.

[0011] S4: Set the coating weight factor p and the number of heterogeneous catalyst coatings, and calculate the required number of catalyst coating grids. Randomly select coordinates that meet the quantity requirements from the new catalyst loading boundary storage matrix obtained in S3, and carry out the catalyst loading coating process.

[0012] S5: If all selected solid boundary lattices complete the catalyst loading and coating process and reach the set number of catalyst coatings, then the random coating simulation of porous media catalyst is completed, and a two-dimensional CDPF model with heterogeneous catalyst coating is obtained.

[0013] Furthermore, in S1, coordinates in the horizontal x-direction and vertical y-direction are established for each separated pore phase lattice and solid phase lattice, and unique coordinates are assigned.

[0014] Furthermore, in S1, the constructed storage matrix is ​​an m-row, 2-column matrix, where m is the number of all solid-phase lattices, the first column is the horizontal coordinate, and the second column is the vertical coordinate.

[0015] Further, in S2, the specific process is as follows: all solid phase lattices in S1 are translated one unit lattice to the four directions to obtain a new translation matrix. Then, the coordinates of the solid phase lattices in the original storage matrix are removed from the new translation matrix. The remaining solid phase lattice coordinates are the boundary coordinates of the entire solid phase region, thus obtaining the solid phase boundary matrix. The four directions are up, down, left, and right.

[0016] Furthermore, in S3, the simulated loading region is selected to be loaded in the entire porous media image region generated in S1, or selected in a portion of the porous media image region that needs to be studied.

[0017] Furthermore, in S4, since the simulated catalyst is coated heterogeneously, the specific value of the weighting factor p is determined by the content under study: the larger the weighting factor p is, the more catalyst is simulated in one coating, that is, the catalyst is more widely distributed on the surface of the porous medium.

[0018] Furthermore, in S4, the catalyst loading and coating process specifically involves: selecting lattices whose coordinates meet the quantity requirements and are all porous phase lattices, directly assigning values ​​to them, recording their coordinates, and marking them as catalyst coating lattices.

[0019] Furthermore, in S5, if any of the selected solid boundary lattices have not completed the catalyst coating process, the coating process in S4 is repeated.

[0020] Furthermore, in S5, if the set number of catalyst coatings is not reached, the boundary grabbing in S2 is repeated.

[0021] Furthermore, in S5, in the two-dimensional CDPF model with heterogeneous catalyst coating, the gray area represents the catalyst coating area, the white area represents the solid phase area, and the black area represents the porous phase area.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] This invention provides a modeling method for heterogeneous coating of DPF porous media catalysts. It constructs a porous media structure of CDPF support at the microscopic pore scale. Based on the two-dimensional porous media white support model structure generated by QSGS, it can simulate the heterogeneous coating mode of catalyst on the solid surface of DPF porous media, which is more consistent with the actual support structure. This provides a model basis for the study of CDPF performance and provides theoretical guidance for improving DPF performance. Attached Figure Description

[0024] Figure 1 A two-dimensional DPF porous media white carrier model generated for QSGS;

[0025] Figure 2 A schematic diagram of solid-phase boundary lattice capture;

[0026] Figure 3 This is a flowchart of a catalyst heterogeneous coating simulation program.

[0027] Figure 4 A simulation image showing the effect of heterogeneous coating of catalyst across the entire porous medium.

[0028] Figure 5 This is a simulation of the heterogeneous coating effect of catalyst in a portion of a porous medium. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described below in conjunction with the embodiments and accompanying drawings. These embodiments are implemented under the premise of the solutions described in the present invention, and provide detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments.

[0030] Example 1

[0031] A method for modeling heterogeneous coating of DPF porous media catalysts, such as Figure 3 As shown, it includes the following steps:

[0032] S1: Two-dimensional porous media images are randomly generated using QSGS, such as... Figure 1As shown, the image is binarized. Any two-dimensional porous medium model can be decomposed into tiny square pixel cells, with white cells representing the solid phase and black cells representing the porous phase. The computational region size of the two-dimensional porous medium model is determined based on the porous medium image, and x- and y-coordinates are established, thus assigning each pixel cell a unique coordinate. After binarization, the solid phase (white cells) is represented by 1, and the porous phase (black cells) by 0. Solid phase lattices are extracted from the image, and an m-row, 2-column storage matrix is ​​constructed to record the coordinates of the solid phase lattices within the region, where m represents the total number of solid phase lattices, the first column represents the x-coordinate of the solid phase lattice, and the second column represents the y-coordinate of the solid phase lattice.

[0033] S2: Perform boundary extraction on the storage matrix in S1, such as... Figure 2 As shown, the specific process is as follows: all solid phase lattices in S1 are translated one unit cell to the four directions, including the top, bottom, left, and right, to obtain a new translation matrix. Then, the solid phase lattice coordinates in the original storage matrix are removed from the new translation matrix. The remaining solid phase lattice coordinates are the boundary coordinates of the entire solid phase region, thus obtaining the solid phase boundary matrix.

[0034] S3: Determine the required simulated loading region for the catalyst. This can be done by loading the entire porous media image region generated in S1, or by selecting a portion of the porous media image region to be studied. In the solid boundary matrix obtained in S2, based on the determined catalyst simulated loading region, select all solid boundary lattice coordinates that conform to that loading region, forming a new catalyst loading boundary storage matrix.

[0035] S4: Due to the heterogeneous coating process, a coating weighting factor p needs to be set. This means that each catalyst coating is not uniformly applied to the entire solid surface; some surfaces will have catalyst coating while others will not. The specific value of the weighting factor p is determined by the research content: a larger weighting factor p indicates a larger number of catalyst cells simulated in one coating, meaning a wider distribution of catalyst on the porous media surface. After determining the coating weighting factor p, the required number of catalyst coating cells is calculated. Coordinates meeting this requirement are randomly selected from the new catalyst loading boundary storage matrix. Since these cells represent the porous phase, their values ​​are directly set to 0.5, and their coordinates are recorded and marked as catalyst coating cells. If any of the selected boundary cells have not completed the coating process, the catalyst loading and coating process is repeated. Throughout the simulation, the number of heterogeneous catalyst coating cycles needs to be set to simulate different catalyst amounts. A complete catalyst coating cycle is considered complete when all selected solid boundary cells have completed the catalyst loading and coating process; otherwise, the boundary selection process in S2 is repeated.

[0036] S5: Repeat the above process sequentially. When all the selected solid boundary lattices have completed the catalyst loading and coating process and the set number of catalyst coatings has been reached, the random coating simulation of the porous media catalyst is completed, resulting in a two-dimensional CDPF model with heterogeneous catalyst coating, such as... Figure 4 and Figure 5 As shown, the gray area represents the catalyst coating area, the white area represents the solid phase area, and the black area represents the porous phase area.

[0037] Catalyst coating can improve DPF performance, but different coating methods and the number of coating passes have varying effects on performance improvement. This method can more realistically simulate the heterogeneous loading morphology of the catalyst on the DPF surface. Based on this model, combined with other numerical simulation methods, the influence of heterogeneous coating methods and coating amounts on DPF back pressure and soot deposition characteristics can be explored, seeking the optimal heterogeneous catalyst coating scheme and providing theoretical guidance for improving CDPF performance.

[0038] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for modeling heterogeneous coating of DPF porous media catalysts, characterized in that, Includes the following steps: S1: A two-dimensional porous medium image is generated using a four-parameter random generation method and binarized. All obtained pixels are divided into pore phase lattices and solid phase lattices, and a storage matrix is ​​constructed to store the coordinates of all solid phase lattices. S2: Perform boundary extraction on the storage matrix constructed in S1 to obtain the solid-phase boundary matrix; S3: Determine the required catalyst simulation loading region, and select all solid phase boundary lattice coordinates that conform to the simulation loading region from the solid phase boundary matrix obtained in S2 to form a new catalyst loading boundary storage matrix. S4: Set the coating weight factor p and the number of heterogeneous catalyst coatings, and calculate the required number of catalyst coating grids. Randomly select coordinates that meet the quantity requirements from the new catalyst loading boundary storage matrix in S3, and carry out the catalyst loading coating process. S5: If all selected solid boundary lattices complete the catalyst loading and coating process and reach the set number of catalyst coatings, then the random coating simulation of porous media catalyst is completed, and a two-dimensional CDPF model with heterogeneous catalyst coating is obtained.

2. The method for modeling heterogeneous coating of DPF porous media catalysts according to claim 1, characterized in that, In S1, coordinates in the horizontal x-direction and vertical y-direction are established for each pore phase lattice and solid phase lattice after differentiation, and unique coordinates are assigned.

3. The method for modeling heterogeneous coating of DPF porous media catalysts according to claim 1, characterized in that, In S1, the constructed storage matrix is ​​an m-row, 2-column matrix, where m is the number of all solid phase lattices, the first column is the horizontal axis, and the second column is the vertical axis.

4. The method for modeling heterogeneous coating of DPF porous media catalysts according to claim 1, characterized in that, In S2, the specific process is as follows: all solid phase lattices in S1 are translated one unit cell to the four directions to obtain a new translation matrix. Then, the coordinates of the solid phase lattices in the original storage matrix are removed from the new translation matrix. The remaining solid phase lattice coordinates are the boundary coordinates of the entire solid phase region, thus obtaining the solid phase boundary matrix. The four directions are up, down, left, and right.

5. The method for modeling heterogeneous coating of DPF porous media catalysts according to claim 1, characterized in that, In S3, the simulated loading region is selected to be loaded in the entire porous media image region generated in S1, or a portion of the porous media image region to be studied is selected for loading.

6. The method for modeling heterogeneous coating of DPF porous media catalysts according to claim 1, characterized in that, In S4, due to the heterogeneous coating of the simulated catalyst, the specific value of the weighting factor p is determined by the content under study: the larger the weighting factor p, the more catalyst is simulated in one coating, that is, the wider the distribution of the catalyst on the surface of the porous medium.

7. The method for modeling heterogeneous coating of DPF porous media catalysts according to claim 1, characterized in that, In S4, the catalyst loading and coating process specifically involves: selecting lattices whose coordinates meet the quantity requirements and are all porous phase lattices, directly assigning values ​​to them, recording their coordinates, and marking them as catalyst coating lattices.

8. The method for modeling heterogeneous coating of DPF porous media catalysts according to claim 1, characterized in that, In S5, if any of the selected solid boundary lattices have not completed the catalyst coating process, the coating process in S4 is repeated.

9. The method for modeling heterogeneous coating of DPF porous media catalysts according to claim 1, characterized in that, In S5, if the set number of catalyst coatings is not reached, the boundary grabbing in S2 will be repeated.

10. The method for modeling heterogeneous coating of DPF porous media catalysts according to claim 1, characterized in that, In S5, in the two-dimensional CDPF model with heterogeneous catalyst coating, the gray area represents the catalyst coating area, the white area represents the solid phase area, and the black area represents the porous phase area.

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