CN113447189A - Automobile exhaust aftertreatment catalytic unit backpressure testing device and testing method - Google Patents
Automobile exhaust aftertreatment catalytic unit backpressure testing device and testing method Download PDFInfo
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- CN113447189A CN113447189A CN202110683815.4A CN202110683815A CN113447189A CN 113447189 A CN113447189 A CN 113447189A CN 202110683815 A CN202110683815 A CN 202110683815A CN 113447189 A CN113447189 A CN 113447189A
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Abstract
The invention discloses a backpressure testing device and a backpressure testing method for an automobile exhaust aftertreatment catalytic unit. The test device comprises: a catalytic unit and a packaging cylinder; the front end and the rear end of the packaging cylinder are connected with a front-end airflow stabilizing cylinder, a front cone cover, a rear-end airflow stabilizing cylinder and a rear cone cover which have the same structure; the front and back pressure sampling points are symmetrically arranged on the front and back stabilizing cylinders relative to the center of the packaging cylinder; the inner diameters of the front and rear stable cylinders are the same as the length of the packaging cylinder, and the lengths of the front and rear stable cylinders are half of the length of the packaging cylinder; the front cone cover and the rear cone cover are both composed of a diameter-changing section and a connecting section. The testing method comprises the steps of installing a testing device and testing the back pressure of the catalytic unit. The device and the testing method thereof are characterized in that a section of cylinder is specially additionally arranged at the front end and the rear end of the catalytic unit, the structure ensures that front and rear flow fields of airflow of the catalytic unit have better uniformity and stability, front and rear backpressure sampling points are on a straight cylinder stabilizing the airflow, and the backpressure value obtained by testing is closer to the true value.
Description
Technical Field
The invention belongs to the technical field of tail gas treatment catalysis, and relates to a device and a method for testing the backpressure of an automobile tail gas post-treatment catalytic unit.
Background
In recent years, with the rapid development of social economy and the increasingly developed road traffic in China, various automobiles are added to the daily life of people. Although the automobile brings convenience to people, the ecological environment is polluted and even threatens the life of human beings; for example, the pollutants emitted from the exhaust of automobiles mainly include CO, THC, NOx, particulate matters and the like. In order to limit the pollution of the automobile exhaust to the ecological environment, the ministry of environmental protection of the people's republic of China issued a notice approving emission limits of light automobile pollutants and measurement methods (sixth stage of China) in 12/23 of 2016. National six regulations place strict limits on gaseous and solid pollutants for engines. In order to meet the national emission requirements, the aftertreatment technical route designs Diesel Oxidation Catalysts (DOCs), diesel particulate filter catalysts (DPFs), Selective Catalysts (SCRs), Selective Catalytic Reduction Filters (SCRFs) and the like to treat the tail gas generated by the engine, the catalytic unit mainly comprises a honeycomb ceramic carrier and a catalytic coating, and the backpressure of the aftertreatment catalytic unit is an important index for investigating the catalysts. The understanding of the backpressure of the catalytic unit is relatively insufficient during the national five-standard period, in order to meet the more strict national six-emission standard, the backpressure of the catalytic unit is controlled to further improve the emission standard of automobile exhaust, the requirement is met, the stability of an aftertreatment system can be maintained even for a long time, the backpressure is prevented from increasing, the oil consumption is further increased, and the service life of an engine is prolonged.
In the development process of the national sixth development, the back pressure of the integral post-treatment system needs to be controlled within a certain range, and the integral back pressure of the post-treatment system consists of an encapsulation structure and a catalytic unit. However, in the actual development process, when evaluating the overall backpressure of the aftertreatment system, the backpressure of the catalytic unit and the backpressure of the packaging structure cannot be accurately distinguished, which causes great difficulty to the problem troubleshooting.
The existing test mainly aims at the test of cold state backpressure, can not test hot state or high temperature backpressure, and does not form industry unified standard, and the test result can not truly reflect the backpressure condition of a carrier/catalytic unit. Meanwhile, the test results of the existing tests under different seasons and weather conditions have larger deviation. For the backpressure test of an aftertreatment system connected to an engine, backpressure data at a certain exhaust flow rate and a certain temperature are required, and the requirement that the backpressure data tested at room temperature cannot truly reflect the actual situation.
In the first route of the prior art, (1) compressed air is adopted to simulate the air flow rate in an exhaust pipeline; (2) the related electronic flowmeter is additionally arranged in the pipeline to control the air flow rate in the pipeline; (3) fixing the catalytic unit on a tool clamp with a certain diameter; (4) respectively installing pressure sensors in front of and behind a clamp for fixing the catalytic unit; (5) after the fixed catalytic unit is installed, starting compressed air, and controlling the introduction amount of the compressed air through an electronic flowmeter switch in a pipeline; (6) and after the air quantity is stable, reading the data of the pressure gauge before and after the catalytic unit, and calculating the back pressure of the catalytic unit by adopting the numerical difference of the pressure before and after the catalytic unit.
Route two of the prior art, (1) the catalytic unit is assembled into a post-processing package structure that matches the actual vehicle design; (2) designing positions where a differential pressure sensor can be installed at relevant positions according to the requirements of a finished automobile sensor; (3) installing a post-treatment system assembled with a catalytic unit on an exhaust pipeline of a rack engine, and installing a differential pressure sensor at a corresponding position; (4) starting the engine, adjusting the exhaust flow and temperature, recording sensor data of relevant positions after the exhaust flow and temperature are stable, and calculating the back pressure value of the relevant catalytic unit according to the pressure difference data before the sensor positions.
The first technical route has the advantages that the test method and the equipment are simple, the operation is carried out at normal temperature, and the risk coefficient is small; the disadvantages are that non-standard equipment is adopted, the test structure is greatly influenced by the environment, the test result feasibility is low, and the backpressure of the catalytic unit at high temperature cannot be tested.
The technical route II has the advantages that the bench is adopted to test the back pressure of the catalytic unit, so that the back pressure of the catalytic unit can be truly reflected, and the back pressure test of the catalytic unit at high temperature can be carried out; the second technical route has the disadvantages that a whole vehicle packaging structure is adopted to test the back pressure of the catalytic unit, on one hand, no pressure difference detection points are designed before and after part of the catalytic unit, and the back pressure of all the catalytic units cannot be tested; on the other hand, due to the design of the packaging structure of the whole vehicle, the position of the pressure difference sampling point does not meet the requirement, and the tested backpressure value can comprise the backpressure values of some packaging structures, so that the tested backpressure value is higher than the backpressure value of the actual catalytic unit.
In the structure of the existing testing device, when exhaust gas flows from a pipeline of an engine to an inlet of a catalytic unit, after the airflow is changed from a small pipe diameter to a large pipe diameter, because resistance suddenly decreases, the uniformity and stability of a flow field of exhaust gas in front of the catalytic unit can be influenced, and the accuracy of testing a backpressure value in front of the catalytic unit is further influenced. The air current is discharged into the atmosphere after passing through the catalytic unit, the air current is suddenly changed from a large pipe diameter to a small pipe diameter, the air current resistance is increased, the air current can flow around after the catalytic unit, the backpressure test value after the catalytic unit is further influenced, and the tested backpressure value also comprises the backpressure of the rear cone cover because the backpressure test point after the catalytic unit is on a pipeline behind the cone cover. Therefore, the test accuracy of the existing test apparatus structure and the method thereof needs to be further improved.
Disclosure of Invention
The invention aims to provide a test structure and a test method capable of truly reflecting dynamic back pressure of a catalytic unit in an automobile aftertreatment system on an engine exhaust pipeline. The invention discloses a packaging structure and a testing method thereof, wherein the testing structure is closer to a backpressure structure of a catalytic unit under the actual exhaust flow and temperature of an engine, and the backpressure obtained by the structural test under a certain exhaust flow and temperature is more accurate and more accords with the real backpressure state of the catalytic unit.
The invention is realized by the following technical scheme:
an automobile exhaust aftertreatment catalytic unit backpressure testing arrangement includes: the catalytic unit is used for backpressure test, a cylindrical structure made by cutting, and a packaging cylinder body used for packaging the catalytic unit, a gasket is arranged between the catalytic unit and the packaging cylinder body for filling and sealing, and the catalytic unit is characterized in that:
the front end and the rear end of the packaging cylinder are connected with a front-end airflow stabilizing cylinder, a front cone cover, a rear-end airflow stabilizing cylinder and a rear cone cover which have the same structure;
the inner diameters of the front-end airflow stabilizing cylinder and the rear-end airflow stabilizing cylinder are the same as the inner diameter of the packaging cylinder, the lengths of the front-end airflow stabilizing cylinder and the rear-end airflow stabilizing cylinder are half of the length of the packaging cylinder, and the front-end airflow stabilizing cylinder is provided with a front back pressure sampling point and is symmetrically arranged relative to the center of the packaging cylinder along with a rear back pressure sampling point arranged on the rear-end airflow stabilizing cylinder;
the front cone cover and the rear cone cover are both composed of a reducing section and a connecting section, the connecting section is provided with an inner diameter the same as that of an exhaust port or a tail gas outlet of an engine, the reducing section is of a conical structure, one end of the reducing section is connected with the front-end airflow stabilizing cylinder or the rear-end airflow stabilizing cylinder, and the other end of the reducing section is connected with the connecting section.
The packaging cylinder body and the front end airflow stabilizing cylinder body, the packaging cylinder body and the rear end airflow stabilizing cylinder body, the front end airflow stabilizing cylinder body and the front cone cover, and the rear end airflow stabilizing cylinder body and the rear cone cover are detachably connected through flanges.
The front backpressure sampling point and the back backpressure sampling point are both arranged at the position 40-60 mm away from the front end surface or the back end surface of the catalytic unit.
The tapered sections of the front cone cover and the rear cone cover form a bell-mouth-shaped tapered structure with 60-degree taper.
The method for testing the backpressure of the automobile exhaust aftertreatment catalytic unit by adopting the device comprises the following steps:
mounting a testing device:
(1) manufacturing a testing catalytic unit, wrapping the catalytic unit by using a packaging gasket and pressing the packaging gasket into a packaging cylinder;
(2) the front end airflow stabilizing cylinder and the rear end airflow stabilizing cylinder of the packaging cylinder are connected through flanges;
(3) the front cone cover and the rear cone cover are connected through flange connection;
(4) the packaged integral structure is connected with an exhaust pipeline of an engine by a hoop, and the tightness of the connection part is ensured;
(5) installing a differential pressure sensor and a temperature sensor at the back pressure sampling points of the front-end airflow stabilizing cylinder and the rear-end airflow stabilizing cylinder;
backpressure testing of catalytic units:
(6) checking the engine, and starting the engine after checking;
(7) adjusting the rotating speed and torque of an engine, adjusting the temperature and exhaust flow under a specific working condition, and recording back pressure values before and after the temperature and the exhaust flow are stable, wherein the back pressure value at the front end of the catalytic unit is k1, and the back pressure value at the rear end of the catalytic unit is k 2; the back pressure difference k under a specific working condition is k1-k 2;
(8) and adjusting the working condition of the engine, and carrying out backpressure tests on the catalytic unit under other temperature and exhaust flow conditions.
The invention has the following beneficial effects: the backpressure testing device for the automobile exhaust aftertreatment catalytic unit is characterized in that a section of cylinder is specially additionally arranged at the front end of the catalytic unit, and has the main functions that when the exhaust of an engine is changed from a small pipe diameter to a large pipe diameter, the flow field of airflow entering the catalytic unit has better uniformity and stability, and a backpressure sampling point in front of the catalytic unit is on a straight cylinder stabilizing the airflow, so that the backpressure value measured under specific exhaust flow and temperature is more real; the device of the invention is additionally provided with a straight cylinder section at the rear end of the catalytic unit, and exhaust is discharged from the catalytic unit and then discharged into the atmosphere through the straight cylinder section, so that the resistance of airflow when the airflow is suddenly changed from a large pipe diameter to a small pipe diameter is reduced, the flow field of the airflow has better uniformity and stability, and the backpressure value of the catalytic unit tested is closer to the true value.
Drawings
FIG. 1 is a schematic diagram of a backpressure test of a catalytic unit in accordance with the method of the present invention;
FIG. 2 is a schematic of a prior art catalytic unit backpressure test;
in the figure, 1 is a front cone cover, 2 is a front back pressure sampling point, 3 is a front end airflow stabilizing cylinder, 4 is a packaging cylinder, 5 is a catalytic unit, 6 is a back pressure sampling point, 7 is a back end airflow stabilizing cylinder, and 8 is a back cone cover.
Detailed Description
The present invention is further described below in conjunction with the following detailed description, which is intended to further illustrate the principles of the invention and is not intended to limit the invention in any way, but is equivalent or analogous to the present invention without departing from its scope.
The back pressure test of the automobile exhaust after-treatment catalytic unit is explained in three parts of a packaging structure, the installation of the back pressure test of the integral catalytic unit and the back pressure test of the catalytic unit.
And (3) packaging structure:
according to the diameter and the length of the specification of the catalytic unit carrier to be tested and the model of the gasket to be used during the type selection packaging, the cylinder body capable of meeting the requirement of packaging the catalytic unit is designed, wherein the structure of the cylinder body is a straight cylinder, and the inner diameter of the cylinder body is larger than the diameter of the catalytic unit to be tested by about 10mm, so that the cylinder body is favorable for packaging the catalytic unit after being wrapped by the conventional gasket, and the air tightness of the packaged catalytic unit meets the testing requirement. The length of the cylinder is twice that of the testing catalytic unit, so that corresponding temperature testing points are favorably arranged at the front end and the rear end of the cylinder for packaging the catalytic unit. Install simple and easy flange respectively additional at the both ends of barrel, wherein the flange internal diameter is unanimous with the external diameter of barrel, and the external diameter of flange is greater than about 79mm of flange internal diameter, processes 8 bolt holes that the aperture is 11mm on the ring flange, and the position interval of every bolt hole is 45, installs the simple and easy flange of such structure additional at encapsulation barrel both ends and is favorable to using repeatedly and testing other catalytic unit with the co-diameter co-altitude of barrel.
The front end and the rear end of the catalytic unit are respectively provided with a section of cylinder body with the structure consistent with that of the cylinder body for packaging the catalytic unit, and flanges consistent with the cylinder body of the catalytic unit are additionally arranged at the two ends of the cylinder body. The front end of the catalytic unit is additionally provided with a section of cylinder body, so that when the exhaust of an engine is changed from a small-diameter pipeline to a large-diameter pipeline, the flow field of airflow before entering the catalytic unit can be uniformly distributed, and the backpressure value before testing the catalytic unit is stable; the rear end of the catalytic unit is additionally provided with a section of cylinder body, so that the flow field of gas is stable after the gas flow passes through the catalytic unit, and the backpressure value tested after the catalytic unit is stable. And a backpressure sampling point is respectively designed at the front end and the rear end of a flange of a cylinder body for packaging the catalytic unit, so that the backpressure test of the catalytic unit is mainly carried out at the place where the front airflow and the rear airflow of the catalytic unit are uniform and stable, the tested backpressure data of the front and the rear of the catalytic unit is more stable, and the tested backpressure value of the catalytic unit is more accurate.
According to the diameter of an exhaust pipeline of an engine on a rack, a simple connecting conical cover is designed, the pipe diameter of an air inlet end of the conical cover is consistent with the diameter of the exhaust pipeline of the engine, and a chuck matched with the pipe diameter is welded at an inlet, so that the conical cover is conveniently connected with the engine pipeline; at the other end of the cone cover, a horn mouth-shaped cone with the taper of 60 degrees is designed, the air inlet diameter of the cone is consistent with the pipe diameter of the air inlet end of the cone cover, the diameter of the air outlet end of the cone is consistent with the diameter of the cylinder of the testing catalytic unit, and an upper flange of the cylinder of the packaging catalytic unit is additionally arranged at the air outlet end of the cone so as to be connected with the packaging cylinder.
Installation of backpressure test of the integral catalytic unit:
the catalytic unit to be tested is wrapped by a proper packaging gasket and is pressed into the designed packaging cylinder body according to the air inlet direction of the catalytic unit, so that the gap between the catalytic unit and the packaging cylinder body is in a closed state, and air flow during the backpressure test of the catalytic unit can completely pass through the whole catalytic unit.
The cylinder body designed with the backpressure sampling points is respectively connected to the front end and the rear end of the cylinder body packaged with the catalytic unit through bolt holes at the flange by bolts, and the cone covers are respectively connected to the front part and the rear part of the cylinder body of the backpressure sampling points, so that the air flow in the engine exhaust pipe is favorably introduced into the cylinder body from the inlet of the cone cover; a section of empty cylinder is additionally arranged at the rear end of the cylinder for packaging the catalytic unit, the rear end of the cylinder is connected with a conical cover, and the additional arrangement of a section of cylinder can reduce airflow disturbance when airflow is changed from a large pipe diameter to a small pipe diameter, so that the airflow passing through the catalytic unit is stable, and finally, the back pressure value of the rear end of the catalytic unit to be tested is more real.
The packaged integral structure is connected with an exhaust pipeline of an engine by a hoop, and the tightness of the joint is ensured. A differential pressure sensor and a temperature sensor are installed at a backpressure sampling point on the catalyst, so that the backpressure values before and after the catalytic unit can be tested under the conditions of stable exhaust flow and stable temperature.
Backpressure testing of catalytic units:
and checking the engine, and starting the engine after checking.
And adjusting the rotation speed and torque of the engine, adjusting the temperature and the exhaust flow under a specific working condition, and recording the back pressure values before and after the temperature and the exhaust flow are stable, wherein the back pressure value at the front end of the catalytic unit is k1(kPa), and the back pressure value at the rear end of the catalytic unit is k2 (kPa).
The back pressure value k of the catalytic unit under a specific working condition is k1-k 2.
And adjusting the working condition of the engine, and carrying out back pressure tests on the catalytic unit at different temperatures and different exhaust flow rates under the condition of changing other temperatures and exhaust flow rates.
The following describes the apparatus and method of the present invention with specific detection as an example.
Example 1:
(1) the test pass-through catalytic unit was 190.5mm in diameter, 76.2 in height, 400cpsi in mesh, 4mil in wall thickness, and 2.17L in catalyst volume.
(2) According to the size and specification of a test catalytic unit, a section of cylinder with the diameter (inner diameter) of 201.5 +/-0.3 mm, the wall thickness of 1.5mm and the height of 150mm is designed, and flanges with bolt holes are additionally arranged at two ends of the cylinder, wherein the inner diameter of the flange is 204.5mm, the outer diameter of the flange is 272mm, the interval of diagonal bolt holes is 244 +/-0.2 mm, and the bolt holes are evenly distributed with 8 holes on the flange. 3 cylinders with the size specification are prepared, wherein a differential pressure sampling point is arranged at the middle section of each of the two cylinders.
(3) Packaging a catalytic unit for testing back pressure to the middle position of the designed cylinder, respectively installing cylinders designed with differential pressure sampling points at two ends of the catalytic unit, and then installing the designed conical covers at two ends of a test sample. And then the installed catalyst is installed on an exhaust pipeline of the engine according to the air inlet and outlet directions.
(4) The engine is started, the exhaust flow is adjusted to 280 +/-10 kg/h and the temperature is 350 +/-5 ℃ by adjusting the rotation speed of the engine to 1020r/min and the torque to 488Nm, when the temperature and the exhaust flow are stable, the pressure difference k1 before the catalyst is recorded to be 0.5kPa, and the pressure difference k2 after the catalyst is recorded to be 0 kPa.
(5) The backpressure of the test catalytic unit was calculated using the formula k-k 1-k 2: k is 0.5-0.5 kPa.
(6) Adjusting the running working condition of the engine, adjusting the rotating speed of the engine to 1190r/min and the torque to 426Nm to enable the exhaust flow to reach 336 +/-10 kg/h, controlling the exhaust temperature to be 350 +/-5 ℃, and recording the pressure difference k1 before the catalyst to be 0.6kPa and the pressure difference k2 after the catalyst to be 0kPa after the temperature and the exhaust flow are stabilized.
(7) The backpressure of the test catalytic unit was calculated using the formula k-k 1-k 2: k is 0.6-0.6 kPa.
Example 2:
(1) the test pass-through catalytic unit was 190.5mm in diameter, 101.6mm in height, 400cpsi in mesh, 4mil in wall thickness, and 2.89L in catalyst volume.
(2) According to the size and specification of a test catalytic unit, a section of cylinder with the diameter (inner diameter) of 201.5 +/-0.3 mm, the wall thickness of 1.5mm and the height of 150mm is designed, and flanges with bolt holes are additionally arranged at two ends of the cylinder, wherein the inner diameter of the flange is 204.5mm, the outer diameter of the flange is 272mm, the interval of diagonal bolt holes is 244 +/-0.2 mm, and the bolt holes are evenly distributed with 8 holes on the flange. 3 cylinders with the size specification are prepared, wherein a differential pressure sampling point is arranged at the middle section of each of the two cylinders.
(3) Packaging a catalytic unit for testing back pressure to the middle position of the designed cylinder, respectively installing cylinders designed with differential pressure sampling points at two ends of the catalytic unit, and then installing the designed conical covers at two ends of a test sample. And then the installed catalyst is installed on an exhaust pipeline of the engine according to the air inlet and outlet directions.
(4) Starting the engine, adjusting the rotation speed of the engine to 1097r/min and the torque to 445Nm to enable the exhaust flow to reach 298 +/-10 kg/h and the temperature to be 350 +/-5 ℃, and recording the pressure difference k1 before the catalyst to be 0.8kPa and the pressure difference k2 after the catalyst to be 0kPa after the temperature and the exhaust flow are stable.
(5) The backpressure of the test catalytic unit was calculated using the formula k-k 1-k 2: k is 0.8-0.8 kPa.
(6) Adjusting the operation condition of the engine, adjusting the rotation speed of the engine to 1300r/min and the torque to 414Nm to enable the exhaust flow to reach 373 +/-10 kg/h, controlling the exhaust temperature to be 350 +/-5 ℃, and recording the pressure difference k1 before the catalyst to be 1.0kPa and the pressure difference k2 after the catalyst to be 0kPa after the temperature and the exhaust flow are stabilized.
(7) The backpressure of the test catalytic unit was calculated using the formula k-k 1-k 2: k is 1.0-0 and 1.0 kPa.
Example 3:
(1) the test wall flow catalytic unit was 190.5mm in diameter, 152.4mm in height, 300cpsi mesh, 9mil wall thickness, and 4.34L catalyst volume.
(2) According to the size and specification of a test catalytic unit, a section of cylinder with the diameter (inner diameter) of 201.5 +/-0.3 mm, the wall thickness of 1.5mm and the height of 200mm is designed, and flanges with bolt holes are additionally arranged at two ends of the cylinder, wherein the inner diameter of the flange is 204.5mm, the outer diameter of the flange is 272mm, the interval of diagonal bolt holes is 244 +/-0.2 mm, and the bolt holes are evenly distributed with 8 holes on the flange. 3 cylinders with the size specification are prepared, wherein a differential pressure sampling point is arranged at the middle section of each of the two cylinders.
(3) Packaging a catalytic unit for testing back pressure to the middle position of the designed cylinder, respectively installing cylinders designed with differential pressure sampling points at two ends of the catalytic unit, and then installing the designed conical covers at two ends of a test sample. And then the installed catalyst is installed on an exhaust pipeline of the engine according to the air inlet and outlet directions.
(4) Starting the engine, adjusting the rotation speed of the engine to 1200r/min and the torque to 432Nm to enable the exhaust flow to reach 336 +/-10 kg/h and the temperature to be 350 +/-5 ℃, and recording the pressure difference k1 before the catalyst to be 3.4kPa and the pressure difference k2 after the catalyst to be 0.98kPa after the temperature and the exhaust flow are stable.
(5) The backpressure of the test catalytic unit was calculated using the formula k-k 1-k 2: k is 3.4-0.98-2.42 kPa.
(6) Adjusting the operation condition of the engine, adjusting the rotation speed of the engine to 1790r/min and the torque to 355Nm to enable the exhaust flow rate to reach 560 +/-10 kg/h, controlling the exhaust temperature to 350 +/-5 ℃, recording the pressure difference k1 before the catalyst to be 8.3kPa after the temperature and the exhaust flow rate are stable, and recording the pressure difference k2 after the catalyst to be 3.76 kPa.
(7) The backpressure of the test catalytic unit was calculated using the formula k-k 1-k 2: k 8.3-3.76 4.54 kPa.
Example 4:
(1) the test wall flow catalytic unit was 190.5mm in diameter, 177.8mm in height, 300cpsi mesh, 9mil wall thickness, and 5.07L catalyst volume.
(2) According to the size and specification of a test catalytic unit, a section of cylinder with the diameter (inner diameter) of 201.5 +/-0.3 mm, the wall thickness of 1.5mm and the height of 200mm is designed, and flanges with bolt holes are additionally arranged at two ends of the cylinder, wherein the inner diameter of the flange is 204.5mm, the outer diameter of the flange is 272mm, the interval of diagonal bolt holes is 244 +/-0.2 mm, and the bolt holes are evenly distributed with 8 holes on the flange. 3 cylinders with the size specification are prepared, wherein a differential pressure sampling point is arranged at the middle section of each of the two cylinders.
(3) Packaging a catalytic unit for testing back pressure to the middle position of the designed cylinder, respectively installing cylinders designed with differential pressure sampling points at two ends of the catalytic unit, and then installing the designed conical covers at two ends of a test sample. And then the installed catalyst is installed on an exhaust pipeline of the engine according to the air inlet and outlet directions.
(4) Starting the engine, adjusting the rotation speed of the engine to 1350r/min and the torque to 383Nm to enable the exhaust flow to reach 392 +/-10 kg/h and the temperature to be 350 +/-5 ℃, and recording the pressure difference k1 before the catalyst to be 4.0kPa and the pressure difference k2 after the catalyst to be 1.24kPa after the temperature and the exhaust flow are stable.
(5) The backpressure of the test catalytic unit was calculated using the formula k-k 1-k 2: k is 4.0-1.24-2.76 kPa.
(6) Adjusting the operation condition of the engine, adjusting the rotation speed of the engine to 2050r/min and the torque to 371Nm to enable the exhaust flow rate to reach 671 +/-10 kg/h, controlling the exhaust temperature to be 350 +/-5 ℃, recording the pressure difference k1 before the catalyst to be 11.4kPa after the temperature and the exhaust flow rate are stable, and recording the pressure difference k2 after the catalyst to be 6.78 kPa.
(7) The backpressure of the test catalytic unit was calculated using the formula k-k 1-k 2: k 11.4-6.78-4.62 kPa.
The test structure and the test method are adopted to test another sample, the diameter of the test sample is 190.5mm, the height is 203.2mm, the number of holes is 300cpsi, the wall thickness is 9mil, the volume of the catalyst is 5.79L, two types of software AVL BOOST and AVL FIRE are adopted to carry out backpressure simulation on the tested sample backpressure value under the test conditions (flow and temperature), the difference between the actual test backpressure value and the simulation value is compared, specific comparison data are detailed in table 1, the difference between the experimental test backpressure value and the simulated backpressure value is small, and the backpressure value tested by the backpressure test structure and the method is consistent with the theoretical backpressure value.
TABLE 15.79L catalytic Unit backpressure test and simulation values
| Flow rate | Temperature of | Testing backpressure | Simulating back pressure |
| kg/h | ℃ | kpa | kpa |
| 288 | 202 | 1.7 | 1.62 |
| 295 | 250 | 1.9 | 1.94 |
| 290 | 300 | 2.25 | 2.2 |
| 280 | 375 | 2.5 | 2.58 |
Claims (5)
1. An automobile exhaust aftertreatment catalytic unit backpressure testing arrangement includes: the catalytic unit is used for backpressure test, a cylindrical structure made by cutting, and a packaging cylinder body used for packaging the catalytic unit, a gasket is arranged between the catalytic unit and the packaging cylinder body for filling and sealing, and the catalytic unit is characterized in that:
the front end and the rear end of the packaging cylinder are connected with a front-end airflow stabilizing cylinder, a front cone cover, a rear-end airflow stabilizing cylinder and a rear cone cover which have the same structure;
the inner diameters of the front-end airflow stabilizing cylinder and the rear-end airflow stabilizing cylinder are the same as the inner diameter of the packaging cylinder, the lengths of the front-end airflow stabilizing cylinder and the rear-end airflow stabilizing cylinder are half of the length of the packaging cylinder, and the front-end airflow stabilizing cylinder is provided with a front back pressure sampling point and is symmetrically arranged relative to the center of the packaging cylinder along with a rear back pressure sampling point arranged on the rear-end airflow stabilizing cylinder;
the front cone cover and the rear cone cover are both composed of a reducing section and a connecting section, the connecting section is provided with an inner diameter the same as that of an exhaust port or a tail gas outlet of an engine, the reducing section is of a conical structure, one end of the reducing section is connected with the front-end airflow stabilizing cylinder or the rear-end airflow stabilizing cylinder, and the other end of the reducing section is connected with the connecting section.
2. The automobile exhaust aftertreatment catalytic unit backpressure testing device of claim 1, characterized in that: the packaging barrel and the front end airflow stabilizing barrel, the packaging barrel and the rear end airflow stabilizing barrel, the front end airflow stabilizing barrel and the front cone cover, and the rear end airflow stabilizing barrel and the rear cone cover are detachably connected through flanges.
3. The automobile exhaust aftertreatment catalytic unit backpressure testing device of claim 1, characterized in that: and the front back pressure sampling point and the back pressure sampling point are both arranged at a position 40-60 mm away from the front end surface or the back end surface of the catalytic unit.
4. The automobile exhaust aftertreatment catalytic unit backpressure testing device of claim 1, characterized in that: the tapered sections of the front cone cover and the rear cone cover form a bell-mouth-shaped tapered structure with 60-degree taper.
5. A backpressure testing method for an automobile exhaust aftertreatment catalytic unit is characterized by comprising the following steps:
mounting a testing device:
(1) manufacturing a testing catalytic unit, wrapping the catalytic unit by using a packaging gasket and pressing the packaging gasket into a packaging cylinder;
(2) the front end airflow stabilizing cylinder and the rear end airflow stabilizing cylinder of the packaging cylinder are connected through flanges;
(3) the front cone cover and the rear cone cover are connected through flange connection;
(4) the packaged integral structure is connected with an exhaust pipeline of an engine by a hoop, and the tightness of the connection part is ensured;
(5) installing a differential pressure sensor and a temperature sensor at the back pressure sampling points of the front-end airflow stabilizing cylinder and the rear-end airflow stabilizing cylinder;
backpressure testing of catalytic units:
(6) checking the engine, and starting the engine after checking;
(7) adjusting the rotating speed and torque of an engine, adjusting the temperature and exhaust flow under a specific working condition, and recording back pressure values before and after the temperature and the exhaust flow are stable, wherein the back pressure value at the front end of the catalytic unit is k1, and the back pressure value at the rear end of the catalytic unit is k 2; the back pressure difference k is k1-k 2;
(8) and adjusting the working condition of the engine, and carrying out backpressure tests on the catalytic unit under other temperature and exhaust flow conditions.
Priority Applications (1)
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