CN117516941A - Post-treatment NOx conversion efficiency bench test method - Google Patents
Post-treatment NOx conversion efficiency bench test method Download PDFInfo
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- CN117516941A CN117516941A CN202310461204.4A CN202310461204A CN117516941A CN 117516941 A CN117516941 A CN 117516941A CN 202310461204 A CN202310461204 A CN 202310461204A CN 117516941 A CN117516941 A CN 117516941A
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- 238000006243 chemical reaction Methods 0.000 title claims abstract description 31
- 238000010998 test method Methods 0.000 title claims abstract description 19
- 238000012360 testing method Methods 0.000 claims abstract description 42
- 238000002425 crystallisation Methods 0.000 claims abstract description 15
- 230000008025 crystallization Effects 0.000 claims abstract description 15
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims abstract description 12
- 239000004202 carbamide Substances 0.000 claims abstract description 12
- 238000002347 injection Methods 0.000 claims abstract description 11
- 239000007924 injection Substances 0.000 claims abstract description 11
- 238000002156 mixing Methods 0.000 claims abstract description 9
- 239000011248 coating agent Substances 0.000 claims abstract description 8
- 238000000576 coating method Methods 0.000 claims abstract description 8
- 238000000034 method Methods 0.000 claims abstract description 4
- 230000002265 prevention Effects 0.000 claims abstract description 4
- 230000008929 regeneration Effects 0.000 claims description 10
- 238000011069 regeneration method Methods 0.000 claims description 10
- 238000011144 upstream manufacturing Methods 0.000 claims description 6
- 239000013078 crystal Substances 0.000 claims description 5
- 238000005507 spraying Methods 0.000 claims description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 3
- 238000009825 accumulation Methods 0.000 claims description 3
- 229910052799 carbon Inorganic materials 0.000 claims description 3
- 238000002224 dissection Methods 0.000 claims description 3
- 238000011156 evaluation Methods 0.000 claims description 3
- 238000004080 punching Methods 0.000 claims description 3
- 238000013461 design Methods 0.000 abstract description 3
- 230000008569 process Effects 0.000 abstract description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 22
- 229910002089 NOx Inorganic materials 0.000 description 16
- 229910000069 nitrogen hydride Inorganic materials 0.000 description 9
- MGWGWNFMUOTEHG-UHFFFAOYSA-N 4-(3,5-dimethylphenyl)-1,3-thiazol-2-amine Chemical compound CC1=CC(C)=CC(C=2N=C(N)SC=2)=C1 MGWGWNFMUOTEHG-UHFFFAOYSA-N 0.000 description 4
- JCXJVPUVTGWSNB-UHFFFAOYSA-N nitrogen dioxide Inorganic materials O=[N]=O JCXJVPUVTGWSNB-UHFFFAOYSA-N 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 229910021529 ammonia Inorganic materials 0.000 description 2
- 230000003197 catalytic effect Effects 0.000 description 2
- 238000010531 catalytic reduction reaction Methods 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 239000003054 catalyst Substances 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M15/00—Testing of engines
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M15/00—Testing of engines
- G01M15/04—Testing internal-combustion engines
- G01M15/05—Testing internal-combustion engines by combined monitoring of two or more different engine parameters
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M17/00—Testing of vehicles
- G01M17/007—Wheeled or endless-tracked vehicles
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Combustion & Propulsion (AREA)
- Exhaust Gas After Treatment (AREA)
Abstract
The invention relates to the field of vehicles, and provides a post-treatment NOx conversion efficiency bench test method, which comprises the following steps of; for determining SDPF and SCR sizes, coating amounts, and mixer airflow uniformity and crystallization prevention capability, the aftertreatment NOx conversion efficiency bench test method includes the steps of; back pressure testing; testing NH3 mixing uniformity; testing NOx conversion efficiency; and (5) testing crystallization of the mixer. Through carrying out back pressure test to the engine, the maximum back pressure of the whole system is compared with the maximum back pressure value of the allowable exhaust under the rated power point of the engine, then the uniformity of distribution of NH3 in the urea injection process after passing through the mixer is verified, the full reaction of NOX and NH3 is ensured, the preliminary design of the mixer is verified, and finally the NOX conversion efficiency and the crystallization of the mixer are tested, so that the overall experimental operability is strong.
Description
Technical Field
The invention relates to the field of vehicles, in particular to a bench test method for conversion efficiency of aftertreatment NOx.
Background
The current mainstream aftertreatment technology route of the light diesel vehicle type meeting the national six-emission regulation is DOC (catalytic converter) +SDPF (diesel particulate filter) +SCR (selective catalytic reduction) +ASC (ammonia oxidation catalyst), compared with the national five-type diesel vehicle type, SDPF and SCR devices are added, meanwhile, a mixer is added before SCR to meet the requirement of reducing NOx (nitrogen dioxide) emissions, the factors influencing the conversion efficiency of NOx (nitrogen dioxide) are various, the size of the SDPF and the SCR, the coating amount and the mixer design influence the conversion efficiency, and when the conversion efficiency of NOx (nitrogen dioxide) is generally tested, all tests are carried out on a bench, and the bench cost is high, so that the test cost is high. Based on this, the present application is presented.
Disclosure of Invention
The invention aims to provide a bench test method for the conversion efficiency of post-treatment NOx, which aims to solve the technical problems that in the prior art, all tests for testing the conversion efficiency of NOx (nitrogen dioxide) are carried out on a bench, the bench cost is high, and the test cost is high.
In order to achieve the above purpose, the invention adopts the following technical scheme: an aftertreatment NOx conversion efficiency bench test method for determining SDPF and SCR size, coating amount, and mixer airflow uniformity and crystallization prevention capability, the aftertreatment NOx conversion efficiency bench test method comprising the steps of;
s1, back pressure testing;
s2, testing the mixing uniformity of NH 3;
s3, testing NOx conversion efficiency;
s4, crystallizing and testing by a mixer.
Preferably, step S1 specifically includes: arranging a rack, installing and debugging an engine, checking engine boundary and data, preparing three groups of post-treatment of carrier size and coating amount schemes, sequentially installing a DOC, an SDPF and an SCR on the rack engine, arranging an air duct at a corresponding position, connecting the air duct to a rack pressure tester, defining the front of the DOC as P0, the front of the SDPF as P1, the front of the SCR as P2, the rear of the SCR as P3, starting an engine heat engine until the output power of the engine is maximum, acquiring pressure points from P0 to P3 in the three groups of schemes when the exhaust flow of the engine is maximum, defining P0 as the maximum back pressure of the whole system, wherein the P0-P1 difference is the pressure drop of the DOC, the P1-P2 difference is the pressure drop of the SDPF, the P2-P3 difference is the pressure drop of the SCR, comparing the P0 size with the target value, when P0 is smaller than the target value, the scheme OK, and the scheme NG when P0 is larger than the target value.
Preferably, step S2 specifically includes: checking urea injection accuracy, punching and arranging an air duct at the rear end of the mixer, respectively marking 1-9 around a position of a carrier surface taking point 9, selecting an original working point of an engine, taking one point near the inlet temperature of the SDPF at 300 ℃, taking one point for high, medium and low flows respectively, and taking an injection coefficient of 0.7, intercepting NH3 content of each point, calculating air flow mixing uniformity UI, and judging Ok when the UI is larger than 0.95.
Preferably, step S3 specifically includes: selecting a plurality of test working condition points, selecting the test working condition points of engine operation, wherein the NH3 leakage value is less than 10ppm, the urea overspray coefficient is 1.2, recording data, and calculating the SDPF and SCR efficiency and the total efficiency by acquiring the NOx values of the upstream of the DOC, the downstream of the DPF and the downstream of the SCR.
Preferably, step S4 specifically includes: adopting a whole vehicle rapid test mode, continuously spraying urea with the spraying quantity in the interval of 0.8-1.5, dissecting SDPF, if no crystallization exists, and ending the evaluation; if crystals exist, the original is welded and reduced, carbon accumulation triggers regeneration, after regeneration is completed, the crystallization condition is observed through dissection, if no crystals exist after DPF regeneration, and the test is ended.
Preferably, the target value is an allowable exhaust maximum back pressure value at a rated power point of the engine.
Preferably, the step of deriving a NOx value upstream of the DOC, downstream of the DPF, and downstream of the SCR to calculate SDPF and SCR efficiencies and overall efficiencies comprises:
preferably, when the whole vehicle rapid test mode is adopted, the speed of the whole vehicle is below 40km/h, and the whole vehicle runs to be 500km.
The above-mentioned one or more technical solutions in the embodiments of the present invention at least have the following technical effects or advantages:
by adopting the technical scheme, the engine is subjected to back pressure test, the maximum back pressure of the whole system is compared with the maximum back pressure value of the allowed exhaust under the rated power point of the engine, then the distribution uniformity of the NH3 in the urea injection process is verified after passing through the mixer, the full reaction of NOX and NH3 is ensured, the preliminary design of the mixer is verified, finally the NOX conversion efficiency and the crystallization of the mixer are tested, the whole experiment has strong operability and high control precision, the test data is reliable, and the test cost is reduced by combining a rack with the whole vehicle.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments or the description of the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is an overall workflow diagram provided by an embodiment of the present invention;
FIG. 2 is a diagram of a pressure point placement location provided by an embodiment of the present invention;
FIG. 3 is a rear end cross-sectional view of a mixer provided in an embodiment of the invention;
FIG. 4 is a schematic diagram of a UI for intercepting NH3 content of each point and calculating air flow mixing uniformity according to an embodiment of the invention;
Detailed Description
Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative and intended to explain the present invention and should not be construed as limiting the invention.
In the description of the present invention, it should be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like indicate orientations or positional relationships based on the orientation or positional relationships shown in the drawings, merely to facilitate describing the present invention and simplify the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present invention.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.
In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
Referring to fig. 1-4, an embodiment of the present application provides a post-treatment NOx conversion efficiency bench test method for determining SDPF and SCR size, coating amount, and mixer airflow uniformity and crystallization prevention capability, the post-treatment NOx conversion efficiency bench test method comprising the steps of;
s1, back pressure testing;
1. arranging a rack, installing and debugging an engine, checking engine boundaries and data, wherein the data are shown in the following table 1;
| engine displacement (ml) | 2499 |
| Rated torque (N.m) | 360 |
| Rated power (KW) | 110 |
| Maximum rotation speed (rpm) | 4000 |
TABLE 1
2. Preparing three groups of carrier size and coating amount scheme post-treatment, and sequentially installing a DOC (catalytic converter), an SDPF (diesel particulate filter) and an SCR (selective catalytic reduction) on a bench engine, wherein an air duct is arranged at a corresponding position and connected to a bench pressure tester, and P0 is defined before the DOC, P1 is defined before the SDPF, P2 is defined before the SCR and P3 is defined after the SCR;
3. starting the engine heat engine, gradually increasing the engine speed to be about 90 ℃ when the water temperature reaches the rated speed 3600rpm, wherein the engine output power is maximum, the exhaust flow is maximum, three groups of pressure points of each point of the schemes P0 to P3 are obtained, P0 is defined as the maximum back pressure of the whole system, the difference value P0-P1 is the pressure drop of DOC, the difference value P1-P2 is the pressure drop of SDPF, the difference value P2-P3 is the pressure drop of SCR, the size of P0 is compared with the back pressure of a target value (the target value is the maximum back pressure value of the allowable exhaust under the rated power point of the engine), when P0 is smaller than the target value, the scheme is feasible, and when P0 is larger than the target value, the scheme is overruled.
S2, testing the mixing uniformity of NH 3;
1. urea injection accuracy verification was performed as shown in table 2 below: the deviation value allows a range of 5%;
TABLE 2
2. Punching and arranging an air duct at the rear end of the mixer, wherein the position of the air duct is shown in figure 2, and 1-9 is marked at a position around a carrier surface taking point 9 at the rear end of the mixer;
3. the original working condition point of the engine is selected,
point1:160 rpm@97Nm (Low temperature Low flow);
point2:2200rpm@80Nm (high temperature high flow);
point3:3600rpm@65Nm (high temperature low flow);
setting the injection coefficient to be 0.7 at a point of each of high, medium and low flows near the inlet temperature of the SDPF 300 ℃;
4. and intercepting the NH3 (ammonia) content of each point to calculate air flow mixing uniformity UI, and verifying the distribution uniformity of the NH3 in the urea injection process after passing through the mixer through a test, wherein the air flow mixing uniformity UI reaches a target value of 0.95 to ensure that NOX and NH3 fully react, and the mixer is preliminarily verified to be qualified, so that the next link can be entered, as shown in the figure 4.
S3, testing NOx conversion efficiency;
1. the following test operating point is selected,
point1:1020rpm@70Nm (Low temperature Low flow);
point2:2300rpm@338Nm (high temperature and high flow);
point3:940rpm@204Nm (high temperature low flow);
point4:3600rpm@50Nm (low temperature high flow);
2. when the engine is operated at each point above, the NH3 leakage value is less than 10ppm, the urea overspray coefficient is 1.2, and the following data are recorded, as shown in the following table 3, the SDPF and SCR efficiency and the total efficiency can be calculated by obtaining the DOC upstream value, the DPF downstream value and the SCR downstream NOX value;
the step of obtaining a DOC upstream value, a DPF downstream value, and an SCR downstream NOx value to calculate SDPF and SCR efficiencies and overall efficiencies includes:
TABLE 3 Table 3
S4, testing crystallization of a mixer;
the crystallization test of the mixer adopts a whole vehicle rapid test mode, so that the test cost can be saved, and the test method comprises the following steps:
1. under urban working conditions, (namely, the speed of the whole vehicle is lower than 40 km/h), the continuous injection of urea injection quantity in the interval of 0.8-1.5 is ensured;
2. the whole car runs to 500km (period shielding regeneration trigger);
3. dissecting the SDPF, cutting at a location between the mixer and the T5 base, if no crystallization, and ending the evaluation; if the mixer has crystals, the original is welded and reduced, carbon accumulation triggers regeneration, and then the crystallization is observed through dissection after the regeneration is completed;
4. if the mixer is not crystallized after DPF regeneration, the test is ended.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention.
Claims (8)
1. An aftertreatment NOx conversion efficiency bench test method for determining SDPF and SCR size, coating amount, and mixer airflow uniformity and crystallization prevention capability, the aftertreatment NOx conversion efficiency bench test method comprising the steps of;
s1, back pressure testing;
s2, testing the mixing uniformity of NH 3;
s3, testing NOx conversion efficiency;
s4, crystallizing and testing by a mixer.
2. The aftertreatment NOx conversion efficiency bench test method of claim 1, wherein,
the step S1 specifically comprises the following steps: arranging a rack, installing and debugging an engine, checking engine boundary and data, preparing three groups of post-treatment of carrier size and coating amount schemes, sequentially installing a DOC, an SDPF and an SCR on the rack engine, arranging an air duct at a corresponding position, connecting the air duct to a rack pressure tester, defining the front of the DOC as P0, the front of the SDPF as P1, the front of the SCR as P2, the rear of the SCR as P3, starting an engine heat engine until the output power of the engine is maximum, acquiring pressure points from P0 to P3 in the three groups of schemes when the exhaust flow of the engine is maximum, defining P0 as the maximum back pressure of the whole system, wherein the P0-P1 difference is the pressure drop of the DOC, the P1-P2 difference is the pressure drop of the SDPF, the P2-P3 difference is the pressure drop of the SCR, comparing the P0 size with the target value, when P0 is smaller than the target value, the scheme OK, and the scheme NG when P0 is larger than the target value.
3. The aftertreatment NOx conversion efficiency bench test method of claim 2, wherein,
the step S2 specifically comprises the following steps: checking urea injection accuracy, punching and arranging an air duct at the rear end of the mixer, respectively marking 1-9 around a position of a carrier surface taking point 9, selecting an original working point of an engine, taking one point near the inlet temperature of the SDPF at 300 ℃, taking one point for high, medium and low flows respectively, and taking an injection coefficient of 0.7, intercepting NH3 content of each point, calculating air flow mixing uniformity UI, and judging Ok when the UI is larger than 0.95.
4. The aftertreatment NOx conversion efficiency bench test method of claim 1, wherein,
the step S3 specifically comprises the following steps: selecting a plurality of test working condition points, selecting the test working condition points of engine operation, wherein the NH3 leakage value is less than 10ppm, the urea overspray coefficient is 1.2, recording data, and calculating the SDPF and SCR efficiency and the total efficiency by acquiring the NOx values of the upstream of the DOC, the downstream of the DPF and the downstream of the SCR.
5. The aftertreatment NOx conversion efficiency bench test method of claim 1, wherein,
the step S4 specifically comprises the following steps: adopting a whole vehicle rapid test mode, continuously spraying urea with the spraying quantity in the interval of 0.8-1.5, dissecting SDPF, if no crystallization exists, and ending the evaluation; if crystals exist, the original is welded and reduced, carbon accumulation triggers regeneration, after regeneration is completed, the crystallization condition is observed through dissection, if no crystals exist after DPF regeneration, and the test is ended.
6. The aftertreatment NOx conversion efficiency bench test method of claim 2, wherein the target value is a maximum allowable exhaust back pressure value at the rated engine power point.
7. The aftertreatment NOx conversion efficiency bench test method of claim 4, wherein the step of obtaining a NOx value upstream of the DOC, downstream of the DPF, downstream of the SCR to calculate SDPF and SCR efficiencies and overall efficiency comprises:
8. the method for testing the post-treatment NOx conversion efficiency bench according to claim 5, wherein the speed of the whole vehicle is below 40km/h and the whole vehicle runs to 500km in a whole vehicle rapid test mode.
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| CN117988954A (en) * | 2024-04-03 | 2024-05-07 | 江西五十铃汽车有限公司 | SCR low-temperature thawing system and method for vehicle-mounted urea |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117988954A (en) * | 2024-04-03 | 2024-05-07 | 江西五十铃汽车有限公司 | SCR low-temperature thawing system and method for vehicle-mounted urea |
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