Ammonia concentration uniformity testing method for exhaust aftertreatment system

Abstract

The invention discloses an ammonia gas concentration uniformity testing method for an exhaust aftertreatment system. The exhaust aftertreatment system comprises a selective catalytic reducing agent and an ammonia gas generating device which are located at the downstream of an exhaust source. The ammonia gas concentration uniformity testing method comprises the following steps: a) sampling gas at aplurality of detection positions on a detection end surface through a sampling probe, and obtaining ammonia gas concentration values at the detection positions; and b) calculating the ammonia gas concentration uniformity value of the exhaust aftertreatment system by utilizing the following formula: UIN3 represents the ammonia gas concentration uniformity value of the exhaust aftertreatment system; CNH3, i represents the ammonia concentration value of the ith detection position; CNH3 <-> represents the ammonia concentration average value of all detection positions; Ai represents the area of the ith detection position; and sigma<n><i=1> represents the sum of the numerical values from the first detection position to the nth detection position.

Description

technical field [0001] The invention relates to a method for testing the uniformity of ammonia gas concentration in an exhaust aftertreatment system, and belongs to the technical field of engine exhaust aftertreatment. Background technique [0002] With the continuous upgrading of global emission regulations, it puts higher and higher requirements on the exhaust aftertreatment system, in which the uniformity of ammonia concentration has an important impact on the system design. [0003] The method commonly used in the prior art is the method of measuring the uniformity of ammonia gas by nitric oxide. However, the nitric oxide used in this method is not only expensive and highly toxic, but also the amount of ammonia gas is calculated indirectly by using the converted amount of nitric oxide. This test method process will introduce other factors, not direct measurement, so it has a certain impact on the accuracy of the results. Another measurement method in the prior art is to...

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Problems solved by technology

[0003] The method commonly used in the prior art is the method of measuring the uniformity of ammonia gas by nitric oxide, but the nitric oxide used in this method is not only expensive, but also highly toxic, and the amount of ammonia gas is calculated indirectly by using the converted amount of nitric oxide

This test method process will introduce other factors, not a direct measurement, so it has a certain impact on the accuracy of the results

Another measurement method in the prior art is to make holes in the same pipe section, and measure the uniformity of ammonia by changing the position of the sampling hole. However, this method has the problem of a small number of measurement points, and it is easy to distort the results.

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