A study on the indirect urea dosing method in the Selective Catalytic Reduction system

Brzeżański, Marek; Sala, Rafal

doi:10.1088/1757-899x/148/1/012062

Cited by 6 publications

(8 citation statements)

References 1 publication

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“…The exhaust line was not equipped with a clean-up catalyst (CUC) to oxidise excessive ammonia, and therefore, sudden release of NH 3 was noted with the gas-temperature increase. The NH 3 storage capacity of an SCR catalyst is inversely proportional to its temperature, and therefore, the greater the temperature the less NH 3 can be stored inside the catalyst [20][21][22]. The NH 3 concentration measured downstream of the SCR was greater for the gaseous urea system for both α = 0.8 and α = 1.0.…”

Section: Relying Onmentioning

confidence: 98%

“…Figure 2 presents the results of an experiment of heating up the UWS in an open vessel. It was found that urea decomposition to NH 3 and CO 2 occurred also at temperatures below 103 • C [12].…”

Section: Relying Onmentioning

confidence: 99%

“…One of the major issues is cold-start emission in the time period before light-off temperature is reached and the catalyst becomes activated. For an SCR system, the urea injection is released at 180-200 • C of exhaust gas temperature, mainly in order to prevent formation of solid urea deposits [3,4].…”

Section: Introductionmentioning

confidence: 99%

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Concept of Vaporized Urea Dosing in Selective Catalytic Reduction

2017

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This work tried to identify the influence of dosing vaporized urea solution in a selective catalytic reduction (SCR) system. In the SCR method, optimising the urea evaporation and mixing properties can significantly improve the NO x conversion efficiency in the catalyst. It can also exert a positive effect on the uniformity of NH 3 concentration distribution across the catalyst face. The concept of an electrically evaporated urea-dosing system was investigated and it was found that urea pre-heating prior to introduction into the exhaust gas is favourable for enhancing NO x removal under steady-state and transient engine operation. In the urea evaporating system the heating chamber was of a cylindrical tube shape and the urea vapour was introduced into the exhaust by means of a Venturi orifice. The concept urea dosing was only a custom-made solution, but proved to be superior to the regular dosing system operating in the liquid phase.

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Section: Relying Onmentioning

confidence: 98%

Section: Relying Onmentioning

confidence: 99%

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Concept of Vaporized Urea Dosing in Selective Catalytic Reduction

2017

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“…Further advantages of SCR are durable performance, width of performance window, reasonable cost and also available infrastructure. In order to meet current Euro VI regulations, the average NOx conversion efficiency calculated from cold and hot cycles often needs to exceed the 95% [4][5][6].…”

Section: Scr Operation Under Engine Warm Up Conditionsmentioning

confidence: 99%

The influence of engine warm up phase on nitrogen oxides emission for heavy-duty Euro VI diesel engine

2017

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Abstract. This article presents test results achieved under World Harmonized Transient Driving Cycle (WHTC) run on heavy-duty diesel engine compliant with Euro VI standard. The emission cycle was performed both for cold and hot engine start up conditions. Modal analysis of emission compounds was carried out with the focus on nitro-gen oxides (NOx) emission. The scope of the work was to assess the influence of cold start effect on selective catalytic reduction (SCR) system operation efficiency. Due to the fact that the urea injection strategy in SCR system can by activated only after certain exhaust gas temperature threshold is achieved, the NOx emission on WHTC cold start cycle is significantly greater than for the hot start one. Result analysis included also determination of time period needed for achieving the readiness of SCR system to work efficiently. The occurrence of ammonia slip emissions downstream SCR was also monitored.

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“…This correlates the catalyst efficiency to the degree of uniformity of the ammonia. Consequently, with poor ammonia distribution, the SCR system will be prone to increased urea consumption, decreased NO x reduction, and increased NH 3 slip [7][8][9]. The uniformity of ammonia entering the SCR reactor has become even more critical, since SCR technology is widely applied to light duty vehicles.…”

Section: Introductionmentioning

confidence: 99%

Ammonia Concentration Distribution Measurements on Selective Catalytic Reduction Catalysts

2018

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This work presents the methodology and accurate evaluation of ammonia concentration distribution measurements at the selective catalytic reduction (SCR) catalyst outlet cross-section. The uniformity of ammonia concentration is a crucial factor influencing overall SCR effectiveness, and it contributes to the necessity of employing a reliable test method. The aftertreatment system design (mainly its geometrical features) can be evaluated in detail. The ammonia concentration is measured at the SCR catalyst outlet at grid points covering from the center to the outer edges of the catalyst. Its execution requires the introduction of a probe hovering over the back face of the SCR. To obtain the expected accuracy, it is necessary to measure a sufficient number of points in a reasonable timeframe. In order to achieve that, a fully automatic sampling device was developed. Sample results are presented showing the capabilities of the created test stand and its importance for the design development and validation stages of SCR-based engine aftertreatment.

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A study on the indirect urea dosing method in the Selective Catalytic Reduction system

Cited by 6 publications

References 1 publication

Concept of Vaporized Urea Dosing in Selective Catalytic Reduction

Concept of Vaporized Urea Dosing in Selective Catalytic Reduction

The influence of engine warm up phase on nitrogen oxides emission for heavy-duty Euro VI diesel engine

Ammonia Concentration Distribution Measurements on Selective Catalytic Reduction Catalysts

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