Highly Efficient Emissions Aftertreatment Systems for Low-emission Combustion Engines
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Highly Efficient Emissions Aftertreatment Systems for Low-emission Combustion Engines © HJS Emission Technology
Diesel engines with modular and integrated exhaust aftertreatment systems show pollutant emissions in the range of the detection limit. With the Swirl Cap, HJS has now compactly integrated the SCR mixing section into the output module of a DOC or DPF. Pollutant emissions are virtually eliminated under all operating conditions, including immediately after cold starts.
MOTIVATION
With the current EU Stage V emissions legislation in Europe [1] and the widespread installation of a combination of a DOC, a full-flow DPF and an SCR catalyst emissions from agricultural and construction machinery have been reduced dramatically [2]. In addition to a further reduction in the limit values, a higher weighting of cold-start emissions is under discussion. This tightening of the legisla-
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tion is consistent with the demand for clean air and compliance with NO2 emissions limits in city centers [3]. Batteryelectric powertrains can replace Internal Combustion Engines (ICEs) in machines with short operating times and low ener gy consumption, but they have major disadvantages when it comes to machines with continuously high power requirements. ICE powertrains with pollutant emissions in the range of the detection limit (zero impact), which in the next
phase of development will be powered by CO2-neutral fuels, are far more productive for such applications. As seen in FIGURE 1, highly efficient exhaust aftertreatment systems are the key technology here. DEVELOPMENT FOCUS
In addition to an almost complete reduction of pollutants for exhaust gas temperatures > 250 °C in the SCR catalyst, cold-start emissions and low-load realworld operation are particularly relevant for a genuine zero-impact powertrain. This drives functional requirements such as lowest possible exhaust backpressures and enhanced catalysts with high lowand high-temperature activity even for high space velocities and minimal thermal losses in the warm-up phase. To ensure a high NOx conversion rate, it is crucial to supply the SCR catalyst with sufficient ammonia (NH3) even when
AUT H O R S
Dr.-Ing. Christoph Menne is Managing Director at HJS Emission Technology GmbH & Co. KG in Menden (Germany).
Dipl.-Ing. Klaus Schrewe is Head of the Development Division at HJS Emission Technology GmbH & Co. KG in Menden (Germany).
exhaust temperatures are low. An ex haust aftertreatment system design that is as compact and modular as possible is crucial for the wide variety of non-road applications. Based on these functional requirements, HJS has defined two main development priorities: – Passive and active thermal management measures are crucial to enable catalyst to perform well for cold-start and real-world operating conditions. –– Besides sufficient temperature levels of the catalyst it is essential to
Dr. Bernd Maurer is Development Engineer in the Technology Development Department at HJS Emission Technology GmbH & Co. KG in Menden (Germany).
maintain a
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