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SCR System and Performance Innovation (Part 2)

The stringent standards that are set out in Euro 6/VI legislation for NOX emissions reduction will be

followed by even stricter targets for 2020 when details of the EU’s Euro 7/VII regulations are

announced. Manufacturers of vehicles, engines, and SCR systems are researching and developing

systems and components which can improve performance and efficiency, to enable them to meet

these standards.

New innovations in components are being designed continually as the industry gathers pace, and two

of the most recent advances are detailed below.

Delphi SCR ammonia (NH3) sensor technology

Due for initial production in 2012, Delphi has developed an ammonia sensor for the automotive

industry, which enables more efficient emissions control. The system allows the SCR to work at

optimized NOX conversion rates, which in turn improves fuel efficiency.

The sensor dynamically measures the content of ammonia in emissions and the system can adapt the

urea dosage accordingly. Some existing SCR technology use a timed urea dosing process; without

accurate means of measurement and control excess and residual ammonia can escape via the exhaust

stream. It is anticipated that part of the EU directives will relate to the control of ammonia slip from

SCR systems, so the monitoring of ammonia levels will soon be an essential requirement.

Source: Delphi

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IQPC GmbH | Friedrichstr. 94 | D-10117 Berlin, Germany

t: +49 (0) 30 2091 3330 | f: +49 (0) 30 2091 3263 | e: eq@iqpc.de | w: www.iqpc.de

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The ammonia sensor is placed downstream of the SCR catalyst and NOX sensor; it detects the levels of

ammonia in the exhaust stream over a range of 0-100ppm. The sensor converts the ammonia into an

electrical signal that the electronic control system uses to control the urea solution dosage.

The ammonia sensor is the first technology that enables an SCR system to have a direct closed loop

control system; allowing the optimisation of the urea dosage to be controlled by measurement of the

emissions.

Future innovation and design

SCR systems have been developed and improved upon very quickly since the EU implemented their

emissions strategy and the standards for the industry to comply with. To develop SCR systems to meet

requirements of Euro 6/VI regulations, and systems that can be used beyond 2020, manufacturers will

require more innovative designs to provide even greater efficiency.

Want to learn more about current technologies

and developments in SCR systems?

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