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Mon May 10 2021

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Solution found to AdBlue failings

31 May 17 Researchers at Loughborough University have developed technology that they say has the potential to significantly cut nitrogen oxide (NOx) emissions in diesel engines.

Jonathan Wilson (left) and Professor Graham Hargrave with ACCT
Jonathan Wilson (left) and Professor Graham Hargrave with ACCT

The Ammonia Creation & Conversion Technology (ACCT) created at the university’s School of Mechanical, Electrical & Manufacturing Engineering effectively increases the capacity of existing after-treatment systems in engines.

Currently most new diesel vehicles are fitted with a selective catalytic reduction (SCR) system to reduce NOx emissions by combustion. This system uses AdBlue to provide the ammonia required to reduce NOx into harmless nitrogen and water.

The drawback is that AdBlue only functions well at high exhaust temperatures, typically in excess of 250°C. Therefore, the SCR does not necessarily operate at all engine conditions, for example, during short, stop-start working such as on construction sites.

Furthermore, at these lower temperatures AdBlue can result in exhaust blockages and engine damage.

ACCT is an AdBlue conversion technology that uses waste energy to modify AdBlue to work effectively at these lower exhaust temperatures. By extending the temperature range at which SCR systems can operate, the new technology enhances existing NOx reduction systems.

Loughborough’s Professor Graham Hargrave, a specialist on the optimisation of combustion engines, developed the technology with research associate Jonathan Wilson.

“We are all familiar with the ‘cold start’, where diesel vehicles spew out plumes of toxic emissions before their catalytic systems are up to temperature and able to work effectively,” explained Prof Hargrave.

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“Unfortunately with many vehicles doing short stop/start journeys, such as buses and construction vehicles, many engines never reach the optimal temperature required for the SCR systems to operate efficiently. The result is excessive NOx being released into the urban environment, especially in large cities.

“Our system enables the SCR systems to work at much lower temperatures – as low as 60oC. This means that the NOx reduction system remains active through the whole real world driving cycle, leading to significant reductions in tailpipe emissions.”

Currently the Loughborough technology has been tailored for HGVs but the same system is fully scalable for use in all diesel vehicles, the developers say.

“No viable alternative to the diesel engine currently exists for the heavy duty market and is going to be in use for many more years,” added Jonathan Wilson. “Systems are needed now that tackle NOx emissions, to help reduce the number of air pollution related deaths and enable vehicle manufactures to meet the ever reducing emissions targets set by the government. ACCT is the answer.”

Chris Thorne, chief technology officer for heavy duty vehicles at the Energy Technology Institute's (ETI) attested to the invention’s potential: “Based upon a brief review, the ACCT technology recently developed by Loughborough has the potential to viably produce gaseous ammonia at temperatures significantly below 190°C, thus enabling increased conversion efficiency and lower NOx emissions.

“It is likely that emissions legislation will become even tighter and vehicle manufacturers will need to develop technologies to address this, and it is our belief that the ACCT technology should be further developed as it could help address this challenge in the real world.”

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