We all know of the emissions issues that surround the diesel engine community. It has been a battle between the EPA, Manufacturers and Consumers for well over 20 years now. Physics.org has just broken a story that might revolutionize the industry in terms of emissions control.
Scientists at Loughborough University’s School of Mechanical, Electrical and Manufacturing Engineering have developed new technology that further converts NOx exhaust into harmless nitrogen and water. The problem with current emissions technology is that it doesn’t fully burn emissions particles a lower temperature points. The standard Selective Catalytic Reduction System (SCR) takes exhaust gas and further recirculates it through the combustion chamber to burn off larger hydrocarbon chains.
The technology works great however it does not factor in exhaust created at lower temperatures. The SCR operates best when exhaust temperatures are at or above 250 C°. The SCR works with Diesel Exhaust Fluid (DEF) which is a mixture of urea and water (ammonia mixture) that neutralizes NOx particles. The problem is that DEF fluid doesn’t operate well at lower temperatures and is subject to clogging and damaging the engine. Despite the SCR and DEF technology, when a diesel engine encounters a cold start they still eject a great deal of untreated emissions. The catalytic converter doesn’t have time to warm up and work efficiently in conjunction with the DEF. These small bursts of fuel generally occurs with short start/stop trips such as city buses, construction equipment and standby generators. The result is that excessive NOx plumes are released into the environment without being properly neutralized.
The new technology, called Ammonia Creation and Conversion Technology (ACCT), works by thermally decomposing NOx using waste exhaust heat further downstream than other after treatment components. Then the system uses the decomposed waste to reform it into less toxic compounds which can be stored at low temperature points. Once the SCR system warms up the exhaust can be further cleaned by extending the standard SCR function to include ACCT waste. The ACCT system can neutralize carbon emissions at temperatures as low as 60 C°.
The current Loughborough technology is being designed with heavy duty diesel vehicles in mind but will be fully saleable for use in all diesel vehicles. In 2015 the UK estimated that 52,000 deaths could be attributed to prolonged exposure to diesel exhaust particulate matter. The Energy Technology Institute (ETI) is on board with the project saying “ACCT has the potential to viably produce gaseous ammonia at temperatures well below 190 C°, thus enabling increased conversion efficiency and lower NOx emissions.”
Time will tell if Ammonia Creation and Conversion Technology catches on in Europe and the US. It is a given that tougher environmental legislation will continue to be implemented as emission and environmental technology continues to improve.
