Ricardo claims to have achieved a significant milestone in its push to develop a cleaner diesel engine.
The company has now demonstrated that a diesel engine it has under development can meet the US Federal Tier II Bin 5 standard for emissions without the use of NOx aftertreatment.
The research is continuing with the aim of demonstrating clean diesel technology capable of achieving US Super Ultra-Low Emission (SULEV) and Tier II Bin 2 requirements.
Started in late 2005, the early stages of the research project focused on developing technologies to deliver engine-out exhaust emissions without NOx aftertreatment that achieve the Tier II Bin 5 US emission requirements, delivering NOx levels approximately one-sixth those of Euro 5.
These technologies include advanced air handling systems, two-stage series-sequential turbocharging, advanced exhaust gas recirculation, and application of closed-loop cylinder pressure-based engine controls.
In parallel, an exhaust aftertreatment system has been developed which combines a diesel oxidation catalyst (DOC) and diesel particulate filter (DPF). When combined with engine optimisation, this has delivered Tier II Bin 5 emission levels without NOX aftertreatment.
Further research has established the feasibility of adding a lean NOX trap (LNT) into the system. And, through simulation and test results, early predictions indicate that the diesel will be capable of meeting the requirements of US SULEV/Tier II Bin 2 emissions standards, thereby achieving NOx levels less than one-tenth of the Euro 5 levels.
‘ While there clearly remain many challenges in translating this research into high volume production solutions, this achievement provides significant new confidence in the future viability of the clean diesel in North America,’ said Dean Harlow, president of Ricardo.