Shinya Hirota

Effect of Sulfur-free and Aromatics-free Diesel Fuel on Vehicle Exhaust Emissions using Simultaneous PM and NOx Reduction System

A new diesel after-treatment system, Diesel Particulate and NOx Reduction System (DPNR), is being developed for reducing PM and NOx emissions. We examined the effects of sulfur content in lubricants on exhaust NOx emission from DPNR catalyst, and examined the PM reduction ability using sulfur-free and aromatics-free fuel. After vehicle durability testing of 40,000 km without forced regeneration of PM and sulfur poisoning on DPNR catalyst, deterioration of DPNR was lower than using higher sulfur contents in fuel and oil. In addition to decreasing fuel sulfur, decreasing oil sulfur was also effective to maintain high NOx conversion efficiency. Although the catalyst was poisoned by sulfur in the lubricants, the influence of oil sulfur poisoning on the catalyst was lower than fuel sulfur poisoning. On the other hand, engine out PM emissions decreased by 70 % because of aromatics-free fuel. The pressure drop of DPNR did not increase during the 40,000 km vehicle durability test. Engine-out PM emissions are much lower than the PM oxidation capability of the catalyst. Thus, the combination of sulfur-free and aromatics-free fuel with the DPNR system effectively maintains low PM and NOx emissions, and reduces the frequency of regeneration due to PM accumulation and sulfur poisoning.

A new combustion concept for clean diesel system with DPNR

This article presents a new combustion concept that enables effective after-treatment. A sufficient quantity of inert gas lowers the combustion temperature and therefore suppresses soot formation. Smokeless and yet stable rich combustion can be achieved in the advanced injection timing and high EGR rate region. In the European transient test mode, this combustion concept enables a diesel engine to maintain a high catalyst bed temperature with a minor fuel penalty and to drastically reduce NOx and PM emissions.

Neues Verbrennungsverfahren fuer ein "Clean Diesel System" mit DPNR

Berichtet wird ueber ein neues, im Bereich der theoretischen Luftmenge rauchlos verbrennendes Verbrennungsverfahren, das mit einer Abgasbehandlung kombiniert, eine wirksame Massnahme fuer Dieselmotoren darstellt, um die kuenftig strenger werdenden Emissionsbestimmungen zu erfuellen und Substanzen zu reduzieren, die fuer die Erwaermung der Erdatmosphaere verantwortlich sind. Die Anwendung des Konzepts ermoeglicht bei nur geringfuegig erhoehtem Kraftstoffverbrauch eine hohe Katalysatorbetttemperatur und zeigt im europaeischen Testzyklus eine drastische Reduktion von NOx und der Partikelmasse. Beschrieben werden Testverfahren und Ergebnisse der Tests.