Diesel Emissions Improvement by RME in a High Boost and EGR Single Cylinder Engine

The biomass fuel is expected to solve the global warming due to a carbon neutral. A rapeseed oil methyl ester (RME) as biomass fuel was selected, and also a low sulfur diesel fuel is tested as reference fuel in this study. The experiments were carried out to improve diesel emissions and engine performance using high boost and high rate EGR system and a common rail injection system in a single cylinder engine.

The diesel emissions and engine performance have been measured under the experimental conditions such as charging boost pressure from atmospheric pressure to 401.3kPa maximum and changing EGR rate from 0% to 40% maximum. RME contain about 10 mass % oxygen in the fuel molecule. Furthermore, RME does not contain aromatic hydrocarbons in the fuel. Due to these chemical properties, RME can be used at 40% high EGR condition. It is effective to use high-pressure fuel injection such as 150MPa in order to reduce smoke at engine out and using an oxidation catalyst is effective to reduce BSHC and PM at exhaust pipe, though the higher temperature of RME boiling point compared to that of diesel fuel. From the experimental results, RME can reduce BSNOx and PM in comparison with a low sulfur diesel fuel in the case of increasing EGR rate and with oxidation catalyst, unless there was deterioration of smoke.