Effect of Fuel Oxygen on Engine Performance and Exhaust Emissions Including Ultrafine Particle Fueling with Diesel-Oxygenate Blends

In this study, experiments were performed on a 4-stroke, 6-cylinder turbocharged, direct injection (DI) diesel engine using two oxygenated fuels blended with European auto diesel fuel (DF) to investigate the engine performance and exhaust emissions with special interest in fine particles. In the investigation, 20 vol% jatropha biodiesel was added to the DF; while 6.31 vol% diethylene glycol dimethyl ether (DGM) was added to the DF to maintain same oxygen percentage (2.26 wt%) in the blended fuels. The fuel is designated as DDGM for the DF-DGM blend and DB20 for the DF-biodiesel blend. The fine particle number was determined with a scanning mobility particle sizer (SMPS). Carbon monoxide (CO), total unburnt hydrocarbon (THC), smoke, total particulate matter (TPM) and oxides of nitrogen (NOx) were also measured. The results showed that at accumulation mode (AM) (particle size range 50-225 nm), significantly lower fine particle number were observed with both oxygenated fuel blends (DDGM and DB20) compared to the reference DF. However, the particle number was significantly higher for the DB20 in the size range of 5 to 50 nm. The TPM, which was measured by gravimetric method, was lower for both the DDGM and the DB20. DDGM and DB20 reduced CO, THC and smoke. NOx emissions were unchanged or increased slightly with the two blends.