The Influence of an On Line Oil Recycler on Emissions from a Low Emission DI Diesel Engine as a Function of Oil Age

A method of cleaning lubricating oil on line was investigated using a fine 1μm bypass particulate filter followed by a 150°C infra-red heater, to remove water and light diesel fractions in the oil. The impact of this oil recycler on diesel particulate and gaseous emissions was investigated over a 72 hour oil age. Comparison tests were undertaken without and with the recycler on a Euro 2 Perkins Phaser 180Ti, 6-cylinder, 6-litre, turbo-charged inter-cooled DI diesel engine fitted with an oxidation catalyst. Emissions were sampled from both upstream and downstream of the catalyst about every 10 hours. The tests were carried out at 2000rpm and 100kW with 473 Nm load. A stop start test cycle was used with a cold start each time and a typical test period of 2 hours. The results showed that this engine had extremely low particulate emissions and was well inside the Euro 2 emissions limits. The average value of particulate emissions downstream of the catalyst without the recycler was 0.06 g/kg fuel under the steady state test condition. The engine out particulate emissions were reduced by 17% and the particulate emissions sampled downstream of the catalyst were reduced by 29% on average using the recycler. The reduction in total particulate emissions was mainly due to the reduction in particulate carbon and unburned lube oil VOF emissions. There was no significant impact of the recycler on gaseous and smoke emissions. The reduction in particulate emissions was attributed to the 21% reduced oil consumption and improved oil quality using the recycler. The catalyst efficiencies for the total particulate mass and VOF were improved by 41% and 74% respectively using the recycler, which could be due to the reduced engine out ash emissions.