Influence of Oil Age on Particulate Size Distributions with an On Line Oil Recycler from an IDI Passenger Car Diesel Engine 2004-01-2905
Mass weighted size distributions of particulate emissions as a function of oil age were investigated using a set of Anderson Impactors on an IDI passenger car engine test. This engine was fitted with an on-line bypass lubricating oil recycler aiming to extend the oil life, reduce fuel consumption and exhaust emissions. A stop start test cycle was used with a cold start each time and a typical cycle period of 2∼3 hours. The whole test was carried out for nearly 500 hours. The first 310 hours of testing were with the oil recycler fitted and thereafter the test continued with the oil recycler disconnected.
The results show that 60∼80% of mass particulates were smaller than 1.1 μm in aerodynamic diameter with the oil recycler fitted and this percentage was reduced to 40∼60% after disconnection of the oil recycler. The changes in size distribution with oil age mainly happened in the size ranges of 1.1∼0.65 μm, 0.65∼0.43 μm and <0.43 μm. There was a large peak of total particulate emissions (by smoke meter measurement) at around 100 hours of oil age. This peak was due to a significant increase in fractions of particulates smaller than 1.1 μm (increased by 80%), especially due to the increase of particulates ranging from 0.65 to 1.1 μm shown by Andersen Impactors analysis.
Particulate samples were analyzed by TGA (Thermo gravimetric Analyzer) for particulate composition. The results have shown that VOF and carbon fractions occupied 30∼50% of total particulate mass respectively. Particulate ash took up 5∼25% of total particulate mass.