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This paper summarizes a program to investigate the impact of a variety of oxygenates on diesel exhaust emissions, especially particulate matter (PM) and NOx emissions. Oxygenates have been studied at great length already and have been shown to be an effective method for reducing particulate emissions, although high cost remains a barrier to their widespread use. Our objectives were to assess whether some oxygenates could be more effective than others and why. Fourteen different oxygenates were studied. Testing was carried out primarily in a single cylinder heavy duty Caterpillar engine under high and low load conditions. Complementary testing was performed in three vehicles spanning a range of vehicle technologies. Most of the testing used a single base fuel which served as the reference fuel although some tests were also done using a newly produced ultra low sulfur automotive diesel oil (ULSADO). Larger particulate matter reductions were found at high load than at low load.

The objective of this work was to establish whether two detergent-type additives(A and B) influence the drop size and evaporation of two Diesel fuels (1 and 2) under Diesel engine conditions. Two experiments were performed: visualization of liquid and vapor fuel by the exciplex technique in a motored single-cylinder engine and measurement of the Sauter mean diameter, total drop cross sectional area and total drop volume by laser diffraction in a spray chamber. The same Diesel injector and pump system were used in the two experiments. The engine tests were carried out using a high aromatic content fuel (1) particularly suited for the exciplex studies. These studies showed that additive A yielded a lower vapor signal than additive B, which in turn gave a lower vapor signal than untreated fuel. Spray chamber results were obtained for both fuel 1 and 2. Additive A reduced the evaporation of fuel 1 whereas additive B gave a smaller and less consistent affect.