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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 formation of Nitric oxide (NO) in a Diesel engine has been studied as a function of crank angle through-out the whole combustion cycle, using the Laser Induced Fluorescence (LIF) technique. Measurements were performed in an optically accessible one-cylinder, two-stroke, direct injection Diesel engine. The engine was operated in steady state at different loads and compression ratios. A tunable ArF excimer laser beam was used to excite the NO molecules in the D2∑+(v′=0) ← X2Π(v″=1) band at 193 nm. Dispersed fluorescence spectra allowed to discriminate between NO and interfering oxygen fluorescence. From the spectra, a relative measure for the NO density present in the probed volume of the cylinder was obtained. This density was transformed into an in-cylinder NO content, taking into account the changes in laser intensity, pressure, temperature and volume during the stroke.

The objective of this work was to investigate the effect of fuel properties on atomization and spray structure of a diesel engine fuel injector, based on PDA (Phase Doppler Anemometry) measurements. Few studies have addressed the question of how fuels affect droplet size and spray structure. Thus three diesel fuels were selected: two which broadly represent the range of base fuel properties seen in current European fuels and a third which contained a high treat rate of a detergent-type additive, which, being polar, may have some surface effects which could impact spray formation. This range of diesel fuels was injected into a high pressure and temperature wind tunnel, using a single hole Bosch injector. Phase Doppler Anemometry (PDA) was used to measure the diameter, velocity and arrival time of spray droplets passing through numerous radial and longitudinal positions in the spray.