Particulate and Hydrocarbon Emissions from a Spray Guided Direct Injection Spark Ignition Engine with Oxygenate Fuel Blends

Abstract

The blending of oxygenated compounds with gasoline is projected to increase because oxygenate fuels can be produced renewably, and because their high octane rating allows them to be used in substitution of the aromatic fraction in gasoline. Blending oxygenates with gasoline changes the fuels' properties and can have a profound affect on the distillation curve, both of which are known to affect engine-out emissions. In this work, the effect of blending methanol and ethanol with gasoline on unburned hydrocarbon and particulate emissions is experimentally determined in a spray guided direct injection engine. Particulate number concentration and size distribution were measured using a Cambustion DMS500. These data are presented for different air fuel ratios, loads, ignition timings and injection timings. In addition, the ASTM D86 distillation curve was modeled using the binary activity coefficients method for the fuel blends used in the experiments. In general, unburned hydrocarbon emissions were reduced at low load but increased at high load for the alcohol blends. The effect on particulate emissions was dependent on the operating point: for rich mixtures the accumulation mode number concentration and count median diameter were reduced with the oxygenate blends. However, blending gasoline with oxygenates also caused the nucleation mode number concentration to increase, particularly for M85. The distillation curve modeling showed that blending oxygenates affects the distillation curve much more than would be expected from a linear blending relationship: the front end volatility is reduced a little, whilst the mid range volatility is increased significantly, particularly for methanol blends.

Characterisation of flame development with ethanol, butanol, iso-octane, gasoline and methane in a direct-injection spark-ignition engine

“…Saturation in temperature drop during injection has also been measured optically by Beyrau et al [56]. In an identical engine to that of the current study, the overall effect of saturation was a temperature difference between gasoline and ethanol at the spark-plug location at ignition timing of only ~8 K [51], i.e. well in agreement with what quoted earlier.…”

“…Analysis of data from evaporation modelling and wall heat flux measurements with the exact same liquid fuels by [39], and from charge cooling measurements with various oxygenated blends using a cold wire resistance thermometer by [51], indicated that the higher levels of charge cooling during injection with alcohol fuels can result in gradual reduction in the evaporation rate overall because the latter can be limited by fuel saturation due to the higher mass injected and/or by diffusion and mixing. Saturation in temperature drop during injection has also been measured optically by Beyrau et al [56].…”

Particulate Matter and Gaseous Emission of Hydrous Ethanol Gasoline Blends Fuel in a Port Injection Gasoline Engine

“…When the engine is working at the same load, a significant reduction of the PN distribution of the particles can be observed for the ethanol blends equated to gasoline (HE0). The results here are consistent with the PN distribution results reported in previous publications [43][44][45][46][47][48][49]62]. There are many causes leading to a decrease of the PN in the ethanol blends; compared with gasoline fuel, hydrous ethanol and anhydrous ethanol have no aromatic content, a higher laminar flame propagation speed, and a higher percentage of oxygen content.…”

“…Price et al [43] reported that anhydrous ethanol blends E85 and E30 showed the lowest PM emissions, followed by methanol blends M85 and M30 for lean fuel-air mixtures. Another investigation issued by Chen et al [44] detected a reduction of PM emissions when running E10 over gasoline under cold conditions by a coolant temperature of 20 • C. Muralidharan et al [45] noticed that the addition of anhydrous ethanol in gasoline had decreased the particle number in both steady speed and transient conditions.…”

“…A number of researchers [43][44][45][46][47][48][49] have made a significant reduction in engine-out PM emissions from gasoline engines by using anhydrous ethanol. Price et al [43] reported that anhydrous ethanol blends E85 and E30 showed the lowest PM emissions, followed by methanol blends M85 and M30 for lean fuel-air mixtures.…”