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Non-petroleum based liquid fuels are essential for reducing oil dependence and greenhouse gas generation. Increased substitution of alcohol fuel for petroleum based fuels could be achieved by 1) use in high efficiency spark ignition engines that are employed for heavy duty as well as light duty operation and 2) use of methanol as well as ethanol. Methanol is the liquid fuel that is most efficiently produced from thermo-chemical gasification of coal, natural gas, waste or biomass. Ethanol can also be produced by this process but at lower efficiency and higher cost. Coal derived methanol is in limited initial use as a transportation fuel in China. Methanol could potentially be produced from natural gas at an economically competitive fuel costs, and with essentially the same greenhouse gas impact as gasoline. Waste derived methanol could also be an affordable low carbon fuel.

Chemiluminescence imaging has been applied to a parametric investigation of diesel autoignition. Time-resolved images of the natural light emission were made in an optically accessible DI diesel engine of the heavy-duty size class using an intensified CCD video camera. Measurements were obtained at a base operating condition, corresponding to a motored TDC temperature and density of 992 K and 16.6 kg/m3, and for TDC temperatures and densities above and below these values. Data were taken with a 42.5 cetane number blend of the diesel reference fuels for all conditions, and measurements were also made with no. 2 diesel fuel (D2) at the base condition. For each condition, temporal sequences of images were acquired from the time of first detectable chemiluminescence up through fully sooting combustion, and the images were analyzed to obtain quantitative measurements of the average emission intensity.

SOF and de-NOx catalysts are applied to heavy-duty diesel trucks which are regulated by European 13 mode or Japanese 13 mode cycles. Precious metal free catalysts can reduce SOF at low temperatures without increasing sulfates up to 670C. This catalyst shows little deterioration after 400 hours of high temperature engine aging. 32% PM and 47% SOF reduction is observed under 13 mode tests when the exhaust gas temperature exceeds 700C (ECE-13 mode). This precious metal free catalyst is suitable for diesel trucks, especially trucks with natural aspirating engine whose exhaust gas temperature is very high. De-NOx catalysts with a 300-500C NOx reduction temperature window are applied to the Japanese heavy-duty test cycle (Japan 13 mode). When secondary diesel fuel is added under modes 8 to 12, (secondary fuel addition only when catalyst inlet temperature is more than 300C), 19-25% NOx can be reduced with 2-4% fuel penalty.

Diesel particulate mass emissions and their corresponding size distributions have been investigated on a diesel passenger car at steady state conditions using standard filters and a cascade impactor. These tests have been carried out at two different engine operating conditions (2100 rpm, 2.7 and 13.3 kW, respectively) corresponding to low and high exhaust gas temperatures. Two diesel fuels differing in their sulfur content (150 ppm and 2500 ppm S) have been used for these investigations. The particulate size distribution after diesel oxidation catalyst was found to be affected by the sulfur content of the diesel fuel and by the exhaust gas temperature. Interpretations of these results on a mechanistic basis are given. The diesel particulate emission studies have been extended to dynamic vehicle tests.

Research conducted at the Supercritical (SC) facility of MIT's Energy Laboratory provided visual confirmation of a single phase, homogeneous water/fuel mixture near the critical temperature and pressure of water. Equal volumes of water and diesel fuel were observed to be completely miscible, and high temperature polymerization of fuel molecules was not found. This is believed to be the first observation of a solution of diesel fuel and water. This mixture was subsequently burned under atmospheric spray conditions with very low NOx, smoke, CO, and HC. The results suggested that in-cylinder combustion in a compression ignition engine was warranted. Tests were conducted in a single cylinder, air-cooled, naturally aspirated, 3.5 horsepower Yanmar diesel engine. The compressibility of this new fuel composition necessitated a modified injector to provide smooth operation.

Long-haul and other heavy-duty trucks, presently almost entirely powered by diesel fuel, face challenges meeting worldwide needs for greatly reducing nitrogen oxide (NOx) emissions. Dual-fuel gasoline-alcohol engines could potentially provide a means to cost-effectively meet this need at large scale in the relatively near term. They could also provide reductions in greenhouse gas emissions. These spark ignition (SI) flexible fuel engines can provide operation over a wide fuel range from mainly gasoline use to 100% alcohol use. The alcohol can be ethanol or methanol. Use of stoichiometric operation and a three-way catalytic converter can reduce NOx by around 90% relative to emissions from diesel engines with state of the art exhaust treatment.

The effect of fuel additives based on the alkali metals sodium and lithium on the regeneration behaviour of diesel particulate filters was studied. For this purpose the diesel fuel was doped with the lithium and sodium salts of an aliphatic alcohol. The efficiency of these additives was assessed by comparing it to ferrocene, which is, at present, the best studied additive for particulate filter regeneration. The additives were tested on an engine test bench under steady state conditions, on a transient dynamometer and finally in a real driving test. As a result of the addition of the alkali metal salts, the ignition temperature of the soot trapped in the particulate filter is considerably lower than the ignition temperature without additives. The results with the alkali metal additives are similar to those of ferrocene or other additives with transition metals like manganese or copper.

1 In recent years Diesel DeNOx catalysts using additional hydrocarbons as reducing agents have been the focus of exhaust aftertreatment. The NOx reduction potential was often limited to 20 - 30 % in the European MVEG-A or the US FTP cycle by just adding a DeNOx catalyst on a vehicle. This result is explained by the fact that the catalyst was treated as a separate item and that the emission reduction strategy was not developed in a system approach. This paper summarizes results regarding the potential of state of the art Diesel DeNOx catalysts fitted to passenger cars and trucks when the exhaust gas system is optimized as a whole. The easiest way for a system approach is the combination of DeNOx catalysts with different working temperatures for NOx reduction. This has been demonstrated by the usage of several base metal catalysts for heavy duty applications. For passenger cars Platinum containing catalysts are strongly favored.

Blendings of methanol and diesel fuel can only be produced in form of emulsions. The stability of those emulsions strongly depends on the concentration of surface active agents. It is shown that observed changes in mixture formation of emulsions in comparison to pure diesel fuel conditions can be explained by a theory of spontaneous evaporation. Several feasible droplet models are discussed. Emulsion droplets evaporate spontaneously if the droplet temperature exceeds the superheating limit of the disperse phase. The superheating limit is only exceeded at the outer zone of the injection jet.