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Four different vegetable oils, degummed soybean, once refined cottonseed, peanut and sunflower oils, were injected into a high-pressure, high-temperature environment of nitrogen. The environment was controlled to resemble, thermodynamically, conditions present in a diesel engine at the time of fuel injection. Samples were removed from the sprays of these oils while they were being injected. A sonic, water-cooled probe and a cold trap were used to collect the samples. Chemical analyses of the samples indicated that significant chemical changes occur in the oils during the injection process. The major change is the formation of low-molecular weight compounds from the C18:2 and C18:3 fatty acids.

High-speed movie films, and laser-diffraction drop sizing were used to evaluate the structure, penetration rate, cone angle, and drop size distribution of diesel sprays in a constant volume pressure vessel. As further means of evaluating the data, comparisons are made between the film measurements, and calculations from a dense gas jet model. In addition to the high-speed film data that describes the overall structure of the spray as a function of time, a laser diffraction instrument was used to measure drop size distribution through a cross-section of the spray. In terms of the growth of the total spray volume (a rough measure of the amount of air entrained in the spray), spray impingement causes an initial delay, but generally the same overall growth rate as an equivalent unimpeded spray. Agreement between measurements and calculations is excellent for a diesel spray with a 0.15 mm D orifice and relatively high injection pressures.

It is now a fairly well established fact that excessive ring and cylinder bore wear can result from the operation of an S. I. engine on neat methanol. The mechanism leading to the excessive wear were investigated using both engine and bench tests. Engine tests using prevaporized superheated methanol indicated that the wear results from reactions between the combustion products and the cast iron cylinder liner, where the presence of liquid methanol in the combustion chamber appears to be an important part of the mechanism. These reactions were investigated using a spinning disc combustor. The spinning disc combustor was used to provide a source of burning methanol droplets which were subsequently quenched on a water-cooled cast iron surface. The condensate formed on the cast iron surface was collected and analyzed for chemical composition. Infrared analysis indicated the presence of large quantities of iron formate, a reaction product of iron and formic acid.

AN INVESTIGATION OF THE EFFECTS of methanol fuel on spark ignition engine wear and deposits is being conducted using a Ford 2.3-liter engine and a modified ASTM sequence V-D test procedure. This testing indicates that at the low temperature conditions of this procedure, methanol reduces the buildup of engine deposits but greatly increases the engine wear rate. Various experiments to identify the wear mechanisms were conducted in a CLR single-cylinder engine and are reported here.

A constant volume bomb was used to determine basic combustion characteristics of isooctane, n-heptane, methanol, propane and methane. Results show that the laminar flame velocity of a quiescent homogeneous air/fuel mixture can be derived from pressure-time data in the bomb. The effects of pressure, temperature, and charge dilution on flame velocity and ignition are presented. A thermo-chemical kinetic model accurately predicted concentrations of nitric oxide during combustion and in the burned gas.

As a part of an overall project to improve the techniques for rating the ignition quality of diesel engine fuels, the experiments described in this paper involve examination of the relationship between cetane number and both the physical and chemical ignition delay times. The ignition delay times have been determined from accurate pressure histories obtained during the injection and ignition of a variety of test fuels in a constant volume combustion bomb using a quiescent, high-temperature, high-pressure air environment. The test fuels have included blends of the primary reference fuels as well as other fuels selected because of specific physical properties or chemical composition. The correlation between the cetane numbers of the fuels and various ignition delay times are examined.

One of the major problems created by the use of methanol fuels in SI engines is the high cylinder bore and ring wear rates observed during operation at low engine temperatures. The objective of the work reported in this paper was to identify the processes controlling the corrosion/wear mechanism in methanol-fueled, spark-ignition engines. Basically, three different types of experiments were performed during this project. The experiments consisted of: 1. Combustion experiments designed to identify the combustion products of methanol at various locations within a confined methanol flame; 2. Exposure studies designed to define the specific role of each of the combustion products on the corrosion mechanism; 3. Lubricant screening experiments designed to identify the mode of penetration of the oil film, and the location, in the microscale, of the surface attack. Performic acid was identified as the corrosive agent.

The specific goal of this project was to determine if there is a difference in the lube oil degradation rates in a heavy-duty diesel engine equipped with an EGR system, as compared to the same configuration of the engine, but minus the EGR system. A secondary goal was to develop FTIR analysis of used lube oil as a sensitive technique for rapid evaluation of the degradation properties of lubricants. The test engine selected for this work was a Caterpillar 3176 engine. Two engine configurations were used, a standard 1994 design and a 1994 configuration with EGR designed to meet the 2004 emissions standards. The most significant changes in the lubricant occurred during the first 50-100 hours of operation. The results clearly demonstrated that the use of EGR has a significant impact on the degradation of the engine lubricant.