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Recently, research and testing of oxygenated diesel fuels has increased, particularly in the area of exhaust emissions. Included among the oxygenated diesel fuels are blends of diesel fuel with ethanol, or E diesel fuels. Exhaust emissions testing of E diesel fuel has been conducted by a variety of test laboratories under various conditions of engine type and operating conditions. This work reviews the existing public data from previous exhaust emissions testing on E diesel fuel and includes new testing performed in engines of varied design. Emissions data compares E diesel fuel with normal diesel fuel under conditions of different engine speeds, different engine loads and different engine designs. Variations in performance under these various conditions are observed and discussed with some potential explanations suggested.

Experiments have been conducted in a laminar flow system and in a research engine to investigate the effect of additives on the combustion of gasoline-like fuels. The purpose of the laminar system is to enable rapid screening of additives to determine which, if any, have an enhancing effect on the early stages of combustion, especially under conditions of poor fuel vaporization which exist during cold-start in a spark ignited engine and which make flame propagation difficult to start and sustain. The base fuel used in the laminar and engine systems was a 9 component mixture formulated to simulate those components of gasoline expected to be present in the vapor phase in the intake system of an engine under cold-start conditions. In the laminar system, the pre-mixed, pre-vaporized fuel-air mixture is ignited and a time history of the combustion generated, hydroxyl radical chemiluminescence is recorded.

A new gas phase kinetic model using Westbrook's gas phase n-heptane model and Frenklach's soot model was constructed. This model was then used to predict the impact on PAH formation as an indices of soot formation on ethanol/diesel fuel blends. The results were then compared to soot levels measured by various researchers. The ignition delay characteristics of ethanol were validated against experimental results in the literature. In this paper the results of the model and the comparison with experimental results will be discussed along with implications on the method of incorporation of additives and alternative fuels.

This paper features the results of emission tests conducted on diesel oxidation catalysts, and the combination of diesel oxidation catalysts and water blend fuel (diesel fuel continuous emulsion). Vehicle chassis emission tests were conducted using an urban bus. The paper reviews the impact and potential benefits of combining catalyst and water blend diesel fuel technologies to reduce exhaust emissions from diesel engines.

The objective of this investigation is to verify and characterize the influence of fuel volatility on maximum liquid-phase fuel penetration for a variety of actual Diesel fuels under realistic Diesel engine operating conditions. To do so, liquid-phase fuel penetration was measured for a total of eight Diesel fuels using laser elastic-scatter imaging. The experiments were carried out in an optically accessible Diesel engine of the “heavy-duty” size class at a representative medium speed (1200 rpm) operating condition. In addition to liquid-phase fuel penetration, ignition delay was assessed for each fuel based on pressure-derived apparent heat release rate and needle lift data. For all fuels examined, it was observed that initially the liquid fuel penetrates almost linearly with increasing crank angle until reaching a maximum characteristic length. Beyond this characteristic length, the fuel is entirely vapor phase and not just smaller fuel droplets.

Despite the many years of widespread use of the BMW Intake Valve Deposit (IVD) vehicle test, relatively little has been published quantifying the variation in the test procedure. This paper presents an analysis of the variability in the BMW test. Though results from 8045 km (8K; 5,000 mile) tests rather than 16090 km (16K; 10,000 mile) are highlighted due to the size of the available database and relative sensitivity of the data, analysis suggests that variation at 8K is representative of 16K variation. A square root transformation of average deposit weight at 8K, though more cumbersome than the more common log transformation, is found to be the most appropriate way to eliminate the dependence of variation on the absolute level of deposits. Within-car variation is found to account for over half of the test-to-test variation, contradicting the notion that car-to-car differences are the dominant source of variability.

In response to industry demands for a method to qualify fuels for their intake valve deposit (IVD) forming tendencies, the Coordinating Research Council (CRC) has developed an engine dynamometer test procedure. In Phase I, the 2.3L Ford engine was chosen as the focus test engine in comparison testing with two other high volume U.S. manufactured engines.1* A two-mode dynamometer test was developed in Phases II-A & II-B and shown to discriminate among the test fuels at a 95% confidence level.2 In Phase III, both an interlaboratory study (ILS) of the two-mode dynamometer test and a vehicle fleet study were performed. The ILS was conducted to determine the repeatability and reproducibility of the test procedure and also to fulfill requirements for consideration of the test as an American Society for Testing and Materials (ASTM) standard.

Two V-6 engine types were investigated for the physical mechanisms causing combustion chamber deposit (CCD) formation. Experimental techniques and parameters such as combustion chamber deposit weights, thicknesses, thermogravimetric analysis (TGA), inductively coupled plasma (ICP) and solid state 13C nuclear magnetic resonance (NMR) were used to determine both the chemical and physical characteristics of combustion chamber deposit material. An analysis of the results indicated a mechanism for combustion chamber deposit formation consistent with that originally developed by Lepperhoff.1 Lepperhoff proposed that four layers exist in the combustion chamber deposit morphology. In contrast, the investigation described below has led to identification of only two distinct CCD morphologies.

The Coordinating Research Council (CRC) Intake Valve Deposit Group is evaluating a dynamometer based test to rank fuels for their relative tendency to form intake valve deposits. The Ford 2.3L OHC, dual spark plug equipped engine was previously selected (1*) for use in the current test program to determine optimum test conditions. A fifteen test design of experiments was constructed to reproduce intake valve deposit weight and morphology, representative of that causing field driveability problems. Test results were analyzed and a two-mode composite test was deduced from deposit weights, visual ratings, observations on the test valves and thermogravimetric analysis (TGA) results. Once the test was optimized, an additional ten test matrix was conducted to assess both repeatability and the performance of the test over a range of deposit levels. Base fuel and base fuel + two additive combinations were tested to provide a range of deposit tendencies.

Today's high technology engines are designed with fast-burn combustion chambers, swirl-generated intake ports, and improved intake manifold designs to achieve high specific power output, improved fuel economy and lower exhaust emissions. Consequently, the engine performance is greatly affected by deposit build up in these critical areas. Deposits may result in cold-start driveability problems, degradation of fuel economy, loss of power, and increase in NOx emissions. Most gasoline marketers have added polymeric additives to control deposits, though these additives have caused Octane Requirement Increase (ORI) higher than normal. Recently, a new type of chemistry has been developed to control induction system deposits and reduced octane requirement increase.