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Future regulations have put increased focus on reducing criteria pollutant emissions, improving engine efficiency, and ensuring these benefits are maintained for the useful life of the equipment. Engine builders continue to require improved lubricants as enablers to meet these regulatory requirements. Most recently, these improvements have focused on lower engine lubricant viscosity, improved oxidative stability, and constraints on lubricant additives that interfere with emission control system performance. This study quantifies the synergistic benefits derived from combining a renewable base oil with ultra-low ash additive technology to improve fuel economy retention (FER). These benefits derive from their inherently low volatility and high oxidative stability, which limits lubricant thickening and deposits that would otherwise degrade fuel efficiency over the life of the lubricant.

Diesel particulate filters are remarkably efficient in reducing emissions of particulate matter from heavy-duty diesel engines. However, their efficiency and performance are negatively impacted by contaminants derived from consumed engine lubricant. This accumulation of incombustible ash imparts a fuel economy penalty due to increased system backpressure and demand for more frequent regeneration events. This study documents a systematic evaluation of lubricant impacts on DPF ash loading, system performance, and fuel economy. A novel, ultra-low ash heavy-duty engine oil demonstrates significant advantages in aged systems when compared to tests using conventional lubricants. The ultra-low ash oil yields a significantly lower ash loading that is also more dense therefore offering extended DPF maintenance interval and potential for 3% fuel economy retention benefit. These advantages offer potential for significant reduction in cost to operate and maintain a DPF equipped engine.

Over the last two decades, global emission regulations have become more stringent and have required the use of more advanced fuel injection systems. This includes the use of tighter tolerances, more rapid injections and internal components actuated by weaker injection forces. Unfortunately, these design features make the entire system more susceptible to fuel contaminants. Over the last six years, the composition of these contaminants has evolved from hard insoluble debris, such as dust and rocks, to soluble chemical contaminants. Recent research by the diesel engine manufacturers, fuel injection equipment suppliers and the fuel and fuel additive industry has discovered a major source of the soluble chemical contaminant that leads to injector deposits to be derived from cost effective and commonly used additives used to protect against pipeline corrosion.

Effects of methyl ester biodiesel fuel blends on NOx emissions are studied experimentally and analytically. A precisely controlled single cylinder diesel engine experiment was conducted to determine the impact of a 20% blend of soy methyl ester biodiesel (B20) on NOx emissions. The data were then used to calibrate KIVA chemical kinetics models which were used to determine how the biodiesel blend affects NOx production during the combustion process. In addition, the impact on the engine control system of the lower specific energy content of biodiesel was determined. Both factors, combustion and controls, must be taken into account when determining the net NOx effect of biodiesel compared to conventional diesel fuel. Because the magnitude and even direction of NOx effect changes with engine load, the NOx effect associated with burning biodiesel blends over a duty cycle depends on the duty cycle average power and fuel cetane number.

Pure biodiesel fuel (B100) is typically made of fatty acid methyl esters (FAME). FAME has different physical properties as compared to mineral diesel such as higher surface tension, lower volatility and higher specific gravity. These differences lead to a larger droplet size and thus more wall impingement of the fuel during injection in the combustion chamber. This results in higher levels of fuel dilution as the oil is scraped down into the crankcase by the scraper ring. The lower volatility also makes biodiesel more difficult to evaporate once it enters the crankcase. For these reasons, levels of fuel dilution in biodiesel fueled engines are likely to be higher compared to mineral diesel fueled engines. When in-cylinder dosing is applied to raise the exhaust temperature required for the regeneration of Diesel Particulate Filters (DPF's), biodiesel dilution in the engine oil may be elevated to high levels.

A technique for rapid in situ measurement of the fuel dilution of oil in a diesel engine is presented. Fuel dilution can occur when advanced in-cylinder fuel injection techniques are employed for the purpose of producing rich exhaust for lean NOx trap catalyst regeneration. Laser-induced fluorescence (LIF) spectroscopy is used to monitor the oil in a Mercedes 1.7-liter engine operated on a dynamometer platform. A fluorescent dye suitable for use in diesel fuel and oil systems is added to the engine fuel. The LIF spectra are monitored to detect the growth of the dye signal relative to the background oil fluorescence; fuel mass concentration is quantified based on a known sample set. The technique was implemented with fiber optic probes which can be inserted at various points in the engine oil system. A low cost 532-nm laser diode was used for excitation.

In this study, a 15-L heavy-duty diesel engine and an emission control system consisting of diesel oxidation catalysts, NOx adsorber catalysts, and diesel particle filters were evaluated over the course of a 2000 hour aging study. The work is a follow-on to a previously documented development effort to establish system regeneration and sulfur management strategies. The study is one of five projects being conducted as part of the U.S. Department of Energy's Advanced Petroleum Based Fuels - Diesel Emission Control (APBF-DEC) activity. The primary objective of the study was to determine if the significant NOx and PM reduction efficiency (>90%) demonstrated in the development work could be maintained over time with a 15-ppm sulfur diesel fuel. The study showed that high NOx reduction efficiency can be restored after 2000 hours of operation and 23 desulfation cycles.

This paper outlines the development and integration of an advanced emission control system with a modern heavy-duty diesel engine for use in a series of catalyst aging tests. The project that is discussed is one of several being conducted under the Department of Energy's Advanced Petroleum-Based Fuels - Diesel Emission Control (APBF-DEC) activity. This government/industry collaboration is examining how systems of advanced fuels, engines, and emission control systems can deliver significantly lower emissions while maintaining or improving vehicle fuel economy. This project is using a Cummins ISX EGR engine (15 L) with a secondary fuel injection system to enable NOx adsorber catalyst regeneration. Development of the strategies for NOx regeneration and sulfur removal as well as integration of the emission control hardware is discussed. Performance of oven aged systems tested over transient and steady-state cycles is summarized.