The Experts below are selected from a list of 49551 Experts worldwide ranked by ideXlab platform
Chang Sik Lee - One of the best experts on this subject based on the ideXlab platform.
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Effect of two-stage fuel injection parameters on NOx Reduction characteristics in a DI diesel engine
Energies, 2011Co-Authors: Kyusoo Jeong, Donggon Lee, Sungwook Park, Chang Sik LeeAbstract:The aim of this study was to confirm the effects of two-stage combustion on the combustion and NO x reduction characteristics of a four cylinder direct injection diesel engine. In order to analyze the combustion and emission characteristics, various injection parameters, such as injection quantity, injection timing and injection pressure were used under constant engine speed and engine load. In addition, the experimental results of two-stage combustion are compared to the single injection when injection timing is 5? BTDC. The experimental results showed that NO x emissions were significantly reduced when applying two-stage combustion. In particular, an injection strategy when the first and second injections have a same quantity, the results showed the maximum reduction of NOx emissions in this experiment. The NO x emissions were also reduced when the timing of the first injection was advanced. However, NO x emissions indicated almost similar concentration regardless of first injection timings when the first injection timing was earlier than 50? BTDC. In the case of soot emissions were slightly increased compare to the single injection cases at tested conditions. ? 2011 by the authors.
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An investigation of the effects of spray angle and injection strategy on dimethyl ether (DME) combustion and exhaust emission characteristics in a common-rail diesel engine
Fuel Processing Technology, 2010Co-Authors: S.-h. Yoon, June Pyo Cha, Chang Sik LeeAbstract:An experimental investigation was performed on the effects of spray angle and injection strategies (single and multiple) on the combustion characteristics, concentrations of exhaust emissions, and the particle size distribution in a Direct-Injection (DI) compression ignition engine fueled with dimethyl ether (DME) fuel. In this study, two types of narrow spray angle injectors (??spray = 70?? and 60??) were examined and its results were compared with the results of conventional spray angle (??spray = 156??). In addition, to investigate the optimal operating conditions, early single-injection and multiple-injection strategies were employed to reduce cylinder wall-wetting of the injected fuels and to promote the ignition of premixed charge. The engine test was performed at 1400 rpm, and the injection timings were varied from TDC to BTDC 40?? of the crank angle. The experimental results showed that the combustion pressure from single combustion for narrow-angle injectors (??spray = 70?? and 60??) is increased, as compared to the results of the wide-angle injector (??spray = 156??) with advanced injection timing of BTDC 35??. In addition, two peaks of the rate of heat release (ROHR) are generated by the combustion of air-fuel premixed mixtures. DME combustion for all test injectors indicated low levels of soot emissions at all injection timings. The NOx emissions for narrow-angle injectors simultaneously increased in proportion to the advance in injection timing up to BTDC 25??, whereas BTDC 20?? for the wide-angle injector. For multiple injections, the combustion pressure and ROHR of the first injection with narrow-angle injectors are combusted more actively, and the ignition delay of the second injected fuel is shorter than with the wide-angle injector. However, the second combustion pressure and ROHR were lower than during the first injection, and combustion durations are prolonged, as compared to the wide-angle injector. With advanced timing of the first injection, narrow-angle injectors with multiple injections could achieve low NOx levels and soot levels similar to single-injection cases.
Rolf Reitz - One of the best experts on this subject based on the ideXlab platform.
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An Experimental Investigation of the Effects of Common-Rail Injection System Parameters on Emissions and Performance in a High-Speed Direct-Injection Diesel Engine
Journal of Engineering for Gas Turbines and Power, 2001Co-Authors: P. J. Tennison, Rolf ReitzAbstract:An investigation of the effect of injection parameters on emissions and performance in an automotive diesel engine was conducted. A high-pressure common-rail injection system was used with a dual-guided valve covered orifice nozzle tip. The engine was a four-valve single cylinder high-speed Direct-Injection diesel engine with a displacement of approximately 1/2 liter and simulated turbocharging. The engine experiments were conducted at full load and 1004 and 1757 rev/min, and the effects of injection pressure, multiple injections (single vs pilot with main), and pilot injection timing on emissions and performance were studied. Increasing the injection pressure from 600 to 800 bar reduced the smoke emissions by over 50 percent at retarded injection timings with no penalty in oxides of nitrogen (NOx) or brake specific fuel consumption (BSFC). Pilot injection cases exhibited slightly higher smoke levels than single injection cases but had similar NOx levels, while the single injection cases exhibited slightly better BSFC. The start-of-injection (SOI) of the pilot was varied while holding the main SOI constant and the effect on emissions was found to be small compared to changes resulting from varying the main injection timing. Interestingly, the point of autoignition of the pilot was found to occur at a nearly constant crank angle regardless of pilot injection timing (for early injection timings) indicating that the ignition delay of the pilot is a chemical delay and not a physical (mixing) one. As the pilot timing was advanced the mixture became overmixed, and an increase of over 50 percent in the unburned hydrocarbon emissions was observed at the most advanced pilot injection timing.
P. J. Tennison - One of the best experts on this subject based on the ideXlab platform.
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An Experimental Investigation of the Effects of Common-Rail Injection System Parameters on Emissions and Performance in a High-Speed Direct-Injection Diesel Engine
Journal of Engineering for Gas Turbines and Power, 2001Co-Authors: P. J. Tennison, Rolf ReitzAbstract:An investigation of the effect of injection parameters on emissions and performance in an automotive diesel engine was conducted. A high-pressure common-rail injection system was used with a dual-guided valve covered orifice nozzle tip. The engine was a four-valve single cylinder high-speed Direct-Injection diesel engine with a displacement of approximately 1/2 liter and simulated turbocharging. The engine experiments were conducted at full load and 1004 and 1757 rev/min, and the effects of injection pressure, multiple injections (single vs pilot with main), and pilot injection timing on emissions and performance were studied. Increasing the injection pressure from 600 to 800 bar reduced the smoke emissions by over 50 percent at retarded injection timings with no penalty in oxides of nitrogen (NOx) or brake specific fuel consumption (BSFC). Pilot injection cases exhibited slightly higher smoke levels than single injection cases but had similar NOx levels, while the single injection cases exhibited slightly better BSFC. The start-of-injection (SOI) of the pilot was varied while holding the main SOI constant and the effect on emissions was found to be small compared to changes resulting from varying the main injection timing. Interestingly, the point of autoignition of the pilot was found to occur at a nearly constant crank angle regardless of pilot injection timing (for early injection timings) indicating that the ignition delay of the pilot is a chemical delay and not a physical (mixing) one. As the pilot timing was advanced the mixture became overmixed, and an increase of over 50 percent in the unburned hydrocarbon emissions was observed at the most advanced pilot injection timing.
Albert Boretti - One of the best experts on this subject based on the ideXlab platform.
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Numerical study of the substitutional diesel fuel energy in a dual fuel diesel-LPG engine with two direct injectors per cylinder
Fuel Processing Technology, 2017Co-Authors: Albert BorettiAbstract:The paper proposes a numerical study of the operation of a dual fuel diesel-Liquefied Petroleum Gas (LPG) engine featuring direct injection (DI) of both the diesel and the LPG with two separate injectors per cylinder. Aim of the study is the determination of the pilot/pre diesel fuel energy needed to operate the engine diesel-like in terms of combustion with a main injection of LPG. Computational results are proposed over the full range of speeds and loads for a 1.6 l high speed direct injection (HSDI) diesel engine. The engine is modified to accept the direct injection of the LPG fuel through the adoption of a second direct injector per cylinder. Only the opportunity of injecting the main LPG after the pilot/pre diesel injections is considered in the study. However, more complex strategies are certainly possible. The results demonstrate the opportunity to achieve diesel-like fuel conversion efficiency and torque and power outputs while replacing the most part of the diesel energy – up to 95% at medium – high loads - with the more environmentally friendly LPG. This replacement reduces the pollutants' emissions and improves the energy mix of transportation fuels.
Nicola Zamboni - One of the best experts on this subject based on the ideXlab platform.
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high throughput accurate mass metabolome profiling of cellular extracts by flow injection time of flight mass spectrometry
Analytical Chemistry, 2011Co-Authors: Tobias Fuhrer, Dominik Heer, Boris Begemann, Nicola ZamboniAbstract:Direct injection of samples on high-resolving mass spectrometers is an effective way to maximize analytical throughput and yet allow analyte discrimination in complex samples by mass-to-charge ratio. We present a platform of flow injection electrospray–time-of-flight mass spectrometry to profile small molecules in >1400 biological extracts per day at native mass resolution. We comprehensively benchmark the performance with more than 5000 injections of chemically defined standards and Escherichia coli cellular extracts obtained from miniscale cultivations. For at least 90% of tested compounds, we attain a linear response over 3 decades of concentration, interday coefficient of variation of 1500 distinct ions in each mode. The accurate mass and correlation analysis enabled one to assign with good confidence 400–800 ions to electrospray derivatives of metabolites listed in the genome-wide reconstruction of...