The Effect of Cycle-to-Cycle Variations on the NOx-SFC Tradeoff in Diesel Engines under Long Ignition Delay Conditions

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Event
13th International Conference on Engines & Vehicles
Authors Abstract
Content
Cycle-to-cycle variations in internal combustion engines are known to lead to limitations in engine load and efficiency, as well as increases in emissions. Recent research has led to the identification of the source of cyclic variations of pressure, soot and NO emissions in direct injection common rail diesel engines, when employing a single block injection and operating under long ignition delay conditions. The variations in peak pressure arise from changes in the diffusion combustion rate, caused by randomly occurring in-cylinder pressure fluctuations. These fluctuations result from the excitation of the first radial mode of vibration of the cylinder gases which arises from the rapid premixed combustion after the long ignition delay period. Cycles with high-intensity fluctuations present faster diffusion combustion, resulting in higher cycle peak pressure, as well as higher measured exhaust NO concentrations. In this study the effects of pressure fluctuations on the NOx-specific fuel consumption (SFC) tradeoff are determined. The investigation is performed on a single-cylinder heavy-duty diesel engine, and focuses on the variation of injection parameters (injection timing and pressure) under constant, long ignition delay conditions. Single-cycle NO concentrations are measured using a fast-NO analyzer placed near the exhaust valve, whereas the indicated SFC is determined from the measured cylinder pressure. The results show that the presence of pressure fluctuations is not beneficial for the NOx-SFC tradeoff, with the cycles showing higher fluctuation intensities leading to higher emission levels for constant indicated SFC.
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DOI
https://doi.org/10.4271/2017-24-0100
Pages
10
Citation
Kyrtatos, P., Zivolic, A., Brueckner, C., and Boulouchos, K., "The Effect of Cycle-to-Cycle Variations on the NOx-SFC Tradeoff in Diesel Engines under Long Ignition Delay Conditions," SAE Int. J. Engines 10(5):2451-2460, 2017, https://doi.org/10.4271/2017-24-0100.
Additional Details
Publisher
Published
Sep 4, 2017
Product Code
2017-24-0100
Content Type
Journal Article
Language
English