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Possibilities to Reduce Influence of Compression Ratio on Total Hydrocarbon Emission from a D.I. Diesel Engine
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Abstract
The compression ratio of a direct-injection Diesel engine was decreased by steps. The total hydrocarbon emissions and various component stresses were measured.
HC emissions rise hyperbolically when compression ratio decreases. The curve can be shifted towards lower CR values by increasing load, charge air pressure or charge air temperature. The measured ignition delays are in every respect in significant agreement with the HC emissions, leading to the hypothesis that excessive quantities of the injected fuel are deposited on the wall when the compression ratio decreases. If the calculated paths of the whole jet up to the beginning of combustion are put in relation to the HC emissions there result critical ranges for the jet tips beyond which the emissions increase drastically.
By that the conditions for reducing the influence of compression ratio can be considered for granted. For example any possibility to reduce the ignition delays is suitable for decreasing emissions since by that the range of the injection jets diminishes accordingly. Beside the influence of various engine specific parameters, the influences of higher charge air pressure, exhaust gas recirculation, exhaust back pressure and intake throttling were investigated in this paper.
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Sprogis, W., "Possibilities to Reduce Influence of Compression Ratio on Total Hydrocarbon Emission from a D.I. Diesel Engine," SAE Technical Paper 831293, 1983, https://doi.org/10.4271/831293.Also In
References
- Syassen O. “Zukunftsaussichten der zweistufigen Aufladung für Zweiund Viertakt--Großdieselmotoren.” Motortechnische Zeitschrift (MTZ) Stuttgart 37 November 1976
- SAE Recommended Practice Continuous Hydrocarbon Analysis of Diesel Exhaust SAE J 215
- Sprogis W.A. “Der Einfluß des Verdichtungsverhältnisses auf die Gesamtkohlen-wasserstoff-Emission eines direkteinspritzenden Dieselmotors.” Thesis University of Hannover Germany 1982
- Greeves G. Khan I.M. Wang C.H.T. Fenne I. “Origins of Hydrocarbon Emissions from Diesel Engines.” SAE-Paper 770259
- Hardenberg H.O. Hase F.W. “An Empirical Formula for Computing the Pressure Rise Delay of a Fuel from its Cetane Number and from the Relevant Parameters of Direct-Injection Diesel Engines.” SAE-Paper 790493
- Pischinger R. Cartellieri W. “Combustion System Parameters and Their Effect Upon Diesel Engine Exhaust Emissions.” SAE-Paper 720756