Low-Load Limit in a Diesel-Ignited Gas Engine

Autor: Richard Hutter, Johannes Ritzmann, Philipp Elbert, Christopher Onder
Jazyk: angličtina
Rok vydání: 2017
Předmět:
Zdroj: Energies, Vol 10, Iss 10, p 1450 (2017)
Druh dokumentu: article
ISSN: 1996-1073
DOI: 10.3390/en10101450
Popis: The lean-burn capability of the Diesel-ignited gas engine combined with its potential for high efficiency and low CO 2 emissions makes this engine concept one of the most promising alternative fuel converters for passenger cars. Instead of using a spark plug, the ignition relies on the compression-ignited Diesel fuel providing ignition centers for the homogeneous air-gas mixture. In this study the amount of Diesel is reduced to the minimum amount required for the desired ignition. The low-load operation of such an engine is known to be challenging, as hydrocarbon (HC) emissions rise. The objective of this study is to develop optimal low-load operation strategies for the input variables equivalence ratio and exhaust gas recirculation (EGR) rate. A physical engine model helps to investigate three important limitations, namely maximum acceptable HC emissions, minimal CO 2 reduction, and minimal exhaust gas temperature. An important finding is the fact that the high HC emissions under low-load and lean conditions are a consequence of the inability to raise the gas equivalence ratio resulting in a poor flame propagation. The simulations on the various low-load strategies reveal the conflicting demand of lean combustion with low CO 2 emissions and stoichiometric operation with low HC emissions, as well as the minimal feasible dual-fuel load of 3.2 bar brake mean effective pressure.
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