http://www.cnr.it/ontology/cnr/individuo/prodotto/ID137037

Analysis of crevice mechanism for UHC formation process in a CNG fuelled Diesel engine (Contributo in volume (capitolo o saggio))

Type

Prodotto della ricerca (Classe)
Contributo in volume (capitolo o saggio) (Classe)

Label

Analysis of crevice mechanism for UHC formation process in a CNG fuelled Diesel engine (Contributo in volume (capitolo o saggio)) (literal)

Anno

1996-01-01T00:00:00+01:00 (literal)

Alternative label

Cordiner S. 1, Gambino M. 2, Rocco V. 1, Unich A. 2 (1996)
Analysis of crevice mechanism for UHC formation process in a CNG fuelled Diesel engine
American Society Of Mechanical Engineers, New York (USA), 1996
(literal)

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Cordiner S. 1, Gambino M. 2, Rocco V. 1, Unich A. 2 (literal)

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New York (USA) (literal)

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ICE Vol. 26-1, pp. 33-42. (literal)

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In the 1990 US Clean Air Act Amendment natural gas has been indicated as an alternative fuel for automotive applications, so improving the interest in developing new engines and in retrofitting existing ones. Following this latter trend, at the Istituto Motori of the Italian National Research Council (CNR) in Naples a multi cylinder DI diesel engine for Heavy Duty application has been modified to be fueled with CNG and has been monitored with special attention to unburned hydrocarbons (UHC) emissions. In the present work, the experimental data have been, then, compared with the results of a numerical model developed to assess the influence of the original engine crevices geometry on HC emissions during gas fueled operation. In fact, under these particular conditions HC emissions are primarily affected by dimensions and overall geometry of crevices volume and ring pack arrangement, because the diffusion process of natural gas in the oil layer is unimportant. The crevice effects have been studied by means of a computational model obtained by linking a phenomenological cylinder approach and a 1-D model of the exhaust manifolds able to describe the main phenomena which influence the HC emissions such as flows inside and outside crevices volumes, the motion of the typical HC rich roll vortices scraped out by piston movement and, finally, the post-oxidation process in engine cylinders which significantly reduces the HC exhaust emissions. The comparison of the experimental results with the calculated ones outlines the model capability to describe the process with a good level of accuracy under different engine operating conditions. The results analysis has also proved that, as for the tested engine, a different ring pack design, specifically tailored for Natural Gas fueling operating conditions, can significantly modify the HC emissions level. (literal)

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