Injection Nozzle Coking Mechanism in Common-rail Diesel Engine

Ikemoto, Masato; Omae, Kazuhiro; Nakai, Kyoko; Ueda, Reiko; Kakehashi, Nobuhisa; Sunami, Kazuo

doi:10.4271/2011-01-1818

Cited by 38 publications

(20 citation statements)

References 11 publications

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“…This is further suggested by the slight decrease in zinc signal at the outlet where the carbon signal is enhanced due to increased deposit build up (clearly a thicker deposit as the Fe signal was minimal). The range in the composition of nozzle deposits, with decreasing concentration of zinc towards the outlet, due to this bulbous more carbonaceous deposit becoming dominant is in agreement with previous observations of sectioned minisac type injectors [8] [15].…”

Section: Deposit Chemistrysupporting

confidence: 78%

“…Furthermore, the closure of each nozzle in the DW10B VCO injector versus the constantly open minisac will have led to different mixes of residual fuel and combustion chamber gas from which the deposits can grow. It has been suggested that enhanced diesel injector nozzle fouling through the inclusion of zinc salts in the fuel relies on precipitation of the zinc salt in the hot diesel injector as the primary fouling mechanism [8,15]. The evidence from the sectioned DW10B injector of uniform deposits with consistent zinc content supports this theory.…”

Section: Deposit Chemistrysupporting

confidence: 70%

“…Additionally the high temperatures in the engine, when thermally conducted along the injector, will likely act as an accelerant to deposit formation. It is generally observed that higher engine temperatures increase deposit severity [6,8,9,12].…”

Section: Deposit Morphologymentioning

confidence: 99%

“…The deposits are thought to be formed as a remnant of the combustion process, as a result of residual fuel, particulates and vapours, and this would explain why the layers are thicker and more developed towards the outlet, where these components are all readily available [8,9]. Deposition has occurred all the way into the minisac of the CD DU injector.…”

Section: Deposit Morphologymentioning

confidence: 99%

“…Previous examination of sectioned minisac type diesel injectors indicated that deposits range in composition, depending on the temperature at which the deposit formed [8]. In analysis of a cross-sectioned diesel injector from a medium-duty truck engine, Tang et al showed the deposit composition changed through the cross-section; in particular zinc appeared to be concentrated close to the metal surface of the nozzle and the deposit became more carbonaceous away from the metal interface as it grew thicker [9].…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

A Chemical and Morphological Study of Diesel Injector Nozzle Deposits - Insights into their Formation and Growth Mechanisms

Rounthwaite

Williams

McGivery

et al. 2017

SAE Int. J. Fuels Lubr.

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Modern diesel passenger car technology continues to develop rapidly in response to demanding emissions, performance, refinement, cost and fuel efficiency requirements. This has included the implementation of high pressure common rail fuel systems employing high precision injectors with complex injection strategies, higher hydraulic efficiency injector nozzles and in some cases <100µm nozzle hole diameters. With the trend towards lower diameter diesel injector nozzle holes and reduced cleaning through cavitation with higher hydraulic efficiency nozzles, it is increasingly important to focus on understanding the mechanism of diesel injector nozzle deposit formation and growth. In this study such deposits were analysed by cross-sectioning the diesel injector along the length of the nozzle hole enabling in-depth analysis of deposit morphology and composition change from the inlet to the outlet, using state-of-the-art electron microscopy techniques. Deposits produced in the injector nozzles of the industry standard fouling test (CEC F-98-08 DW10B bench engine) were compared with those formed in a vehicle driven on a chassis dynamometer, using a drive cycle more representative of real world vehicle conditions, to explore the effects of differing drive cycles and engine technologies. Fouling in all tests was accelerated with the addition of 1ppm zinc neodecanoate, as specified in the CEC DW10B test. This in-depth characterisation revealed a complex multi-layered system of deposits inside the diesel injector nozzle. Through analysing these layers the mechanisms enabling the initial deposit formation and growth can be postulated.

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Section: Deposit Chemistrysupporting

confidence: 78%

Section: Deposit Chemistrysupporting

confidence: 70%