Formation and Removal of Injector Nozzle Deposits in Modern Diesel
                    Cars

Williams, Rod; Smith, Alastair G.; Buttery, Ian

doi:10.4271/2013-01-1684

Cited by 19 publications

(14 citation statements)

References 4 publications

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“…The sediment amounts formed on the new generation diesel injectors are much more than gasoline injectors because of diesel fuel nature and high temperature operating mode of the diesel engines and smaller holes of their injectors. In most studies (Arpaia et al 2009;Mancaruso et al 2013;Risberg et al 2013;Smith and Williams 2015;Tang et al 2009;Williams et al 2013), some techniques for accelerating the injector deposition (such as adding zinc to diesel fuel) have been used in order to investigate its destructive effects.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study of the Coking Phenomenon Effects on Spray Characteristics of the High Pressure Diesel Injector

Sheykhvazayefi¹,

Gorji-Bandpy²,

Hajialimohammadi³

et al. 2020

JAFM

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The novel diesel engines with advanced fuel injection systems are equipped with solenoid injectors comprising multiple small nozzle orifices which makes considerable improvement in fuel spray characteristics and engine performance along with providing high pressure fuel injection system. On the other hand, poor fuel quality, impurities and heavy metal elements in the diesel fuel, and high temperature medium in the diesel engines combustion chamber lead to remarkable deposits formation in the small holes of the nozzle. In addition, it results in partial or complete nozzle hole obstruction which is called injector nozzle coking having detrimental effects on discharged spray ideal behavior and proper engine performance. In this work, the analysis of coking phenomenon influences on diesel spray macroscopic characteristics have been done. Initially, the coked injectors with different time operation and deposit amounts are prepared under experimental and specific operating conditions. Then, the images recorded from the spatial and temporal evolution of a diesel spray in various injection and chamber pressures, are processed through the extended code in MATLAB software in order to analyze discharged fuel spray characteristics. The SCHLIEREN Imaging Method with high speed camera has been utilized in a CVC (constant volume chamber) without combustion. Non-Destructive Electron Microscopy Method of SEM (Scanning Electron Microscope) imaging was utilized in order to analyze sediments quantity and construction changes during injector working in the real engine conditions. The results show that, sediments occupy 20, 40, 75 and 90% of the total hole opening surface, respectively in the injectors with 300, 700, 800 and 900 hours operating time. By increasing the injector operation time and accumulated sediment amount on the nozzle, the discharged injector spray exhibits a more inappropriate behavior. Moreover, The Results revealed that coking has considerable effects on the spray tip penetration at low injection pressures. As injection pressure increases, the decreasing rate of the penetration length alleviates gently. In other words, at high injection pressures (1500 bar and higher) the penetration length has minor drop compared with non-utilized injectors even at 900 hours operating time, but the spray projected area can be reduced up to 28% in high chamber pressures.

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Section: Introductionmentioning

confidence: 99%

Experimental Study of the Coking Phenomenon Effects on Spray Characteristics of the High Pressure Diesel Injector

Sheykhvazayefi¹,

Gorji-Bandpy²,

Hajialimohammadi³

et al. 2020

JAFM

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“…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%

“…This vehicle was driven on a chassis dynamometer (CD) following a test procedure designed to evaluate fouling in vehicles [6]. The test cycle employed on the CD was developed to be more representative of driving conditions found in real vehicle operation than that specified in the DW10B engine test.…”

Section: Sources Of Injectorsmentioning

confidence: 99%

“…Similarly fouling accelerants have been applied to other test procedures designed to be more representative of real world conditions in terms of vehicles and drive cycle, thus providing alternative testing platforms with which to rate deposit formation and control characteristics of fuels and additives. Additionally, fouling tests across a range of vehicles have shown the potential for injector nozzle deposits to detrimentally effect BSFC in chassis dynamometer tests [6] [7].…”

Section: Introductionmentioning

confidence: 99%

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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.

Self Cite

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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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“…In addition, coked nozzles exhibit larger cyclic variations of cylinder peak pressure than clean nozzles, even though the visible spray pattern appears unchanged [4]. Ultimately, external deposits lead to a deterioration of combustion efficiency, a decrease in rated power and cause a rise in brake specific fuel consumption [5]. The formation of coking deposits is driven by higher temperatures at the nozzle and in its spray holes, while cavitation inside the nozzle serves as an inhibitor to their built-up [6] [7].…”

Section: Introductionmentioning

confidence: 99%

Characteristics of Control Piston Motion and Pressure Inside of a Common Rail Diesel Injector

Schuckert

Wachtmeister

2017

Proceedings ILASS–Europe 2017. 28th Conference on Liquid Atomization and Spray Systems

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In this paper the experimental setup of a commercial third generation common rail solenoid injector with advanced measurement is discussed. The motion of the control piston is measured while performing injection rate investigations using a purpose-built injection rate analyzer of the Bosch type. At the same time fuel pressure in the feed line of the nozzle is gauged and contrasted to fuel pressure before the inlet connector. In contrast to the steady rise observed in a similar study, the motion of the control piston in this case is characterized by a changing gradient in the upward movement. The magnitude of the negative displacement of the upper part of the control piston due to the fuel pressure in the control volume corresponds to simulation results of the elastic deformation. Pressure before the inlet connector and pressure in the feed line exhibit a similar course with a difference in magnitude that is rising with higher rail pressures. Precisely with the end of injection the pressure in the feed line surpasses the pressure before the inlet connector for a short moment. The measurement results of control piston motion and pressure inside the injector are of particular interest because these parameters are to serve as indicators for changes in the injection rate caused by phenomena like wear and coking amongst others.Keywords common rail injector, injection rate measurement, eddy current sensor, control piston motion, feed line pressure IntroductionThe act of injecting diesel not only supplies the fuel for the subsequent combustion, but at the same time also determines the start of combustion with the diesel combustion process. This is unlike the gasoline combustion process, where injection and ignition are separated. Thus, the injection process is a major influence factor to consider in order complying with the increasingly severe emission legislation for compression ignition engines. Furthermore, alterations affecting the injection parameters of common rail diesel injectors that emerge during engine operation have been identified. Research efforts focused on brittle external nozzle deposits mostly consisting of carbon referred to as coking. In recent years, a type of sticky, the so-called internal diesel injector deposits (IDID) have appeared in production engines and caused needles to stick in common rail diesel injectors. It has been observed that the addition of certain additives (polyisobutylene succinimide; PIBSI) to diesel fuel, which are to inhibit the formation of coking deposits, have the side effect of contributing to the formation of IDID [1] [2]. These PIBSI react with acids that emerge from fatty acid methyl ester (FAME), a biodiesel supplement to common diesel in the European Union, to form IDID. Other major factors that influence the occurrence of IDID are high fuel temperatures and the content of aromatics and oxygen in the diesel fuel [2]. Deposits on the nozzle tip and inside the nozzle holes due to coking cause numerous adverse effects. It is proven that this type of deposits exe...

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Formation and Removal of Injector Nozzle Deposits in Modern Diesel Cars

Cited by 19 publications

References 4 publications

Experimental Study of the Coking Phenomenon Effects on Spray Characteristics of the High Pressure Diesel Injector

Experimental Study of the Coking Phenomenon Effects on Spray Characteristics of the High Pressure Diesel Injector

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

Characteristics of Control Piston Motion and Pressure Inside of a Common Rail Diesel Injector

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