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Barker J.,Innospec | Snape C.,University of Nottingham | Scurr D.,University of Nottingham
SAE Technical Papers | Year: 2014

The nature of internal diesel injector deposits (IDID) continues to be of importance to the industry, with field problems such as injector sticking, loss of power, increased emissions and fuel consumption being found. The deposits have their origins in the changes in emission regulations that have seen increasingly severe conditions experienced by fuels because of high temperatures and high pressures of modern common rail systems and the introduction of low sulphur fuels. Furthermore, the effect of these deposits is amplified by the tight engineering tolerances of the moving parts of such systems. The nature and thus understanding of such deposits is necessary to both minimising their formation and the development of effective diesel deposit control additives (DCA). The focused ion beam technique coupled with time of flight secondary -ion mass spectrometry (ToF-SIMS) has the ability to provide information on diesel engine injector deposits as a function of depth for both organic and inorganic constituents. Our previous work with this novel technique is unique in that it has shown layering effects in deposits which may be due to the residual fuel either evaporating and leaving residues or being unable to keep insoluble residues in solution during the injection process. As part of our on-going work to understand the nature of field deposits, the aromatic compounds present have been investigated. To help interpret the results for the aromatic structures present, spectra of a model polycyclic aromatic hydrocarbon (PAH), coronene (C24H12), and coal tar pitch (CTP) have been used as a basis to determine the ring structure of internal diesel; deposits. This work confirms the presence of aromatic ring structures of greater than six rings in composition in injector needle carbonaceous deposits. Copyright © 2014 SAE International. Source

Barker J.,Innospec | Barker J.,Innospec Ltd | Cook S.,Innospec | Richards P.,Innospec ret.
SAE International Journal of Fuels and Lubricants | Year: 2013

Diesel fuel distilled from crude oil should contain no greater than trace amounts of sodium. However, fuel specifications do not include sodium; there is a limit of five parts per million for the amount of sodium plus potassium in fatty acid methyl esters (FAME) used as biodiesel. Sodium compounds are often used as the catalyst for the esterification process for producing FAME and sodium hydroxide is now commonly used in the refining process to produce ultra-low sulphur diesel (ULSD) fuel from crude oil. Good housekeeping should ensure that sodium is not present in the finished fuel. A finished fuel should not only be free of sodium but should also contain a diesel fuel additive package to ensures the fuel meets the quality standards introduced to provide reliable operation, along with the longevity of the fuel supply infrastructure and the diesel engines that ultimately burn this fuel. There has recently been an upsurge in reported field problems due to fouling of the fuel injection system in modern diesel engines. This can take the form of deposits in the fuel filters or within the fuel injectors themselves. Recent work proposed a mechanism whereby sodium contaminated fuel can undergo adverse reactions between the sodium compounds and fuel additives leading to the formation of material that can impede the operation of diesel fuel injectors. This paper presents new work carried out to enhance the understanding of this mechanism and demonstrates that the fate of any sodium contaminant is highly dependent on (i) the fuel additives present in the fuel (ii) the amount of water in the system, (iii) potentially the intensity of fuel/water mixing and (iv) the identity of the sodium salt involved in the reaction. This can lead to sodium accumulating in the water bottoms, forming sodium compounds that go on to plug fuel filters or which may cause injector fouling. The data found may explain the variation in engine test data regarding sodium induced fouling reported in the recent literature. Copyright © 2013 SAE International and Copyright © 2013 KSAE. Source

Barker J.,Innospec | Reid J.,Innospec | Snape C.,University of Nottingham | Scurr D.,University of Nottingham | Meredith W.,University of Nottingham
SAE International Journal of Fuels and Lubricants | Year: 2014

Since 2009, there has been a rise in deposits of various types found in diesel fuel injection systems. They have been identified in the filter, the injector tip and recently inside the injector. The latter internal diesel injector deposits (IDIDs) have been the subject of a number of recent publications, and are the subject of investigations by CRC (Central Research Council Diesel Performance Group-Deposit Panel Bench/ Rig Investigation sub panel) in the US and CEN (Committee European de Normalisation TC19/WG24 Injector Deposit Task Force) and CEC (Coordinating European Council TDFG-110 engine test) in Europe. In the literature one of the internal injector deposit types, amide lacquers, has been associated with a poorly characterised noncommercial low molecular weight polyisobutylene succinimide detergent which also lacked provenance. This work will describe a well characterised non-commercial low molecular weight polyisobutylenesuccinimide, the engine tests associated with it and the spectroscopic analysis of the needle of the resultant stuck injectors. An engine test of a commercial grade PIBSI detergent that showed no sticking will also be described. Copyright © 2014 SAE International. Source

Reid J.,Innospec | Cook S.,Innospec | Barker J.,Innospec
SAE International Journal of Fuels and Lubricants | Year: 2014

There have been reports of internal injector deposits causing problems in diesel engines in the field from 2008. Such problems manifest themselves as rough idling, power loss, high emissions, high-pressure fuel pump wear, injector sticking, internal component corrosion and engine failure. These reports coincided with the use of common rail diesel injection systems and of ultra-low sulphur fuels introduced because of emission regulation demands. The injection systems have design features that are more conducive or susceptible to deposit formation such as severe high temperature and pressure operating conditions, the tolerances of critical parts, and lower force internal component actuation. The changes to fuels have also affected the fuels ability to solubilise these deposits. The deposits formed manifest themselves in complex form in the field, often being mixtures of inorganic and organic compounds. One sub-group of this complex picture that is of current major interest is "sodium soaps", also known as sodium carboxylates. Various sources of sodium have been used to research IDID with varying results. Work with the different sodium precursors, sodium hydroxide and sodium 2-ethylhexanote (a fuel soluble sodium salt) showed that interaction with monoacid lubricity additives produced filter blocking in one case and injector sticking in the other. With the possible development of a standard engine test it is important to understand the effects of a variety of sodium sources to ensure any future test reflects field problems. Investigation of a number of sodium salts and their interactions with different acid species in fuels are described in this paper. The effect of water and other factors are also presented. Finally, a commercial deposit control additive that is effective in controlling this type of IDID is provided. Copyright © 2014 SAE International. Source

Barker J.,Innospec | Richards P.,Innospec | Pinch D.,Innospec | Cheeseman B.,Innospec
SAE International Journal of Fuels and Lubricants | Year: 2010

The fuel injection equipment (FIE) has always been paramount to the performance of the Diesel engine. Increasingly stringent emissions regulations have dictated that the FIE becomes more precise and sophisticated. The latest generation FIE is therefore less tolerant to deposit formation than its less finely engineered predecessors. However, the latest emissions regulations make it increasingly difficult for engine manufacturers to comply without the use of exhaust aftertreatment. This aftertreatment often relies on catalytic processes that can be impaired by non-CHON (carbon, hydrogen, oxygen and nitrogen) components within the fuel. Fuel producers have therefore also been obliged to make major changes to try and ensure that with the latest technology engines and aftertreatment systems the fuel is still fit for purpose. However, there has recently been a significant increase in the incidence of reported problems due to deposit build-up within vehicle fuel systems. Understanding the underlying processes leading to this problem is complicated by the coincident change in vehicle specification to meet the latest emissions limits, the change in fuel sulphur specification and the increasing use of bio-diesel. Various analytical techniques have been used to study these deposits in order to prove or disprove different hypotheses regarding the formation mechanism leading to these deposits. Temperature programmed oxidation (TPO) is an analytical technique which can be used to determine the oxidation reactivity of the carbonaceous deposits. This may yield additional information regarding the structure of the carbonaceous deposits now being encountered. This paper describes the technique as it has been applied in analysing deposits from vehicle fuel filters and high pressure fuel injectors. The results from the application of TPO to a variety of the currently encountered deposits is presented and placed within the context of other analytical work used to determine possible causes for this current spate of field problems. © 2010 SAE International. Source

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