Search Results

Internal Diesel Injector Deposits (IDID) in compression ignition engines have been widely studied in the past few years. Published results indicate that commonly observed IDID chemistries may be replicated using full-scale engine tests and subsequently fuel injection equipment (FIE) operated on non-fired electric motor driven test stands. Such processes are costly, complex and by nature can be difficult to repeat. The next logical simplification is to replicate IDID formation using laboratory-scale apparatus that recreate the appropriate chemical reaction process under well controlled steady state conditions. This approach is made more feasible by the fact that IDID, unlike nozzle hole coking, are not directly exposed to gasses involved in the combustion process. The present study uses an instrument designed to measure thermal oxidation stability of aviation turbine fuels to successfully replicate the deposit chemistries observed in full-scale FIE.

Retrofitting current and legacy diesel vehicles with Diesel Particulate Filters (DPFs) and associated aftertreatment technology has long been an option to enable vehicles with older engines to meet specific regional emissions legislation. A major positive is the ability for enforced vehicle retrofitting to have an immediate impact on the local air quality in urban environments without vehicle owners having to purchase new vehicles. Retrofit in China in comparison to Europe, for example, is in its relative infancy as China's emission legislation rapidly moves towards adopting European like limits whilst available diesel fuel continues to have variable sulphur concentrations. This paper details the results from a two phase retrofit-study conducted to investigate the ability for Fuel Borne Catalyst (FBC) technology to regenerate DPFs in retrofitted Light Duty (LD) vehicles in China.

Internal Diesel Injector Deposits (IDIDs) have been known for some time. With the latest powertrains becoming ever more sophisticated and reliant on efficient fuel delivery, the necessity for a continued focus on limiting their formation remains. Initial studies probed both carbonaceous based/ashless polymeric and sodium salt based IDIDs. The reported occurrence of the latter variety of IDID has declined in recent years as a result of the removal of certain additives from the diesel distribution system. Conversely, ashless polymeric based deposits remain problematic and a regular occurrence in the field.

The use of Diesel Particulate Filters (DPFs) as a means to meet ever more stringent worldwide Particulate Matter/ Particle Number (PM/ PN) emissions regulations is increasing. Fuel Borne Catalyst (FBC) technology has now been successfully used as an effective system for DPF regeneration in factory and service fill as well as retrofit applications for several years. The use of such a technology dictates that it be stable in long term service and that it remains compatible with new and emerging diesel fuel grades. In order to ensure this, neat additive stability data have been generated in a very severe and highly transient temperature cycle and a large selection of current (Winter 2012) market fuels have been evaluated for stability with this FBC technology. Results indicate that FBC technology remains suitable. The incidence of Internal Diesel Injector Deposits (IDIDs) is increasing, particularly for advanced FIE systems.

The high frequency reciprocating rig (HFRR) was developed in the early 1990s as a test method to assess diesel fuel lubricity in order to provide wear protection for fuel injection pumps. This was necessary in response to the many field failures that occurred following the introduction of ultra-low sulphur diesel in Sweden. The prevalent fuel injection equipment (FIE) technology at this time utilised rotary pumps capable of reaching maximum fuel pressures of ∼650 bar in systems for direct injection engines. The continued drive for efficiency led to many changes in FIE technologies, materials and pressures. Modern high pressure common rail pumps reach significantly higher pressures, with 2200 bar available today and pressures up to 3000 bar discussed in the industry.

Modern diesel Fuel Injection Equipment (FIE) systems are susceptible to the formation of a variety of deposits. These can occur in different locations, e.g. in nozzle spray-holes and inside the injector body. The problems associated with deposits are increasing and are seen in both Passenger Car (PC) and Heavy Duty (HD) vehicles. Mechanisms responsible for the formation of these deposits are not limited to one particular type. This paper reviews FIE deposits developed in modern PC and HD engines using a variety of bench engine testing and field trials. Euro 4/ IV and Euro 5/V engines were selected for this programme. The fuels used ranged from fossil only to distillate fuels containing up to 10% Fatty Acid Methyl Ester (FAME) and then treated with additives to overcome the formation of FIE deposits.

Diesel fuel is a major grade in the Thai market used in transportation of goods and in most light duty vehicles. Over the last fifteen years the quality of this fuel has continuously increased. This is one of the major factors that have allowed a substantial improvement in air quality. The improvement in diesel fuel quality has been achieved by using a mix of measures, some well known like reduction in sulphur content, whilst others are unique to this market. Since 1993, in Thailand it has been mandatory to use a diesel detergent. This has ensured best driveability and lowest emissions due to the control of injector deposits. This measure was unique in the world and although not mandatory any longer, this market has a large proportion of automotive diesel treated with this type of additive. Another action has been the evaluation of Palm Oil Methyl Ester (PME) and its potential impact in the market. However, experience with PME is limited.

This paper looks at the underlying fundamentals of diesel fuel system lubrication for the highly-loaded contacts found in fuel injection equipment like high-pressure pumps. These types of contacts are already occurring in modern systems and their severity is likely to increase in future applications due to the requirement for increased fuel pressure. The aim of the work was to characterise the tribological behavior of these contacts when lubricated with diesel fuel and diesel fuel treated with lubricity additives and model nitrogen and sulphur compounds of different chemical composition. It is essential to understand the role of diesel fuel and of lubricity additives to ensure that future, more severely-loaded systems, will be free of any wear problem in the field.

A variety of additives are used in automotive diesel fuel to meet specification limits and to enhance quality. For example, lubricity additives and cold flow improvers are used to meet specifications whilst diesel detergents further enhance the quality of the fuel. Recently, several premium fuels that use high levels of diesel detergents and, in some cases, cetane improver have been introduced in the market place. The purpose of the work carried out was to assess the potential impact of these additives on vehicle performance. In order to do this, a fuel free of any additive was treated with very high levels of all the diesel fuel additives currently used to meet specification limits and to enhance diesel fuel performance. A common rail vehicle using an advanced common rail system was then driven in a controlled manner for 50.000 km. Emissions and driveability tests took place at 0km to provide baseline data.

1 High precision high pressure diesel common rail fuel injection systems play a key role in emission control, fuel consumption and driving performance. Deposits have been observed on internal injector components, for example in the armature assembly, in the slots of the piston and on the nozzle needle. The brownish to colourless deposits can adversely impact driveability and result in non-compliance with the Euro 4 or Euro 5 emission limits. The deposits have been extensively studied to understand their composition and their formation mechanism. Due to the location of these deposits, the influence of combustion gas can be completely ruled out. In fact, their formation can be explained by interactions of certain diesel fuel additives, including di- and mono-fatty acids. This paper describes the methodology used and the data generated that support the proposed mechanisms. Moreover, approaches to avoid such interactions are discussed.

The addition of a proportion of Fatty Acid Methyl Esters (FAME) in automotive diesel fuel is becoming prevalent in different areas of the world. Indeed, in several countries it is now a legislative requirement that a proportion of diesel fuel must be derived from natural sources. This trend is increasing continuously, both in terms of geographical coverage and for the use of higher percentages of bio-derived fuel. Our work has focused mostly on Rapeseed Methyl Ester (RME). A variety of diesel fuels containing different ratios of RME has been tested to assess their propensity to form injector deposits in engines using different fuel injection systems: Swirl chamber (for indirect fuel injection) Current common rail Future common rail Results have been obtained using industry recognised tests and a new test that uses future fuel injection system design.

Diesel engines will require new hardware to meet future emissions levels required by upcoming legislation. One of the key enablers towards meeting such legislation is the use of better fuel injection equipment (FIE). However, these systems can produce temperatures at the injector tips that are considerably higher than those seen today. This environment can exacerbate the rate of deposit formation or generate new types of deposits at and around the injector tip. Previous and ongoing investigations continue to further our understanding of this phenomenon using a modern passenger car diesel engine, various commercial 10 ppm S diesel fuels, a severe test cycle and injector nozzles representative of those likely to be in use in EURO V engines. The engine tests show good repeatability with clear and treated fuels. This supports the validity of the data generated. The test protocol used has recently been released to the industry.

Future diesel engines will require new hardware to reduce emissions to the levels required by upcoming legislation. Advances in the fuel injection equipment (FIE) of the engine are a key enabler towards meeting such legislation. These modern systems produce temperatures and pressures at the injector tips that are considerably higher than those experienced today. This environment can initiate or increase the rate of deposit formation at and around the injector tip compared with current systems. Investigations have been carried out to further the understanding of this phenomenon using experimental nozzles simulating a similar deposit build-up as expected in EU 5 engines. The investigation used a protocol that has recently been released to the industry, commercial 10 ppm S fuel and a commercial diesel fuel detergent. Testing was carried out with both clean and zinc contaminated fuel. Zinc contamination with a fuel soluble salt was used to simulate severe market conditions.

Continued legislative pressure to reduce diesel emissions has resulted in the development of engines with advanced fuel injection equipment (FIE). These injection systems produce temperatures and pressures at the injector tips that are considerably higher than those seen in previous technologies. This environment is initiating deposit formation at and around the injector tip which is leading to significant power loss and increased smoke generation. Investigations have been carried out to understand this phenomenon. Cyclic bench engine testing has generated high levels of deposits when minimal amounts of a fuel soluble zinc salt are doped into clear fuels. The deposits are found both in and around the nozzle tips. Analysis of the deposit shows the presence of zinc. These deposits are proving to be more challenging than those previously seen with older FIE technology. Detergents that have historically been effective in resolving injector deposits are proving less effective.

The Co-ordinating European Council (CEC) for the development of performance tests for transportation fuels, lubricants and other fluids has set up a working group to develop a laboratory pump rig test able to discriminate between diesel fuels of different lubricity performance. This test was expected to correlate with the performance of fuels and Fuel Injection Equipment (FIE) in the field, therefore providing a way to avoid costly field trials. This test could also enhance the understanding of the results from the High Frequency Reciprocating Rig (HFRR) method. The CEC working group was supported by representatives of Oil Companies, Test Houses, Additive Companies and all the European FIE Manufacturers. After a thorough investigative phase, the group focused on a Bosch VE 4 distributor-type pump run according to the Bosch WP2 test cycle. This choice was also widely accepted throughout the industry.

The use of a diesel particulate filter (DPF) is one of the most flexible methods of reducing particulate emissions from diesel engines, and has the advantage of controlling both the number and mass of particulate emissions. To maintain engine performance over time, the soot accumulated in the filter needs to be removed by oxidation. This paper describes the development of a novel iron based fuel-borne additive that controls soot deposit build-up in DPFs. This technology controls soot accumulation at significantly lower treat rates than those of previously reported [1] additives at temperatures well below those previously required for soot combustion. Ash accumulation testing and the chemical characterisation of the ash are also described. Any successful solution to the problem of soot accumulation in the filter needs to be harm free in the field.