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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.

Traditionally, diesel fuel injection equipment (FIE) has frequently relied on the diesel fuel to lubricate the moving parts. When ultra low sulphur diesel fuel was first introduced into some European markets in the early 1980's it rapidly became apparent that the process of removing the sulphur also removed other components that had bestowed the lubricating properties of the diesel fuel. Diesel fuel pump failures became prevalent. The fuel additive industry responded quickly and diesel fuel lubricity additives were introduced to the market. The fuel, additive and FIE industries expended much time and effort to develop test methods and standards to try and ensure this problem was not repeated. Despite this, there have recently been reports of fuel reaching the end user with lubricating performance below the accepted standards.

The fuel economy and emissions performance of a Diesel engine is strongly influenced by the fuel injection process. This paper presents early results of an experimental investigation into diesel spray development carried out in a novel in-house developed optical pressure chamber capable of operating at pressure up to 50 bar and temperatures up to 900 K. The spatial evolution of a diesel spray tends to experience many transitory macroscopic phenomena that directly influence the mixing process. These phenomena are not considered highly reproducible and are extremely short lived, hence recording and understanding these transient effects is difficult. In this study, high-speed backlight-illuminated imaging has been employed in order to capture the transient dynamics of a short signal duration diesel spray injected into incremental back pressures and temperatures reaching a maximum of 10 bar and 473 K respectively.

The need to meet the US 2007 emissions legislation has necessitated a change in Diesel engine technology, particularly to the fuel injection equipment (FIE). At the same time as these engine technology changes, legislation has dictated a reduction in fuel sulphur levels and there has also been increased use of fatty acid methyl esters (FAME) or biodiesel as a fuel blending component. The combination of changes to the engine and the fuel has apparently led to a sharp rise in the number of reports of field problems resulting from deposits within the FIE. The problem is usually manifested as a significant loss of power or the engine failing to start. These symptoms are often due to deposits to be found within the fuel injectors or to severe fouling of the fuel filter. The characteristics of the deposits found within different parts of the fuel system can be noticeably different.

Recent developments in diesel fuel injection equipment coupled with moves to using ULSD and biodiesel blends has seen an increase in the number of reports, from both engine manufacturers and fleet operators, regarding fuel system deposit issues. Preliminary work performed to characterise these deposits showed them to be complicated mixtures, predominantly carbon like but also containing other possible carbon precursor materials. This paper describes the application of the combination of hydropyrolysis, gas chromatography and mass spectrometry to the analysis of these deposits. It also discusses the insights that such analysis can bring to the constitution and origin of these deposits.

The operating cycle of many vehicles fitted with diesel particulate filters is such that soot accumulates within the filter and must periodically be oxidised. Work was carried out on a passenger car engine to elucidate how fuel borne catalyst (FBC) to soot ratio, oxygen mass flow rate, temperature and soot loading influence the oxidation rate of soot accumulated in a sintered metal filter (SMF). Results show that soot loading had a major influence; increased soot loading increased the oxidation rate. The other parameter had a smaller influence with increasing oxygen flow rate and FBC/soot ratio each increasing the oxidation rate.

With growing concern over greenhouse gases there is increasing emphasis on reducing CO2 emissions. Despite engine efficiency improvements plus increased dieselisation of the fleet, increasing vehicle numbers results in increasing CO2 emissions. To reverse this trend the fuel source must be changed to renewable fuels which are CO2 neutral. A common route towards this goal is to substitute diesel fuel with esterified seed oils, collectively known as Fatty Acid Methyl Esters. However a fundamental change to the fuel chemistry produces new challenges in ensuring compatibility between fuel and engine performance/durability. This paper discusses the global situation and shows how fuel additives can overcome the challenges presented by the use of biodiesel.

Due to concerns over NO2 emissions from platinum catalysts a base metal catalysed diesel particulate filter (DPF) has been developed and used in combination with fuel borne catalysts (FBC). Results are presented showing reductions in HC, NOX, NO2, and PAH emissions along with an assessment of the emissions of metals used in the FBC and the catalysed DPF. This data is used to show the likely reduction in overall iron and other metal emissions as a result of using the catalysed DPF/FBC system. A similar system has also been assessed for durability for over 2000 hours when fitted to a bus in regular service in Switzerland.

Continuing research into the effect of vehicle emissions is driving legislation, which is increasingly being enacted to encourage the retrofitting of emissions control devices. Of particular concern are emissions of diesel particulate matter and nitrogen oxides. More recently the adverse effects of nitrogen dioxide in particular, have been highlighted. A programme of work is underway in Santiago to demonstrate the suitability of retrofitting diesel particulate filters (DPF) to urban buses. This paper presents data, including regulated and unregulated emissions, from a bus fitted with a DPF that relies on a fuel borne catalyst (FBC) to facilitate regeneration of the DPF.

Transport Refrigeration Units (TRU) powered by small diesel engines emit high PM and cause locally high PM levels. The concomitant health risks spurred efforts to devise a cost-effective curtailment of these emissions. Diesel particulate filters (DPF) of ceramic honeycomb construction very efficiently trap PM emissions, even ultrafines in the lung penetrating size range of below 300 nm. A fuel borne catalyst (FBC) can facilitate trap regeneration, by lowering the exhaust temperature requirements, but cannot alone guarantee reliable regeneration under all operating conditions of the TRU. A Swiss development team together with industrial partners therefore developed a fully automatic active regeneration system for the California Air Resources Board.

The most cost-effective way to reduce the level of diesel particulate emissions is to retrofit exhaust aftertreatment devices. While diesel oxidation catalysts will reduce the mass of particles emitted, they will not significantly reduce the number of ultrafine particles, that are considered the most harmful to health. Diesel Particulate Filters (DPFs) are therefore considered the most effective retrofit devices. One obstacle to the widespread adoption of DPFs is that many DPF technologies require low sulphur fuel. Using a Fuel Borne Catalyst (FBC) to facilitate regeneration of the DPF allows a sulphur tolerant DPF system to be produced.

In an attempt to improve ambient air quality, retrofit programmes have been encouraged; targeting reductions in PM emissions by means of diesel particulate filters (DPFs). However depending on the DPF design and operating conditions increased nitrogen dioxide (NO2) emissions have been observed, which is causing concern. Previous work showed that retrofitting a DPF system employing a fuel borne catalyst (FBC) to facilitate regeneration, reduced NO2 emissions. This paper outlines the investigation of a base metal coated DPF to enhance the reduction of NO2. Such a DPF system has been fitted to older technology buses and has demonstrated reliable field performance.

Diesel particulate filters (DPF), in conjunction with fuel borne catalysts (FBC) to facilitate regeneration, are now an accepted technology for passenger car application. Retrofitting of such systems has demonstrated the possibility of applying this technology to heavy-duty vehicles. To demonstrate the efficacy of DPF/FBC systems and to assess their affect on engine durability and economy, five heavy-duty trucks were fitted with DPF/FBC systems. After the completion of over ¼ million kms four trucks underwent a full engine strip-down and rating. This paper briefly reviews the installation of the systems and their effect on the regulated emissions, present details of the mileage accumulation and of the engine strip-downs. The conclusions drawn are that after a ¼ million km of use with the DPF/FBC systems the trucks had not suffered any abnormal deterioration and in fact there was some indication of reduced wear on the engine.

For many years now, epidemiologists have been highlighting the potential damage to health and the associated cost, caused by diesel particulate emissions. There is still debate concerning the crucial characteristics of these particles, however many authorities have concluded that it is their duty to legislate the reduction of such emissions. The most common approach is to legislate that all new vehicles should meet ever stricter emissions limits. This puts the onus and the cost on the engine manufacturers. The emissions limits in developing countries are inevitably less stringent than those in the developed world, this gives the indigenous manufacturers the opportunity to compete and develop. However, vehicle replacement intervals dictate that the effect of legislation controlling new vehicles takes many years to propagate throughout the existent vehicle fleet.

A diesel particulate filter (DPF) is a crucial weapon in the fight to control the downsides traditionally associated with diesel engined vehicles. The DPF not only produces the benefits required from an environmental standpoint but also has the consumer benefit of eliminating the visible black smoke associated with diesel engines. Thus DPFs have now become a reality, both for series production vehicles and as a retrofit application. Inevitably there are a number of alternative types of DPF and alternative techniques are used for ensuring they continue to function in an acceptable manner. Due to the complexity of the diesel combustion process and the emissions produced it is only to be expected that a device intended primarily to control one parameter would have some effect on other parameters. This paper looks at some different DPF technologies and how they effect emissions, with the emphasis on particulate emissions and the speciation of oxides of nitrogen.

A novel dosing system for fuel borne catalyst (FBC), used to assist regeneration with a diesel particulate filter (DPF), has been developed. The system was designed for on-board vehicle use to overcome problems encountered with batch dosing systems. Important design features were simplicity, to minimise system cost, and the use of in-line dosing rather than batch dosing linked to tank refuelling. The paper describes the development of the dosing system which continuously doses FBC into the fuel line feeding the engine injection pump. The theoretical considerations behind the concept are explored, together with the realities imposed by fuelling regimes in which a variable proportion of the fuel flowing through the injection pump is passed back to the fuel tank. Two types of system are considered, ie where 1) FBC is added to the fuel in direct proportion to the flow rate of fuel and 2) FBC is added at a constant time-based rate.

Future emissions limits are pushing vehicle manufacturers towards the fitting of Diesel Particulate Filters (DPFs) as original equipment. However due to the replacement rate of the vehicle fleet, there is a delay before the full benefit of these measures are fully realised. To overcome this problem, in areas with a particular problem such as heavily congested city centres, retrospective legislation has been, and may be introduced. Legislation mandating the retrofitting of DPFs obviously has an immediate effect on particulate emissions. In some countries including the UK there are also fiscal incentives to fit DPFs. Due to its duty cycle the London taxi or Black Cab is one of the more challenging areas of application for the DPF. Previous work has shown that the use of a fuel borne catalyst (FBC) can extend the operating range of DPF systems providing the possibility of a viable system for such applications.

Growing concern over the health effects of airborne particles and a desire to reduce the associated cost has resulted in legislation, regulations and other measures, in the industrialised world to severely restrict particulate emissions from diesel-fuelled automotive transport. Developing countries are also introducing initiatives to try and reduce emissions, an example is the legislation in India to replace diesel engines with gas fuelled engines in some major conurbations. Such measures are expensive, both in terms of replacing the engines of the vehicles and of implementing the required infrastructure. There is still also debate over whether such measures reduce the number of ultra-fine particulates. A well-proven alternative is to fit diesel engines with Diesel Particulate Filters (DPFs), either as original equipment or as a retrofit system. Regenerating DPFs has in the past been an obstacle to their widespread application.

Forthcoming emissions legislation is driving the passenger car manufacturers towards the fitting of Diesel Particulate Filters (DPFs) as original equipment. In areas with a particular problem such as heavily congested city centres, retrospective legislation has also been introduced, for example in Hong Kong and Tokyo. Legislation mandating the retrofitting of DPFs obviously has an immediate effect on particulate emissions. Other authorities are thus investigating the efficacy of such measures. However with the increasing use of DPF technology concerns are now being raised over some currently unregulated emissions such as ultra fine particulate and NO2, although total particulate mass and oxides of nitrogen are regulated. To add to the data base for such issues a programme of work was run using London Black Cabs. Four cars were fitted with a DPF, an on-board dosing system to meter a fuel borne catalyst (FBC) into the fuel and a data logger to monitor the DPF performance.

Forthcoming emissions legislation is driving the passenger car manufacturers towards the fitting of Diesel Particulate Filters (DPFs) as original equipment. However such initiatives are not retrospective and due to the replacement rate of the vehicle fleet, there is a time lag before the full benefit of the new measures are fully realised. To overcome this drawback, in areas with a particular problem such as heavily congested city centres, retrospective legislation has been introduced, for example in Hong Kong and Tokyo. Legislation mandating the retrofitting of DPFs obviously has an immediate effect on particulate emissions. Other authorities are thus investigating the efficacy of such measures. To add to the data base for such assessments Octel is running a demonstration programme using London Black Cabs. Four cars have been fitted with a DPF, an on-board dosing system to meter a fuel borne catalyst (FBC) into the fuel and a data logger to monitor the DPF performance.