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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.

Initial results are presented for the production of hydrogen from waste lubricating oil using a chemical looping reforming (CLR) process. The development of flexible and sustainable sources of hydrogen will be required to facilitate a "hydrogen economy." The novel CLR process presented in this paper has an advantage over hydrogen production from conventional steam reforming because CLR can use complex, low value, waste oils. Also, because the process is scalable to small and medium size, hydrogen can be produced close to where it is required, minimizing transport costs. Waste lubricating oil typically contains 13-14% weight of hydrogen, which through the steam reforming process could produce a syngas containing around 75 vol% H₂, representing over 40 wt% of the fuel. The waste oil was converted to a hydrogen-rich syngas in a packed bed reactor, using a Ni/ Al₂O₃ catalyst as the oxygen transfer material (OTM).

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.

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.

An investigation was conducted into particulate PAH emissions from a heavy duty DI diesel engine using; a typical diesel fuel, 100% methyl ester derived from waste cooking oils, and 100% rapeseed oil supplied as fresh cooking oil. This study quantifies the particulate PAH levels emitted at two steady state load conditions, with comparison of the oxidation catalyst efficiency for the main species identified. The engine used was a 6 cylinder, turbocharged, intercooled Perkins Phaser engine, with emission compliance of EURO 2. Particulate samples were also analysed for VOF and carbon content. Both biofuels resulted in reductions in the most abundant particulate PAH species, particularly at the lower load condition. Larger species such as Benzo(a)anthracene, chrysene, benzo(b)fluoranthene and benzo (k)fluoranthene were detectable for all fuels upstream of the catalyst but were oxidized to near or below detection limits downstream of the catalyst.

Rape oil, as used in fresh cooking oil (FCO), and the methyl ester derived from waste cooking oil (WCOB100) were tested as 100% biofuels (B100) on a heavy duty DI diesel engine under steady state conditions. The exhaust emissions were measured and compared to those for conventional low sulphur (<50ppm) diesel fuel. The engine used was a 6 cylinder, turbocharged, intercooled Perkins Euro2 Phaser Engine, fitted with an oxidation catalyst. The engine out gaseous emissions results for WCOB100 showed a large decrease in CO and HC emissions, but a small increase in NOx emissions compared to diesel. However, for FCO the CO and HC increased relative to WCOB100 and CO was higher than for diesel, indicating deterioration in fuel/air mixing. The particulate matter (PM) emissions for WCOB100 were similar to those for diesel at the 23kw condition, but greatly reduced at 47kw. The FCO produced higher engine out PM at both power conditions due to a higher volatile organic fraction (VOF).

New Diesel exhaust gas aftertreatment systems, with combined DPF*) and deNOx (mostly SCR) systems represent a very important step towards zero emission Diesel fleet. These combined systems are already offered today by several suppliers for retrofitting of HD vehicles. Reliable quality standards for those quite complex systems are urgently needed to enable decisions of several authorities. The present report informs about the international network project VERT *) dePN (de-activation, de-contamination, disposal of particles and NOx), which was started in Nov. 2006 with the objective to introduce the SCR-, or combined DPF+SCR-systems in the VERT verification procedure. Examples of results for some of the investigated systems are given. These investigations included parameters, which are important for the VERT quality testing: besides the regulated gaseous emissions several unregulated components such as NH3, NO2 and N2O were measured.

In view of increasing concern over diesel particulates and tightening legislation to control their emission, much work has been done to develop diesel particulate filters (DPFs) and systems to allow them to work reliably. Although a filter will effectively trap solid particles, any material in the vapour phase, such as unburned hydrocarbons, may pass through the filter and subsequently condense. The use of a catalytic wash coat, either on the DPF itself or on a separate substrate, has been proposed to oxidise these hydrocarbons and thus reduce the total material emitted. The use of fuel borne catalysts to aid the regeneration of trapped material within the DPF is also well documented. Such catalyst will also catalyse the oxidation of any hydrocarbons bound up within the particulate. The oxidation of such hydrocarbon occurs at a lower temperature than that of carbon itself, thus allowing lower temperature regeneration of the DPF.

1 A methodology for correctly matching trap systems to the vehicle types was developed within the scope of a feasibility study to retrofit the entire Swiss fleet of on-road HDV. Representative test vehicles from 11 vehicle categories were equipped with high capacity data loggers during a period of 4-6 weeks. Statistical evaluation of exhaust temperatures indicate that data on averages, peaks and frequency distributions alone can be misleading, because these tend to over-estimate the available exhaust enthalpy. Analysis of dwell time intervals, at certain temperature levels, is a better method to assess the energy available for the regeneration. Such verification of duty cycles is indispensable before retrofitting traps and choosing either active or passive regeneration systems.

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.

By means of catalysts, either coatings or fuel-borne, the temperature level for triggering the combustion of soot stored in particulate traps can be lowered from 600°C to 300°C, in case of CRT even to 250°C; but even that may fail, if in dense traffic application of a city-bus only 150 - 200°C are attained - similar situations of low load duty cycles exist in most other applications too. Mere passive regeneration may then not be sufficient, active support is needed. This paper presents an “active” method applicable to any Diesel engine to increase the exhaust temperature whenever required: load of Diesel engines is controlled by the fuel flow only; consequently, excess of air above stochiometric requirement is increasing from λ = 1.5 to λ = 8 with decreasing load, which is in fact the principal cause of the low temperature at light loads.

A dosing system has been developed to facilitate the addition of a fuel borne catalyst (FBC) to a vehicle's fuel supply. The on-board dosing system was primarily designed to reduce cost and complexity. One embodiment of the design provided an additional benefit, namely the automatic adjustment of treat rate according to duty cycle. For high duty operating cycles where average exhaust gas temperatures are high, a low treat rate of FBC is supplied. Conversely at low duty where the exhaust temperature is lower, a higher treat of FBC is delivered. Data from field applications are presented to demonstrate this feature.

Knitted fiber particulate traps facilitate deep-bed structures. These have excellent filtration properties, particularly for ultra-fine particulates. They are also suitable as substrate for catalytic processes. The two characteristics are: high total surface area of the filaments, and good mass transfer. These are prerequisites for intense catalytic activity. The deposited soot is uniformly distributed. Therefore, temperature peaks are avoided during regeneration. The tested coatings lower the regeneration temperature by about 200°C to burn-off temperatures below 350°C. Further improvements seem attainable. Thus, a purely passive regeneration appears feasible for most applications. The system is autonomous and cost effective. However, in extreme low load situations, e.g. city bus services, the necessary exhaust temperatures are not attained. Hence, burners or electrical heating is necessary for trap regeneration.

In the quest for improved fuel efficiency and reduced CO2 emissions, motor manufacturers are increasingly turning to the High Speed Direct Injection (HSDI) diesel engine for passenger car use. To achieve acceptable levels of noise and emissions at low loads two stage injection is being utilised. Such injection systems are prone to nozzle coking due to the small fuel metering holes, low opening pressures and low fuel flow rates under part load operation. This coking leads to a rapid deterioration of emissions performance. This paper describes work done to investigate conditions leading to this phenomena and the possible mechanisms involved.

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.

Based on the emission inventory Fig. 1, the Swiss 1998 Ordinance on Air Pollution Control (OAPC) mandates curtailment of carcinogenic diesel particle emissions at type B construction sites [1]. Moreover, particle traps are compulsory at underground workplaces [2]. In compliance, more than 6,000 Diesel engines were retrofitted with various particle trap systems. Many traps surpassed 99% filtration efficiency and secondary emissions were mostly prevented. However, trap failure due to mechanical and thermal damage was initially rather high at about 10%. By the year 2000 the failure rate was halved to about 6%. Thanks to focussed improvements, the year 2003 statistics show yearly failures of “only” about 2%. The Swiss target is to retrofit 15,000 construction machines with traps, fully compliant with environmental directives, having 5,000 operating hours durability and failure rates below 1%. Traps must pass the VERT suitability test before deployment.

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.

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 is mounting worldwide concern over the health effects of airborne ultra-fine particles. Of greatest concern are the risks due to the cancer-inducing properties of these particles and the aggravation of existing respiratory diseases by the ultra-fine (i.e. <2.5 micron) fraction. This disquiet has already resulted in legislation, regulations and other measures, either mandated or proposed, in the industrialised world to severely restrict particulate emissions from diesel-fuelled automotive transport. Emissions of particles from both new and existing vehicles have been addressed. With the rapid growth anticipated in some developing countries they to will need to address this problem. This paper outlines some alternative solutions to the problem, ranging from alternative power sources, alternative fuels, alternative engine technologies and after-treatment strategies. It also outlines what is required to implement these different solutions.

Fuel-borne catalysts are now an accepted means of aiding the self-regeneration of diesel particulate filters (DPFs). In the past it has been possible to assess the effect of these fuel additives by investigating the temperature at which the filter reaches a pressure drop equilibrium. Under these temperature conditions, the particulate matter is oxidised at the same rate as it is being deposited and there is thus no change in pressure drop across the filter. This technique adequately demonstrates the oxidation temperature of the carbon in the presence of the catalyst. However, it is now well known that such fuel additives also influence the low temperature oxidation of particulate bound hydrocarbons. This phenomenon is not detected by the filter equilibrium technique.