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In a modern diesel engine, a high fuel injection pressure is achieved by a common-rail system. Therefore, it is important to understand the effects of fuel properties on engine performances because a diesel fuel could deteriorate inside an injector at such severe conditions. The test methods so far basically use the fuel with pro-fouling agent to form deposit on injector. In this study, a novel test procedure was developed to evaluate the effect of the use of the fuel with and without zinc contaminant on injector performance. With Zn doped European specification B7 fuel (7% biodiesel) as a reference, the test result showed that an engine torque decreased almost lineally over time, and the overall torque drop was 9% after 300 hours. The investigation of the dismantled injector after the test revealed that the deposit was not formed on the sliding parts of the injector, but on the nozzle hole surface.

The performance aspect of gasoline combustion has traditionally been measured using Research Octane Number (RON) and Motor Octane Number (MON) which describe antiknock performance under different conditions. Recent literature suggests that MON is less important than RON in modern cars and a relaxation in the MON specification could improve vehicle performance, while also helping refiners in the production of gasoline. At the same time, for the same octane number change, increasing RON appears to provide more benefit to engine power and acceleration than reducing MON. It has also been suggested that there could be fuel efficiency benefits (on a tank to wheels basis) for specially adapted engines, for example, operating at higher compression ratio, on very high RON (100+). Other workers have advocated the use of an octane index (OI) which incorporates both RON and MON to give an indication of octane quality.

An increasing range of conventional and unconventional feed stocks will be used to produce fuel of varying chemical and physical properties for use in compression ignition engines. Fischer-Tropsh (F-T) technology can be used to produce fuels of consistent quality from a wide range of feed stocks. The present study evaluates the performance of F-T fuel in advanced common rail fuel injection systems. Laboratory scale tests are combined with proprietary engine and electrically driven common rail pump hydraulic rig tests to predict long-term performance. The results obtained indicate that the performance of F-T fuel is at least comparable to conventional hydrocarbon fuels and superior in a number of areas. In particular, the lubricity of F-T fuel was improved by addition of lubricity additives or FAME, with minimal wear under a wide range of operating conditions and temperatures.

In this study, the influence of gasoline composition on exhaust emissions has been evaluated using three gasoline vehicles. Although the vehicles were obtained within Europe, each is representative of models to be found in Asian markets. Two of the vehicles were current Euro 4 certification, while the third was of Euro 2 certification equivalent to that available in specific Asian markets. Fuel effects studied included aromatics, olefins and benzene content. Other fuel properties were held constant within the normal constraints of blending when using realistic gasoline components. An orthogonal matrix of eight fuels was blended to evaluate these properties over the ranges: Aromatics (excluding benzene) 34% to 49%, olefins 18% to 25% and benzene 1% to 5%. All fuels were tested in all three cars driving the current legislative NEDC cycle, using a randomised block design with at least 3 repeats on each fuel/vehicle combination.

Worldwide concern about air quality has led to ever-tougher emissions legislation for vehicles and a concomitant tightening of fuel specifications. However, not all countries or regions will move at the same rate. For example, parts of Europe and the US have already seen the introduction of the so-called “sulphur-free” fuels (i.e. <10 and <15ppm S). However, in many developing countries there are fuel specifications with sulphur limits in higher range of 1500 - 2500ppm, and other properties are also more relaxed, such as distillation or density. For a future world where larger volumes of GTL Fuel are available (2010 and beyond), it is essential to know the environmental impact of using both neat GTL and GTL blends, when compared to conventional market diesel. Moreover it is important to take into account the significant variation still anticipated for specifications of diesel between different countries.

The introduction of sulphur-free fuels will enable advanced engine and exhaust after-treatment technologies to meet increasingly stringent exhaust emissions regulations. As these cleaner fuels and vehicles are introduced, the potential for further improvements in air quality through changes to fuel properties can be expected to diminish. Nevertheless, CONCAWE has continued to update knowledge by evaluating fuel effects on emissions from new engine/vehicle technologies as they approach the market. In this work, carried out as part of CONCAWE's contribution to the EU “PARTICULATES” consortium [1], two advanced light-duty diesel vehicles and three heavy-duty diesel engines covering Euro-3 to Euro-5 technologies, were tested. The fuels tested covered a range of sulphur content and compared conventional fuels with extreme fuel compositions such as Swedish Class 1 and Fischer Tropsch diesel fuels.

The influence of gasoline quality on exhaust emissions has been evaluated using four modern European gasoline cars with advanced features designed to improve fuel economy and CO2 emissions, including stoichiometric direct injection, lean direct injection and MPI with variable valve actuation. Fuel effects studied included sulphur content, evaluated over a range from 4 to 148 mg/kg, and other gasoline properties, including aromatics content, olefins content, volatility and final boiling point (FBP). All four cars achieved very low emissions levels, with some clear differences between the vehicle technologies. Even at these low emissions levels, all four cars showed very little short-term sensitivity to gasoline sulphur content. The measured effects of the other gasoline properties were small and often conflicting, with differing directional responses for different vehicles and emissions.

This paper presents an overview of the results on light duty vehicles collected in the “PARTICULATES” project which aimed at the characterization of exhaust particle emissions from road vehicles. A novel measurement protocol, developed to promote the production of nucleation mode particles over transient cycles, has been successfully employed in several labs to evaluate a wide range of particulate properties with a range of light duty vehicles and fuels. The measured properties included particle number, with focus separately on nucleation mode and solid particles, particle active surface and total mass. The vehicle sample consisted of 22 cars, including conventional diesels, particle filter equipped diesels, port fuel injected and direct injection spark ignition cars. Four diesel and three gasoline fuels were used, mainly differentiated with respect to their sulfur content which was ranging from 300 to below 10 mg/kg.

The aim of this study was to investigate the changes in mass and number based heavy duty diesel engine particle emissions with respect to various test conditions, engine technologies and fuel specifications. Comparative particle size data and regulated particulate matter are presented from three heavy duty engines and three fuels. This paper describes results from the DETR/CONCAWE/SMMT Particle Research Programme. Three heavy duty diesel (HDD) engines representing Euro I, II and III technologies were tested with a range of fuels. These fuels included UK ultra low sulphur diesel (UK-ULSD), EN590 (EU2000) specification and Swedish Class I fuels. Continuing research suggests that when changes in regulated particulate mass emissions are compared to both individual mode and total cycle mass and number weighted particle size distributions there is often no significant correlation. In an attempt to provide further data in this area the following measurement methodology was adopted.

This paper describes the observed effects of parameters such as tunnel dilution ratio, test procedures and measurement methods on particle emissions. Attention is drawn to the transient behavior of nanoparticles within real legislated cycle conditions using conventional dilution systems. The aim of the paper is to communicate the limitations of widely used measurement equipment to enable a more confident interpretation of the particle size data. The paper describes the information obtained during the DETR/CONCAWE/SMMT Particle Research Programme with regard to the sampling and measurement of particles emitted from light duty vehicles and heavy duty engines. Light duty vehicles were tested on gasoline, diesel and LPG, while heavy duty engines were tested on both diesel and compressed gaseous fuels. Two Scanning Mobility Particle Sizer (SMPS) instruments were employed in order to cover a measurement range from a lower limit of ∼7nm up to ∼710nm.

Air quality monitoring of PM10 and associated health studies have focused interest on the size and the number of particles emitted to, and found in, the atmosphere. Automotive sources are one of the important elements in this, and CONCAWE have completed a study of heavy duty diesel particle emissions, complementing their previously reported light duty work. This heavy duty programme, presented here, investigated the nature of particulate emissions from two heavy duty engines (representative of different emissions levels), operating on three marketed fuels, over their respective European legislative heavy duty test cycles. The programme has investigated some of the complexities associated with obtaining credible data (e.g. dilution ratios, system stabilisation time etc.). The number distributions, which were measured over a wide size range (3 to 1000 nm), have been split into two size ranges, representative of nucleation mode and accumulation mode particles.