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Port fuel injected (PFI) technology remains the most common fuel delivery type present in the marketplace for gasoline spark ignition engines and a legacy vehicle fleet featuring PFI technology will remain in the market for decades to come. This is especially the case in parts of Asia where PFI technology is still prominent, although direct injection (DI) technology adoption is starting to catch up. PFI engines can, when operated with lower quality fuels and lubricants, build up performance impairing deposits on a range of critical engine parts including in the fuel injectors, combustion chamber and on inlet valves. Inlet valve deposits (IVDs) in more severe cases have been associated with drivability issues such as engine stumble and engine hesitation on sudden acceleration. Deposit control additives in gasoline formulations are a well-established route to managing and even reversing fuel system fouling.

Injector cleanliness is well characterised in the literature [1,2,3,4] as a key factor for maintained engine performance in modern diesel cars. Injector deposits have been shown to reduce injector flow capacity resulting in power loss under full load; however, deposit effects on fuel economy are less well characterised. A study was conducted with the aim of developing an understanding of the impact of diesel injector nozzle deposits on fuel economy. A series of tests were run using a previously published chassis dynamometer test method. The test method was designed to evaluate injector deposit effects on performance under driving conditions more representative of real world driving than the high intensity test cycle of the industry standard, CEC DW10B engine test, [1]. The efficacy of different additive levels in maintaining injector cleanliness and therefore power and fuel economy was compared in a light duty Euro 5 certified vehicle.

With a push to continuously develop traditional engine technology efficiencies and meet stringent emissions requirements, there is a need to improve the precision of injection rate measurement used to characterise the performance of the fuel injectors. New challenges in precisely characterising injection rate present themselves to the Original Equipment Manufacturers (OEMs), with the additional requirements to measure multiple injection strategies, increased injection pressure and rate features. One commonly used method of measurement is the rate tube injection analyser; it measures the pressure wave caused by the injection within a column of stationary fluid. In a rate tube, one of the significant sources of signal distortion is a result of the injected fluid pressure waves reflected back from the tube termination.

The measurement of the rate of fuel injection using a constant volume, fluid filled chamber and measuring the pressure change as a function of time due to the injected fluid (the so called “Zeuch” method) is an industry standard due to its simple theoretical underpinnings. Such a measurement device is useful to determine key timing and quantity parameters for injection system improvements to meet the evolving requirements of emissions, power and economy. This study aims to further the understanding of the nature of cavitation which could occur in the near nozzle region under these specific conditions of liquid into liquid injection using high pressure diesel injectors for heavy duty engines. The motivation for this work is to better understand the temporal signature of the pressure signals that arise in a typical injection cycle.

Enhanced octane is one route to fuels differentiation where associated vehicle performance benefits are generally measured under controlled wide-open throttle tests on a chassis dynamometer. The combined availabilities of relevant ECU data via OBD and telematic loggers present new opportunities to assess such fuel benefits on the road in normal real-world driving environments. A novel methodology is described in this paper which utilised the remote logging of key engine EOBD data from a fleet trial and the results successfully demonstrated significant octane-derived benefits in many vehicles throughout normal mixed-roads driving. The availability and the reliability of telematic loggers mean that the method could be implemented in a scalable way as a complementary approach in addition to conventional laboratory vehicle testing.

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.

Improved fuel economy is a key measure of performance in the automotive industry, driven both by market demand and increasingly stringent government emissions regulations. In this climate, targeting even small benefits to fuel consumption (FC) can have a large impact when considering fleet average CO2 emissions. Lubricant properties over the course of an oil drain interval (ODI) directly influence long-term fuel consumption. Furthermore, viscosity control gasoline additives have been shown to provide FC benefit via fuel-to-lubricant transfer. This study investigated whether consistently fueling with gasoline containing friction modifier (FM) additives could provide a long-term fuel consumption benefit via a lubricant transfer mechanism. A robust fleet trial method was employed to quantify fuel consumption benefits of two friction modifier additive packages relative to a baseline deposit control additive (DCA) package in a 95 RON, E5 fuel.

If fuels that are more resistant to auto-ignition are injected near TDC in compression ignition engines, they ignite much later than diesel fuel and combustion occurs when the fuel and air have had more chance to mix. This helps to reduce NOX and smoke emissions at much lower injection pressures compared to a diesel fuel. However, PPCI (Partially Premixed Compression Ignition) operation also leads to higher CO and HC at low loads and higher heat release rates at high loads. These problems can be significantly alleviated by managing the mixing through injector design (e.g. nozzle size and centreline spray angle) and changing CR (Compression Ratio). This work describes results of running a single-cylinder diesel engine on fuel blends by using three different nozzle design (nozzle size: 0.13 mm and 0.17 mm, centreline spray angle: 153° and 120°) and two different CRs (15.9:1 and 18:1).

The EU Commission's “Clean Power for Transport” initiative aims to break the EU's dependence on imported oil whilst promoting the use of alternative fuels to reduce greenhouse gas emissions. Among the options considered is the use of liquefied natural gas (LNG) as a substitute for diesel in long haul trucks. It is interesting to ask how the lifecycle greenhouse gas (GHG) emissions of LNG compare with conventional diesel fuel for this application. The LNG available in Europe is mainly imported. This paper considers the “well-to-tank” emissions of LNG from various production routes, including: gas production, treatment and liquefaction, shipping to Europe, terminal, distribution and refuelling operations. “Tank-to-Wheel” emissions are considered for a range of currently-available engine technologies of varying efficiency relative to diesel.

Increasing fuel injection pressure has enabled reduction of diesel emissions while retaining the advantage of the high thermal efficiency of diesel engines. With production diesel injectors operating in the range from 300 to 2400 bar, there is interest in injection pressures of 3000 bar and higher for further emissions reduction and fuel efficiency improvements. Fundamental understanding of diesel spray characteristics including very early injection and non-vaporizing spray penetration is essential to improve model development and facilitate the integration of advanced injection systems with elevated injection pressure into future diesel engines. Studies were conducted in an optically accessible constant volume combustion vessel under non-vaporizing conditions. Two advanced high pressure multi-hole injectors were used with different hole diameters, number of holes, and flow rates, with only one plume of each injector being imaged to enable high frame rate imaging.

The need for improved emissions and fuel economy are placing increasingly severe performance requirements on compression ignition engines. These are satisfied in part by advanced fuel injection equipment that provide multiple injections and increased injection pressures along with higher operating temperature. Fuel composition is also changing, with increased use of non-traditional feedstocks combined with a range of additive chemistries to restore or enhance fuel quality. Within this environment, a number of worldwide automotive companies have noted a trend towards increased Internal Injector Deposits (IID). Little quantitative information to understand the root cause is available, largely due to difficulty in reproducing the issue under controlled conditions. The present study details the results of an accelerated test methodology, which is used to evaluate the interrelated effects of fuel composition and operating environment.

Current developments in fuels and emissions regulations are resulting in an increasingly severe operating environment for diesel fuel injection systems. The formation of deposits within the holes or on the outside of the injector nozzle can affect the overall system performance. The rate of deposit formation is affected by a number of parameters, including operating conditions and fuel composition. For the work reported here an accelerated test procedure was developed to evaluate the relative importance of some of these parameters in a high pressure common rail fuel injection system. The resulting methodology produced measurable deposits in a custom-made injector nozzle on a single-cylinder engine. The results indicate that fuels containing 30%v/v and 100% Fatty Acid Methyl Ester (FAME) that does not meet EN 14214 produced more deposit than an EN590 petroleum diesel fuel.

It is expected that the world's energy demand will double by 2050, which requires energy-efficient technologies to be readily available. With the increasing number of vehicles on our roads the demand for energy is increasing rapidly, and with this there is an associated increase in CO₂ emissions. Through the careful use of optimized lubricants it is possible to significantly reduce vehicle fuel consumption and hence CO₂. This paper evaluates the effects on fuel economy of high quality, low viscosity heavy-duty diesel engine type lubricants against mainstream type products for all elements of the vehicle driveline. Testing was performed on Shell's driveline test facility for the evaluation of fuel consumption effects due to engine, gearbox and axle oils and the variation with engine operating conditions.

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.

Fatty Acid Methyl Ester (FAME) products derived from vegetable oils and animal fats are now widely used in European diesel fuels and their use will increase in order to meet mandated targets for the use of renewable products in road fuels. As more FAME enters the diesel pool, understanding the impact of higher FAME levels on the performance and emissions of modern light-duty diesel vehicles is increasingly important. Of special significance to Well-to-Wheels (WTW) calculations is the potential impact that higher FAME levels may have on the vehicle's volumetric fuel consumption. The primary objective of this study was to generate statistically robust fuel consumption data on three light-duty diesel vehicles complying with Euro 4 emissions regulations. These vehicles were evaluated on a chassis dynamometer using four fuels: a hydrocarbon-only diesel fuel and three FAME/diesel fuel blends containing up to 50% v/v FAME. One FAME type, a Rapeseed Methyl Ester (RME), was used throughout.

The growing availability of different biofuels and synthetic fuels is leading to increased diversity of automotive fuels. Understanding how fuel properties affect combustion and how engine calibration strategies can compensate for variations in fuel composition is crucial for ensuring proper engine operation in this world of increased fuel diversity. This study looks at the ability to compensate for wide changes in cetane quality. Four different fuels with variations in cetane number, volatility and composition have been tested in a single cylinder engine and compared to diesel fuel. The selected operating conditions represent the entire engine map of a passenger car diesel engine. In part load the effects were investigated for conventional and premixed Diesel combustion. The results show that part load operation is especially relevant for the detection and compensation of varying fuel properties and that, depending on engine load, different control strategies have to be applied.

Previous work has shown that it may be advantageous to use gasoline type fuels with long ignition delays compared to today's diesel fuels in compression ignition engines. In the present work we investigate if high volatility is also needed along with low cetane (high octane) to get more premixed combustion leading to low NO and smoke. A single-cylinder light-duty compression ignition engine is run on four fuels in the diesel boiling range and three fuels in the gasoline boiling range. The lowest cetane diesel boiling range fuel (DCN = 22) also has very high aromatic content (75%vol) but the engine can be run on this to give very low NO (≺ 0.4 g/kWh) and smoke (FSN ≺ 0.1), e.g,. at 4 bar and 10 bar IMEP at 2000 RPM like the gasoline fuels but unlike the diesel fuels with DCNs of 40 and 56. If the combustion phasing and delay are matched for any two fuels at a given operating condition, their emissions behavior is also matched regardless of the differences in volatility and composition.

Biodiesel offers a potentially viable alternative fuel source for diesel automotive applications. However, biodiesel may present problems at colder temperatures due to the crystallization of fatty acid methyl esters and precipitation of other components, such as unreacted triglycerides and sterol glycosides in biodiesel. At lower temperatures, the fuel gels until it solidifies in the fuel lines, clogging the fuel filter, and shutting down the engine. A laboratory-based continuous loop fuel system was utilized to determine the flow properties at low temperatures of biodiesel in B100, B20, and B10 blends for soybean and choice white grease (pig fat) biodiesel fuel. The continuous loop fuel delivery system was designed to be similar to those that can be found in engines and vehicles currently in use, and provided a mechanical pump or an electric pump as a means to simulate systems found in the different types of vehicles.

Six diesel, kerosene, gasoline-like, and naphtha fuels have been tested in a single cylinder diesel engine and a demonstrator vehicle, both equipped with similar engine technology and optimized for advanced combustion performance. This study was completed in order to investigate the potential to reduce engine-out emissions while maintaining engine efficiency and noise levels through changes in both engine hardware and fuel properties. The fuels investigated in this study were selected in order to better understand the effects of ignition quality, volatility, and molecular composition on engine-out emissions and performance. The optimized bench engine used in this study included engine hardware enhancements that are likely to be used to meet Euro 6 emissions limits and beyond, in part by operating under advanced combustion conditions, at least under some speed and load conditions.

This research describes the potential to adopt detailed chemical kinetics for practical and potential future fuels using tri-component surrogate mixtures capable of simulating fuel octane “sensitivity” . Since the combustion characteristics of modern fuels are routinely measured using the RON and MON of the fuel, a methodology to generate detailed chemical kinetic mechanisms for these fuels based on these data is presented. Firstly, a novel correlation between various tri-component blends (comprised of i-octane, n-heptane and toluene) and fuel RON and MON was obtained by carrying out standard octane tests. Secondly, a chemical kinetic mechanism for tri-component fuels was validated using a Stochastic Reactor Model (SRM) suite, an in-cylinder engine combustion simulator, and a series of engine experiments conducted in HCCI operating mode.