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Diesel engine emissions (DEE) are classified as probably carcinogenic to humans. Since 1995 we observed an appreciable reduction of mutagenicity of DEE driven by reformulated or newly designed fuels in several studies. We compared the mutagenic effects of DEE from two different batches of rapeseed oil (RSO) with rapeseed methyl ester (RME, biodiesel), natural gas derived synthetic fuel (gas-to-liquid, GTL), and a reference diesel fuel (DF). Additionally, we determined the regulated emissions of total hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NOX), and particulate matter (PM). Compared with the reference DF the two RSO qualities significantly increased the mutagenic effects of the particle extracts by factors of 9.7 up to 59. RME extracts had a moderate but significant higher mutagenic response. GTL samples did not differ significantly from DF.

The need of a more realistic and dynamic driving cycle which simulates real-world driving conditions in the largest city in the greater area of Balkans, led to the development of the Athens Driving Cycle (ADC). Emission and fuel consumption measurements were conducted over the ADC and compared with those of the New European Driving Cycle (NEDC) using a chassis dynamometer. A Euro II compliant diesel vehicle was used in this study, fuelled with a typical automotive diesel fuel and biodiesel blends at proportions of 5, 10, and 20 % respectively. The unregulated emissions were characterized by determining the soluble organic fraction (SOF) in the particulate matter, together with qualitative hydrocarbon analysis present in the SOF fraction, and of carbonyl compounds (aldehydes, ketones). Emissions of NOx, CO, THC, CO2, and PM10 were also measured over the two test cycles.

There is an increasing interest in India, to search for suitable alternative fuels that are environment friendly. This led to the choice of non edible mahua oil as one of the main alternative fuels to diesel oil. Hence in the present work, Methyl Ester of Mahua Oil (MEMO) was used as pilot fuel and Liquefied Petroleum Gas (LPG) was used as primary fuel. A single cylinder, direct injection, four stroke, diesel engine was modified to work in dual fuel mode and the effect of injection time on the performance and emission of the dual fuel engine was studied. During tests, the engine was running smoothly with the MEMO. From the test results, it is observed that, at part loads, the advanced injection timing of 30° bTDC results in slight increase in brake thermal efficiency and lower exhaust emissions as compared to rated injection timing of 27° bTDC and retarded injection timing of 25° bTDC.

In order to investigate effects of the multi-hole nozzle with micro orifices on mixture formation processes in Direct-Injection Diesel engines, mixture characteristics were examined via an ultraviolet-visible laser absorption scattering (LAS) technique under various injectors. The injection quantity per orifice per cycle was reduced by nozzle hole sizes. The LAS technique can provide the quantitative and simultaneous measurements of liquid and vapor phases concentration distributions inside of the fuel spray. Mass of ambient gas entrained into the spray, liquid/ vapor mass and mean equivalence ratio of total fuel were obtained based on Lambert Beer's law. As a result, the leaner and more homogeneous fuel-gas mixture can be achieved by reducing the nozzle hole diameter, in the meanwhile more ambient gas were entrained into the spray. Moreover, relationships between mixture formation and D.I.

The flow through the valves of an engine cylinder head is very complex in nature due to very high gas velocities and strong flow separation. However, it is also the typical situation in almost every engine related flow. In order to gain better understanding of the flow features after the cylinder head, and to gain knowledge of the performance level that can be expected from CFD analysis, flow field measurements and computations were made in an engine rig. Particle image velocimetry (PIV) and paddle wheel measurements have been conducted in a static heavy-duty diesel engine rig to characterize the flow features with different valve lifts and pressure differences. These measurements were compared with CFD predictions of the same engine. The simulations were done with the standard k-ε turbulence model and with the RNG turbulence model using the Star-CD flow solver.

The CFD simulation of the turbulent flow induced by the intake port of a modern direct injection gasoline engine requires the application of advanced turbulence models taking into account the unsteady nature of the flow. The validation of such models necessitates the availability of high quality experimental data. The present paper describes a comparative analysis between Detached Eddy Simulation, a “standard” hybrid Large Eddy Simulation approach, and an innovative concept called Scale Adaptive Simulation. The flow field generated by the cylinder-head of a production four-valve gasoline engine in a configuration with fixed valve positions has been simulated. The same configuration has been investigated experimentally using a stereoscopic High-Speed Particle Image Velocimetry system. The main focus of the work has been put on the very high time-resolution of the measured data, as well as on the strong refinement of the numerical mesh employed.

Near-term energy policy for ground transportation is likely to have a strong focus on both gains in efficiency as well as the use of alternate fuels; as both can reduce crude oil dependence and carbon loading on the environment. Stratified-charge spark-ignition direct-injection (SIDI) engines are capable of achieving significant gains in efficiency. In addition, these engines are likely to be run on alternative fuels. Specifically, lower alcohols such as ethanol and iso-butanol, which can be produced from renewable sources. SIDI engines, particularly the spray-guided variant, tend to be very sensitive to mixture preparation since fuel injection and ignition occur within a short time of each other. This close spacing is necessary to form a flammable mixture near the spark plug while maintaining an overall lean state in the combustion chamber. As a result, the physical properties of the fuel have a large effect on this process.

In this work fuel dilution of engine oil, and the impact of biodiesel fuel on dilution, were examined. New emissions requirements have driven the adoption of a range of aftertreatment systems for diesel engines. These aftertreatment devices in many cases have specific requirements for exhaust composition and temperature. Meeting these requirements can lead to fuel dilution of the engine oil. Measurement of fuel dilution of engine oil can be challenging, and in this study a new strategy for utilizing Fourier Transform Infrared Spectroscopy (FTIR) was examined. A synthetic component of aviation oil, pentaerythritol ester (PE), was found to be a very useful tracer for measuring dilution with ultra low sulfur diesel (ULSD), but not useful for measuring dilution with B20. Fuel dilution and evaporation rates were measured for both ULSD and for a blend of biodiesel and ULSD (B20).

In an attempt to study the numerous contributors towards cyclic variations in combustion in a direct injection spark ignition engine, simultaneous high-speed imaging of fuel injection and flame growth are undertaken on a crank-angle resolved basis in a single-cylinder optical research engine. Batches of images from 100 consecutive cycles are acquired for all conditions with synchronised in-cylinder pressure logging. The engine is motored and fired at stoichiometric conditions at 1500 RPM under part-load and wide-open-throttle conditions (0.5-1.0 bar intake pressure), with injection timing set early in the intake stroke to promote homogeneous mixture formation with a centrally mounted multi-hole injector. Liquid impingement is observed on the cylinder walls and on the piston crown with early intake injection and multiple injection strategies are employed in an attempt to reduce impingement and alter mixture preparation and subsequent combustion.

The diesel fuel reforming process in an exhaust gas recirculation (EGR) loop of a diesel engine is capable of utilizing the engine exhaust energy to support the endothermic process of hydrogen gas generation. However, the EGR stream commonly needs to be heated to enable the operation of the reformer and thus to sustain higher yield of hydrogen. A central-fuelling and flow-reversal embedment that is energy-efficient to raise the central temperatures of the catalytic flow-bed is therefore devised and tested to drastically reduce the supplemental heating to the EGR reformer. One-dimensional modeling analyses are conducted to evaluate the fuel delivery strategies and temperature profiles of the reformer at various reforming gas flow rates and engine-out exhaust temperatures and compositions. This research attempts to quantify the energy saving by the catalytic flow-reversal and central-fuelling embedment in comparison to a unidirectional flow EGR reformer.

While emission standards are becoming more stringent with every new legislation level, the engineering of compact aftertreatment system is becoming extremely challenging. This paper outlines a road map for cost-effective, compact aftertreatment systems through use of catalysts with standard and structured foil substrates. The longitudinal-structure (LS) foil disrupts laminar flow regimes within channels enhancing mass transfer and gas reconditioning. The presented results were applied to DOC catalyst functionality including parameters such as cross-section, substrate type and substrate volume. The catalysts were degreend and tested on a production 15ltr ISX Cummins engine calibrated for US 1998 emissions. Various load points were selected to determine catalyst performance as a function of exhaust gas temperature, exhaust flow rate (space velocity) and exhaust gas composition. A HC injector system was used to characterize oxidation performance at various concentration levels.

The application of biodiesel fuel (BDF) to diesel engines is very effective at reducing CO2 emissions, because biodiesel is considered to be carbon neutral in principle. Gas-to-liquid (GTL) fuel, a synthetic fuel, is expected to reduce emissions from diesel engines. This study focused on the effects of driving conditions and fatty acid methyl ester (FAME) and GTL blended fuel on emissions from diesel engines/vehicles meeting Japan's new short-term regulations, or '03 regulations. FAME including rape methyl ester (RME), palm oil methyl ester (PME) and soybean methyl ester (SME) were studied. Major technologies for emissions reduction may include common-rail high-pressure fuel injection system, cooled exhaust gas recirculation (EGR) system, diesel oxidation catalyst (DOC) and diesel particulate filter (DPF).

Palladium-based catalyst can be employed for natural gas exhaust clean up due to its high activity for light hydrocarbon oxidation. Unfortunately, trace amounts of sulfur in the natural gas feed severely deactivate the catalyst. In this paper, SO2 adsorption over a monolithic Pd/Al2O3 oxidation catalyst is monitored in a time-resolved manner in the presence of 100 ppm SO2 under simulated aging conditions of a natural gas engine, which is correlated with the oxidation activity for CO and hydrocarbons such as CH4, C2H6 and C3H8. The SO2 adsorption is saturated in 0.5 h at 400°C and 100,000 h-1. The molar ratio of adsorbed SO2 and Pd is about 2/1, indicating SO2 molecules adsorbed, or transferred to the Al2O3 support. The oxidation activity gets stabilized upon saturation of sulfur adsorption, and the hydrocarbon oxidation activity cannot recover even when 100 ppm SO2 is completely removed from the stream.

A series of paired fuel tests were conducted comparing certification-grade highway diesel fuel with 5 to 50 vol% soy-methyl-ester biodiesel blends. Each fuel pair was tested for up to seven transient cycles representing various load conditions, using a 2006 model year Cummins ISB compression ignition engine equipped with exhaust gas recirculation. Except for the most lightly-loaded cycle, the results show statistically significant differences in NOx emission for all fuel pairs. The average NOx emissions due to biodiesel increased over each cycle, ranging from 0.9 to 6.6% and from 2.2 to 17.2% for the B20/B0 and B50/B0 fuel pairs, respectively. Significant reductions in CO and PM were observed over a majority of the cycles tested. The data also reveal that the change in NOx emissions increases linearly with the average cycle load. To complement the transient results, a single modal point was monitored daily to investigate biodiesel effects on engine operating parameters.

This paper includes a numerical and experimental study of fluid flow in automotive catalytic converters. The numerical work involves using computational fluid dynamics (CFD) to perform three-dimensional calculations of turbulent flow in an inlet pipe, inlet cone, catalyst substrate (porous medium), outlet cone, and outlet pipe. The experimental work includes using hot-wire anemometry to measure the velocity profile at the outlet of the catalyst substrate, and pressure drop measurements across the system. Very often, the designer may have to resort to offset inlet and outlet cones, or angled inlet pipes due to space limitations. Hence, it is very difficult to achieve a good flow distribution at the inlet cross section of the catalyst substrate. Therefore, it is important to study the effect of the geometry of the catalytic converter on flow uniformity in the substrate.

The increasing number of controllable parameters in modern engine systems has led to increasingly complicated and enlarged engine control software. This in turn has created dramatic increases in software development time and cost. Model-based control design seems to be an effective way to reduce development time and costs and also to enable engineers to understand the complex relationship between the many controllable parameters and engine performance. In the present study, we have developed model-based methodologies for the engine calibration process, employing engine cycle simulation and regression analysis. The reliability of the proposed method was investigated by validating the regression model predictions with measured data.

A Controllable Active Thermo-Atmosphere (CATA) Combustor enables the investigation of stabilization mechanisms in an environment that decouples the turbulent chemical kinetics from the complex recirculating flow. Previous studies on combustion of the low-pressure fuel jets in the Controllable Active Thermo-Atmosphere (CATA) showed non-linear effect of coflow temperature on autoignition delay and the randomness of autoignition sites. In this work, a diesel spray is injected into the CATA with the injection pressure at 20MPa from a single-hole injector and the autoignition and combustion process of the spray is recorded by a high-speed camera video. The multipoint autoignition of diesel spray is observed in the CATA and the subsequent combustion process is analyzed. The results show that autoignition phenomenon plays an important role in the stabilization of the lifted flames of diesel spray under low coflow temperature.

Diesel particulate matter collection results of a new design for a non-blocking diesel particulate filter are presented. Engine/dynometer testing with partial flow dilution tunnel DPM sampling show the device is capable of greater than 50% DPM trapping efficiency. Parameters in the design of the device such as, the quantity and type of filtration media is shown to directly impact on the trapping efficiency of the device. Preliminary durability results show minimal effects on device performance. In addition, history effects due to engine mode on DPM trapping performance are discussed

In this study we identify components of a typical biodiesel fuel and estimate both their individual and mixed thermo-physical and transport properties. We then use the estimated mixture properties in computational simulations to gauge the extent to which combustion is modified when biodiesel is substituted for conventional diesel fuel. Our simulation studies included both conventional diesel combustion (DI) and premixed charge compression ignition (PCCI). Preliminary results indicate that biodiesel ignition is significantly delayed due to slower liquid evaporation, with the effects being more pronounced for DI than PCCI. The lower vapor pressure and higher liquid heat capacity of biodiesel are two key contributors to this slower rate of evaporation. Other physical properties are more similar between the two fuels, and their impacts are not clearly evident in the present study.

An experimental method was set up in a single cylinder optical engine in GDI configuration to study UHC origins in both homogeneous and stratified operation. On the one hand, UHC were observed in the combustion chamber by formaldehyde LIF (excitation at 355 nm and collection from 400 to 470 nm). Formaldehyde is a natural UHC tracer since it results from partly decomposed fuel that has not been fully oxidized during combustion. A quartz cylinder liner was used in order to benefit from a large optical access. On the other hand, UHC emissions measurement were simultaneously performed with a fast FID analyzer whose sampling probe was located 2 cm downstream the exhaust valve, in one of the two exhaust ports. An instantaneous exhaust mass flow model was also developed using 0-D simulation. The computed mass flow rate was coupled to fast FID measurements to estimate instantaneous and cycle to cycle UHC emissions.