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The introduction around the world of low sulphur diesel fuel has required extensive use of lubricity additive technology in some markets. At the same time, the use of performance diesel additives such as detergents and defoamers is becoming more widespread. The wider application of performance diesel additives demands the introduction of proven technologies in new markets, whilst new requirements are met with a combination of existing and new additive technologies. Such developments are not without risk. These new applications could generate a variety of field problems and extensive testing is necessary to prove that the use in a new environment is trouble-free. This paper illustrates how diesel fuel additives can be efficient in solving specific problems and, at the same time, can generate a host of new problems such as plugging of fuel filters, in-line diesel pump failures, increased level of engine bore polish and deactivation of other performance diesel additives.

An experimental study was conducted to investigate the flame propagation characteristics in the presence of a heterogeneous concentration distribution of a fuel-air mixture in order to provide fundamental knowledge of the effects of gaseous mixture concentration heterogeneity on the combustion process. Different propane-air mixture distributions were produced by the reciprocating movements of a pair of perforated plates in a constant volume combustion chamber. The mean equivalence ratio of the fuel-air mixture was varied from 0.7 on the lean side to 1.6 on the rich side, the turbulence intensity in the combustion chamber was also varied at levels of 0.185 m/s, 0.130 m/s, 0.100 m/s, and 0.0 m/s. By an independent control of the mixture distribution and the turbulence intensity in the combustion chamber, the flame structure and flame propagation speed at various heterogeneous levels of the mixture distribution were investigated in detail.

The continuing trend toward “cleaner” distillate fuels has prompted concerns about the lubricity characteristics of current and future distillates. Since many U.S. Navy ships utilize seawater-compensated fuel tanks to maintain the ship's trim, the Navy performed a detailed study in order to better understand the relationship between fuel water content and lubricity characteristics. The lubricity test methods, modified for this study, were ASTM D 6078 (SLBOCLE), D 6079 (HFRR), and D 5001 (BOCLE). The results indicated that, with few exceptions, there was generally no evidence of a correlation between the water content of the fuels and the corresponding lubricity measurements as determined by the laboratory tests.

A study of one of the first batches of local low sulphur diesel fuels was conducted in order to determine the fuel's lubricity effects on VE rotary pump performance. This study involved a 30,000 km accumulation field test. Two types of fuels were used. Both were not additised with lubricity improvers. The first fuel, with HFRR WSD value of 358 μm, was used on three test vehicles, each fitted with new VE rotary pumps. The other fuel (HFRR value of 467 μm) was used with the other three test vehicles, each fitted with new pumps that were evaluated prior to field use. Camplate, cam-roller, pins and flyweight were evaluated after completing 30,000 km. No evidence of abnormal wear was found for all six pumps. However, slight but noticeable differences were found between pumps running on Test Fuels 1 and 2. These differences were found in flyweight stroke and axial wears. Despite these differences, the pumps were considered to be capable of further use.

Many components on both aircraft and ground vehicles rely on fuel for lubrication and cooling of sliding contacts. Reliable performance of these power sources depends on the fuel providing sufficient lubrication to protect each of the many contact types within the pump and injection system. This characteristic of fuel has come to be known as lubricity. The subject of fuel lubricity has gone through a number of phases, most of which resulted from changing the composition of the fuel, which historically has been driven by fuel stability and by environmental regulations. This paper reviews these phases in chronological order. Beginning with the fuel system failures reported in aviation equipment in the 1960s and 70s, through the Military experience with low lubricity kerosene fuels in compression ignition engines in the 80s and 90s, to the ongoing introduction of more severely refined diesel fuel in progress in many developed countries around the world.

The purpose of this research was to investigate the effect of fuel type and mixture composition on hydrocarbon (HC) emissions from a homogeneous charge spark ignition engine. Detailed chemical kinetic modeling indicated that at the temperatures of relevance for HC consumption in engines (T > 1500 K) a majority of the parent fuel decomposes by unimolecular thermal decomposition and that the radical pool which consumes the remaining smaller HC species is produced from the decomposition of the fuel. These results suggested that chemical kinetic interactions should exist between fuel components in a fuel mixture. Engine experiments were performed with iso-octane/toluene and n-octane/toluene fuel mixtures to determine whether kinetic interactions exist within an engine. Engine-out HC emissions exhibited a non-linear response to the amount of the paraffin in the fuel mixture and demonstrated that kinetic interactions do occur between fuel species.

The role of post-combustion oxidation in influencing exhaust hydrocarbon emissions from spark ignition engines has been identified as one of the major uncertainties in hydrocarbon emissions research [l]*. While we know that post-combustion oxidation plays a significant role, the factors that control the oxidation are not well known. In order to address some of these issues a research program has been initiated at Drexel University. In preliminary studies, seven gaseous fuels: methane, ethane,ethene,propane,propene, n-butane, 1-butene and their blends were used to examine the effect of fuel structure on exhaust emissions. The results of the studies presented in an earlier paper [2] showed that the effect of fuel structure is manifested through its effect on the post-combustion environment and the associated oxidation process. A combination of factors like temperatures, fuel diffusion and reaction rates were used to examine and explain the exhaust hydrocarbon emission levels.

This paper deals with oxygen storage effect and NOx conversion reaction modeling. It was found that the oxygen stored in the catalyst increases with catalytic wall temperature and lean ( or rich ) depth from experiments using a well controlled flow reactor. Oxygen storage-release model (OSR model), incorporated with the NOx reduction reaction and THC or CO oxidation reaction, was established from the experimental results. Reaction rate parameters for three-way catalyst have been determined from the least data of flow reactor experiments using Evolutionary Algorithm. Transient temperatures and emissions are predicted using the developed OSR model and the determined reaction rate parameters for three-way catalyst, which are incorporated in the numerical algorithms used in the previous paper to predict flow and temperature field in a catalytic converter.

The investigation and results presented hereafter are based on the use of a novel technique to improve the performance and emission characteristics of gasoline and diesel engines. The technique involved generating corona discharges within the engine's pre-combustion air stream. These discharges were created by a multi-points charged electrodes. The onset of the discharges facilitated the ionization and excitation process of the neutral air species. New radicals and highly oxidizing species such as atomic oxygen (O) and ozone (O3) were produced and these are known to modify some of the chemical reactions involved in the combustion of hydrocarbon fuels. Measurements of both gasoline and diesel engine torque, speed, various temperatures, fuel consumption and exhaust gas composition were obtained, using a constant throttle position under both normal and coronas operating conditions.

Using a fast-sampling valve, residual-fraction levels were determined in a 2.0L spark-ignited production engine, over varying engine operating conditions. Individual samples for each operating condition were analyzed by gas-chromatography which allowed for the determination of in-cylinder CO and CO2 levels. Through a comparison of in-cylinder measurement and exhaust data measurements, residual molar fraction (RMF) levels were determined and compared to analytical results. Analytical calculations were performed using the General Engine SIMulation (GESIM) which is a steady state quasi-dimensional engine combustion cycle simulation. Analytical RMF levels, for identical engine operating conditions, were compared to the experimental results as well as a sensitivity study on wave-dynamics and heat transfer on the analytically predicted RMF. Similarly, theoretical and experimental NOx emissions were compared and production sensitivity on RMF levels explored.

Time resolved exhaust port sampling results show that the gas mixture in the port at exhaust valve closing contains high concentrations of hydrocarbons. These hydrocarbons are mixed with hot in-cylinder gases during blowdown and can react either via gas phase kinetics in the exhaust port/runner system or subsequently on the exhaust catalyst before they are emitted. Studies were conducted on a single cylinder, four stroke engine in our laboratory to determine the interaction between the hot blowdown gases and the hydrocarbons which remain in the exhaust port. A preselected concentration and volume of hydrocarbon tracers (propane, propene, n-butane, and 1-butene) in either oxygen/nitrogen mixtures or pure nitrogen were injected into the exhaust port just behind the exhaust valve to control the initial conditions for any potential oxidation in the port.

An experimental study was carried out to characterize the exhaust flow structure inside the closed-coupled catalytic converter, which is installed on a firing four-cylinder 12-valve passenger car gasoline engine. Simultaneous velocity and pressure measurements were taken using cycle-resolved Laser Doppler anemometer (LDA) technique and pressure transducer. A small fraction of titanium (IV) iso-propoxide was dissolved in gasoline to generate titanium dioxide during combustion as seeding particles for the LDA measurements. It was found that the velocity is highly fluctuating due to the pulsating nature of the engine exhaust flow, which strongly depends on the engine operating conditions and the measuring locations. The pressure oscillation is correlated with the transient exhaust flow characteristics. The main exhaust flow event from each cylinder can only be observed at the certain region in front of the monolith brick.

The reduction of emissions of future SI engines is of prime importance for their development. Hence, investigations of the formation of unburned hydrocarbons in SI engines have been the subject of intensive research for many years. The scope of this work was to investigate several pistons with different top land geometry with respect to the potential of HC reduction. The observation of flame intrusion into the top land crevice was enabled by an optical fiber measurement technique. For this, six optical probes were inserted into the cylinder liner of a production four-cylinder SI engine. The emissions were detected with a conventional exhaust gas measuring system. The results of the investigation show reductions of about 30% in the HC emission. The flame intrusion depth and the frequency of intrusion are clearly dependent on the top land geometry.

A series of experimental studies has been conducted to make clear the characteristics of a new type of diesel sprays, which are injected from an elliptic nozzle. The spray counter has been visualized by Laser induced fluorescence method. An instrument based on the Laser Diffraction principle was used to detect the droplet size of the sprays and a LDV system was used to measure the air entrainment. The fuel was provided from an accumulator pressurized with nitrogen. Four elliptic nozzles with different aspect ratio of the hole from 1.43 to 4.5 were tested. The equivalent diameter of the hole was about 0.33 to 0.36 mm. The injection pressure was 10 MPa. For comparison, a circular spray was also measured. The results show that the spray angle of elliptic sprays is much larger than that of the circular spray while the SMD of elliptic sprays is smaller than that of the circular spray at same experimental condition.

In small high speed direct injection diesel engines the injected fuel spray impinges on the walls of the piston bowl. The mixture formation process is influenced considerably by the spray-wall interaction. Stringent exhaust gas emission regulations and growing demands for fuel economy are leading to the application of high-pressure fuel injection systems, e.g. common-rail. The trend towards downsized engines with smaller piston displacements leads to reduced distances between nozzle and wall. Higher injection pressures and smaller nozzle-wall distances both increase the significance of spray-wall interaction and near-wall mixture formation. In the present study the influence of governing parameters like injection pressure and wall temperature on the characteristics of the impinged spray was investigated.

The objective of this work was to investigate the effect of fuel properties on atomization and spray structure of a diesel engine fuel injector, based on PDA (Phase Doppler Anemometry) measurements. Few studies have addressed the question of how fuels affect droplet size and spray structure. Thus three diesel fuels were selected: two which broadly represent the range of base fuel properties seen in current European fuels and a third which contained a high treat rate of a detergent-type additive, which, being polar, may have some surface effects which could impact spray formation. This range of diesel fuels was injected into a high pressure and temperature wind tunnel, using a single hole Bosch injector. Phase Doppler Anemometry (PDA) was used to measure the diameter, velocity and arrival time of spray droplets passing through numerous radial and longitudinal positions in the spray.

A catalyst system, consisting of two different catalyst technologies within a single canister, was developed for MDV2 (Medium-Duty Vehicles, Class 2) to meet ULEV targets. The catalyst volume versus engine displacement is less than 50%. Three approaches taken: substrate study, PM loading study and new catalyst technology development are illustrated here. The most promising system features new catalyst technologies coated on high cell density substrates.

Results from an experimental study of flow distribution in a close-coupled catalytic converter (CCC) are presented. The experiments were carried out with a flow measurement system specially designed for this study under steady and transient flow conditions. Flow distribution at the exit of the first monolith was measured by a pitot tube. Numerical analysis was also performed for comparison. Experimental results showed that the flow uniformity index decreases as Reynolds number for the flow increases. For steady flow conditions, the flow through each exhaust pipe concentrates on a specific region of the monolith. The transient test results showed that the flow through each exhaust pipe, in the engine firing order, interacts with each other to make the flow distribution uniform. The numerical analysis results supported the experimental results, and helped explain the flow distribution in the CCC.

This paper presents a system concept of the On-Board Diagnostics system (OBD-II) in the Hyundai Accent. New-α and α-DOHC engine developed by Hyundai are installed in the Accent. The ECU (Engine Control Unit) developed by BOSCH is adopted for this vehicle. To comply with the OBD-II regulation mandated by CARB (California Air Resources Board), some monitoring algorithms originally developed by BOSCH were introduced and modified for the Hyundai Accent. Using modified algorithms, many kinds of test were carried out during more than four years. Through the demonstration test and various field tests, it was confirmed that the OBD-II system fulfilled the regulation and had good performance.

Individual hydrocarbon conversion efficiencies of engine-out emissions have been measured for four different catalyst formulations (Pd-only, trimetallic, Pd/Rh, and Pt/Rh) during stoichiometric and rich operation. The measurements were carried out as a function of fuel-air equivalence ratio (Φ) using a dynamometer-controlled 1993 Ford V8 engine and capillary gas chromatography. HC conversion efficiency was examined in terms of mass conversion efficiency and also using three new definitions of catalyst conversion efficiency. The efficiencies across the four catalysts show similar trends with Φ for almost all HC species. The catalyst efficiencies for alkanes, alkenes, and aromatic species decrease as Φ increases above stoichiometric: alkane efficiencies decrease faster than alkenes which in turn decrease faster than aromatics. All efficiencies fall to zero near Φ = 1.08 except those of MTBE and acetylene, which remain near 100%.