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A 1998 Toyota Corona passenger car with a direct injection spark ignition (DISI) engine was tested via a variety of driving cycles using California Phase 2 reformulated gasoline. A comparable PFI vehicle was also evaluated. The standard driving cycles examined were the Federal Test Procedure (FTP), Highway Fuel Economy Test, US06, simulated SC03, Japanese 10-15, New York City Cycle, and European ECE+EDU. Engine-out and tailpipe emissions of gas phase species were measured each second. Hydrocarbon speciations were performed for each phase of the FTP for both the engine-out and tailpipe emissions. Tailpipe particulate mass emissions were also measured. The results are analyzed to identify the emissions challenges facing the DISI engine and the factors that contribute to the particulates, NOx, and hydrocarbon emissions problems of the DISI engine.

The effects of operating parameters (speed, load, spark-timing, EGR, and end of fuel injection timing [EOI]) on engine-out, regulated (total HC, NOx, and CO) and speciated HC emissions have been investigated for a 1.83 L direct-injection, spark-ignition (DISI) engine. As the EOI is varied over the range from high to low stratification with other engine parameters held constant, the mole fractions of all regulated emissions vary sharply over relatively small (10-20 crank angle degrees [CAD]) changes in EOI, suggesting that emissions are very sensitive to the evaporation, mixing, and motion of the stratified fuel cloud prior to ignition. The contribution of unburned fuel to the HC emissions decreases while the olefinic partial oxidation products increase as the fuel stratification increases, increasing the smog reactivity of the HC in the exhaust gas by 25%.

The ring-pack behavior in a modern gasoline engine represent complicated phenomena. The process of ring pack design consists of two stages: understanding the physical behavior and design synthesis on the systematic manner. Computer models give an inside on the physical processes associated with the ring-pack behavior. Mathematical optimization techniques provide the tools for design synthesis on the systematic way based on an optimal criteria. The mathematical optimization technique was developed and applied to ring pack design synthesis. When applied to the existing engine ring-pack designs, the optimized results indicated the potential for significant reduction in blow-by through the ring-pack by optimizing ring pack geometry. The optimization results were compared with the original ring pack designs for two gasoline engines for a wide range of operating conditions.

This paper reports attempts to gain better understanding of the influence of bearing wear on the performance of hydrodynamically lubricated bearings. An analysis was carried out on bearings from a Sapphire bearing test rig using an elastohydrodynamic model. This involved the use of both the original and worn bearing surface profiles. The results indicated that bearing wear could improve the lubrication conditions. Also the progress of wear in the bearing was simulated using a simple model of the wear process. This model predicted that the wear would progress at a reducing rate. The predicted wear agreed well with measurements both in terms of the wear profile and the location of wear.

U.S. Army arctic engine oil, MIL-L-46167B, designated OEA, provides excellent low-temperature operation and is multi functional. It is suitable for crankcase lubrication of reciprocating internal combustion engines and for power-transmission fluid applications in ground equipment. However, this product required 22-percent derated conditions in the two-cycle diesel engine qualifications test. Overall, OEA oil was limited to a maximum ambient temperature use of 5°C for crankcase applications. The technical feasibility of developing an improved, multi functional arctic engine oil for U.S. military ground mobility equipment was investigated. The concept was proven feasible, and the new oil, designated as OEA-30, has exceptional two-cycle diesel engine performance at full engine output and can be operated beyond the 5°C maximum ambient temperature limit of the MIL-L-46167B product.

In order to meet EPA's emission requirements for 1999 diesel engines, soot levels in the crankcase oil will increase significantly due to retarded timing to lower NOx. This study uses the Cummins M11 engine at soot levels up to 9% in the crankcase oil to demonstrate how oils can be formulated to prevent valve train wear, extend filter life, and maintain oil pumpability. The study includes the oil formulation development and the evaluation of API CG-4/SJ oils at 4.5% soot and API CH-4/SJ oils at 9% soot. In addition it includes X-Ray Photoelectron Spectroscopy (XPS) for surface film analysis and Surface Optical Profilometry and Scanning Electron Microscopy (SEM) of the valve train valve-bridges and rocker pads to determine the mechanism of failure. The oil's low temperature rheology as it affects oil pumpability is defined by Mini Rotary Viscometer (MRV TP-1), Scanning Brookfield Test (SBT), and Cold Cranking Simulator (CCS).

An experimental study was made to investigate in-cylinder flow field in a natural gas fueled spark ignition engine and the effects of engine specifications on in-cylinder flow field. The instantaneous two-dimentional flow fields in a single-cylinder visualization engine, which has 75mm bore and 62mm stroke, were measured in various cross sections perpendicular to the cylinder axis by using the laser light sheet PTV method at various crank angles during intake, compression, and expansion strokes over the wide range of piston combustion chamber configuration, top clearance, and nominal swirl ratio. Flow fields during compression and expansion strokes were also calculated using KIVA2 simulation code for better understanding of the measured results. The results showed that induction-generated swirl is getting concentric to the cylinder center in compression stroke, and is shifted in the radial direction in expansion stroke.

A phenomenological multi-zone model for prediction of heat release and exhaust emissions in DI Diesel engines is developed in an attempt to diminish the common trade-off between model accuracy and computing efficiency. This task is achieved by uncoupling the kinetic emission models from the detailed calculations of spray formation and heat release, which allows to substantially reduce the number of zones in that the kinetics of NOx- and soot-formation have to be solved. The predicted results of the model are compared with experimental data obtained from a turbo-charged, high-speed Diesel engine. The results for heat release and pressure histories as well as the estimated nitric oxide emissions are in good agreement with the test data, indicating that an appropriate simplification of the complex combustion process has been established. The soot model is capable of predicting trends, but there are further improvements necessary in order to produce quantitatively correct results.

Development of Caterpillar Fuel Systems' MEUI-B injector has involved application of Computational Fluid Dynamics (CFD) in order to improve performance of the high pressure spill valve. Initial performance bench testing with concept stage experimental injectors indicated that the chamber pressure was decaying at an unacceptably slow rate, and the valve demonstrated erratic behavior at some operating conditions. The slow pressure decay and inconsistent spill valve motion were believed to be caused by flow forces generated during the low lift portion of the spill valve opening event. This theory was pursued by utilizing CFD to design two valves for testing in the next phase of the injector development cycle: A baseline geometry, similar to the original concept injector valve, and a new design incorporating localized seat geometry changes for inducing flow force assisted valve opening.

This paper describes work aimed at developing an underwater power system and an environmental control EGR system based on the recycle and closed-cycle operations of conventional diesel engines. Particular emphasis is placed on one of the key problems associated with the recycling some of carbon dioxide in closed-cycle diesel engine (CCDE). A quasi-dimensional model has been developed to investigate the effects of different intake compositions on engine performances. The paper also introduces the development of instrumentaion for measurement and control combustion conditions in CCDE. With the objective of improving fuel ignitability and reducing the ignition delay, the paper experimentally investigates the effects of heated fuel on fuel injection characteristics, engine performance and exhaust emissions in DI and IDI diesel engines.

The numbers, sizes, and derived mass emissions of particles from a production DISI engine are examined over a range of engine operating conditions. Particles are sampled directly from the exhaust pipe using heated ejector pump diluters. The size distributions are measured using a scanning mobility particle sizer. The numbers and sizes of the emitted particles are reported for stratified versus homogeneous operation and as a function of fuel injection timing, spark timing, engine speed, and engine load. The principal finding is that particle number emissions increase by about a factor of 10 - 40 going from homogeneous to stratified charge operation. The particulate emissions exhibit a strong sensitivity to injection timing; generally particle number and volume concentrations increase steeply as the injection timing is retarded, except over a narrow portion of the range where the trend reverses.

Exhaust odor of DI diesel engines is worse than that of gasoline engines, especially at low temperatures and at idling. As the number of passenger cars with DI diesel engines is increasing worldwide because of their low CO2 emissions, odor reduction research of DI diesel engines is important. Incomplete combustion is a major cause of exhaust odor. Generally, odor worsens due to overleaning of the mixture in the cylinder and due to fuel adhering on the combustion chamber walls. To confirm this, the influences of different engine running conditions and fuel properties were investigated. The reason for the changes in exhaust odor with injection timing is evaluated by considerations of optimum positions of the maximum heat release. With n-heptane, a low boiling point fuel, odorous emissions increase because of overleaning of the mixture.

This paper explores the feasibility of using in-cylinder pressure-based variables to predict gaseous exhaust emissions levels from a Navistar T444 direct injection diesel engine through the use of neural networks. The networks were trained using in-cylinder pressure derived variables generated at steady state conditions over a wide speed and load test matrix. The networks were then validated on previously “unseen” real-time data obtained from the Federal Test Procedure cycle through the use of a high speed digital signal processor data acquisition system. Once fully trained, the DSP-based system developed in this work allows the real-time prediction of NOX and CO2 emissions from this engine on a cycle-by-cycle basis without requiring emissions measurement.

Influence of the inter-ring crevice, the volume between the top and second piston rings, on unburned hydrocarbon (UHC) emission was experimentally and numerically investigated. The ultimate goal of this study was to estimate the level of UHC emission induced by the blow-up of inter-ring mixture, i.e., unburned gases trapped in the inter-ring crevice. In the experiments, the inter-ring mixture was extracted to the crankcase during the late period of expansion and the early period of exhaust stroke through the engraved grooves on the lower part of cylinder wall. Extraction of the mixture resulted in the significant reductions of UHC emission in proportion to the increments of blowby flow rate, without any losses in efficiency and power. This experimental study has confirmed the importance of inter-ring crevice on UHC emission in an SI engine and established a relationship between the inter-ring mixture and UHC emission.

Early stage combustion systems, with lean homogeneous charge compression ignition (HCCI), have been studied, with the intent to decrease the pollutant emission characteristics of DI diesel engines. Early stage combustion enables drastic reductions in both nitrogen oxides (NOx) and smoke emission, but the operating load range is restricted, due to combustion phenomena, such as unsteady combustion and knocking. In this study, we explored the possibility of broadening the operating load range in HCCI and reducing pollutant emissions using Dimethyl Ether (DME) fumigated through the intake pipe. However, the improvements in load range were found to be less than 0.1 MPa in brake mean effective pressure (BMEP), even when compression ratios were reduced and Methane with high octane number was mixed. Therefore, a DME premixed charge could be used only at light loads. At heavier loads a hybrid fuel system with a DME premixed charge and diesel fuel injection is necessary.

“Gas-to-liquids” catalytic conversion technologies show promise for liberating stranded natural gas reserves and for achieving energy diversity worldwide. Some gas-to-liquids products are used as transportation fuels and as blendstocks for upgrading crude-derived fuels. Methylal (CH3-O-CH2-O-CH3), also known as dimethoxymethane or DMM, is a gas-to-liquid chemical that has been evaluated for use as a diesel fuel component. Methylal contains 42% oxygen by weight and is soluble in diesel fuel. The physical and chemical properties of neat methylal and for blends of methylal in conventional diesel fuel are presented. Methylal was found to be more volatile than diesel fuel, and special precautions for distribution and fuel tank storage are discussed. Steady state engine tests were also performed using an unmodified Cummins B5.9 turbocharged diesel engine to examine the effect of methylal blend concentration on performance and emissions.

The question of whether increasing the fuel economy of light-duty natural gas fueled vehicles can improve their economic competitiveness in the U.S. market, and help the US Department of Energy meet stated goals for such vehicles is explored. Key trade-offs concerning costs, exhaust emissions and other issues are presented for a number of possible advanced engine designs. Projections of fuel economy improvements for a wide range of lean-burn engine technologies have been developed. It appears that compression ignition technologies can give the best potential fuel economy, but are less competitive for light-duty vehicles due to high engine cost. Lean-burn spark ignition technologies are more applicable to light-duty vehicles due to lower overall cost. Meeting Ultra-Low Emission Vehicle standards with efficient lean-burn natural gas engines is a key challenge.

Fleet managers need a tool to assist them in assessing their need to comply with EPAct and to provide them with the ability to obtain information that will allow them to make alternative fuel vehicle purchasing decisions. This paper will describe the Web-based tool that will inform a fleet manager, based on their geographic location, the type of fleet they own or operate, and the number and types of vehicles in their fleet, whether or not they need to meet the requirements of EPAct, and, if so, the percentage of new vehicle purchases needed to comply with the law. The tool provides detailed specifications on available OEM alternative fuel vehicles, including the purchase cost of the vehicles, fuel and fuel system characteristics, and incentives and rebates surrounding the purchase of each vehicle. The full set of federal, state, and local incentives is made available through the tool, as well as detailed access to refueling site and dealership locations.

The blue and white smoke (cold smoke) emitted from diesel engines during warm up at low temperatures and idling conditions contains pollutant gases which irritate eyes and nose, and reductions in this irritating, odorous gas have become important with the increasing numbers of DI diesel engine vehicles. To assess the blue and white smoke a qualitative assessment method is necessary, though, there are no simple and exact measuring methods. In this study a new assessment method using a digital camera and photo analysis system with a computer is introduced. With this method the luminance of the cold smoke is displayed as 8 bit data, and a quantitative evaluation is simple, when the influence of sunshine is corrected for the smoke luminance. This paper describes the correction method for the sunshine illumination and the technique for taking the photographs.

The objective of the work described here is to test the performance of closed-loop controlled, heavy-duty CNG engines in-use, on fuels of different methane content; and to compare their performance with similar diesel vehicles. Performance is measured in terms of pollutant emissions, fuel economy, and driveability. To achieve this objective, three buses powered by closed-loop controlled, dedicated natural gas engines were tested on the heavy-duty chassis dynamometer facility at the Colorado Institute for Fuels and High Altitude Engine Research (CIFER). Emissions of regulated pollutants (CO, NOx, PM, and THC or NMHC), as well as emissions of alde-hydes for some vehicles, are reported. Two fuels were employed: a high methane fuel (90%) and a low methane fuel (85%). It was found that the NOx, CO, and PM emissions for a given cycle and vehicle are essentially constant for different methane content fuels.