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Natural gas is a challenging fuel for HCCI engines because its single-stage ignition and rapid combustion make it difficult to optimize combustion timing over a significant load range. This study investigates direct injection of a pilot quantity of high-cetane fuel near TDC as a range extension and combustion control mechanism for natural gas HCCI engines. The EGR and load range is studied in a supercharged natural gas HCCI engine equipped with external EGR, intake heating and a direct injection system for n-heptane pilot fuel. The operating range and emissions are of primary interest and are compared between both the baseline HCCI engine with variable intake temperature and the direct injected HCCI (DI-HCCI) engine with constant intake temperature. Test results show the EGR and load range at fixed intake temperature can be extended using pilot direct injection.

Because of domestic production from renewable sources and their clean burning nature, alcohols, especially ethanol, have seen growing use as a blending agent and replacement for basic hydrocarbons in gasoline. The increasing use of alcohol in fuels raises questions on the safety of these fuels under certain non-operational situations. Modern vehicles use evaporative emission control systems to minimize environmental emissions of fuel. These systems must be relatively leak-free to function properly and are self-diagnosed by the vehicle On-Board Diagnostic system. When service is required, the service leak testing procedures may involve forcing test gases into the “evap” system and also exposure of the fuel vapors normally contained in the system to atmosphere. Previous work has discussed the hazards involved when performing shop leak testing activities for vehicles fuelled with conventional hydrocarbon gasoline [1, 2].

Given the advantages of ultra low NOx emission and high thermal efficiency at part load, HCCI engines might develop a significant niche in the engine world, provided that a suitable HCCI combustion control mechanism can be found. The problem is that HCCI occurs in a narrow operating range bounded by severe knock and misfire limits. Acceptable combustion behavior can be lost due to minor changes in speed, load, temperature or other variables. One approach to control HCCI combustion is to use a variable blend of base fuel and reformed fuel which can be adjusted on a cycle-by-cycle basis to control the combustion behaviour. Developing this control technique requires researchers to be able to optimize the settings and predict the effects of the many variables that affect HCCI ignition and combustion.

This paper presents an investigation of a reverse flow catalytic converter attached to a diesel/natural gas dual fuel engine. Experimental data were obtained in a ceramic monolith catalytic converter with a palladium based catalyst. A variety of flow reversal cycle times were explored experimentally when the engine load was changed from a high load to a low load. A single channel numerical model was developed for the data set and the effect of reverse flow cycle time was studied using both physical and numerical model systems. The duration of the cycle time is shown to be an important parameter in the operation of the converter. Shorter cycle times produced the least fluctuation in reactor temperature and gave the highest time-averaged conversion. Intermediate cycle times gave the most rapid increase in the maximum reactor temperature.

Life Cycle Assessment (LCA) is commonly used to measure the environmental and economic impacts of engineering projects and/or products. However, there is some uncertainty associated with any LCA study. The LCA inventory analysis generally relies on imperfect data in addition to further uncertainties created by the assessment process itself. It is necessary to measure the effects that data and process uncertainty have on the LCA result and to communicate the level of uncertainty to those making decisions based on the LCA. To accomplish this, a systematic and rigorous means to assess the overall uncertainty in LCA results is required. This paper demonstrates the use of Monte Carlo Analysis to track and measure the propagation of uncertainty in LCA studies. The Monte Carlo technique basically consists of running repeated assessments using random input values chosen from a specified probable range.

Transportation, with its high energy consumption, is commonly recognized as a major contributor to local, regional, and global environmental impacts. With around 95% of transportation energy originating from petroleum and an increasing emphasis on the associated environmental impacts, alternative transportation fuels are receiving great attention from industry, government, researchers, and the public. When the motivation for developing alternative fuels is to reduce environmental impact, a rigorous tool is needed for comparing the effects of very different alternative and conventional fuels. Such an evaluation tool must consider not only the effects of fuel combustion, but also the effects of producing, refining/processing, distributing, and disposing of wastes associated with that fuel… in other words, the life cycle effects of the fuel.

Because of the limitations of their storage batteries, electric cars have always suffered from short range, high weight, and high cost. New battery technologies will provide a significant improvement but all-electric vehicles will still tend to be heavy, costly, and severely limited in range compared with their combustion-engined counterparts. Despite these inherent disadvantages, there is a huge impetus for electric car development because of the pollution disadvantages of the combustion engine. Given the weight/cost/range problems of purely electric cars, it is desirable to develop hybrid cars which have the capability of operating as zero-emission electric cars in urban areas and which use a small internal combustion engine to extend the operating range. The internal combustion engine and its fuel are far lighter, cheaper, and more effective at extending range than carrying enough battery capacity to give an all-electric vehicle a suitable range. The U.S.

Research on ignition, flame growth and flame propagation in engine-like turbulence has produced widely varying correlations between turbulence parameters and flame speed. Some previous work has shown that the burning velocity observed in a given turbulence level depends on the flame size as well as the turbulence intensity and scale. This explains some of the previous experimental discrepancy and emphasizes the importance of measuring flame growth and turbulence effects over the range of interest for a given modelling requirement. This paper reports on an experimental study of flame growth from ignition sparks in spatially uniform, decaying turbulence similar to that found in engine combustion chambers. High speed schlieren video and pressure trace analyses were used to study 3-dimensional turbulent flame growth in a constant volume, cubical combustion chamber. Lean methane-air mixtures of 60%, 70%, 80%, 90% and 100% stoichiometric compositions were ignited at 1 atm and 300 K.

The Alberta Department of Energy has developed a four part Transportation Energy Audit program. The full program incorporates vehicle selection, route planning, driver training, and vehicle maintenance phases. This paper discusses the background and experience using the vehicle maintenance phase. Vehicle maintenance condition is assessed using a simple inspection procedure based on tire pressure and tailpipe exhaust emissions at idle and fast-idle conditions. With these measurements, vehicles are ranked in order of maintenance condition and estimates are made of the potential fuel cost savings obtainable by improved maintenance. Tire under-inflation is converted to potential fuel cost savings using an equation based on tire rolling resistance properties, inflation pressure, and the relative importance of tire rolling resistance in total vehicle fuel consumption.

This paper describes tests of friction-reducing coatings applied to single-cylinder, splash-lubricated, gasoline engines. The suppliers of the coatings anticipated a significant, (10-15%), decrease in fuel consumption as a result of covering most engine contact surfaces with a proprietary, FIFE-type plastic. However, a brief analysis indicates that possible benefits should be closer to 3% at high engine loads. To establish coating effectiveness, carefully controlled fuel economy testing of two engines was performed on a water-braise dynamometer at one engine speed and two output torque levels (approximately 70% and 95% of rated load). Test results showed increased fuel consumption on both coated engines compared with uncoated engines. Direct comparisons showed fuel consumption was 8% higher at full load and 10% higher at part load. This unexpected increase in fuel consumption was attributed to increased friction in the journal bearings of the engine.

The use of cylinder pressure transducers in engine control systems will permit optimum performance under all operating conditions. Previous research has shown that it is possible to automatically detect and evaluate knocking combustion based on low frequency (1 point per crank angle degree) pressure data from research and production engines. However, the previous work was done in a single cylinder research engine and a production engine with relatively slow combustion and large knock pressure peaks. In this study, a spark-plug-mounted pressure transducer and an in-cylinder flush mounted pressure transducer were used to monitor the combustion pressure in a modern four cylinder engine during knocking and normal full load operation over a speed range of 1800 RPM to 4000 RPM. This engine features much more rapid combustion and much smaller knock pressure peaks.

In a previous paper, a knock indicator based on the third derivative of the cylinder pressure trace has been developed. This knock indicator measures the rate at which pressure trace curvature changes from positive to negative during the knock peak. Since it is dealing only with the general shape of the pressure trace, it gives a measurement of combustion severity based on low frequency data such as is commonly used for engine cycle analysis. This low frequency sampling makes it useful for adding knock analysis to existing engine analysis programs without changes of equipment or significant increases in computational effort. It may also make it useful for future on-board engine controls using limited frequency response or heavily filtered pressure transducers. Results of using this knock indicator as a diagnostic tool on a multi-cylinder engine with a spark plug-mounted transducer are presented.

THE WORK REPORTED in this paper is part of an on-going study of cyclic variability in spark-ignition engines. In order to analyze knock and its variability from cycle to cycle in a meaningful way, an algorithm has been developed to characterize the severity of the bulk pressure change associated with knocking combustion. This algorithm depends on the third differential of pressure over the period when autoignition might occur. A large negative value of third differential indicates the abrupt pressure rise and narrow pressure peak commonly associated with end gas autoignition. This knock diagnostic has the advantage of working on a low frequency data acquisition rate (1 point/CA° or less) and of producing consistent results in spite of high frequency noise on the pressure signal such as might be caused by resonance of a spark plug-mounted pressure transducer.