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Blends of gasoline, diesel fuel and ethanol (“dieseline”) have shown promise in engine studies examining low temperature combustion using compression ignition. They offer the possibility of high efficiency combined with low emissions of oxides of nitrogen and soot. However, unlike gasoline or diesel fuel alone, such mixtures can be flammable in the headspace above the liquid in a vehicle fuel tank at common ambient temperatures. Quantifying their flammability characteristics is important if these fuels are to see commercial service. The parameter of most interest is the Upper Flammable Limit (UFL) temperature, below which the headspace vapour is flammable. In earlier work a mathematical model to predict the flammability of dieseline blends, including those containing ethanol, was developed and validated experimentally. It was then used to study the flammability of a wide variety of dieseline blends parametrically.

Low Temperature Combustion using compression ignition may provide high efficiency combined with low emissions of oxides of nitrogen and soot. This process is facilitated by fuels with lower cetane number than standard diesel fuel. Mixtures of gasoline and diesel (“dieseline”) may be one way of achieving this; however, a gasoline/diesel mixture in a fuel tank can result in a flammable headspace, particularly at very cold ambient temperatures. A mathematical model to predict the flammability of dieseline blends, including those containing ethanol, was previously validated. In this paper, that model is used to study the flammability of dieseline blends parametrically. Gasolines used in the simulations had Dry Vapour Pressure Equivalent (DVPE) values of 45, 60, 75, 90 and 110 kPa.

Low Temperature Combustion using compression ignition may provide high efficiency combined with low emissions of oxides of nitrogen and soot. This process is facilitated by fuels with lower cetane number than standard diesel fuel. Mixtures of gasoline and diesel (“dieseline”) may be one way of achieving this, but a practical concern is the flammability of the headspace vapours in the vehicle fuel tank. Gasoline is much more volatile than diesel so, at most ambient temperatures, the headspace vapours in the tank are too rich to burn. A gasoline/diesel mixture in a fuel tank therefore can result in a flammable headspace, particularly at cold ambient temperatures. A mathematical model is presented that predicts the flammability of the headspace vapours in a tank containing mixtures of gasoline and diesel fuel. Fourteen hydrocarbons and ethanol represent the volatile components. Heavier components are treated as non-volatile diluents in the liquid phase.

Gasoline Compression Ignition (GCI) has been identified as a technology which could give both high efficiency and relatively low engine-out emissions. The introduction of any new vehicle technology requires widespread availability of appropriate fuels. It would be ideal therefore if GCI vehicles were able to operate using the standard grade of gasoline that is available at the pump. However, in spite of recent progress, operation at idle and low loads still remains a formidable challenge, given the relatively low autoignition reactivity of conventional gasoline at these conditions. One conceivable solution would be to use both diesel and gasoline, either in separate tanks or blended as a single fuel (“dieseline”). However, with this latter option, a major concern for dieseline would be whether a flammable mixture could exist in the vapour space in the fuel tank.

This paper describes the development and proof-of-concept testing of an electrically based (i.e., non-optical) smoke sensor for diesel engines. The sensor is intended to provide a means of detecting smoke levels that exceed certain pre-defined limits. Potential applications for the sensor include closed loop control of Exhaust Gas Recirculation (EGR) and the diagnosis of fuel injection faults. Engine dynamometer tests were carried out using a heavy duty diesel engine equipped with a laboratory EGR system. EGR levels were adjusted to vary exhaust smoke levels at a fixed speed/load test point. Reference smoke measurements were provided by an AVL 415S variable sampling smoke meter. The experimental results showed a correlation between the sensor signal and the Filter Smoke Number (FSN) at FSN values between approximately 1 and 3. The sensor was able to detect relative changes in smoke levels, but its absolute sensitivity was not consistent.

This paper describes an experimental study of the effects of ignition spark characteristics on combustion behaviour in a light duty automotive engine. A prototype programmable energy ignition system was used to investigate the influence of both spark energy and the current/time profile used to deliver a given amount of energy. The engine was tested under part load conditions using a stoichiometric air/fuel ratio and relatively high levels of exhaust gas recirculation (EGR). In addition to tests with port-injected gasoline, tests were also carried out using propane (premixed upstream of the throttle) in order to investigate the possibility that improvements in the homogeneity of the mixture might influence the impact of varying the spark characteristics.

The present study investigated three techniques for predicting combustion chamber deposit formation in a direct injection diesel engine. One non-intrusive technique, based on the factorial experimental design method was used to develop an empirical model. This model predicts deposit weight as a function of time, but is dependent on engine type, type of lubricating oil, and engine operating parameters. Two intrusive techniques were also investigated for predicting deposit formation: a fast response thermocouple and a deposit conductivity probe, both being located within the combustion chamber. It was shown that the fast response thermocouple technique provided a correlation between in-cylinder peak temperature phase lag and deposit thickness. The conductivity probe correlated electrical conductivity with deposit growth. As well, the waveform characteristics from the conductivity probe showed the potential to predict the physical structure of the deposits.

This paper describes an experimental study to determine the potential for fuel efficiency improvements offered by dedicated, high compression E85 engines with optimized powertrain calibration strategies. The study involved a prototype variable fuel engine that could operate using either gasoline or E85, and a high compression version of the same engine that was suitable only for E85. Fuel consumption and engine-out emissions were evaluated using steady-state engine dynamometer tests to represent urban and highway speed/load conditions. For each fuel and engine combination, the fuel efficiency and emissions trade-offs provided by varying Exhaust Gas Recirculation (EGR) levels were determined. For the high compression engine, operation at lower speed/higher load conditions (producing the same power as the standard speed/load settings) was also investigated.

This paper describes an experimental study comparing the peak ignition voltage requirements of natural gas and gasoline in a typical bi-fuel vehicle application. Chassis dynamometer tests were carried out in which the vehicle was subjected to different types of transient wide open throttle events to create “worst case” voltage requirements. In addition to measurements of ignition voltage, other factors known to influence voltage requirements (such as cylinder pressure, electrode temperature, and fuel/air ratio) were recorded during the transient tests in order to obtain a better understanding of the underlying reasons for observed differences in voltage requirements between the two fuels and between the different transient test procedures. The results presented in this paper quantify the increased peak voltage requirements (relative to gasoline) for reliable ignition of natural gas under various operating conditions.