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Particulate matter emissions from gasoline direct injection engines are a concern due to the health effects associated with ultrafine particles. This experimental study investigated sources of particulate matter emissions variability observed in previous tests and also examined the effect of ethanol content in gasoline on particle number (PN) concentrations and particle mass (PM) emissions. FTIR measurements of gas phase hydrocarbon emissions provided evidence that changes in fuel composition were responsible for the variability. Exhaust emissions of toluene and ethanol correlated positively with emitted PN concentrations, while emissions of isobutylene correlated negatively. Exhaust emissions of toluene and isobutylene were interpreted as markers of gasoline aromatic content and gasoline volatility respectively.

Large-scale emergency or off-grid power generation is typically achieved through diesel or natural gas generators. To meet governmental emission requirements, emission control systems (ECS) are required. In operation, effective control over the generator’s acoustic emission is also necessary, and can be accomplished within the ECS system. Plug flow mufflers are commonly used, as they provide a sufficient level of noise attenuation in a compact structure. The key design parameter is the transmission loss of the muffler, as this dictates the level of attenuation at a given frequency. This work implements an analytically decoupled solution, using multiple perforate impedance models, through the transfer matrix method (TMM) to predict the transmission loss based on the muffler geometry. An equivalent finite element model is implemented for numerical simulation. The analytical results and numerical results are then evaluated against experimental data from literature.

Biodiesel and other renewable fuels are of interest due to their impact on energy supplies as well as their potential for carbon emissions reductions. Waste animal fats from meat processing facilities, which would otherwise be sent to landfill, have been proposed as a feedstock for biodiesel production. Emissions from biodiesel fuels derived from vegetable oils have undergone intense study, but there remains a lack of data describing the emissions implications of using animal fats as a biodiesel feedstock. In this study, emissions of NOx, unburned hydrocarbons and particulate matter from a compression ignition engine were examined. The particulate matter emissions were characterized using gravimetric analysis, elemental carbon analysis and transmission electron microscopy. The emissions from an animal fat derived B20 blend were compared to those from petroleum diesel and a soy derived B20 blend.

Polymers are often blended to create compounds with new or enhanced properties in order to compensate for an individual polymer's weakness or lack of inherent properties. In the field of polymer foaming, polymer blends are also used to generate fine-cell structures via heterogeneous nucleation. Recently, an interest in physical blowing agents, such CO2 and N2, has increased because of their low impact on the environment. It has thus become additionally important to pursue research on the foaming of polymer blends employing these particular physical blowing agents in an effort to keep up with the demand for environmentally friendly products. In this study, thermoplastic polyolefin (TPO) blends were prepared with polypropylene (PP) and a metallocene-based polyolefin elastomer (POE) using twin-screw extruders and a batch mixer.

This research investigates the foaming behaviors of polypropylene (PP) and PP/clay nanocomposites blown with supercritical CO2. In this context, special attention is paid to the effects of varied clay content on the foamed structures. First, a master batch of nanocomposites with 1% and 5% clay are prepared; the nanocomposites are then characterized using X-Ray Diffraction (XRD) prior to and after their subjection to the foaming process. Subsequently, foaming experiments are conducted using supercritical CO2 as a blowing agent. The cell nucleation and expansion behaviors of the PP-based nanocomposite foams are studied at various clay contents and die temperatures. Finally, the effects of the clay content on the cell morphology, the cell density, and the expansion ratio of the PP/clay nanocomposite foams are identified.

Crevices in the combustion chamber are the main source of hydrocarbon (HC) emissions from spark ignition (SI) engines fuelled by natural gas (NG). Instantaneous in-cylinder and engine exhaust port HC concentrations were measured simultaneously using a Cambustion HFR400 fast response flame ionization detector (FRFID) concentrated on the post-flame period. The raw data was reconstructed to account for variation in the FFRID sample transit time and time constant due to fluctuating in-cylinder pressure. HC concentration development during the post-flame period is discussed. Comparison is made of the post-flame in-cylinder and exhaust port HC concentrations under different engine operating conditions, which gives a better understanding of the mechanism by which HC emissions form from crevices in SI engines.

A counter–flow propane/air diffusion flame (ϕ= 1.79) is used for a fundamental analysis of the effects of oxygenated additives on soot precursor formation. Experiments are conducted at atmospheric pressure using Gas Chromatography for gas sample analysis. The oxygenated additives dimethyl carbonate (DMC) and ethanol are added to the fuel keeping the total volumetric fuel flow rate constant. Results show 10 vol% DMC significantly reduces acetylene, benzene, and other flame pyrolysis products. Ethanol (10 vol%) shows, instead, more modest reductions. Peak acetylene and benzene levels decrease as the additive dosage increases for both DMC and ethanol. The additive's effect on the adiabatic flame temperature and the fuel stream carbon content does not correlate significantly with acetylene levels. However, there does appear to be a linear relationship between acetylene concentrations and both the additive's oxygen and C–C bond content.

The Enhanced/Synthetic Vision System (E/SVS) is a Technology Demonstrator (TD) project supported by the Chief, Research and Development of the Canadian Department of National Defence. E/SVS displays an augmented visual scene to the pilot that includes three separate image sources: a synthetic computer - generated terrain image; an enhanced visual image from an electro-optical sensor (fused as an inset); and aircraft instrument symbology, all displayed to the pilot on a Helmet Mounted Display (HMD). The synthetic component of the system provides a 40 degree vertical by 80 degree horizontal image of terrain and local features. The enhanced component digitizes imagery from electro-optic sensors and fuses the sensor image as an inset (20 degrees by 25 degrees) within the synthetic image. Symbology can be overlaid in any location within the synthetic field-of-view and may be head, aircraft, target or terrain referenced.

Throttle tip-in and tip-out tests on a 2.0 litre passenger car engine were performed using four different natural gas fuelling systems an air-valve or variable restriction type mixer, a venturi type mixer, central fuel injection, and port fuel injection. The in-cylinder fuel-air equivalence ratio, ϕ, was measured using a fast response flame ionization detector sampling about 7 mm from the spark plug gap. The data reveal characteristics of each fuel system's in-cylinder fuel-air ratio response and torque response.

The air/fuel ratio (AFR) is a key contributor to both the performance and emissions of an automotive engine. Its variation between cylinders - and between engine cycles - is of particular importance, especially during throttle transients. This paper explores the use of a fast flame ionisation detector (FFID) to quantify these rapid changes of in-cylinder composition in the vicinity of the spark gap. While this instrument actually measures fuel concentration, its results can be indicative of the AFR behaviour. Others have used the FFID for this purpose, but the planned test conditions placed special demands on the instrument. These made it prudent to explore the limits of its operating envelope and to validate the experimental technique. For in-cylinder sampling, the instrument must always be insensitive to the large pressure changes over the engine cycle. With the wide range of engine loads of interest here, this constraint becomes even more crucial.

The hydrogen-fueled engine has been identified as a viable power unit for ultra-low emission senes-hybrid vehicles The absence of carbon in hydrogen fuel eliminates exhaust emissions of CO, CO2, and hydrocarbons, with the exception of small contributions from the combustion of lubricating oil Thus, the only regulated emission of a hydrogen-fueled engine is NOx, and the engine may be optimized to minimize NOx since the usual constraint of the NOx -hydrocarbon trade-off is not applicable Hydrogen-fueled homogeneous charge piston engines have, however, generally suffered from a variety of combustion difficulties, most notably a proclivity to ignition on hot surfaces such as exhaust valves, spark plug electrodes and deposits on combustion chamber walls The Wankel engine is particularly well suited to the use of hydrogen fuel, since its design minimizes most of the combustion difficulties In order to evaluate the possibilities offered by the hydrogen fueled rotary engine, dynamometer tests were conducted with a small (2 2kW) Wankel engine fueled with hydrogen Preliminary results show an absence of the combustion difficulties present with hydrogen-fueled homogenous charge piston engines The engine was operated unthrottled and power output was controlled by quality governing, i.e. by varying the fuel-air equivalence ratio on the lean side of stoichiometric The ability to operate with quality governing is made possible by the wide flammability limits of hydrogen-air mixtures NOx emissions are on the order of 5 ppm for power outputs up to 70% of the maximum attainable on hydrogen fuel Thus, by operating with very lean mixtures, which effectively derates the engine, very low NOx emissions can be achieved Since the rotary engine has a characteristically high power to weight ratio and a small volume per unit power compared to the piston engine, operating a rotary engine on hydrogen and derating the power output could yield an engine with extremely low emissions which still has weight and volume characteristics comparable to a gasoline-fueled piston engine Finally, since engine weight and volume affect vehicle design, and consequently in-use vehicle power requirements, those factors, as well as engine efficiency, must be taken into account in evaluating overall hybnd vehicle efficiency

An experiment was conducted to evaluate the efficiency and emissions of an engine fuelled with a mixture of natural gas and approximately 15% hydrogen by volume. This mixture, called Hythane™, was compared with natural gas fuel using engine efficiency and engine-out emissions at various engine operating conditions as the basis of comparison. Throughout most of the experiment, fuel mixtures were slightly rich of stoichiometry. It was found that at low engine loads, using the same spark timing, engine efficiency increased under HythaneTM fuelling but at higher engine loads, natural gas and Hythane™ had the same efficiency. At low engine speed and load conditions with the same spark timing, engine-out total hydrocarbon (THC) emissions were lower for Hythane™ fuelling. When compared on a carbon specific basis, however, natural gas hydrocarbon emissions were lower. At some test conditions, engine-out carbon monoxide (CO) emissions were lower under Hythane™.

Measurements were taken of the speciated aldehyde and ketone exhaust emissions from a modern four-cylinder engine fuelled with natural gas. The effect on these emissions of varying the engine operating parameters spark timing, exhaust gas recirculation rate, engine speed, and fuel/air equivalence ratio was examined. The influence of these operating parameters on the complete reactivity-weighted emissions with natural gas fuelling is predicted. With stoichiometric fuel/air mixtures, both the total hydrocarbons and formaldehyde emissions declined with increasing exhaust gas temperature and increasing in-cylinder residence time, suggesting that formaldehyde burn-up in the exhaust process largely controls its emissions levels. Closer examination of the aldehyde emissions shows they follow trends more like those of the non-fuel, intermediate hydrocarbon species ethane and acetylene, than like the trends of the fuel components methane and ethane.

Many current aftermarket natural gas conversions of gasoline fuelled spark ignited engines use an air-valve type mixer with closed loop control of the gas pressure. This control is often provided by an electronic integral controller that uses the output from an exhaust gas oxygen (EGO) sensor to control the duty cycle of a solenoid valve. By varying the duty cycle of this fuel control valve (FCV), the average pressure in the low pressure regulator (LPR) reference chamber and thus the gas pressure can be varied. The transient behaviour of these fuel systems is affected mainly by the mechanical response of the gas mixer and the LPR. The electronic controller can provide compensation only after the EGO sensor has detected an air-fuel ratio excursion. The main weaknesses of this type of fuel system seems to be associated with the finite response of the mixer and the LPR and by the use of an airflow dependent vacuum signal strength for control.

The effects of engine operating parameters on the speciated engine-out hydrocarbon emissions from a natural gas fueled spark ignition 16 valve four-cylinder engine were examined. Total hydrocarbon emissions were dominated by methane, the main component of natural gas. The non-methane hydrocarbons consisted primarily of ethane, ethene, and acetylene. Except for changes in the fuel-air equivalence ratio rich of the stoichiometric condition, emissions of unsaturated species were found to be less sensitive to engine operating parameters than were the fuel components. A single species, ethene, dominated the engine-out hydrocarbon reactivity, accounting for over 80% of the NMHC reactivity.

A study was performed to determine the effects of engine operating variables and piston and ring parameters on the crevice hydrocarbon emissions from a spark-ignition engine. Natural gas was used as the test fuel in an effort to isolate crevice mechanisms as the only major source of unburned hydrocarbons in the test engine's exhaust. The largest of the in-cylinder crevices, the piston ring pack crevices, were modified, both in size and accessibility, by altering the piston top land height and the number of piston rings and their end gaps. Each piston and ring configuration was subjected to a series of test sweeps of engine operating variables known to affect exhaust hydrocarbon emissions. None of the physical crevice modifications had any significant effect on the level of the exhaust hydrocarbon emissions, although the cycle-to-cycle repeatability of these emissions, measured with a fast hydrocarbon analyzer, was found to vary between the different configurations.

As a result of CAFE (corporate average fuel economy) requirements, the trend in passenger car engine design is to smaller displacement engines of higher specific output which provide reductions in vehicle driving cycle fuel consumption without an accompanying decrease in maximum power output. Design features such as four valves per cylinder and compact combustion chambers give these engines significantly different combustion characteristics than traditional pushrod OHV (overhead valve) engines. In general, their combustion chambers are fast burning, enabling the use of higher compression ratios without knock on unleaded gasoline. Since fuel consumption decreases with increasing compression ratio, and since natural gas has a substantially higher octane rating than the best unleaded gasoline, it would appear to be desirable to operate with even higher compression ratios in a dedicated natural gas engine.

Some current aftermarket natural gas closed loop carburetion systems use an integral control strategy to maintain a fuel-air equivalence ratio centered in the peak conversion window of a three-way catalytic converter. Fuel control system performance under steady-state engine operating conditions can be characterized by the time-averaged value of the fuel-air equivalence ratio, the rich and lean excursion limits, and a skewness parameter that represents the non-symmetry of the time varying fuel-air equivalence ratio about the control value (ϕaverage). Using a representative aftermarket feedback control system, the effect of these parameters on the exhaust emissions of a natural-gas fueled four-cylinder engine has been investigated. In addition, the effect of EGO sensor characteristics on control system performance has been examined.

The increasing use of natural gas as a vehicle fuel has generated considerable research activity to characterize the performance and emissions of engines utilizing this fuel. However, virtually all of the results reported have been for pushrod OHV spark ignition engines or SI conversions of heavy-duty diesel engines. Because of the pressure to improve fuel economy imposed by CAFE requirements, passenger cars are increasingly tending toward high specific output, small displacement engines. These engines employ such features as four valves per cylinder and centrally located spark plugs which give them a different dependence on operating variables than traditional pushrod OHV engines. In this study, experiments were carried out with a two-liter four-cylinder Nissan SR20DE engine representative of modern design practice. The engine was operated on gasoline and natural gas at six different loads and three different speeds. Some tests were also done with isooctane.

Methanol, in common with other alternative fuels including natural gas and LPG, has autoignition characteristics which are poorly suited for use in compression ignition engines. Some sort of ignition assist has proven to be necessary. Considerable work has been carried out with hot surface (glow plug) ignition. The geometric relationship between the fuel injection nozzle and the glow plug is critical to achieving high efficiency and low emissions. Moreover, it is difficult to establish a single geometry which provides reliable ignition and stable operation over the entire range of engine speeds and loads. The work described in this paper investigated extending the range of operation of a particular glow plug/fuel injection nozzle geometry by placing the glow plug in the wake of a bluff body. Bluff-body flame stabilization is a well-known technique in continuous combustors. Experiments were carried out in a single-cylinder CFR cetane rating engine fueled with methanol.