Search Results

A comparison of scanning mobility particle sizer (SMPS) and laser-induced incandescence (LII) measurements of diesel particulate matter (PM) was performed. The results reveal the significance of the aggregate nature of diesel PM on interpretation of size and volume fraction measurements obtained with an SMPS, and the accuracy of primary particle size measurements by LII. Volume fraction calculations based on the mobility diameter measured by the SMPS substantially over-predict the space-filling volume fraction of the PM. Correction algorithms for the SMPS measurements, to account for the fractal nature of the aggregate morphology, result in a substantial reduction in the reported volume. The behavior of the particulate volume fraction, mean and standard deviation of the mobility diameter, and primary particle size are studied as a function of the EGR for a range of steady-state engine speeds and loads for a turbocharged direct-injection diesel engine.

The present paper aims at developing an innovative procedure to create a one-dimensional (1D) real-time capable simulation model for a heavy-duty diesel engine. The novelty of this approach is the use of the top-level engine configuration, test cell measurement data, and manufacturer maps as opposite to common practice of utilizing a detailed 1D engine model. The objective is to facilitate effective model adjustments and hence further increase the application of Hardware-in-the-Loop (HiL) simulations in powertrain development. This work describes the development of Fast Running Model (FRM) in GT-SUITE simulation software. The cylinder and gas-path modeling and calibration are described in detail. The results for engine performance and exhaust emissions produced satisfactory agreement with both steady-state and transient experimental data.

In order to meet emissions and power requirements, modern engine design has evolved in complexity and control. The cost and time restraints of calibration and testing of various control strategies have made virtual testing environments increasingly popular. Using Hardware-in-the-Loop (HiL), Volvo Penta has built a virtual test rig named VIRTEC for efficient engine testing, using a model simulating a fully instrumented engine. This paper presents an innovative Artificial Neural Network (ANN) based model for engine simulations in HiL environment. The engine model, herein called Artificial Neural Network Engine (ANN-E), was built for D8-600 hp Volvo Penta engine, and directly implemented in the VIRTEC system. ANN-E uses a combination of feedforward and recursive ANNs, processing 7 actuator signals from the engine management system (EMS) to provide 30 output signals.

TPO is being used to make automotive parts for its number of advantages: i) low temperature flexibility and ductility, ii) excellent impact/stiffness/flow balance, iii) excellent weatherability, and iv) free-flowing pellet form for easy processing, storage, and handling. However, by foaming TPO, due to its higher rigidity-to-weigh ratio, it would offer additional advantages over the solid counterparts in terms of reduced weight, reduced material cost, and decreased fuel usage without compromising their performance. Since a major component in TPO is polypropylene (PP), understanding PP foaming behaviours is an important step towards understanding TPO foaming. For foam materials, cell density and cell size are two significant parameters that affect their material properties. In this research, we observed the cell nucleation and initial growth behaviours of PP foams blown with CO2 under various experimental conditions in a batch foaming simulation system.

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.

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.

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.

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.

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.

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.

Charge dilution is commonly used to reduce emissions of nitrogen oxides (NOx) from internal combustion engine exhaust gas. The question of whether to use air or exhaust gas recirculation (EGR) as a charge diluent for the natural gas-fuelled test engine is addressed first. The decision to use EGR is based on the potentially lower NOx and unburned hydrocarbon emissions that could be achieved if a three-way catalyst were applied to the engine. The effect of EGR on the spark advance for maximum brake torque (MBT), NOx, and unburned hydrocarbon emissions is then examined in detail. The effect on fuel efficiency is discussed briefly.

Optical fiber probes were used to measure the soot temperature and estimate the soot concentration inside the cylinder of a DI diesel engine. The probes were mounted at various locations on the head of the test engine, and the measurements were performed under different load levels. Using the two-color method, the variations in temperature and soot mass concentration during the combustion process were examined with temporal and spatial resolution. It was observed that soot formation is rapid and is associated with heterogeneity in the early stage of combustion. Moreover, the soot formation mechanism seems to be independent of the engine load. In contrast, soot oxidation is relatively slow. Data obtained at several different load levels are presented, and the effects of various error sources on the accuracy of the measurement technique are also investigated.

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.

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

The concentration of carbonaceous particulate matter in the exhaust of diesel engines depends on the rates of formation and oxidation of soot in the combustion chamber. Soot forms early in the combustion process when local fuel-rich areas exist, whereas soot oxidation occurs later when more air is entrained into the fuel spray. Based on this understanding, a phenomenological combustion model is established. In the model, the cylinder volume is divided into four zones: a rich fuel spray core, a premixed-burning/burned gas zone, a mixing controlled burning zone and a lean air zone. Soot formation takes place in the mixing controlled burning zone where the local C/O ratio is above the critical value. Soot oxidation occurs in the premixed-burning/burned gas zone as air is entrained. By using a quasi-global chemical reaction scheme, the oxidation of soot particles by different species can be investigated.

This paper presents an experimental study on the foaming behavior of recyclable high-melt-strength (HMS) branched polypropylene (PP) with CO2 as a blowing agent. The foamability of branched HMS PP has been evaluated using a tandem foaming extruder system. The effects of CO2 and nucleating agent contents on the final foam morphology have been thoroughly investigated. The low density (i.e., 12~14 fold), fine-celled (i.e., 107–109 cells/cm3) PP foams were successfully produced using a small amount of talc (i.e., 0.8 wt%) and 5 wt% CO2.

This paper demonstrates the effects of nano-clay on the microcellular foam processing of nylon. First, Nylon 6 nanocomposites with 1 wt% clay were prepared by a twin screw extruder. The nanocomposite structures were characterized by XRD and TEM. Nylon and its nanocomposites were foamed in extrusion using CO2. The cell morphologies of nylon and its nanocomposite foams were investigated. It appeared that the nano-clay not only enhanced cell nucleation, but also suppressed cell deterioration in the microcellular foaming of nylon.

The performance of low-adhesion surfaces in a realistic, in-flight icing environment with supercooled liquid droplets is evaluated using a NACA 0018 airfoil in the National Research Council of Canada Altitude Icing Wind Tunnel. This project was completed in collaboration with McGill University, the University of Toronto and the NRC Aerospace Manufacturing Technologies Centre in March 2022. Each collaborator used significantly different methods to produce low-adhesion surface treatments. The goal of the research program was to demonstrate if the low-adhesion surfaces reduced the energy required to de-ice or anti-ice an airfoil in an in-flight icing environment. Each collaborator had been developing their own low-adhesion surfaces, using bench tests in cold rooms and a spin rig in the wind tunnel to evaluate their performance. The most promising surface treatments were selected for testing on the airfoil.