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Technical Paper

A Quasi-Steady Diffusion-Based Model for Design and Analysis of Fuel Tank Evaporative Emissions

2019-04-02
2019-01-0947
In this paper, a fuel tank evaporation/condensation model was developed, which was suitable for calculation of evaporative emissions in a fuel tank. The model uses a diffusion-controlled mass transfer approach in the form of Fick's second law in order to calculate the average concentration of fuel vapor above the liquid level and its corresponding evaporation rate. The partial differential equation of transient species diffusion was solved using a separation of variables technique with the appropriate boundary conditions for a fuel tank. In order to simplify the solution, a quasi-steady assumption was utilized and justified. The fuel vapor pressure was modeled based on an American Petroleum Institute (API) procedure using either a distillation curve or a Reid Vapor Pressure (RVP) as an experimental input for the specific fuel used in the system.
Technical Paper

Heavy Duty Diesel Engine Modeling with Layered Artificial Neural Network Structures

2018-04-03
2018-01-0870
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.
Technical Paper

Development and Calibration of One Dimensional Engine Model for Hardware-In-The-Loop Applications

2018-04-03
2018-01-0874
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.
Technical Paper

Fuel Effects on Particulate Matter Emissions Variability from a Gasoline Direct Injection Engine

2018-04-03
2018-01-0355
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.
Technical Paper

Modelling and Optimization of Plug Flow Mufflers in Emission Control Systems

2017-06-05
2017-01-1782
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.
Technical Paper

Impact of Powertrain Type on Potential Life Cycle Greenhouse Gas Emission Reductions from a Real World Lightweight Glider

2017-03-28
2017-01-1274
This study investigates the life cycle greenhouse gas (GHG) emissions of a set of vehicles using two real-world gliders (vehicles without powertrains or batteries); a steel-intensive 2013 Ford Fusion glider and a multi material lightweight vehicle (MMLV) glider that utilizes significantly more aluminum and carbon fiber. These gliders are used to develop lightweight and conventional models of internal combustion engine vehicles (ICV), hybrid electric vehicles (HEV), and battery electric vehicles (BEV). Our results show that the MMLV glider can reduce life cycle GHG emissions despite its use of lightweight materials, which can be carbon intensive to produce, because the glider enables a decrease in fuel (production and use) cycle emissions. However, the fuel savings, and thus life cycle GHG emission reductions, differ substantially depending on powertrain type. Compared to ICVs, the high efficiency of HEVs decreases the potential fuel savings.
Technical Paper

Emissions from Compression Ignition Engines with Animal-Fat-Derived Biodiesel Fuels

2014-04-01
2014-01-1600
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.
Technical Paper

Effect of CO2 Content on Foaming Behavior of Recyclable High-Melt-Strength PP

2006-04-03
2006-01-0336
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.
Technical Paper

Cell Nucleation and Growth Study of PP Foaming with CO2 in a Batch-Simulation System

2006-04-03
2006-01-0507
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.
Technical Paper

The Effects of Nano-clay on Extrusion Microcellular Foaming of Nylon

2005-04-11
2005-01-1670
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.
Technical Paper

Injection Molded Hybrid Natural Fibre - Thermoplastic Composites for Automotive Interior Parts

2004-03-08
2004-01-0014
Eco-efficient and cost effective natural fibre - thermoplastic composites have gained attention to a great extent in the automotive industry. Most of the OEM specifications for automotive interior parts, for example, instrument panels, recommend the composite should have a minimum flexural modulus of 1900 MPa, a notched Impact strength greater than 150 J/m at room temperature and a melt flow index of 5 g/10min and above [1, 2 and 3]. The objective of this work was to develop a high performance hybrid composite by injection molding process of the composites made from natural fibre in combination with glass fibre or calcium carbonate in a thermoplastic matrix to meet the specifications required for automotive interior parts applications. Mechanical properties, such as tensile and flexural strengths and moduli of the composites prepared, were found to be highly promising.
Technical Paper

Concurrent Quantitative Laser-Induced Incandescence and SMPS Measurements of EGR Effects on Particulate Emissions from a TDI Diesel Engine

2002-10-21
2002-01-2715
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.
Technical Paper

The Effect of Oxygenated Additives on Soot Precursor Formation in a Counterflow Diffusion Flame

1999-10-25
1999-01-3589
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.
Technical Paper

An Experimental Investigation into the Characteristics of a Fast-Response Flame Ionization Detector for In-Cylinder Sampling

1999-10-25
1999-01-3538
The Cambustion fast-response flame ionization detector (FFID) has been successfully used for instantaneous exhaust port hydrocarbon (HC) concentration measurement in IC engines for a decade. Measurements of in-cylinder HC concentration have also been made, but these present greater challenge. As the sample transit time and the time constant of the system always change when the sampling pressure is changed, it is necessary to investigate the characteristics of the system before it was used for in-cylinder sampling. A unique method was designed to study the influence of the diameter and length of the transfer sample line and the operating parameters of the FFID on the transit time and time constant. A database of transit time and time constant was built up for different simulated in-cylinder pressures. The database can be used for correcting eventual in-cylinder HC concentration measurement.
Technical Paper

Instantaneous In-Cylinder Hydrocarbon Concentration Measurement during the Post-Flame Period in an SI Engine

1999-10-25
1999-01-3577
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.
Technical Paper

Evaluation of the Hydrogen-Fueled Rotary Engine for Hybrid Vehicle Applications

1996-02-01
960232
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
Technical Paper

Exhaust Emission and Energy Consumption Effects from Hydrogen Supplementation of Natural Gas

1995-10-01
952497
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™.
Technical Paper

Engine Operating Parameter Effects on the Speciated Aldehyde and Ketone Emissions from a Natural Gas Fuelled Engine

1995-10-01
952500
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.
Technical Paper

A Phenomenological Model for Soot Formation and Oxidation in Direct-Injection Diesel Engines

1995-10-01
952428
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.
Technical Paper

In-Cylinder Measurement of Temperature and Soot Concentration Using the Two-Color Method

1995-02-01
950848
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.
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