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Vehicle Duty Cycles and Their Role in the Design and Evaluation of Advanced Vehicle Technologies

2012-04-10
Understanding in-use fleet operating behavior is of paramount importance when evaluating the potential of advanced/alternative vehicle technologies. Accurately characterizing real world vehicle operation assists in properly allocating advanced technologies, playing a role in determining initial payback period and return on investment. In addition, this information contributes to the design and deployment of future technologies as the result of increased awareness regarding tractive power requirements associated with typical operating behavior. In this presentation, the concept of vehicle duty cycles and their relation to advanced technologies will be presented and explored. Additionally, current research attempts to characterize school bus operation will be examined, and existing computational analysis and evaluation tools associated with these efforts discussed. Presenter Adam Duran, National Renewable Energy Laboratory
Technical Paper

Development of a charge motion controlled combustion system for DI SI engines and its vehicle application to EU-4 emission regulations

2000-06-12
2000-05-0058
The development of new passenger car powertrains with gasoline direct- injection engines is facing new requirements which result from the need of different operational modes with stratified and homogeneous air-fuel mixture. Moreover, the exhaust aftertreatment system causes a discontinuous operation with lean-burn absorption periods followed by short rich spikes for catalyst regeneration. Recent work on combustion system development has shown, that gasoline direct injection can create significant fuel economy benefits. Charge motion controlled combustion systems have proven to be of advantage in terms of low raw emissions compared to wall-guided concepts. Based on an initial single-cylinder development phase, a multi-cylinder engine was realized with excellent fuel economy, low raw emissions and operational robustness. Finally, the new engine''s potential has been demonstrated in a mid-class vehicle.
Technical Paper

Reduction in Vehicle Temperatures and Fuel Use from Cabin Ventilation, Solar-Reflective Paint, and a New Solar-Reflective Glazing

2007-04-16
2007-01-1194
A new type of solar-reflective glass that improves reflection of the near-infrared (NIR) portion of the solar spectrum has been developed. Also developed was a prototype solar-reflective paint that increases the NIR reflection of opaque vehicle surfaces while maintaining desired colors in the visible portion of the spectrum. Both of these technologies, as well as solar-powered parked car ventilation, were tested on a Cadillac STS as part of the Improved Mobile Air Conditioning Cooperative Research Program (I-MAC). Significant reductions in interior and vehicle skin temperatures were measured. The National Renewable Energy Laboratory (NREL) performed an analysis to determine the impact of reducing the thermal load on the vehicle. A simplified cabin thermal/fluid model was run to predict the potential reduction in A/C system capacity. The potential reduction in fuel use was calculated using a vehicle simulation tool developed by the U.S. Department of Energy (DOE).
Technical Paper

Mechanical Testing - Still Necessary!

2007-04-16
2007-01-1768
Over the last decades, the use of computers has become an integral part of the engine development process. Computer-based tools are increasingly used in the design process, and especially the layout of the various subsystems is conducted by means of simulation models. Computer-aided engineering plays a central role e.g. in the design of the combustion process as well as with regards to work performed in the area of engine mechanics, where CFD, FEM, and MBS are applied. As a parallel trend, it can be observed that various engine performance characteristics such as e.g. the specific power output and the power-to-weight ratio have undergone an enormous increase, a trend which to some extent counteracts the increase in safety against malfunction and failure. As yet, due to the constant need for further optimization, mechanical testing and verification processes have not become redundant, and it is assumed that they will remain indispensable for the foreseeable future.
Technical Paper

Application of Combustion Sound Level (CSL) Analysis for Powertrain

2009-05-19
2009-01-2168
Powertrain noise is a significant factor in determination of the overall vehicle refinement expected by today's discriminating automotive customer. Development of a powertrain to meet these expectations requires a thorough understanding of the contributing noise sources. Specifically, combustion noise greatly impacts the perception of sound levels and quality. The relevance of combustion noise development has increased with the advent of newer efficiency-driven technologies such as direct injection or homogeneous charge compression ignition. This paper discusses the application of a CSL (Combustion Sound Level) analysis-a method for the identification and optimization of combustion noise. Using CSL, it is possible to separate mechanical and combustion noise sources.
Technical Paper

Comparison of Indoor Vehicle Thermal Soak Tests to Outdoor Tests

2004-03-08
2004-01-1376
Researchers at the National Renewable Energy Laboratory conducted outdoor vehicle thermal soak tests in Golden, Colorado, in September 2002. The same environmental conditions and vehicle were then tested indoors in two DaimlerChrysler test cells, one with metal halide lamps and one with infrared lamps. Results show that the vehicle's shaded interior temperatures correlated well with the outdoor data, while temperatures in the direct sun did not. The large lamp array situated over the vehicle caused the roof to be significantly hotter indoors. Yet, inside the vehicle, the instrument panel was cooler due to the geometry of the lamp array and the spectral difference between the lamps and sun. Results indicate that solar lamps effectively heat the cabin interior in indoor vehicle soak tests for climate control evaluation and SCO3 emissions tests. However, such lamps do not effectively assess vehicle skin temperatures and glazing temperatures.
Technical Paper

LOTUS: A Co-operation for Low Temperature Urea-Based Selective Catalytic Reduction of NOx

2004-03-08
2004-01-1294
The European research co-operation Lotus is presented. The main objectives of the project were i) to show the potential for a urea-based SCR system to comply with the EU standard of years 2005 and 2008 for heavy-duty Diesel engines for different driving conditions with optimal fuel consumption, ii) to reach 95 % conversion of NOx at steady state at full load on a Euro III engine, iii) to reach 75 % NOx reduction for exhaust temperatures between 200-300°C, and 85 % average NOx reduction between 200-500°C. The energy content of the consumed urea should not exceed 1.0 %, calculated as specific fuel consumption. These targets were met in May 2003 and the Lotus SCR system fulfilled the Euro V NOx legislative objectives for year 2008.
Technical Paper

Tailor-Made Fuels for Future Advanced Diesel Combustion Engines

2009-06-15
2009-01-1811
The finite nature and instability of fossil fuel supply has led to an increasing and enduring investigation demand of alternative and regenerative fuels. The Institute for Combustion Engines at the RWTH Aachen University carried out an investigation program to explore the potential of tailor made fuels to reduce engine-out emissions while maintaining engine efficiency and an acceptable noise level. To enable optimum engine performance a range of different hydrocarbons having different fuel properties like cetane number, boiling temperature and different molecular compositions have been investigated. Paraffines and naphthenes were selected in order to better understand the effects of molecular composition and chain length on emissions and performance of an engine that was already optimized for advanced combustion performance. The diesel single-cylinder research engine used in this study will be used to meet Euro 6 emissions limits and beyond.
Technical Paper

Diesel Combustion Control with Closed-Loop Control of the Injection Strategy

2008-04-14
2008-01-0651
Current and future emission legislations require a significant reduction of engine-out emissions for Diesel engines. For a further reduction of engine-out emissions, different measures are necessary such as: Especially an advanced emission and closed-loop combustion control has gained increased significance during the past years.
Technical Paper

Prediction of Hydrodynamic Bearing Behaviour for Pre-layout of Cranktrain Dimensions

2010-10-25
2010-01-2186
Calculating the bearing reliability and behavior is one of the primary tasks which have to be performed to define the main dimensions of the cranktrain of an internal combustion engine. Since the bearing results are essential for the pre-layout of the cranktrain, the conclusion on the bearing safety should be met as early as possible. Therefore detailed simulations like T-EHD or EHD analysis may not be applied to define the dimensions in such an early development phase. In the frame of this study a prediction methodology, based on a HD bearing approach, for bearing reliability of inline-4 crankshafts of passenger cars is proposed. In this way not only the design phase is shortened but also achieving the optimal solution is simplified. Moreover the requirement of a CAD model is eliminated for the preliminary design phase. The influencing parameters on the bearing behavior are first selected and divided into two groups: geometry and loading.
Technical Paper

Exhaust Temperature Management for Diesel Engines Assessment of Engine Concepts and Calibration Strategies with Regard to Fuel Penalty

2011-09-11
2011-24-0176
Both, the continuous strengthening of the exhaust emission legislation and the striving for a substantial reduction of carbon dioxide output in the traffic sector depict substantial requirements for the development of future diesel engines. These engines will comprise not only the mandatory diesel oxidation catalyst (DOC) and particulate filter DPF but a NOx aftertreatment system as well - at least for heavier vehicles. The oxidation catalysts as well as currently available NOx aftertreatment technologies, i.e., LNT and SCR, rely on sufficient exhaust gas temperatures to achieve a proper conversion. This is getting more and more critical due to the fact that today's and future measures for CO₂ reduction will result in further decrease of engine-out temperatures. Additionally this development has to be considered in the light of further engine electrification and hybridization scenarios.
Technical Paper

Closed Loop Combustion Control - Enabler of Future Refined Engine Performance Regarding Power, Efficiency, Emissions & NVH under Stringent Governmental Regulations

2011-09-11
2011-24-0171
Both, the continuous strengthening of the exhaust emission legislation and the striving for a substantial reduction of the carbon dioxide output in the traffic sector depict substantial requirements for the global automotive industry and especially for the engine manufacturers. From the multiplicity of possible approaches and strategies for clear compliance with these demands, engine internal measures offer a large and, eventually more important, very economical potential. For example, the achievements in fuel injection technology are a measure which in the last years has contributed significantly to a notable reduction of the emissions of the modern DI Diesel engines at favorable fuel efficiency. Besides the application of modern fuel injection technology, the linked combustion control (Closed Loop Combustion Control) opens possibilities for a further optimization of the combustion process.
Technical Paper

Architecture of a Detailed Three Dimensional Piston Ring Model

2011-09-11
2011-24-0159
Piston rings are faced with a broad range of demands like optimal sealing properties, wear properties and reliability. Even more challenging boundary conditions must be met when latest developments in the fields of direct injection as well as the application of bio fuels. This complex variety of piston ring design requirements leads to the need of a comprehensive simulation model in order to support the development in the early design phase prior to testing. The simulation model must be able to provide classical objectives like friction analysis, wear rate and blow-by. Furthermore, it must include an adequate oil consumption model. The objective of this work is to provide such a simulation model that is embedded in the commercial MBS software ‘FEV Virtual Engine’. The MBS model consists of a cranktrain assembly with a rigid piston that contains flexible piston rings.
Journal Article

Influence of the Mixture Formation on the Lubrication Oil Emission of Combustion Engines

2010-04-12
2010-01-1275
Partly competing objectives, as low fuel consumption, low friction, long oil maintenance rate, and at the same time lowest exhaust emissions have to be fulfilled. Diminishing resources, continuously reduced development periods, and shortened product cycles yield detailed knowledge about oil consumption mechanisms in combustion engines to be essential. There are different ways for the lubricating oil to enter the combustion chamber: for example as blow-by gas, leakage past valve stem seals, piston rings (reverse blow-by) and evaporation from the cylinder liner wall and the combustion chamber. For a further reduction of oil consumption the investigation of these mechanisms has become more and more important. In this paper the influence of the mixture formation and the resulting fuel content in the cylinder liner wall film on the lubricant oil emission was examined.
Technical Paper

Measured Laboratory and In-Use Fuel Economy Observed over Targeted Drive Cycles for Comparable Hybrid and Conventional Package Delivery Vehicles

2012-09-24
2012-01-2049
This research project compares the in-use and laboratory-derived fuel economy of a medium-duty hybrid electric drivetrain with “engine off at idle” capability to a conventional drivetrain in a typical commercial package delivery application. Vehicles in this study included eleven model year 2010 Freightliner P100H hybrids that were placed in service at a United Parcel Service (UPS) facility in Minneapolis, Minn., during the first half of 2010. These hybrid vehicles were evaluated for 18 months against eleven model year 2010 Freightliner P100D diesels that were placed in service at the same facility a couple months after the hybrids. Both vehicle study groups use the same model year 2009 Cummins ISB 200 HP engine. The vehicles of interest were chosen by comparing the average daily mileage of the hybrid group to that of a similar size and usage diesel group.
Technical Paper

Glow-plug Ignition of Ethanol Fuels under Diesel Engine Relevant Thermodynamic Conditions

2011-04-12
2011-01-1391
The requirement of reducing worldwide CO₂ emissions and engine pollutants are demanding an increased use of bio-fuels. Ethanol with its established production technology can contribute to this goal. However, due to its resistive auto-ignition behavior the use of ethanol-based fuels is limited to the spark-ignited gasoline combustion process. For application to the compression-ignited diesel combustion process advanced ignition systems are required. In general, ethanol offers a significant potential to improve the soot emission behavior of the diesel engine due to its oxygen content and its enhanced evaporation behavior. In this contribution the ignition behavior of ethanol and mixtures with high ethanol content is investigated in combination with advanced ignition systems with ceramic glow-plugs under diesel engine relevant thermodynamic conditions in a high pressure and temperature vessel.
Technical Paper

Turbocharging of Downsized Gasoline DI Engines with 2 and 3 Cylinders

2011-09-11
2011-24-0138
Turbocharged DISI engines with four cylinders have established in the market and provide a performance comparable to larger six-cylinder engines in the smaller compartment of a four-cylinder engine. In the Japanese market, also turbo gasoline engines with 500 - 660 cm₃ displacement have a long tradition in Kei-Cars. However, those engines show a lower specific performance as would be required for propelling typical small or compact vehicles in Europe. Recently, two-cylinder turbo engines have come to market, which are found attractive with respect to sound, package, and also enable low vehicle fuel consumption in NEDC test. The paper presents a turbocharger layout study on 2- and 3-cylinder engines. It discusses the influence of cylinder displacement volume on the sizing of turbines and compressors, and how specific flow phenomena in the turbine can be captured in the simulation model.
Technical Paper

A New CFD Approach for Assessment of Swirl Flow Pattern in HSDI Diesel Engines

2010-09-28
2010-32-0037
The fulfillment of the aggravated demands on future small-size High-Speed Direct Injection (HSDI) Diesel engines requires next to the optimization of the injection system and the combustion chamber also the generation of an optimal in-cylinder swirl charge motion. To evaluate different port concepts for modern HSDI Diesel engines, usually quantities as the in-cylinder swirl ratio and the flow coefficient are determined, which are measured on a steady-state flow test bench. It has been shown that different valve lift strategies nominally lead to similar swirl levels. However, significant differences in combustion behavior and engine-out emissions give rise to the assumption that local differences in the in-cylinder flow structure caused by different valve lift strategies have noticeable impact. In this study an additional criterion, the homogeneity of the swirl flow, is introduced and a new approach for a quantitative assessment of swirl flow pattern is presented.
Journal Article

Dedicated GTL Vehicle: A Calibration Optimization Study

2010-04-12
2010-01-0737
GTL (Gas-To-Liquid) fuel is well known to improve tailpipe emissions when fuelling a conventional diesel vehicle, that is, one optimized to conventional fuel. This investigation assesses the additional potential for GTL fuel in a GTL-dedicated vehicle. This potential for GTL fuel was quantified in an EU 4 6-cylinder serial production engine. In the first stage, a comparison of engine performance was made of GTL fuel against conventional diesel, using identical engine calibrations. Next, adaptations enabled the full potential of GTL fuel within a dedicated calibration to be assessed. For this stage, two optimization goals were investigated: - Minimization of NOx emissions and - Minimization of fuel consumption. For each optimization the boundary condition was that emissions should be within the EU5 level. An additional constraint on the latter strategy required noise levels to remain within the baseline reference.
Journal Article

Expanding the Experimental Capabilities of the Ignition Quality Tester for Autoigniting Fuels

2010-04-12
2010-01-0741
This paper reports the development of new fuel ignition quality and combustion experiments performed using the Ignition Quality Tester (IQT). Prior SAE papers (961182, 971636, 1999-01-3591, and 2001-01-3527) documented the development of the IQT constant volume combustion chamber experimental apparatus to measure ignition qualities of diesel-type fuels. The ASTM International test method D6890 was developed around the IQT device to allow the rapid determination of derived cetane number (DCN). Interest in chemical kinetic models for the ignition of diesel and biodiesel model compounds is increasing to support the development of advanced engines and fuels. However, rigorous experimental validation of these kinetic models has been limited for a variety of reasons. Shock tubes and rapid compression machines are typically limited to premixed gas-phase studies, for example.
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