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Technical Paper

Effects of the Differences in Driving Behavior on Fuel Economy and Emission Characteristics during Vehicle Simulator Execution

2018-09-10
2018-01-1768
Fuel economy and exhaust gas regulations around the world have become increasingly stringent year by year. In Europe, the real driving emission (RDE) system was introduced for evaluating the exhaust gas emitted from the road-going vehicles produced after September 2017. There are many cases where each automobile manufacturer has executed exhaust gas tests using actual vehicles on development vehicles. However, the “hardware in the loop simulator” (HILS) was developed recently for improving vehicle development efficiency. The HILS, combined with an actual engine, which is called the extended HILS, has been applied recently for the evaluation of compliance with emission standards. However, if the driver model used in the vehicle simulation does not correctly simulate actual human driving operations, some performance aspects in the development will differ from those in the actual vehicle evaluation, and these aspects must be readjusted.
Technical Paper

Development of Model Predictive Control Strategy of SCR System for Heavy-duty Diesel Engines by a Grey Relation Analysis Approach

2018-09-10
2018-01-1763
Urea selective catalytic reduction (SCR) is a key technology for heavy-duty diesel engines to meet the increasingly stringent nitric oxides (NOx) emission limits of regulations. The aqueous urea injection control is critical for urea-SCR systems to achieve high NOx conversion efficiency while restricting the tailpipe ammonia slip. For Euro VI emission regulation, advanced control strategy is essential for SCR systems due to its more tightened NOx emission limits and more severe test procedure compared to Euro IV and Euro V. The complex chemical kinetics of the SCR process have motivated model based control design approaches. However, the model complexity is too great to allow real-time implementation. This work proposed a model predictive control (MPC) strategy for SCR systems to meet the Euro VI NOx emission limits.
Technical Paper

Methodical Selection of sustainable Fuels for high-performance Racing Engines

2018-09-10
2018-01-1749
As the importance of sustainability increases and dominates the powertrain development within the automotive sector, this issue has to be addressed in motorsports as well. The development of sustainable high-performance fuels defined for the use in motorsports offers technical and environmental potential with the possibility to increase the sustainability of motorsports at the same or even a better performance level. At the moment race cars are predominantly powered by fossil fuels. However due to the emerging shift regarding the focus of the regulations towards high efficient powertrains during the last years the further development of fuels gained in importance. Moreover during the last decades a huge variety of sustainable fuels emerged. This offers a range of fuels with different characteristics produced from waste materials or carbon dioxide. This study investigates which sustainable fuels offer the characteristics suitable for high-performance racing engines.
Technical Paper

Comparison of Primary Sensitive Reactions on Ignition Delay Time between Detailed and Skeletal Mechanisms of Gasoline Surrogates

2018-09-10
2018-01-1737
Combustion simulation is of great importance for internal combustion engine development. With the advance of fundamental combustion experiments and theoretical computation, more detailed combustion mechanisms of gasoline surrogates were proposed with introduction of new reactions and updated reactions rates. However, detailed combustion mechanisms with thousands of reactions are still not practical for engineering use in terms of massive computation cost. Therefore, skeletal mechanisms are usually developed for practical three dimensional engine combustion simulations. In skeletal mechanisms, the reaction rates are mostly different from those applied in detailed combustion mechanisms, and some important reaction rates have large deviations. In addition, some rates are updated recently by ab initio calculations, which are applied in recent detailed mechanisms, but not in skeletal mechanisms.
Technical Paper

Development of a Standardized Test to Evaluate the Effect of Gasoline Engine Oil on the Occurrence of Low Speed Pre-Ignition – The Sequence IX Test

2018-09-10
2018-01-1808
The study described in this paper covers the development of the Sequence IX Low Speed Pre-Ignition (LSPI) test for the new engine oil category, ILSAC GF-6. The purpose of the Sequence IX test is to evaluate a lubricant’s ability to protect against LSPI events which are prevalent when operating a highly boosted/down sized gasoline direct injected engine. LSPI is characterized as a combustion event that starts before ignition spark, typically followed by excessive in-cylinder pressures and heavy knock, which can cause severe engine damage and failure. Industry research has shown that oil formulation can contribute to the frequency of LSPI activity. The Sequence IX test was developed using a turbocharged gasoline direct injected 2.0 liter Ford Ecoboost engine with dual independent variable cam timing. The engine was modified with in-cylinder pressure sensors and a high resolution crank angle encoder to characterize individual engine combustion cycles and identify potential LSPI events.
Technical Paper

Improvement of Thermal Efficiency in a Diesel Engine with High-pressure Split Main Injection

2018-09-10
2018-01-1791
This study aims to establish a strategy for improving thermal efficiency of diesel engines by using split main injection. A series of experiment was conducted using a single cylinder diesel engine varying the injection pressure and the proportion of split main injection. As a result, the thermal efficiency was improved by the combination of increase in injection pressure, advanced injection timing, and split main injection with small proportion of later-part. According to the analysis of heat balance, lower heat loss was achieved by using split main injection. And causes for the lower heat loss were described based on CFD simulation.
Technical Paper

Simulation of Intake Manifold Water Injection in a Heavy Duty Natural Gas Engine for Performance and Emissions Enhancement

2018-09-10
2018-01-1653
The present work discusses the effects of intake manifold water injection in a six-cylinder heavy duty NG engine through one-dimensional simulation. The numerical study was carried out based on GT-Power under different engine working conditions. The established simulation model was firstly calibrated in detail through the whole engine speed sweep under full load conditions before the model of intake manifold water injector was involved,and the calibration was based on experimental data. The intake manifold water injection mass was controlled through adjustment of intake water/intake ratio, a water/intake ratio swept from 0 to 4 was selected to investigate the effects of intake manifold water injection on engine performance and emissions characteristics. On the other hand, the enhancement potential of intake manifold water injection in heavy duty NG engine under lean and stoichiometric condition was also investigated by the alteration of air-fuel ratio.
Technical Paper

0D Modeling of Real-driving NOx emissions for a Diesel Passenger Vehicle

2018-09-10
2018-01-1761
NOx emission from diesel passenger vehicles affects the atmospheric environment. It is difficult to evaluate the NOx emission influenced by environmental conditions such as humidity and temperature, traffic conditions, driving patterns, and so on. In the authors’ previous study, real-driving experiments were carried out in city and highway routes using a diesel passenger car with exhaust gas recirculation (EGR) system. A statistical prediction model of NOx emissions was considered for simple estimation in the real world using instantaneous vehicle data measured by portable emissions measurement system (PEMS) and global positioning system (GPS). The prediction model consisted of explanatory variables, such as velocity, acceleration, road gradient and position of transmission gear. Using explanatory variables, NOx emission in city and highway routes was well predicted using a diesel vehicle without NOx reduction devices.
Technical Paper

Effect of Diesel Injection Timing on Peak Pressure Rise Rate and Combustion stability in RCCI Engine

2018-09-10
2018-01-1731
In the present study, experiments of reactivity control compression ignition (RCCI) combustion mode is performed on a single cylinder automotive diesel engine with development ECU (electronic control unit). For achieving RCCI combustion mode, low reactivity fuel (i.e. gasoline/methanol) is injected in the intake manifold and high reactivity fuel (i.e. diesel) is directly injected into the engine cylinder. Mass of fuel injection per cycle and their injection events are controlled using ECU. This study presents the experimental investigation on the effect of high reactivity fuel injection timing on peak pressure rise rate (PPRR) and combustion instability in RCCI engine. The combustion parameters i.e. PPRR, indicated mean effective pressure (IMEP) and total heat release (THR) are calculated from the in-cylinder pressure measurement. A piezoelectric pressure transducer is installed on the cylinder head for this analysis.
Technical Paper

An optical study on spray and combustion characteristics of gasoline-PODEn blends in a constant volume vessel

2018-09-10
2018-01-1748
Polyoxymethylene dimethyl ethers (PODEn) have high cetane number, high oxygen content and good volatility, therefore can be added to gasoline to optimize the performance and emission of gasoline compression ignition (GCI) engine. Liquid-phase penetration, flame luminosity and flame lift-off length (LOL) of gasoline, PODEn and their blends were obtained using mie-scatter imaging, high speed photography and OH* chemiluminescence, respectly. The ambient condition in the constant volume vessel is maintained at Ta=850K and Pa=4MPa, similar to the cylinder condition when fuel is injected, and the injection parameters are constant (dinj=0.168mm, Pinj=80MPa) as well. EGR was simulated by adding N2 to change the oxygen content in atmosphere gas. In this study, the oxygen content was adjusted to 15%. The results show that with the increasing of PODEn proportion in the blends, liquid-phase penetrations of the jets are almost the same.
Technical Paper

Evaluating the efficiency of a conventional diesel oxidation catalyst for dual-fuel RCCI diesel-gasoline combustion

2018-09-10
2018-01-1729
Reactivity controlled compression ignition (RCCI) combustion has demonstrated to be able to avoid the NOx-soot trade-off appearing during conventional diesel combustion (CDC), with similar or better thermal efficiency than CDC under a wide variety of engine platforms. However, a major challenge of this concept comes from the high hydrocarbon (HC) and carbon monoxide (CO) emission levels, which are orders of magnitude higher than CDC and similar to those of port fuel injected (PFI) gasoline engines. The higher HC and CO emissions combined with the lower exhaust temperatures during RCCI operation present a challenge for current exhaust aftertreatment technologies. RCCI has been successfully implemented on different compression ignition engine platforms with only minor modifications on the combustion system to include a PFI for feeding the engine with the low reactivity fuel.
Technical Paper

Effect of Lubricant Oil on Particle Emissions from a Gasoline Direct Injection Light-Duty vehicle

2018-09-10
2018-01-1708
In recent years, gasoline direct injection (GDI) engines have been widely used by manufacturers in light-duty vehicles to meet stringent fuel economy and emissions standards. Despite improved fuel economy and lower carbon dioxide (CO2) emissions, several studies have shown that GDI engines result in higher particulate matter (PM) mass emissions compared to port fuel injected (PFI) engines and diesel engines equipped with diesel particulate filters (DPF). PM mass emissions from current GDI engines are primarily composed of soot particles or black carbon with a small fraction (15% to 20%) of semi-volatile hydrocarbons generated from unburned/partially burned fuel and lubricating oil. Between 2017 and 2025, PM mass emissions regulations in the USA are expected to become progressively more stringent going down from current level of 6 mg/mile down to 1 mg/mile in 2025.
Technical Paper

Detonation peninsula for TRF-air mixtures: assessment for the analysis of auto-ignition events in spark-ignition engines

2018-09-10
2018-01-1721
Controlling abnormal auto-ignition processes in spark-ignition engines requires understanding how auto-ignition is triggered and how it propagates inside the combustion chamber. The original Zeldovich theory regarding auto-ignition propagation was further developed by Bradley and coworkers who highlighted different modes by considering various hot spot characteristics and thermodynamic conditions around them. Dimensionless parameters (epsilon, ksi) were then defined to classify these modes and to define a detonation peninsula for H2-CO-air mixtures. This article deals with numerical simulations undertaken to check the relevancy of this original detonation peninsula when considering realistic gasoline fuels. 1D calculations of auto-ignition propagation are performed using the Tabulated Kinetics for Ignition model.
Technical Paper

Numerical and Experimental Investigation of Ethyl Alcohol as Oxygenator on the Combustion, Performance, and Emission Characteristics of Diesel/Cotton Seed Oil Blends in Homogenous Charge Compression Ignition Engine

2018-09-10
2018-01-1680
An investigational study was accomplished to establish the burning process, performance, and emission parameters for the Homogenous Charge Compression Ignition (HCCI) diesel engine while using Ethyl Alcohol as an additive to increase the available oxygen for combustion in diesel-biodiesel blends. The combustion characteristics were examined numerically by applying the multi-zone chemical kinetics model. In which three sorts of zones enclosing the crevice zone, boundary layer zone, and center zone of the engine cylinder are activated. The multizone code was joined with a new complete chemical kinetics mechanism that contains 144 species and 737 elementary reactions. The whole HCCI engine combustion and emission characteristics were studded at different volume of biodiesel and ethanol of D70B25E5, D70B20E10, and D70B15E15.
Technical Paper

Auto-ignition Characteristics of Lubricant Droplets under Hot Co-flow Atmosphere

2018-09-10
2018-01-1807
Many researches and technical reports have revealed that lubricant has a great effect on the low-speed pre-ignition (LSPI) frequency in downsizing supercharged direct-injection engines which are developed for better fuel economy. Droplets of lubricant or lubricant-gasoline mixture are considered to be potential pre-ignition sources. Those droplets will fly into the combustion chamber and ignite gasoline-air mixture. To study lubricant droplets more precisely, a novel set of droplet combustion system is designed based on a Dibble Burner for this experiment. Influences of different metallic additive contents, different viscosities, and lubricant diluted with gasoline on the ignition delay of lubricant droplets are recorded by a high-speed camera through testing 10 groups of lubricants or lubricant- gasoline mixture. The equivalent diameter of each droplet generated by micro-syringe keeps nearly the same.
Technical Paper

Effect of butanol addition on performance, combustion stability and nano-particle emissions of a conventional diesel engine

2018-09-10
2018-01-1795
This study presents the experimental investigation of performance, combustion, gaseous and nano-particle emission characteristics of conventional compression ignition (CI) engine fueled with neat diesel and butanol/diesel blends. The experiments were conducted for neat diesel, 10%, 20% and 30% butanol/diesel blend on the volume basis at different engine loads. Combustion characteristics were investigated on the basis of in-cylinder pressure measurement and heat release analysis. The in-cylinder combustion pressure traces were recorded for 2000 consecutive engine combustion cycles for computation of heat release and different combustion parameters. Combustion stability analysis is conducted by analyzing coefficient of variation of in indicated mean effective pressure (IMEP) and total heat release (THR). Wavelet analysis is also used for analyzing the temporal variations in IMEP data series.
Technical Paper

Variation in System Performance While Sorting DEF Heating Hardware Options

2018-09-10
2018-01-1813
The desire to reduce NOx at low ambient temperatures drives the use of heating methods to make DEF available by thawing the solution in the tank. Methods to validate modelling used to design hardware options require testing to gauge the accuracy of the prediction. Using a climatic chassis dynamometer (CCD) to demonstrate the guidance procedure set by the Environmental Protection Agency (EPA) is expensive and time consuming. A method of utilizing a flow controlled cooling supply combined with a standard cold chamber is described as a precursor to running the demonstration in the CCD. Testing multiple quantities of design iterations produced unexpected variation in the results. The sources of the variation and modifications taken to minimize them are discussed and presented. Test to test control of coolant flow, coolant temperature, and specific chamber temperature inconsistencies were found to be critically important to a successful effort.
Technical Paper

Strategies to define surrogate fuels for the description of the multicomponent evaporation behavior of hydrocarbon fuels

2018-09-10
2018-01-1692
Since real hydrocarbon fuels are commonly complex multi-component mixtures, their exact composition is generally neither known nor standardized. This makes the definition of surrogate mixtures to be used in simulations a crucial task to accurately model the evaporation and combustion behavior. Amongst others, this includes the specification of a certain numbers of surrogate components, the definition of optimization targets representing the real fuel properties of interest, the formulation of an appropriate numerical model for the evaluation of these quantities and the utilization of a suitable optimization algorithm to obtain the optimal surrogate composition. Concerning these points, several combinations can lead to a non-optimal representation of the real fuel target properties by the defined surrogate. A well-known example is the uncertainty in the numerical models often used for calculating the distillation curves measured by means of the ASTM D86 standard.
Technical Paper

Assessment of the New Features of a Prototype High-Pressure “Hollow Cone Spray” Diesel Injector by Means of Engine Performance Characterization and Spray Visualization

2018-09-10
2018-01-1697
The application of more efficient compression ignition combustion concepts requires advancement in terms of fuel injection technologies. The injector nozzle is the most critical component of the whole injection system. It is characterized by key factors as hole diameter, number, internal shape and opening angle. The reduction of the nozzle hole diameter seems the simplest way to increase the average fuel velocity and to promote the atomization process but the number of holes must be sufficient to deliver the desired fuel total mass. This logic has been applied to the development of a new generation of injectors. First, the tendency to increase the nozzle number and to reduce the diameter has led to the replacement of the nozzle with a circular plate. The vertical movement of the needle generates an annulus area for the fuel delivery on 360 degrees, so controlling the atomization as a function of the vertical plate position.
Technical Paper

Studies on the influence of engine conditions and different ash levels on the regeneration behavior of particulate filters

2018-09-10
2018-01-1704
Diesel particulate filters (DPF) are particularly effective devices to remove particulate matter (PM) from the diesel exhaust. In case of wall-flow filters, the particulates are deposited in the porous wall and on the surface of the filter channels. This results in an increase of the filter backpressure and thus has a negative impact on the engine performance and the fuel consumption. For this reason, the filter has to be regenerated periodically due to oxidation of the deposited PM. This oxidation behavior should result in an effective regeneration mode that minimizes the fuel penalty and limits the temperature rise while maintaining a high regeneration efficiency at the same time. However, this DPF operating behavior is influenced by the characteristics of the deposited and accumulated soot and ash, which is affected by different diesel engine operating parameters.
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