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Technical Paper
2014-10-13
Shuonan Xu, David Anderson, Amrit Singh, Mark Hoffman, Robert Prucka, Zoran Filipi
The looming shortage of crude oil provides impetus for engineers to use alternative gaseous fuels in existing engines. Dual-fuel natural gas engines preserve diesel thermal efficiencies and reduce fuel cost without imposing consumer range anxiety. Increased complexity poses several challenges, including the transient response of an engine with direct injection of diesel fuel and injection of Compressed Natural Gas (CNG) upstream of the intake manifold. A 1-D simulation model of a Cummins ISX heavy duty, dual-fuel, natural gas-diesel engine modeled in the GT-Power environment is developed to study and improve transient response. The simulated VGT behavior, intake and exhaust geometry, valve timings and injector models are validated through experimental results. A triple Wiebe combustion model is applied to characterize experimental combustion results for both diesel and dual-fuel operation. The ignition delay and injection timing are determined through an iterative calculation based on Start of Combustion (SOC) and a predictive ignition delay correlation.
Technical Paper
2014-10-13
Prasanth Balasubramanian, Bharathan Sivashanmugham
This paper presents the air intake system model for turbocharged diesel engine with EGR. The individual models of intake system components and EGR were assembled to develop a global air intake system. The model monitors the pressure, temperature and air flow rate at various levels in the intake system and predicts the volumetric efficiency of engine and pumping losses in the valves. The validation of the developed model is done by correlating the simulated results with the experimental results. The model showed a good agreement with measurements for both steady state and transient conditions. The validated model is used run a DOE following robust engineering approach (Taguchi method) and the results were analyzed. This approach enabled reduction of the variation of the air intake temperature that is inducted by the cylinders upon wide range of ambient conditions and EGR flow rates. The model is then used to optimize the intake system to reduce the pressure fluctuations and improve the volumetric efficiency of the cylinders.
Technical Paper
2014-10-13
Tao Yin, Tie Li, Longhua Chen, Bin Zheng, Fei Zhao
Worldwide demands for better fuel economy and less pollutant emissions of automobiles are driving vehicle manufactures to seek further technical improvements in reciprocating engines. Spark ignited (SI) engines have a significant optimization potential by techniques such as supercharging, variable valve timing, downsizing, exhaust gas recirculation or direct injection. Each method distinctively influences the engine performance in variable operating conditions, which makes it complex to apply these techniques in a synergy pattern. Therefore, optimization of engine parameters is expected to make full use of the positive coupling techniques.This paper studies the effect of cooled EGR on fuel consumption and anti-knock performance of a boosted port fuel injection (PFI) SI engine. Experimental results show that the cooled EGR increases the thermal efficiency by 2%~18% depending on the operation conditions. Compared to low load operations, more improvements of the thermal efficiency are obtained at higher loads, primarily owing to the enhanced anti-knock performance, advanced combustion phasing, elimination of fuel-rich operations as well as reduced heat transfer loss with cooled EGR.
Technical Paper
2014-10-13
A.F. Khan, A.A. Burluka, Dave OudeNijeweme, Jens Neumeister, John Mitcalf, Paul Freeland
A holistic modelling approach has been employed to predict combustion, cyclic variability and knock propensity of a high power density SI engine fuelled with gasoline. A quasi-dimensional, thermodynamic combustion modelling approach has been coupled with realistic chemical kinetics modelling of autoignition using reduced mechanisms for gasoline surrogates. The quasi-dimensional approach has been found to allow a fast and appreciably accurate prediction of the effects of operating conditions on the engine performance. It has also provided an insight in to the stability of the turbulent flame as the engine load and speed is varied. The cyclic variability was modelled by perturbing the in-cylinder turbulence and charge composition according to a Gaussian distribution. Its coupling with autoignition modelling allowed to elucidate the effects of operating conditions such as spark-timing and charge temperature on the autoignition onset. In this approach, the autoignition propensity has been predicted for the entire spectrum of cyclic variations in cylinder pressure.
Technical Paper
2014-10-13
Yongqiang Han, Jianjian Kang, Xianfeng Wang, Yang Chen, Zhichao Hu
Energy saving and environment protection has been two major subjects in the development of automobile industry. In the internal combustion engine, about 40% of fuel energy is released into the atmosphere through waste gas. The recovery and utilization of the heat from waste gas can realize the goals of energy saving and cost reducing. In fieldof waste heat recovery, the organic Rankine cycle (ORC) has good prospects and has been widely used.Turbo has been selected firstly as the expander in traditional ORC. However, turbo has disadvantages of high manufacturing cost and narrow applicable range. In this paper, a new organic Rankinecycle coupling free piston (ORC-FP) system used in theinternal combustion engine (ICE) exhaust heatrecovery is proposed and its working principle is introduced in detail.In this system, the free piston with constant force outputfunctions as expander in ORC and operates reciprocally to output workunder the driven of working fluid R245ca,which absorbs heat from waste gas and provides vapor power.
Technical Paper
2014-10-13
Pawel Magryta
Nowadays more sophisticated ways are search for alternative supply of combustion engines. One of the commonly used alternative fuels is hydrogen. On the market there are quite a number of passenger cars, which are powered by hydrogen fuel. The development of this technology is primarily connected with the introduction of hydrogen refueling stations, and hydrogen storage and distribution systems. We can predict that much faster popularization trend of hydrogen fuel would bring the possibility of modifying the existing fuel supply systems of internal combustion engines for use this environmentally friendly fuel. Adaptation of existing vehicles equipped with spark-ignition engines in the ability to support combustion by dosing additional dose of hydrogen would enable the introduction of this alternative fuel on a larger scale than at present. In order to verify the assumptions of the additive supplying hydrogen, simulation test model of a spark ignition engine, developed in the AVL BOOST software was presented in the article.
Technical Paper
2014-10-13
Qiyou Deng, Richard Burke
As the requirements of vehicle pollutant emissions and fuel consumption are getting stricter, engine downsizing through turbocharging to improve the efficiency of vehicles is becoming more popular. However, for now, the turbocharger models are based on characteristic maps derived from experimental measurements taken under steady conditions on dedicated gas stand facility. Under these conditions heat transfer is ignored and consequently the predictive performance of the model is compromised, particularly under the part load and dynamic operating conditions that are representative of real powertrain operation. Although some physics based models have been proposed to account for the thermal behaviour of the device, these require considerable experimental effort to determine the model parameters that is not practical for industrial applications. A more accurate model that is easily parameterised would benefit turbocharger-engine matching and engine controller design. This paper proposes to apply a dynamic mathematical model that uses a polynomial structure, the Volterra Series, for the modelling of the turbocharger system.
Technical Paper
2014-10-13
Mohd Farid Muhamad Said, Azhar Bin Abdul Aziz, Zulkanain Abdul Latiff, Amin Mahmoudzadeh Andwari, Shahril Nizam Mohamed Soid
Many efforts have been invested to improve the fuel efficiency of vehicles mainly for the local consumers. The production of a downsized turbocharged engine in the last quarter of 2011 proves that Malaysian is racing towards producing high efficiency engines along with other manufacturers. The effort does not only end there, several research activities on other alternative technology including cylinder deactivation (CDA) has begun. In this paper, the main research area is focus on the investigation of cylinder deactivation (CDA) technology on common engine part load conditions within Malaysian city driving operation. CDA mostly being applied on multi cylinders engines. It has the advantage in improving fuel consumption by reducing pumping losses at part load engine conditions. Here, the application of CDA on 1.6 liter four cylinders gasoline engine is studied. One-dimensional (1-D) engine modeling is performed to investigate the effect of intake and exhaust valve strategy on engine performance with CDA.
Technical Paper
2014-10-13
Daniela Siano, Maria Antonietta Panza, Danilo D'Agostino
The easiest way to identify knock conditions during the operation of a SI engine is represented by the knowledge of the in-cylinder pressure. Traditional techniques like MAPO (Maximum Amplitude Pressure Oscillation) based method rely on the frequency domain processing of the pressure data. This technique may present uncertainties due to the correct specification of some model parameters, like the band-pass frequency range and the crank angle window of interest. In this paper two innovative techniques for knock detection, which make use of the in-cylinder pressure, are explained in detail, and the results are compared with those coming from the MAPO method. The first procedure is based on the use of statistical analysis by applying an Auto Regressive (AR) technique, whilst the second technique makes use of the Discrete Wavelet Transform (DWT). The data useful for the analysis have been acquired on a high compression ratio four cylinder, spark ignition engine. Results demonstrate that the analyzed methods give quite similar outcomes but they also highlight that AR and DWT techniques present an higher sensitivity for soft knock detection.
Technical Paper
2014-10-13
Fabrizio Bonatesta, Salvatore La Rocca, Edward Hopkins, Daniel Bell
Gasoline Direct Injection engines, even in their latest generation, are an important source of ultra-fine particulate matter. The ever more stringent emission regulations across the globe, along with the renewed medical evidence of the adverse impact on human health, indicate further research is needed to improve design and control of the GDI technology, with the aim of reducing PM emissions. Commonly, two phenomena are reported as the most important sources of soot formation in GDI engines: the inherent poor fuel-air mixture preparation; the interaction between high-velocity fuel spray and combustion chamber walls. Computational Fluid Dynamics modelling is a cost-effective alternative to testing and, if appropriately configured, may offer useful insight into the details of fuel spray and mixture preparation. Given the acknowledged connection between combustion and soot formation processes, CFD modelling may also lead to improved understanding useful for the optimization of combustion control strategies specifically designed to minimise engine-out soot emissions.
Technical Paper
2014-10-13
Sophie Porter, Ahmad Kamal Mat Yamin, Svetlana Aleksandrova, Stephen Benjamin, Carol A. Roberts, Jonathan Saul
Flow maldistribution across automotive exhaust catalysts significantly affects their conversion efficiency. This study investigates the application of CFD in modelling flow in a 2D rig consisting of a catalyst monolith downstream of a wide-angled planar diffuser presented with steady flow. Two distinct approaches, porous medium and individual channels, are used to model monoliths of length 27mm and 100mm. Flow predictions are compared to particle image velocimetry (PIV) measurements made in the diffuser and hot wire anemometry (HWA) data taken downstream of the monolith. Upstream of the monolith, the two CFD approaches agree well for velocity profiles across the central jet. CFD predictions diverge outside of this area, with neither one markedly closer to PIV results. Modelling the monolith as a fluid region of individual channels is shown to improve the prediction of flow maldistribution downstream of the monolith when compared to the porous medium approach. The individual channels model also predicts height and placement of secondary peaks closer to those of HWA data.
Technical Paper
2014-10-13
Andrew Pedlow, Geoffrey McCullough, Alexandre Goguet, Ken Hansen
Pedlow, A1). McCullough1), G. Goguet, A2). 1) School of Mechanical and Aerospace Engineering, Queen's University Belfast 2) School of Chemistry and Chemical Engineering, Queen's University Belfast Pedlow, A. Email: apedlow01@qub.ac.uk, Tel.: +4428 9097 4569 Mathematical modelling has become an essential tool in the design of modern catalytic systems. Emissions legislation is becoming increasingly stringent, meaning that mathematical models of after-treatment systems must become more accurate in order to provide confidence that a catalyst will convert pollutants over the required range of conditions in order to meet legislated limits. Automotive Catalytic converter models contain several sub-models that represent processes such as mass and heat transfer, and the rates at which the reactions proceed on the surface of the precious metal. Of these sub-models, the prediction of the surface reaction rates is by far the most challenging due to the complexity of the reaction system and the large number of gas species involved.
Technical Paper
2014-10-13
Jonathan Stewart, Roy Douglas, Alexandre Goguet, Cristina Elena Stere, Luke Blades
Kinetic models are becoming an ever present tool in the development of automotive catalysis, primarily used for characterisation of catalysts and as a predictive tool for performance. This has led to a large number of kinetic models related to automotive catalysis appearing in literature in literature in the past decades. Most kinetic models for automotive application focus primarily on the global kinetic approach for reaction kinetics, with the more chemically accurate micro-kinetics appearing more frequently in the past number of years. One of the most critical aspects in the development of a kinetic model in general is the method used to control the switch between limiting factors over the period of the chemical reaction, namely mass transfer and reaction kinetics. This balance becomes increasingly more critical with the automotive application as the gas composition and gas flow vary throughout the automotive cycles resulting in a large number or reactions competing, with a constantly changing space velocity.
Technical Paper
2014-10-13
Achinta Varna, Konstantinos Boulouchos, Alexander Spiteri, Panayotis Dimopoulos Eggenschwiler, Yuri M. Wright
Simulations for a pressure-assisted multi-stream injector designed for urea-dosing in a selective catalytic reduction SCR exhaust gas system have been carried out and compared to measurements taken in an optically accessible high-fidelity flow test rig. The experimental data comprises four different combinations of mass flow rate and temperature for the gas stream with unchanged injection parameters for the spray. First, a parametric study is carried out to determine the importance of various spray sub-models, including atomization, spray-wall interaction, buoyancy as well as droplet coalescence. Optimal parameters are determined using experimental data for one reference operating condition. The model is subsequently applied to all operating conditions with unaltered parameters and validated by means of the measured droplet velocity fields, droplet diameter distributions and spray-tip propagation which have been characterized by means of Particle Image Velocimetry (PIV), Phase Doppler Anemometry (PDA) and shadowgraph imaging.
Technical Paper
2014-10-13
Lukasz Grabowski
The research on the project to develop a new type of gyroplane required a special gyroplane powertrain to be developed. To meet special research requirements, the correct cooling of a drive unit is particularly important so this paper puts a focus just on the issues of gyroplane powertrain cooling. The Rotax 912S engine was selected as a drive unit following a detailed analysis. A one-dimensional model, simulated with the AVL Boost software, was applied to determine the heat balance for this engine and heat flux penetrating through each engine surface. The geometrical quantities defined in the model were obtained by measuring a three-dimensional geometry provided by an authorized Rotax engine supplier company. It has been shown that 6 kW is absorbed by a direct cooling cylinder, 28 kW by indirect cooling heads and the rest of heat is absorbed by engine oil, the heat due to friction in connecting rod bearing and camshaft bearing and the friction between piston rings and a cylinder surface.
Technical Paper
2014-10-13
Arash Hamzehloo, Pavlos Aleiferis
International obligations to reduce carbon dioxide emissions and requirements to strengthen security of fuel supply, indicate a need to diversify towards the use of cleaner and more sustainable fuels. Hydrogen has been recommended as an encouraging gaseous fuel for future road transportation since with reasonable modifications it can be burned in conventional internal combustion engines without producing carbon-based tailpipe emissions. Direct injection of hydrogen into the combustion chamber can be more preferable than port fuel injection since it offers advantages of higher volumetric efficiency and can eliminate abnormal combustion phenomena such as backfiring. The current work applied a fully implicit coupled computational methodology along with Reynolds-Averaged Navier-Stokes (RANS) technique in order to study the mixture formation and combustion in a direct-injection spark-ignition engine with hydrogen fuelling. Hydrogen was issues into the combustion chamber by a six-hole side-mounted injector.
Technical Paper
2014-10-13
Harun Mohamed Ismail, Hoon Kiat Ng, Suyin Gan, Tommaso Lucchini
Modelling the combustion process of a diesel-biodiesel fuel spray in a 3-dimensional (3D) computational fluid dynamics (CFD) domain remains challenging and time-consuming despite the recent advancement in computing technologies. Accurate representation of the in-cylinder processes is key to the success of CFD studies as they are able to provide invaluable insights into these events, which are limited when using conventional experimental approaches. This is especially true for emerging new fuels such as biodiesels as the fundamental understanding of these fuels under combusting environment is still limited. The reported work here is dedicated to evaluating the Adaptive Local Mesh Refinement (ALMR) approach in OpenFOAM® for accurate simulation of reacting biodiesel-diesel fuel spray. An in-house model for thermo-physical and transport properties is integrated to the code, along with a chemical mechanism comprising 113 species and 399 reactions. Simulation results are compared against data from Chalmers High-Pressure-High-Temperature Constant-Volume Combustion Chamber (HPHT-CVCC) experimental test-bed studies in terms of liquid-droplet penetration length, vapour penetration length and spray temporal distribution.
Technical Paper
2014-10-13
Beini Zhou, Akira Kikusato, Kusaka Jin, Yasuhiro Daisho, Kiyotaka Sato, Hidefumi Fujimoto
Diesel engines for automobiles are required to simultaneously comply with the increasingly more stringent emission regulations and fuel economy standards. As a very useful tool, Computational Fluid Dynamics (CFD) has become an effective tool to develop higher efficiency and lower emission diesel engine combustion systems. Direct Numerical Simulation (DNS) is one of the most precise methods of all CFD codes. Although DNS can describe organized vortex structures in the turbulent flows, it requires excessive cost and computation time to predict diesel spray characteristics. Thus, so far DNS is not a practical method without adopting turbulent modeling for practical applications. In recent years, Large Eddy Simulation (LES) of turbulent combustion is becoming more popular in the field of fluid mechanics as a practical DNS replacement to analyze in-cylinder turbulent phenomena. Thus, in this study, the soot formation process in diesel combustion was analyzed by using LES based on one-equation sub-grid turbulent kinetic energy model.
Technical Paper
2014-10-13
Zhi Wang, Fang Wang, Shi-Jin Shuai
This paper studied the knock combustionprocess in gasoline HCCI engines. The complex chemical kinetics wasimplemented into the three-dimensional CFD code with LES (Largeeddy simulation) to study the origin of the knock in HCCIcombustion process. The model was validated using the experimentaldata from cylinder pressure measurement and combustion analysis.3D-CFD with LES method gives detailed turbulence, species,temperature and pressure distribution during gasoline HCCIcombustion process. The simulation results indicate that HCCIengine knock originates from random multipoint auto-ignition incombustion chamber due to slight inhomogeneity. It is induced bythe significantly different heat release rate of high temperatureoxidation (HTO) and low temperature oxidation (LTO) and theirinteractions. Pressure wave occurrence can be explained by the factof significant pressure gradients in HCCI combustion field, whichcaused by multipoint auto-ignition in constant-volume like heatrelease. For instance, slightly higher temperature spots wereformed before ignition due to wall heat transfer and turbulenceconversion.
Technical Paper
2014-10-13
S F Benjamin, C A Roberts
In an attempt to reduce particulate and NOx emissions from Diesel exhaust, the combined DPF and SCR filter is now frequently chosen as the preferred catalyst. When this device functions effectively it saves valuable packaging space in a passenger vehicle. As part of its development, modelling of its emissions performance is essential. Single channel modelling is the obvious choice for a DPF filter because of its complex geometry. This, however, can be computationally demanding. For a normal flow-through catalyst monolith the porous medium approach is an attractive alternative. This paper attempts to model an SCRF by applying the porous medium approach. The model is essentially 1D but as with all porous medium models, can very easily be applied to 3D cases once developed and validated. The model is described in full in this paper and values for all the key parameters are presented. The filter is assumed to collect soot in the inlet channels, but only the output channels are coated with SCR washcoat, as in the most recent devices.
Technical Paper
2014-10-13
Hiew Mun Poon, Hoon Kiat Ng, Suyin Gan, Kar Mun Pang, Jesper Schramm
This is an extension to the previous work conducted by the authors that the chemical kinetic mechanism reduction scheme was improved for large-scale mechanisms. In this work, Perfectly Stirred Reactor (PSR) was added as a criterion of data source for mechanism reduction instead of using auto-ignition condition only in the previous work. The detailed n-hexadecane mechanism with 2116 species and 8130 elementary reactions for diesel fuel surrogate was chosen to perform mechanism reduction. Operating conditions with equivalence ratio ranging from 0.5 to 2, initial pressure ranging from 40 bar to 80 bar, initial temperature ranging from 650 K to 1350 K for auto-ignition and 300 K for PSR as well as residence time covering the ignition and extinction ranges were sampled. As a result, a reduced n-hexadecane mechanism with 79 species for diesel fuel surrogate was successfully derived from the detailed mechanism. Following that, the reduced n-hexadecane mechanism was validated under auto-ignition and PSR conditions using zero-dimensional (0-D) closed homogeneous batch reactor in CHEMKIN-PRO software.
Technical Paper
2014-10-13
P. Christopher Manning, Eduardo D. Marquez, Leonard Figueroa, Douglas J. Nelson, Eli Hampton White, Lucas Wayne Shoults
The Hybrid Electric Vehicle Team (HEVT) of Virginia Tech is ready to compete in the Year 3 Final Competition for EcoCAR 2: Plugging into the Future. The team is confident in the reliability of their vehicle, and expects to finish among the top schools at Final Competition. During Year 3, the team refined the vehicle while following the EcoCAR 2 Vehicle Development Process (VDP). Many refinements came about in Year 3 such as the implementation of a new rear subframe, the safety analysis of the high voltage (HV) bus, and the integration of Charge Sustaining (CS) control code. HEVT’s vehicle architecture is an E85 Series-Parallel Plug-In Hybrid Electric Vehicle (PHEV), which has many strengths and weaknesses. The primary strength is the pure EV mode and Series mode, which extend the range of the vehicle and reduce Petroleum Energy Usage (PEU) and Greenhouse Gas (GHG) emissions. A primary weakness is its complexity, which made it difficult for the team to truly reap the benefits of the added components to the vehicle which are utilized in Parallel mode.
Technical Paper
2014-10-13
Di Zhu, Ewan Pritchard
EcoCAR 2: Plugging in to the Future is a three-year collegiate engineering competition established by the U.S. Department of Energy (DOE) and General Motors (GM). North Carolina State University is designing a Series Plug-in Hybrid Electric Vehicle (PHEV) on a 2013 Chevrolet Malibu vehicle platform. The designed vehicle has a pure electric range of 55 miles and an overall range of 235 miles with a range extension system. The vehicle is designed to reduce fuel consumption and gas emission while maintaining consumer acceptability in the areas of performance, utility, and safety. This reports details the vehicle development process with an emphasis on control system development and refinement. Advanced manufacturing, modeling, and simulation have been used to ensure a safe and functional vehicle at the upcoming year 3 final competition.
Technical Paper
2014-10-13
John Thomas
Vehicle manufacturers among others are putting great emphasis on improving fuel economy (FE) of light-duty vehicles in the U.S. market, with significant FE gains being realized in recent years. The U.S. Environmental Protection Agency (EPA) data indicates that the aggregate FE of vehicles produced for the U.S. market has improved by 20% from model year (MY) 2005 to 2013. This steep climb in FE includes changes in vehicle choice, improvements in engine and transmission technology, and reducing aerodynamic drag, rolling resistance, and parasitic losses. The powertrain related improvements focus on optimizing in-use efficiency of the transmission and engine as a system, and may make use of what is termed downsizing and/or downspeeding. This study explores quantifying recent improvements in powertrain efficiency, viewed separately from other vehicle alterations and attributes (noting that most vehicle changes are not completely independent). A methodology is outlined to estimate powertrain efficiency for the U.S city and highway cycle tests using data from the EPA vehicle database.
Technical Paper
2014-10-13
Karthik Puduppakkam, Chitralkumar Naik, Ellen Meeks, Christian krenn, Roswitha Kroiss, Johannes Gelbmann, Guenther Pessl
An important goal for CFD simulation in engine design is to be able to predict the combustion behavior as operating conditions are varied and as hardware is modified. Such predictive capability allows virtual prototyping and optimization of design parameters. For low-temperature combustion conditions, such as with high rates of exhaust-gas recirculation, reliable and accurate predictions have been elusive. Soot has been particularly difficult to predict, due to the dependence of soot formation on the fuel composition and the kinetics detail of the fuel combustion. Soot evolution in diesel engines is impacted by fuel and chemistry effects, as well as by spray dynamics and turbulence. In this work, we present a systematic approach to accurately simulate combustion and emissions in a high-performance BMW diesel engine. This approach has been tested and validated against experimental data for a wide range of operating conditions. Nine operating conditions have been modeled that span engine loads of 3-21 bar MEP, engine speeds of 1000-4400 rpm and external EGR of 0-38%.
Technical Paper
2014-10-13
R. Pradeepak, Mihir Bhambri
Motor scooters are popular in most parts of the world, especially in countries with local manufacturers. Parking, storage, and traffic issues in crowded cities, along with the easy driving position makes them a popular mode of transportation. Motor scooters are the segment of 2 wheelers which is driven by the entire family with ease unlike motorcycles which is a male dominated segment. Due to the importance that the scooters hold in the present time, it has become very important to manufacture stable, light weight yet robust scooters. For the best product in the market, testing is given a great importance in automotive manufacturing companies. Virtual testing has been the latest development in terms of testing a vehicle during the design stage itself. Multi Body Dynamics approach is used to study - 1) the articulation of various sub-assemblies and 2) the static & dynamic loads generated at various attachment points of the scooter. Integration of sub-assemblies into a final product creates a minimal scope of modification of the location of different components.
Technical Paper
2014-10-13
Nicolò Frapolli, Michele Bolla, Konstantinos Boulouchos, Yuri M. Wright
In this study, numerical simulations of in-cylinder processes associated to fuel post-injection in a diesel engine operated at Low Temperature Combustion (LTC) have been performed. An extended Conditional Moment Closure (CMC) model capable of accounting for an arbitrary number of subsequent injections has been employed: instead of a three-feed system, the problem has been described as a sequential two-feed system, with the conditioning scalar being the total mixture fraction. A reduced n-heptane chemical mechanism coupled with a two-equation soot model is employed. Numerical results have been validated with measurements from the optically accessible heavy-duty diesel engine installed at Sandia National Laboratories, comparing apparent heat release rate (AHRR), in-cylinder soot mass evolution and exhaust filter smoke number (FSN) for a wide range of post injection dwell times. Subsequently, numerical investigations on the effects of different post injection timings on soot formation and oxidation processes is presented, with particular emphasis on the role of the increased mixing by post injections.
Technical Paper
2014-10-13
Konrad Pietrykowski
Radial aircraft engines were used in aviation since its beginning. Nowadays, there are very few airplanes equipped with this type of engines, however, they are still used and developed. A good example is WSK PZL Kalisz company, which has introduce an electronic fuel injector to the ASz-62IR engine, and in cooperation with Lublin University Technology it has carried out project based on the usage of electronic ignition system in this engine. One of the major difficulties of radial engines is an irregular operation of individual cylinders caused by the unique arrangement of cylinders. Besides, the bore of cylinders very frequently exceed the value of 150 mm, this hinders the combustion of fuel-air mixture. Due to the safety matters and in order to boost the combustion of the mixture, two spark plugs for a cylinder have been used in such engines,. They are placed symmetrically on both sides of a cylinder head. The usage of the electronically controlled injection in combination with two spark plugs provides numerous possibilities of controlling the combustion in the radial engine.
Technical Paper
2014-10-13
Michal Bialy
By reducing fuel consumption, and even replacing a fuel with a different type, it has been attempted to find the methods to reduce carbon dioxide emissions and costs due to the operation of automotive vehicles. Original fuels are replaced with renewable energy sources such as hydrogen or alcohols. Diesel oil is replaced in a diesel engine with a gaseous fuel. This replacement is accompanied by engine modification involving fitting an engine with an ignition system and reducing the compression ratio. Accordingly, a drive unit can be supplied with one type of fuel only, i.e. a gaseous fuel. Another way is to supply the additional portion of fuel into an intake manifold which is combusted in a combustion chamber together with the original fuel. To avoid knock, the additional portion of fuel is a dozen percents of a master dosage. Therefore, the best solution seems to be dual-fuel supply in a drive unit. A gaseous fuel which is compressed natural gas (CNG) is injected directly into an engine working space, and combustion is initiated with injecting a pilot dose of diesel oil.
Technical Paper
2014-10-13
Anders Widd, Magnus Lewander
The Selective Catalytic Reduction (SCR) catalyst with ammonia as reducing agent plays a central role in today’s exhaust after-treatment systems for heavy-duty vehicles and there is a wide selection of possible catalytic materials to use. In order to facilitate the design of future catalysts, several aspects of the materials must be evaluated both in steadystate and transient operation. To this end, this paper presents a methodology for comparing the dynamic properties of different catalysts using full-size engine testing. The studied characteristics include the ammonia storage capacity, the effect on starting with an empty catalyst, the transient response to temperature gradients and changes in the urea dosing level. The temperature response is of particular importance in transient operation, where temperature increases may lead to substantial ammonia slip. A vanadium catalyst is compared to a Cu SAPO catalyst on the same substrate, and they show significant differences in their dynamic response.
Viewing 1 to 30 of 29333