Author: Akio KobayashiPublisher:
ISBN:
Category : Diesel motor
Languages : en
Pages : 8
Book Description
Analysis of Cold Start Combustion in a Direct Injection Diesel Engine
Author: Akio KobayashiPublisher:
ISBN:
Category : Diesel motor
Languages : en
Pages : 8
Book Description
A Study to Quantitatively Analyze Cold Start Emissions for a Gasoline Direct Injection Engine
Author: Jinghu HuPublisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
The gasoline direct injection (GDI) technology is a technology with which the gasoline is directly injected in the cylinder. GDI technology has been gaining popularity among vehicle manufacturers due to multiple advantages it presents compared with the port fuel injection technology, and has been widely implemented in the light-duty passenger vehicles on the US market. One weakness of the GDI engine is the excessive hydrocarbon (HC) emission during the cold start, where the engine speed, cylinder and piston top temperature and engine fuel rail pressure are all far from optimal. Given the more stringent Tier 3 HC emissions regulations enforced by United States Environmental Protection Agency and California Air Resources Board, a detailed research on the GDI engine cold start HC emissions was essential to facilitate the compliance with HC emission standards from the modern GDI engines. A novel experimental system was designed, prototyped and installed. The in-house instrumentation and control system was designed based on the National Instruments hardware and aimed to control the Ford 2.0 L GDI engine and realize the engine cold start using custom engine powertrain parameters. The novel gas collection and analysis system was designed and prototyped to allow a cycle-based emission analysis. The entire study was carried out using three steps. First, the validation experiment was conducted to validate whether the designed system hardware and software operated as desired, and to provide some basic qualitative understanding of the GDI engine cold start profiles. Second, the preliminary quantitative analysis was carried out using both gasoline and iso-pentane as fuel to further understand the contributing factors of the cold start HC emissions for GDI engines. In the final step, a parametric study, multiple parametric sweeps were carried out for various powertrain parameters to identify the quantitative effect of each parameter on the engine power output and emission performances respectively. The initial validation experiment results showed that the designed novel experimental system performed as expected, and that HC emissions actually decreased monotonically among the first five firing cycles of the cold start. The preliminary quantitative analysis revealed that for gasoline-fueled cold starts not all the injected fuel was collected in the exhaust gas. The non-collected fuel was potentially due to fuel wall wetting and piston top impingement, which could be the main reason for the HC emissions. The parametric study found that the main contributing factor of the HC emissions for the very first firing cycle was the injected fuel that did not evaporate in time for combustion but still in time for the emissions. The parametric study also found that the HC emissions increased with injected equivalence ratio. The change in fuel rail pressure had a complicated effect on the HC emissions at the first firing cycle. The increase in injection times, from 2 to 4 injections given the same amount of total injected fuel, did improve the fuel evaporation and combustion status, and led to higher power output and lower HC emissions given the same injected fuel mass. The study showed that the key to mitigate the HC emissions during the GDI engine cold start was improving the fuel evaporation and air-fuel profile, so as to minimize the fuel wall wetting and piston top impingement effect
COLD START ANALYSIS AND MODELING OF A DIRECT-INJECTION GASOLINE ENGINE
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Abstract : In this thesis, two different works related to cold start of a direct-injection (DI) gasoline engine are shown. First, effect of split injection is studied on engine exhaust temperature and hydrocarbon emissions for cold start conditions. Instead of single injection, two injections are done, one injection during the intake stroke and one injection during the compression stroke. Split injection is known to reduce jet wall wetting, thus reducing the hydrocarbon emissions from engine itself. Further, split injection reduces engine cycle-by-cycle variability with respect to the single injection case. Correlations between start of injection for the injection in the intake stroke (SOI), end of injection for the injection in the compression stroke (EOI) and Split Ratio (SR) with Exhaust Temperature (Texh) and engine hydrocarbon emissions are proposed with the help of design of experiments (DOE). These correlations could be used for controlling exhaust temperature during cold start. Second, because of repetitive marshalling of a vehicle, i.e. cold start the engine on the vehicle and drive it a few feet and then turn it off, spark plugs are observed to get fouled. A spark plug is considered to be fouled when the insulator nose becomes coated with a foreign substance including oil, fuel or carbon. This enables the ignition coil voltage to follow along the insulator nose and ground out rather than bridging gap and firing normally. A tool to measure quasi real-time spark plug fouling is proposed in this work, which uses in-cylinder ion data to measure offset voltage which is then used to calculate spark plug shunt resistance. Based on the spark plug shunt resistance, fouling level of the plug can be calculated, and the condition of the plug can be determined.
A Computational Study of In-cylinder Cold Starting Processes in a Diesel Engine
Author: Manuel A. Gonzalez D.Publisher:
ISBN:
Category :
Languages : en
Pages : 472
Book Description
Autoignition and Combustion in Diesel Engines Under Cold Starting Conditions
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
This report includes the results of an investigation on the autoignition and combustion processes in diesel engines at low ambient temperatures. Experiments were conducted on three different single-cylinder direct-injection, four-stroke engines, using fuels of different cetane numbers and physical properties. Tests covered ambient temperatures ranging from 250C to -250C. The engines were soaked at least eight hours before a cold start test. The analysis indicated that the difficulty in starting diesel engines is caused by combustion instability at low temperatures. Combustion instability will cause the engine to misfire once before it fires again. This is referred to as 8-stroke-cycle operation. If it misfires twice, it is referred to as l2-stroke-cycle operation, and so on. This pattern was found to be reproducable. The engine may start on a l2-stroke-cycle operation at low temperatures, shift to an 8-stroke-cycle, and finally shifts to the regular 4-stroke-cycle. This pattern has been found not to be engine or fuel specific. A detailed thermodynamic and combustion analysis of the experimental data indicated that the cause for combustion instability is a combination of dynamic, physical and chemical kinetics factors. Recommendations are made to reduce combustion instability by using the electronic controls already available on engines.
Automotive Spark-Ignited Direct-Injection Gasoline Engines
Author: F. ZhaoPublisher: Elsevier
ISBN: 008055279X
Category : Technology & Engineering
Languages : en
Pages : 129
Book Description
The process of fuel injection, spray atomization and vaporization, charge cooling, mixture preparation and the control of in-cylinder air motion are all being actively researched and this work is reviewed in detail and analyzed. The new technologies such as high-pressure, common-rail, gasoline injection systems and swirl-atomizing gasoline fuel injections are discussed in detail, as these technologies, along with computer control capabilities, have enabled the current new examination of an old objective; the direct-injection, stratified-charge (DISC), gasoline engine. The prior work on DISC engines that is relevant to current GDI engine development is also reviewed and discussed. The fuel economy and emission data for actual engine configurations have been obtained and assembled for all of the available GDI literature, and are reviewed and discussed in detail. The types of GDI engines are arranged in four classifications of decreasing complexity, and the advantages and disadvantages of each class are noted and explained. Emphasis is placed upon consensus trends and conclusions that are evident when taken as a whole; thus the GDI researcher is informed regarding the degree to which engine volumetric efficiency and compression ratio can be increased under optimized conditions, and as to the extent to which unburned hydrocarbon (UBHC), NOx and particulate emissions can be minimized for specific combustion strategies. The critical area of GDI fuel injector deposits and the associated effect on spray geometry and engine performance degradation are reviewed, and important system guidelines for minimizing deposition rates and deposit effects are presented. The capabilities and limitations of emission control techniques and after treatment hardware are reviewed in depth, and a compilation and discussion of areas of consensus on attaining European, Japanese and North American emission standards presented. All known research, prototype and production GDI engines worldwide are reviewed as to performance, emissions and fuel economy advantages, and for areas requiring further development. The engine schematics, control diagrams and specifications are compiled, and the emission control strategies are illustrated and discussed. The influence of lean-NOx catalysts on the development of late-injection, stratified-charge GDI engines is reviewed, and the relative merits of lean-burn, homogeneous, direct-injection engines as an option requiring less control complexity are analyzed.
Diesel Engine Transient Operation
Author: Constantine D. RakopoulosPublisher: Springer Science & Business Media
ISBN: 1848823754
Category : Technology & Engineering
Languages : en
Pages : 408
Book Description
Traditionally, the study of internal combustion engines operation has focused on the steady-state performance. However, the daily driving schedule of automotive and truck engines is inherently related to unsteady conditions. In fact, only a very small portion of a vehicle’s operating pattern is true steady-state, e. g. , when cruising on a motorway. Moreover, the most critical conditions encountered by industrial or marine engines are met during transients too. Unfortunately, the transient operation of turbocharged diesel engines has been associated with slow acceleration rate, hence poor driveability, and overshoot in particulate, gaseous and noise emissions. Despite the relatively large number of published papers, this very important subject has been treated in the past scarcely and only segmentally as regards reference books. Merely two chapters, one in the book Turbocharging the Internal Combustion Engine by N. Watson and M. S. Janota (McMillan Press, 1982) and another one written by D. E. Winterbone in the book The Thermodynamics and Gas Dynamics of Internal Combustion Engines, Vol. II edited by J. H. Horlock and D. E. Winterbone (Clarendon Press, 1986) are dedicated to transient operation. Both books, now out of print, were published a long time ago. Then, it seems reasonable to try to expand on these pioneering works, taking into account the recent technological advances and particularly the global concern about environmental pollution, which has intensified the research on transient (diesel) engine operation, typically through the Transient Cycles certification of new vehicles.
Development of a model for cold start of direct injection diesel engine
Author: Kyoosik ShinPublisher:
ISBN:
Category : Diesel motor
Languages : en
Pages : 294
Book Description
Numerical Modeling of Gasoline Direct Injection Spark Ignition Engines During Cold-start
Author: Arun Cherumuttathu RavindranPublisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
Developing a profound understanding of the combustion characteristics of the cold-start phase of a Direct Injection Spark Ignition (DISI) engine is critical to meeting the increasingly stringent emissions regulations. Computational Fluid Dynamics (CFD) modeling of gasoline DISI combustion under normal operating conditions has been discussed in detail using both the detailed chemistry approach and flamelet models (e.g., the G-Equation). However, there has been little discussion regarding the capability of the existing models to capture DISI combustion under cold-start conditions. Accurate predictions of cold-start behavior involves the efficient use of multiple models - spray modeling to capture the split injection strategies, models to capture the wall-film interactions, ignition modeling to capture the effects of retarded spark timings, combustion modeling to accurately capture the flame front propagation, and turbulence modeling to capture the effects of decaying turbulent kinetic energy. The retarded spark timing helps to generate high heat flux in the exhaust for a rapid catalyst light-off of the after-treatment system during cold-start. However, the adverse effect is a reduced turbulent flame speed due to decaying turbulent kinetic energy. Accordingly, developing an understanding of the turbulence-chemistry interactions is imperative for accurate modeling of combustion under cold-start conditions.This study introduces a modified version of the G-Equation combustion model called the GLR model (G-Equation for Lower Reynolds number regimes) that exhibits improved performance under cold-start conditions. The model attempts to estimate the turbulent flame speed based on the local conditions of fuel concentration and turbulence intensity. The local conditions and the associated turbulent-chemistry interactions are studied by tracking the flame front on the Borghi-Peters regime diagram. To accurately model the DISI combustion process, it is important to account for the effects of the spark energy discharge process. In this work, an ignition model is presented that is compatible with the G-Equation combustion model, and which accounts for the effects of plasma expansion and local mixture properties such as turbulence and the equivalence ratio on the early flame kernel growth. The model is referred to as the Plasma Velocity on G-Surface (PVG) model, and it uses the G-surface to capture the kernel growth. The model derives its theory from the DPIK model and applies its concepts onto an Eulerian framework, thereby removing the need for Lagrangian particles to track the kernel growth. Finally, a methodology of using machine learning (ML) techniques in combination with 3D CFD modeling to optimize the cold-start fast-idle phase of a DISI engine is presented. The optimization process implies the identification of the range of operating parameters, that will ensure the following criteria under cold-start conditions: (1) a fixed IMEP of 2 bar (BMEP of 0 bar), (2) a stoichiometric exhaust equivalence ratio (based on carbon-to-oxygen atoms) to ensure the efficient operation of the after-treatment system, (3) enough exhaust heat flux to ensure a rapid light-off of the after-treatment system, and (4) acceptable NOx and HC emissions. Gaussian Process Regression (GPR)-based ML models are employed to make predictions about DISI cold-start behavior with acceptable accuracy and a substantially reduced computational time.
Experimental Investigation on Combustion and Ionization During Cold Starting and Idling of a Diesel Engine
Author: Sahil Deodatta SanePublisher:
ISBN:
Category : Diesel motor
Languages : en
Pages : 121
Book Description
Diesel engine performance during cold starting is very crucial for smooth engine start at undesirable emission level. The development of cold start strategies that improve combustion stability relies mainly on the understanding of the combustion process during the cold starting. Even for modern diesel engines, the conditions during the cold start is far from normal operation characterized by large amount of unburned hydrocarbon emissions and long start to idling time. Thus, the use of an in-cylinder combustion sensor to measure the combustion quality during engine starting can significantly improve engine cold start control strategies. The ion current sensor has the potential to be used as onboard sensor to measure the combustion process during engine operation and can be used as feedback to the engine control unit. The aim of this research is to study and determine the combustion instability and its impact on various combustion and ionization characteristics by performing cycle analysis for a comparison between engine performance using ultra low sulfur diesel (ULSD) and aviation jet propulsion (JP8) fuels during cold start at 25 degrees Celsius. It also shows a comparison between two ion current sensors during low load idling using the same fuels. For this purpose, the glow plug and fuel injector of VW 2.0L turbocharged diesel engine were modified and electrically insulated to be used as ion current sensors. The experimental test was conducted to study the combustion process and emission product produced during low load idling.