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Author: Changhoon Oh Publisher: ISBN: Category : Languages : en Pages : 162
Book Description
Due to their advantages in higher fuel efficiency and torque compared to conventional port fuel injection (PFI) engines, direct injection spark ignition (DISI) engines have become dominant in gasoline-fueled engines. However, DISI engines have a significant drawback in particulate matter (PM) emission: the PM emission of DISI engines is at least an order of magnitude higher than that of PFI engines. The objective of this study is to investigate PM emission in DISI engines, mainly focusing on particulate number (PN) emission. The study aims to assess, respectively, the plausible PM formation mechanisms: non-fuel originated sources (e.g., lubricant), flame propagation in rich mixture and the pyrolysis of the vapor from liquid fuel film. Through a series of experiments, it has been found that non-fuel contribution is less important than the other two mechanisms. For all operating conditions, the absolute amount of the non-fuel contribution is much smaller than the total emission. In case of PM generated by flame propagation in rich mixture, there is a threshold air-fuel equivalence ratio below which PM starts to form rapidly. The threshold is influenced by the combustion temperature. PM starts to form at lower equivalence ratio when the combustion temperature was lower. Contrary to the PM generated from flame propagation in fuel-rich mixture case, that from the liquid fuel film is suppressed by lowering the combustion temperature. Transmission electron microscopy (TEM) imaging shows that the sizes of primary particles and agglomerated particles become larger as engine load increases, but particulates from different mechanisms have different morphology.
Author: Changhoon Oh Publisher: ISBN: Category : Languages : en Pages : 162
Book Description
Due to their advantages in higher fuel efficiency and torque compared to conventional port fuel injection (PFI) engines, direct injection spark ignition (DISI) engines have become dominant in gasoline-fueled engines. However, DISI engines have a significant drawback in particulate matter (PM) emission: the PM emission of DISI engines is at least an order of magnitude higher than that of PFI engines. The objective of this study is to investigate PM emission in DISI engines, mainly focusing on particulate number (PN) emission. The study aims to assess, respectively, the plausible PM formation mechanisms: non-fuel originated sources (e.g., lubricant), flame propagation in rich mixture and the pyrolysis of the vapor from liquid fuel film. Through a series of experiments, it has been found that non-fuel contribution is less important than the other two mechanisms. For all operating conditions, the absolute amount of the non-fuel contribution is much smaller than the total emission. In case of PM generated by flame propagation in rich mixture, there is a threshold air-fuel equivalence ratio below which PM starts to form rapidly. The threshold is influenced by the combustion temperature. PM starts to form at lower equivalence ratio when the combustion temperature was lower. Contrary to the PM generated from flame propagation in fuel-rich mixture case, that from the liquid fuel film is suppressed by lowering the combustion temperature. Transmission electron microscopy (TEM) imaging shows that the sizes of primary particles and agglomerated particles become larger as engine load increases, but particulates from different mechanisms have different morphology.
Author: Iason Dimou Publisher: ISBN: Category : Languages : en Pages : 83
Book Description
In an effort to build internal combustion engines with both reduced brake-specific fuel consumption and better emission control, engineers developed the Direct Injection Spark Ignition (DISI) engine. DISI engines combine the specific higher output of the spark ignition engine, with the better efficiency of the compression ignition engine at part load. Despite their benefits, DISI engines still suffer from high hydrocarbon, NO2 and particulate matter (PM) emissions. Until recently, PM emissions have received relatively little attention, despite their severe effects on human health, related mostly to their size. Previous research indicates that almost 80% of the PM is emitted during the first few minutes of the engine's operation (cold-start-fast-idling period). A proposed solution for PM emission reduction is the use of fuel blends with ethanol. The present research experimentally measures the effect of ethanol content in fuel on PM formation in the combustion chamber of a DISI engine during the cold-start period. A novel sampling system has been designed and combined with a Scanning Mobility Particle Sizer (SMPS) system, in order to measure the particulate matter number (PN) concentration 15 cm downstream from the exhaust valves of a DISI engine, for a temperature range between 0 and 40"C, under low load operation. Seven gasohol fuels have been tested with the ethanol content varying from 0% (EO) up to 85% (E85). For E10 to E85, PN modestly increases when the engine coolant temperature (ECT) is lowered. The PN distributions, however, are insensitive to the ethanol content of the fuel. The total PN for EQ is substantially higher than for the gasohol fuels, at ECT below 20'C. However, for ECT higher than 20'C, the total PN values (obtained from integrating the PN distribution from 15 to 350 nm) are approximately the same for all fuels. This sharp change in PN from EQ to E10 is confirmed by running the tests with E2.5 and E5; the midpoint of the transition occurs at approximately E5. Because the fuels' evaporating properties do not change substantially from EQ to E10, the significant change in PN is attributed to the particulate matter formation chemistry.
Author: Institution of Mechanical Engineers Publisher: Woodhead Publishing ISBN: 178242184X Category : Technology & Engineering Languages : en Pages : 263
Book Description
This book presents the papers from the Internal Combustion Engines: Performance, fuel economy and emissions held in London, UK. This popular international conference from the Institution of Mechanical Engineers provides a forum for IC engine experts looking closely at developments for personal transport applications, though many of the drivers of change apply to light and heavy duty, on and off highway, transport and other sectors. These are exciting times to be working in the IC engine field. With the move towards downsizing, advances in FIE and alternative fuels, new engine architectures and the introduction of Euro 6 in 2014, there are plenty of challenges. The aim remains to reduce both CO2 emissions and the dependence on oil-derivate fossil fuels whilst meeting the future, more stringent constraints on gaseous and particulate material emissions as set by EU, North American and Japanese regulations. How will technology developments enhance performance and shape the next generation of designs? The book introduces compression and internal combustion engines’ applications, followed by chapters on the challenges faced by alternative fuels and fuel delivery. The remaining chapters explore current improvements in combustion, pollution prevention strategies and data comparisons. Presents the latest requirements and challenges for personal transport applications Gives an insight into the technical advances and research going on in the IC Engines field Provides the latest developments in compression and spark ignition engines for light and heavy-duty applications, automotive and other markets
Author: Jinghu Hu Publisher: 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
Author: Publisher: ISBN: Category : Languages : en Pages : 78
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.
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.
Author: Changhoon Oh
Author: Changhoon Oh
Author: Iason Dimou
Author: Michael James McGhee
Author: Institution of Mechanical Engineers
Author: Clive Robert Tindle
Author: Jinghu Hu
Author: 
Author: Piotr Bielaczyc
Author: 
Author: Justin E. Ketterer