Showing papers on "Spark-ignition engine published in 2011"

Progress in the production and application of n-butanol as a biofuel

Abstract: Butanol is a very competitive renewable biofuel for use in internal combustion engines given its many advantages. In this review, the properties of butanol are compared with the conventional gasoline, diesel fuel, and some widely used biofuels, i.e. methanol, ethanol, biodiesel. The comparison of fuel properties indicates that n-butanol has the potential to overcome the drawbacks brought by low-carbon alcohols or biodiesel. Then, the development of butanol production is reviewed and various methods for increasing fermentative butanol production are introduced in detailed, i.e. metabolic engineering of the Clostridia, advanced fermentation technique. The most costive part of the fermentation is the substrate, so methods involved in renewed substrates are also mentioned. Next, the applications of butanol as a biofuel are summarized from three aspects: (1) fundamental combustion experiments in some well-defined burning reactors; (2) a substitute for gasoline in spark ignition engine; (3) a substitute for diesel fuel in compression ignition engine. These studies demonstrate that butanol, as a potential second generation biofuel, is a better alternative for the gasoline or diesel fuel, from the viewpoints of combustion characteristics, engine performance, and exhaust emissions. However, butanol has not been intensively studied when compared to ethanol or biodiesel, for which considerable numbers of reports are available. Finally, some challenges and future research directions are outlined in the last section of this review.

Analysis of the Impact of 2-Methylfuran on Mixture Formation and Combustion in a Direct-Injection Spark-Ignition Engine

Abstract: Within the Cluster of Excellence “Tailor-Made Fuels from Biomass”, a new reaction sequence to transform biomass into 2-methylfuran has been developed. In the present study, the influence of this potential biofuel on in-cylinder spray formation and evaporation as well as engine performance is studied experimentally using a direct-injection spark-ignition single-cylinder research engine. The results obtained for 2-methylfuran are benchmarked against investigation on the same engine using conventional research octane number (RON) 95 fuel and ethanol. The in-cylinder spray formation and evaporation process is characterized by high-speed Mie scattering visualizations, indicating quicker evaporation of 2-methylfuran compared to ethanol. Engine experiments support the findings of the optical measurements by revealing excellent combustion stability, especially in cold conditions, combined with a hydrocarbon emission reduction of at least 61 % in the relevant spark timing range compared to conventional fuel. The e...

LES study of cycle-to-cycle variations in a spark ignition engine

Abstract: Multi-cycle Large Eddy Simulation (LES) of flow and combustion in a single cylinder engine set-up are presented in order to validate the ability of this technique to reproduce cyclic combustion variability in a spark ignition engine. The simulated engine operating point is part of a larger experimental database acquired at IFP and specifically designed to validate LES techniques in terms of cycle-to-cycle prediction. To characterize individual cycles, the database combines acquisitions of pressure and temperature in different locations of the engine set-up with optical diagnostics in the intake pipe and the cylinder. This new experimental database combined with LES is a powerful tool to study cycle-to-cycle variations (CCV). The operating points include points with low and high CCV levels. The LES includes the whole engine set-up, and covers 25 consecutive four-stroke engine cycles for a reference operating point with low CCV. The results show that LES is able to reproduce the experimental findings, and illustrate how LES can help explain the sources of CCV. In the present case it is shown that CCV are essentially due to velocity fluctuations at the spark plug, which induce variations of the early flame kernel growth and of the overall combustion duration.

Measurement of Enthalpies of Vaporization of Isooctane and Ethanol Blends and Their Effects on PM Emissions from a GDI Engine

Abstract: Experimental measurements have been made of the enthalpies of mixing of isooctane and ethanol blends so as to calculate the enthalpies of vaporization of these mixtures. The enthalpy of vaporization is very important for the performance of spark ignition engines, especially those that use gasoline direct injection (GDI). High enthalpies of vaporization increase the charge cooling effect so that the volumetric efficiency is improved (thereby increasing the specific output) and a higher compression ratio can also be used, because there is a lower temperature at the start of compression. The higher compression ratio increases both the efficiency and the specific output. However, measurements reported here show that the increased enthalpy of vaporization has an adverse effect on the particulate matter (PM) emissions from a GDI engine. This is attributed to the air fuel mixture being less homogeneous.

Ethanol Blends and Engine Operating Strategy Effects on Light-Duty Spark-Ignition Engine Particle Emissions

Abstract: Spark-ignition (SI) engines with direct-injection (DI) fueling can improve fuel economy and vehicle power beyond that of port fuel injection (PFI). Despite this distinct advantage, DI fueling often increases particle number emissions, such that SI exhaust may be subject to future particle emissions regulations. In this study, ethanol blends and engine operating strategy are evaluated for their effectiveness in reducing particle emissions in DI engines. The investigated fuels include a baseline emissions certification gasoline, a blend of 20 vol % ethanol with gasoline (E20), and a blend of 85 vol % ethanol with gasoline (E85). The operating strategies investigated reflect the versatility of emerging cam-based variable valve actuation technology capable of unthrottled operation with either early or late intake valve closing (EIVC or LIVC). Particle emissions are characterized in this study by the particle number size distribution as measured with a scanning mobility particle sizer (SMPS) and by the filter ...

Spark-Ignition-Engine Idle Speed Control: An Adaptive Control Approach

Abstract: The paper presents an application of a recently developed adaptive posicast controller (APC) for time-delay systems to the idle speed control (ISC) problem in spark ignition (SI) internal combustion (IC) engines. The objective is to regulate the engine speed to a prescribed set-point in the presence of accessory load torque disturbances such as those due to air conditioning and power steering. The adaptive controller, integrated with the existing proportional spark controller, is used to drive the electronic throttle actuator. We present both simulation and experimental results demonstrating the performance improvement by employing the adaptive controller. We also present the modifications and improvements to the controller structure which were developed during the course of experimentation to solve specific problems. In addition, the potential for the reduction in calibration time and effort which can be achieved with our approach is discussed.

Abnormal combustion detection method for spark-ignition engine, and spark-ignition engine

Abstract: When a maximum value of vibration intensity (maximum vibration intensity) (Vmax) acquired from a vibration sensor ( 33 ) in a low engine speed/high engine load (operating region (R)) is equal to or greater than a given threshold value (X), a spark timing of a spark plug ( 16 ) is shifted from a point set in a normal state on a retard side with respect to a compression top dead center, farther toward the retard side. Then, when a maximum vibration intensity (Vmax 2 ) acquired after the spark timing retard is greater than a maximum vibration intensity (Vmax 1 ) acquired before the spark timing retard, it is determined that preignition occurs. This technique makes it possible to reliably detect preignition using the vibration sensor, while distinguishing the preignition from knocking. An in-cylinder pressure sensor for detecting an in-cylinder pressure of an engine may be used to determine the presence or absence of the preignition, in the same manner.

Experimental Characterization of Ethyl Acetate, Ethyl Propionate, and Ethyl Butanoate in a Homogeneous Charge Compression Ignition Engine

Abstract: The homogeneous charge compression ignition (HCCI) engine can be run on a large range of fuels if the appropriate operating conditions are chosen. This can improve the efficiency of biofuel production from low-value biomass by suppressing the need for the transformation process to obtain products that are compatible with spark ignition or compression ignition engines. A simple biochemical process that includes acidogenic fermentation and produces a mixture of various esters can take advantage of this flexibility. However, the behavior of this mixture under HCCI conditions needs to be characterized. It can also have a great impact on the HCCI operating limits and its successful implementation. Using an HCCI engine, we investigated how the operating limits are modified by the combustion characteristics of three of these esters: ethyl acetate, ethyl propionate, and ethyl butanoate. This paper reports the experimental results for each of these products and for ethanol taken as the reference fuel. It also analyzes their effects on the ignition timing and the combustion rate. For the selected operating conditions, stable HCCI operations on a large range of equivalence ratios were obtained for every fuel The difference in specific heats of the air/fuel mixtures and in the ignition kinetics both contributed to the ignition characteristics. Ethanol ignites earlier, which leads to a low upper limit, whereas the late ignition of ethyl acetate shifts the operating zone upward due to smoothed high loads but unstable low loads. As a consequence, these low-grade products can be used in an HCCI engine. Fuel blends of these products may take advantage of the different combustion characteristics to extend the HCCI zone. Still, the range of this extension is difficult to estimate and the research of the optimal fuel blend composition will, therefore, remain the focus of future work.

Torque Observers Design for Spark Ignition Engines With Different Intake Air Measurement Sensors

Abstract: This paper presents a design approach and an experimental evaluation of torque observers for Spark Ignition (SI) engines. An engine model simplified from the generally used mean value model is proposed. Based on the developed model, torque observers are designed for engine systems with different intake air measurement sensors. The torque production model is introduced first to give a nominal value of torque estimation. Then, using the rotational dynamic equation of the crankshaft, an online adjusting term is added to modify the nominal estimation. The intake pressure, as an input of the torque production model, is directly measured if a pressure sensor is used. When an air mass flow sensor is adopted instead, an additional intake pressure observer is included in the torque observer. Simulation and experimental results are shown finally to demonstrate the proposed observers.