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The paper presents novel studies on the impact of different ignition control parameters on combustion stability and spark plug wear. First, experimental results from a 32.4-liter biogas fueled large bore single cylinder spark ignition engine are discussed. Two different ignition systems were considered in the experiment: a DC inductive and an AC capacitive. The spark plugs used in the experiment were of dual-iridium standard J-gap design of different electrode gaps. Test results show the importance of different degrees of freedom to control a spark. A robust ignition is found to be achieved by using a very short spark duration, which in turn reduces total energy discharge at the gap. Further observations reveal that once a stable and self-propagating flame kernel is developed, it becomes independent of the spark energy further added to the gap. Finally, results from the spark plug wear tests using a pressurized rig chamber are discussed.

Recently, global warming and energy security have received significant attention. Thus an improvement of the vehicle fuel economy is strongly required. For engines, one effective way is to improve the engine thermal efficiency. Raising compression ratio [1] or turbo charging technologies have potential to achieve high thermal efficiency. However knock does not allow the high thermal efficiency. Knock depends on the fuel composition and the pressure and temperature history of unburnt end-gas [2-3]. For fuels, RON is well known for describing the anti knock quality. High RON fuels have high anti knock quality and result in higher thermal efficiency. This paper investigates the impact of high RON fuels on the thermal efficiency by using high compression ratio engine, turbo charged engine, and lean boosted engine [4]. Finally, it is shown that the high thermal efficiency can be approached with high RON gasoline and ethanol.

Methylcyclopentadienyl manganese tricarbonyl (MMT) is used as an octane-enhancing metallic additive for unleaded gasoline which can prevent engine knock by proactive reaction with the hydrocarbon free radicals before starting the auto-ignition of hydrocarbons. However it has been pointed out that MMT causes automotive catalysts clogging and spark plug severely fouling. Therefore, many countries have fuel standards that prohibit or limit the usage of MMT. Nevertheless, some countries still use MMT as there are no restrictions imposed by fuel standards. As mentioned in several papers, metallic additives of engine oil such as calcium cause an abnormal combustion phenomenon called low-speed pre-ignition (LSPI) in turbocharged spark ignition engines. In contrast, the effect of metallic additives of gasoline such as MMT on LSPI has not been studied.

Since ethanol is a renewable source of energy and it contributes to lower CO2 emissions, ethanol produced from biomass is expected to increase in use as an alternative fuel. It is recognized that for spark ignition (SI) engines ethanol has advantages of high octane number and high combustion speed and has a disadvantage of difficult startability at low temperature. This paper investigates the influence of ethanol fuel on SI engine performance, thermal efficiency, and emissions. The combustion characteristics under cold engine conditions are also examined. Ethanol has high anti-knock quality due to its high octane number, and high latent heat of evaporation, which decreases the compressed gas temperature during the compression stroke. In addition to the effect of latent heat of evaporation, the difference of combustion products compared with gasoline further decreases combustion temperature, thereby reducing cooling heat loss.

Alternative fuels have been proposed as a means for future energy-secure and environmentally sustainable transportation. This review and benchmarking show that several of the alternative fuels (e.g. methanol, ethanol, higher alcohols, RME, HVO, DME, and biogas/CNG) work well with several different engine concepts such as conventional SI, DICI, and dual fuel, and with the emerging concepts HCCI, RCCI, and PPC. Energy consumption is in most cases similar to that of diesel or gasoline, with the exception of methanol and ethanol that use less energy, especially in SI engines. Tailpipe emissions of CO2 with respect to engine work output (tank-to-output shaft) can be reduced by more than 15% compared to a highly efficient gasoline SI engine, and are the lowest with CNG / lean-burn SI and with alcohols in several engine concepts. Alternative fuels are considered safe and in most cases are associated with reduced risk with respect to cancer and other health and environmental issues.

An index to relate fuel properties to HCCI auto-ignition would be valuable to predict the performance of fuels in HCCI engines from their properties and composition. The indices for SI engines, the Research Octane Number (RON) and Motor Octane Number (MON) are known to be insufficient to explain the behavior of oxygenated fuels in an HCCI engine. One way to characterize a fuel is to use the Auto-Ignition Temperature (AIT). The AIT can be extracted from the pressure trace. Another potentially interesting parameter is the amount of Low Temperature Heat Release (LTHR) that is closely connected to the ignition properties of the fuel. A systematic study of fuels consisting of gasoline surrogate components of n-heptane, iso-octane, toluene, and ethanol was made. 21 fuels were prepared with RON values ranging from 67 to 97.

Methanol is not a fuel typically used in compression ignition engines due to the high resistance to auto-ignition. However, conventional diesel combustion and PPC offer high engine efficiency along with low HC and CO emissions, albeit with the trade-off of increased NOx and PM emissions. This trade-off balance is mitigated in the case of methanol and other alcohol fuels, as they bring oxygen in the combustion chamber. Thus methanol compression ignition holds the potential for a clean and effective alternative fuel proposition. Most existing research on methanol is on SI engines and very little exists in the literature regarding methanol auto-ignition engine concepts. In this study, the spray characteristics of methanol inside the optically accessible cylinder of a DI-HD engine are investigated. The liquid penetration length at various injection timings is documented, ranging from typical PPC range down to conventional diesel combustion.

In making our products more attractive, it is becoming increasingly important to balance multiple areas of performance, such as fuel economy, emissions and drivability. Customer expectations and government legislations, to protect global environment, strongly increase the work complexity of auto firms in order to release high quality and eco-friendly vehicles. The balancing between several target is becoming a key factor in the car design: respect current (and anticipate future) emission limits optimization of fuel consumption insure high level of drivability maintain acceptable(or increase) performances sustain acceptable cost, reliability, etc. From recent emissions limitations, engine cold start (at the beginning of driving cycle) plays a major role in the total amount of pollutants. Especially, achievements of HC limitations are a big challenge for vehicles with a conventional spark ignition engine.

Low temperature combustion (LTC), is a promising alternative for combustion engines, because it combines the positive aspects of both CI and SI engines, high efficiency and low emissions. Another positive aspect of LTC is that it can operate with gasoline of different octane ratings. Still, higher octane gasolines prove to be difficult to operate at low load conditions leading to high combustion instability (COV) that leads also to high emissions. This drawback can be reduced by increasing the intake air temperature or increasing compression ratio, but it is not a viable strategy in conventional applications. For a diesel engine running under LTC conditions, a possibility is to use the existing hardware, glow plugs in this case, to increase the in-cylinder temperature at low loads and facilitate an improved combustion event.

From the energy security and CO2 discharge reduction point of view, much attention has been paid to the usage of biofuel, ethanol, as an alternative source of energy in the transportation industry. Yet, the major drawback in applying highly concentrated ethanol in the spark ignited internal combustion engines is cold start instability. This is due to the characteristics of ethanol, large latent heat required to vaporize. This paper investigates necessary conditions for the engine cold start, using highly concentrated ethanol. Tests performed with varieties of ethanol fuel, a relationship between cold startability lower temperature limit and reid vapor pressure was observed. A method to boost the vaporization, intake valve timing control is introduced to obtain high compression peak temperature.

Nitric Oxide (NO) can significantly influence the autoignition reactivity and this can affect knock limits in conventional stoichiometric SI engines. Previous studies also revealed that the role of NO changes with fuel type. Fuels with high RON (Research Octane Number) and high Octane Sensitivity (S = RON - MON (Motor Octane Number)) exhibited monotonically retarding knock-limited combustion phasing (KL-CA50) with increasing NO. In contrast, for a high-RON, low-S fuel, the addition of NO initially resulted in a strongly retarded KL-CA50 but beyond the certain amount of NO, KL-CA50 advanced again. The current study focuses on same high-RON, low-S Alkylate fuel to better understand the mechanisms responsible for the reversal in the effect of NO on KL-CA50 beyond a certain amount of NO.

Increasingly stringent pollutant and CO2 emission standards require the car manufacturers to investigate innovative solutions to further improve the fuel economy and environmental impact of their fleets. Nowadays, NOx emissions standards are stringent for spark-ignition (SI) internal combustion engines (ICEs) and many techniques are investigated to limit these emissions. Among these, an extremely lean combustion has a large potential to simultaneously reduce the NOx raw emissions and the fuel consumption of SI ICEs. Engines with pre-chamber ignition system are promising solutions for realizing a high air-fuel ratio which is both ignitable and with an adequate combustion speed. In this work, the combustion characteristics of an active pre-chamber system are experimentally investigated using a single-cylinder research engine. The engine under exam is a large bore heavy-duty unit with an active pre-chamber fuelled with compressed natural gas.

Alternative fuels, such as natural and bio-gas, are attractive options for reducing greenhouse gas emissions from combustion engines. However, the naturally occurring variation in gas composition poses a challenge and may significantly impact engine performance. The gas composition affects fundamental fuel properties such as flame propagation speed and heat release rate. Deviations from the gas composition for which the engine was calibrated result in changes in the combustion phase, reducing engine efficiency and increasing fuel consumption and emissions. However, the efficiency loss can be limited by estimating the combustion phase and adapting the spark timing, which could be implemented favorably using a closed-loop control approach. In this paper, we evaluate the efficiency loss resulting from varying gas compositions and the benefits of using a closed-loop controller to adapt the spark timing to retain the nominal combustion phase.

The use of compressed natural gas (CNG) in light duty applications is still restricted to conventional spark ignition engines operating at low compression ratio, so overall efficiency is limited. A combustion concept that has been successfully applied on large stationary engines and to some extent on heavy-duty engines is dual-fuel combustion, where a compression-ignited diesel pilot injection is used to ignite a homogeneous charge of methane gas and air. CNG is injected in the intake ports during the intake stroke and later in the cycle the premixed air-CNG mixture is ignited via a pilot diesel injection close to top dead center. However, this concept has not been applied to a significant extent on light duty engines yet. The main reasons are linked to high temperature methane oxidation requirements and poor combustion efficiency at diluted conditions at low loads.

Ethanol blending is one method that can be used to reduce knock in spark ignition engines by decreasing the autoignition reactivity of the fuel and modifying its laminar flame speed. In this paper, the effects of ethanol blending on knock propensity and flame speed of petroleum and low-carbon gasoline fuels is analyzed. To do so, surrogate fuels were formulated for methanol-to-gasoline (MTG) and ethanol-to-gasoline (ETG) based on the fuels’ composition, octane number, and select physical properties; and 0-D and 1-D chemical kinetics simulations were performed to investigate reactivity and laminar flame speed, respectively. Results of MTG and ETG were compared against those of PACE-20, a well-characterized surrogate for regular E10 gasoline. Similarly to PACE-20, blending MTG and ETG with ethanol increases the fuel’s research octane number (RON) and sensitivity.

Occurrence of knock in spark ignition (SI) engines is usually suppressed by inhibiting auto-ignition of the fuel-air mixture. A steep increase in pressure by auto-ignition of the local mixture is thought to initiate the pressure oscillation, which results in knock. Therefore, in order to prevent knock, the strength of the pressure oscillation would be decreased by reducing the local heat release of the end gas. In this study, the oxidation reaction rate of the auto-ignition was attempted to be reduced by dilution of the mixture. The effect of mixture dilution on the strength of pressure oscillation, that is knock intensity, was examined using a rapid compression machine (RCM) and a single cylinder SI engine. The test result of compression ignition of homogeneous mixture using RCM showed that increase in dilution ratio could decrease the knock intensity even if the input heat increased and the auto-ignition timing advanced.

To meet the requirements for lower fuel consumption and emissions as well as higher performances, a “Variable Valve Timing - intelligent by Electric motor (VVT-iE)” system has been newly developed. The system has been firstly adopted to the intake valve train of the Toyota's new 4.6 and 5.0 litter V8 SI engine series. The VVT-iE is composed of a cam phasing mechanism connected to the intake camshaft and brushless motor integrated with its intelligent driver. The motor-actuated system is completely free from operating limitation caused from hydraulic conditions. This enjoys an advantage for reducing cold HC. The system also presents further reduction in fuel consumption.

High EGR rates combined with turbocharging has been identified as a promising way to increase the maximum load and efficiency of heavy duty spark ignition engines. With stoichiometric conditions a three way catalyst can be used which means that regulated emissions can be kept at very low levels. Obtaining reliable spark ignition is difficult however with high pressure and dilution. There will be a limit to the amount of EGR that can be tolerated for each operating point. Open loop operation based on steady state maps is difficult since there is substantial dynamics both from the turbocharger and from the wall heat interaction. The proposed approach applies standard closed loop lambda control for controlling the overall air/fuel ratio for a heavy duty 6-cylinder port injected natural gas engine. A closed loop load control is also applied for keeping the load at a constant level when using EGR.

High EGR rates combined with turbocharging has been identified as a promising way to increase the maximum load and efficiency of heavy duty spark ignition engines. With stoichiometric conditions a three way catalyst can be used which means that regulated emissions can be kept at very low levels. Obtaining reliable spark ignition is difficult however with high pressure and dilution. There will be a limit to the amount of EGR that can be tolerated for each operating point. Open loop operation based on steady state maps is difficult since there is substantial dynamics both from the turbocharger and from the wall heat interaction. The proposed approach applies standard closed loop lambda control for controlling the overall air/fuel ratio. Furthermore, ion-current based dilution limit control is applied on the EGR in order to maximize EGR rate as long as combustion stability is preserved.

A commercially available fuel, E85, a blend of ~85% ethanol and ~15% gasoline, can be a viable substitute for fossil fuels in internal combustion engines in order to achieve a reduction of the greenhouse gas (GHG) emissions. Ethanol is traditionally made of biomass, which makes it a part of the food-feed-fuel competition. New processes that reuse waste products from other industries have recently been developed, making ethanol a renewable and sustainable second-generation fuel. So far, work on E85 has focused on spark ignition (SI) concepts due to high octane rating of this fuel. There is very little research on its application in CI engines. Alcohols are known for low soot particle emissions, which gives them an advantage in the NOx-soot trade-off of the compression ignition (CI) concept.