Spark Ignition Engine Research Articles

Skeletal CH3OH/NOx Kinetic Model for Simulating Spark-Ignition and Turbulent Jet Ignition Engines.

Methanol is a promising renewable fuel for achieving a better engine combustion efficiency and lower exhaust emissions. Under exhaust gas recirculation conditions, trace amounts of nitrogen oxides have been shown to participate in fuel oxidation and impact the ignition characteristics significantly. Despite numerous studies that analyzed the methanol/NOx interaction, no reliable skeletal kinetic mechanism is available for computational fluid dynamics (CFD) modeling. This work focuses on developing a skeletal CH3OH/NOx kinetic model consisting of 25 species and 55 irreversible and 27 reversible reactions, used for full-cycle engine combustion simulations. New experiments of methanol with the presence of 200 ppmv NO/NO2 were conducted in a rapid compression machine (RCM) at engine-relevant conditions (20-30 bar, 850-950 K). Experimental results indicate notable enhancement effects of the presence of NO/NO2 on methanol ignition under the conditions tested, which highlights the importance of including the CH3OH/NOx interactions in predicting combustion performance. The proposed skeletal mechanism was validated against the literature and new methanol and methanol/NOx experiments over a wide range of operating conditions. Furthermore, the skeletal mechanism was applied in three-dimensional (3D) CFD full-cycle simulations of spark-ignition (SI) and turbulent jet ignition (TJI) engine combustion using methanol. Simulation results demonstrate good agreement with experimental measurements of pressure traces and engine metrics, proving that the proposed skeletal mechanism is suitable and sufficient for CFD simulations.

Impact of Cylinder-to-Cylinder Dispersion of Exhaust Gas Recirculation on the Three-Way Catalyst Performance and Tailpipe Emissions of Spark-Ignition Engines

Abstract New generations of spark-ignition engines include exhaust gas recirculation (EGR) to improve the engine efficiency. Depending on the design of the EGR routing, some differences in the total amount of recirculated gases that reach each cylinder can be induced. This affects the air-to-fuel ratio on each cylinder due to the combination of the different temperature and composition of the gases at the intake valve closure. As a consequence, significant deviations in the combustion process and the subsequent composition upstream the three-way catalyst can be reached. This paper explores these effects on catalyst performance and tailpipe emissions, individualizing the behavior for each regulated species. The study was performed in a four-cylinder naturally aspirated engine with Atkinson cycle and a close-coupled three-way catalyst. The most significant deterioration in conversion efficiency appeared for the nitrogen oxides, directly linked to the EGR dispersion level. In the case of carbon monoxide (CO) emissions, no significant impact was observed except at high average EGR rates, where one or more of the cylinders exceeded the EGR tolerance for that speed and load. Based on these results, a strategy where the fuel injector command is adapted to correct the air-to-fuel ratio deviations induced by the EGR was developed and implemented.

Statistical analysis of flow field variations via independent component analysis

The link between in-cylinder flow and subsequent combustion in a single-cylinder gasoline spark-ignition engine is analyzed via independent component analysis (ICA). Experimentally, the two in-plane components of the velocity are measured in the central cylinder plane by high-speed particle image velocimetry (PIV) with the engine running slightly lean at 1500 rpm in skip-fired mode. In 213 cycles, measurements are made during the late compression stroke before ignition with approximately 1° crank-angle temporal resolution. ICA then decomposes the set of 213 flow fields at each time step, yielding a set of “source” flow patterns—the independent components (IC). The temporal coherence between the ICs is then examined in a persistence analysis, comparing each IC with the one from the previous time step starting at ignition timing and going backwards in time. The results show which ICs persist how long throughout the compression stroke. To investigate the link between the ICs and combustion, the crank angle at which 10% of the fuel are burned (CA10) in each cycle is correlated with the extent to which a given IC can be found in each flow field. The most persistent IC can be traced over more than half of the 70 degrees crank angle over which images were acquired. The IC that correlates best with CA10 visually more resembles some of the flow features found in conditional averaging of fast-burning versus slow-burning cycles.

In-cylinder spray evolution in a motored central-injection gasoline engine: Imaging and simulating the effects of flash-boiling and intake crossflow

Accurate predictions of fuel spray behavior and mixture formation in simulations of direct-injection spark-ignition (DISI) engines are fundamental to ensure proper description of all subsequent processes including ignition, combustion, and emissions. In this work, the spray evolution in a single-cylinder optical DISI engine was studied experimentally and numerically with the goal of enabling predictive computational fluid dynamics (CFD) modeling of in-cylinder sprays. The authors explored a wide range of operating conditions characterized by several fuel injection temperatures and engine speeds, using a well-characterized nine-component gasoline surrogate known as PACE-20. The effect of flash boiling and intake crossflow on the spray is discussed, with a focus on evaluating the ability of the spray models to capture highly transient spray behavior. In the experiments, the fuel temperature was varied between 20°C and 80°C, allowing for non-flash- to flash-boiling transition to emerge with enhanced flashing intensity at the highest temperatures. Spray collapse resulted in vapor-rich regions, owing to the locally lower inertia of the fluid. Varying the engine speed from 650 to 1950 rpm promoted increasingly more turbulent in-cylinder crossflow which interacted with the spray during the injection event and resulted in enhanced spray dispersion. The CFD model was able to capture the spray morphology transition at different fuel temperatures and engine speeds adequately. It is shown that the spray breakup model could capture the transitional spray behavior induced by flash boiling atomization and intake flow via proper initialization of the spray cone angle and calibration of the spray models’ constants.

A Complete Assessment of the Emission Performance of an SI Engine Fueled with Methanol, Methane and Hydrogen

This study explores the potentiality of low/zero carbon fuels such as methanol, methane and hydrogen for motor applications to pursue the goal of energy security and environmental sustainability. An experimental investigation was performed on a spark ignition engine equipped with both a port fuel and a direct injection system. Liquid fuels were injected into the intake manifold to benefit from a homogeneous charge formation. Gaseous fuels were injected in direct mode to enhance the efficiency and prevent abnormal combustion. Tests were realized at a fixed indicated mean effective pressure and at three different engine speeds. The experimental results highlighted the reduction of CO and CO2 emissions for the alternative fuels to an extent depending on their properties. Methanol exhibited high THC and low NOx emissions compared to gasoline. Methane and, even more so, hydrogen, allowed for a reduction in THC emissions. With regard to the impact of gaseous fuels on the NOx emissions, this was strongly related to the operating conditions. A surprising result concerns the particle emissions that were affected not only by the fuel characteristics and the engine test point but also by the lubricating oil. The oil contribution was particularly evident for hydrogen fuel, which showed high particle emissions, although they did not contain carbon atoms.

The Effect of Water Injection on a Naturally Aspirated Spark-Ignited Engine

Water injection (WI) is a well-known technique to mitigate knocking phenomena, reducing the in-cylinder gas temperature with a high heat of vaporization and specific heat of water. In this study, the effect of WI directly into the cylinder on fuel efficiency was investigated using a 2.0 L naturally aspirated (NA), four-cylinder, port fuel injection (PFI)-spark-ignited (SI) engine. Spray visualization of water injection by a commercial gasoline direct-injection (GDI) injector was performed to elucidate the water evaporation characteristics. In engine experiments, combustion characteristics were analyzed by adjusting the WI timing and amount. Synergistic effects with other gas dilution techniques, such as EGR and Lean burn, were also investigated. The spray image of WI showed poor evaporation of water compared to gasoline, even at high fuel temperatures. The optimal timing of WI was advanced up to the early intake stroke due to the harsh conditions of NA engines for water evaporation compared to turbocharged engines. With the combination of EGR, the optimal WI timing was advanced by the compression stroke, and further fuel efficiency improvement was achieved. In lean combustion, WI can improve both combustion stability and fuel efficiency.

Experimental Study of Isopropyl Acetate and Acetone Additive Gasoline on a Spark-Ignition Engine and its Impact on Green Environment

Background & Aim: Gasoline engines using alcohol fuels are being researched in the present trend since they are seen to be viable as diesel engines. The effect of isopropyl acetate and acetone additive blends on gasoline is explored in this study using a single-cylinder four-stroke gasoline engine operating at a constant speed of 2500 rpm under all loading conditions. Methods: Two gasoline blends are prepared by adding 5 % and 10 % by volume of isopropyl acetate and acetone separately. Properties are investigated and tested for its engine performance and emission. objective: There are not much research about the effect of Isopropyl acetate as a fuel additive in gasoline engine. Hence the main objective lies on extract information on using this additive in SI engine Results: The trial results demonstrated that the A5 (5% Acetone + 95% Gasoline) brake thermal efficiency improved when compared to pure gasoline. At maximum engine load, all additive blends have lower brake specific fuel consumption than pure gasoline. However, under full load, the emissions of various additive blends are lower than those of pure gasoline. Conclusión: Results revealed that IA5 (5 % Isopropyl acetate + 95 % Gasoline), IA10 (10 % Isopropyl acetate + 90 % Gasoline), and A10 (10 % Acetone + 90 % Gasoline) are considered good for decreasing HC, NOx, and CO emissions respectively. The findings of this study can be considered as a patent to lay the information on these types of alcohols in gasoline engines.

Piston geometry and stroke optimization for high efficiency propane spark ignition engines

Propane has unique properties and offers interesting characteristics for high-efficiency spark ignition engines. Its high volatility reduces or completely eliminates fuel-wall wetting and facilitates fuel air mixing. Furthermore, propane has a research octane number of 112 and a high octane sensitivity of 15. Finally, its laminar flame speed is on the same order as that of conventional gasoline, and it exhibits high dilution tolerance. Modern spark ignition internal combustion engines rely on fast combustion rates and high dilution to achieve high brake thermal efficiencies. To accomplish this, high stroke-to-bore ratios and high geometric compression ratios have been used in new engine designs. Therefore, propane’s relatively high laminar flame speeds, high knock resistance, and dilution tolerance make it an excellent candidate fuel for modern spark ignition engines. The objective of this work is to co-optimize the piston geometry and the engine stroke to maximize the efficiency of a spark-ignition engine fueled with propane. 3D computational fluid dynamics (CFD) simulations employing the extended coherent flamelet model were used to study the parametric effects of piston shape and stroke length. A piston geometry based on high performing pistons was parameterized using four controlling parameters. The piston geometry and engine stroke design space was explored using deterministic and quasi-random sampling techniques. A Gaussian process regression model was built using the simulation data to explain the results observed.

Effect of gasoline-ethanol blends on the performance of a four stroke engine using Ricardo Wave software

Purpose The purpose of this study is to assess the performance of fuel blends containing ethanol and gasoline in spark ignition engines. The aim is to explore alternative fuels that can enhance performance while minimizing or eliminating adverse environmental impacts, particularly in the context of limited fossil fuel availability and the need for sustainable alternatives. Design/methodology/approach The authors used the Ricardo Wave software to evaluate the performance of fuel blends with varying ethanol content (represented as E0, E10, E25, E40, E55, E70, E85 and E100) in comparison to gasoline. The assessment involved different composition percentages and was conducted at various engine speeds (1,500, 3,000, 4,500 and 6,000 rpm). This methodology aims to provide a comprehensive understanding of how different ethanol-gasoline blends perform under different conditions. Findings The study found that, across all fuel blends, the highest brake power (BP) and the highest brake-specific fuel consumption (BSFC) were observed at 6,000 rpm. Additionally, it was noted that the presence of ethanol in gasoline fuel blends has the potential to increase both the BP and BSFC. These findings suggest that ethanol can positively impact the performance of spark-ignition engines, highlighting its potential as an alternative fuel. Originality/value This research contributes to the ongoing efforts in the automotive industry to find sustainable alternative fuels. The use of Ricardo Wave software for performance assessment and the comprehensive exploration of various ethanol-gasoline blends at different engine speeds add to the originality of the study. The emphasis on the potential of ethanol to enhance engine performance provides valuable insights for motor vehicle manufacturers and researchers working on alternative fuel solutions.

Elucidating Optimal Exhaust Manifold Divergence and Temperature Distribution in Improving Low-End Engine Speed Performance

The exhaust manifold plays a crucial role in optimizing the performance of Spark-Ignition (SI) engines by effectively expelling combustion products. This study focuses on the optimization of the exhaust manifold design and temperature distribution in a 115-cc single-cylinder SI engine. The objective is to investigate the association between the design characteristics of the exhaust manifold, particularly its divergence, and the engine's performance in terms of brake power. Using computer-aided design (CAD), a three-dimensional model of the exhaust manifold with reduced diameter was developed. The optimized design aimed to enhance the engine's overall performance by achieving lower temperatures, particularly at low-end speeds. Subsequently, a 1D engine study was conducted to evaluate the performance of the engine with the optimized exhaust manifold design and validate the improved temperature distribution. The results demonstrate that the optimized exhaust manifold design leads to higher brake power while maintaining lower temperatures, especially at low-end speeds. This highlights the importance of exhaust manifold optimization and temperature distribution in maximizing the efficiency of the selected SI engine. To further enhance the engine's performance, future research should focus on identifying the most appropriate value for the exhaust manifold's divergence. This will contribute to the ongoing development of more efficient and high-performance SI engines. The findings of this study provide valuable insights into the optimization of exhaust manifold design and temperature distribution for improved engine performance in the context of the tested engine.

The impact of compression ratio on performance and exhaust emissions in a 100 cc spark ignition engine for green technology

The compression ratio has a significant role in vehicle performance. The arrangement of air entering and leaving the combustion chamber is determined by the design of the air inlet and outlet locations. The design of the combustion chamber is crucial to prevent backflow in the remaining combustion air. Backpressure is the emission of gases flowing back into the combustion chamber, causing non-stoichiometric combustion. The purpose of this research is to find the effect of compression ratio on performance and exhaust emissions of motorcycles, especially spark ignition engines. The research procedure begins with a standard piston modification process to get compression ratios of 9:1, 10:1, 11:1, and 12:1. In order to get uniform weight, pistons with low compression ratios will be equipped with holes at the bottom. Experimental data taken were; dynamometer, gas analyzer, and SFC. An increase in compression ratio causes an increase in vehicle performance in the form of torque and power. The air-fuel mixture is compressed to a smaller volume, leading to increased density. This increased density promotes better flame propagation and faster combustion. When the combustion process is faster and more efficient, there is less time for unburned hydrocarbons to be released into the exhaust gases.

Experimental and numerical study on a SI engine fueled with gasohol and dissociated methanol gas blends at lean conditions

Hydrogen-rich dissociated methanol gas (DMG) and ethanol are both promising alternative fuels for engines. The study investigates the performance of a spark ignition engine using various gasohol-DMG blends under lean conditions, aiming to evaluate the influence of fuel composition, excess air ratio, and operational parameters including engine load and speed. The results demonstrate that the introduction of DMG substantially enhances the engine's fuel economy, combustion efficiency, combustion stability, and the HC and CO emissions. The addition of ethanol has a distinct impact on engine performance, including increased peak cylinder pressure at lower DMG ratios and a subsequent decrease at higher DMG ratios. It also leads to substantial reductions in HC and NOx emissions but shows a non-linear effect on CO emissions with an increasing ethanol blending ratio. An increase in excess air ratio results in simultaneous reductions in peak cylinder pressure, HC, CO, and NOx emissions. Moreover, variations in engine load and speed respectively impact the cylinder's thermal environment and gas flow, consequently influencing combustion and emission characteristics.

Performance and Emission Characteristics of Spark Ignition Engine Operating with Biogas at Graded Purity

Performance and Emission Characteristics of Spark Ignition Engine Operating with Biogas at Graded Purity

Effects of intake manifold geometry in H2 & CNG fueled engine combustion

This study attempted to identify the effect of optimized intake manifold geometry on the behaviors and emission level of hydrogen compressed natural gas (H2CNG) fueled engine. For this purpose, a commercial Hyundai Sonata spark ignition engine (SIE) is modified to operate with CNG and hydrogen blend. The optimal intake pipe length was predicted using an analytical acoustic method. A new intake manifold is designed and implemented utilizing natural supercharging managed by over-pressure waves acoustic propagation. Several tests are conducted on the engine using the new manifold with a speed range from 1000 to 5000 rpm. Based on various engine speeds, the variation of brake torque (BT), in-cylinder pressure, NOx and CO emissions investigated by using gasoline, CNG and hydrogen CNG blend (HCNG) fueled engines via external mixtures. The first finding of the study is that the novel geometry improves the in-cylinder pressure by 10% at 3500 rpm. However, high engine speeds show a reduction of 14% in NOx and 40% in HC while speeds below 2000 rpm reduce CO by 40%. The second finding is that the new optimized geometry serves to get rid of both the auto-igni-tion and the backfire for high ratio of hydrogen in the blend.

Experimental study of spatial distribution of knock events in a turbocharged spark-ignition engine

An experimental investigation on the spatial distribution of knock events in a turbocharged spark-ignition engine for hybrid vehicle applications was conducted by using a multichannel fiber optic method. The knock positions were detected under different conditions to investigate the influence of crucial engine design and operating parameters on the knock characteristics including the spatial distribution in the combustion chamber and its relationship to knock intensity. The measured data reveal that the spatial distribution in the engine with a port fuel injection (PFI) system is mainly located on the exhaust side with insignificant influence of engine speed and load, which is attributed to the elevated thermal load around the exhaust valves. However, the knock events under gasoline direct-injection (DI) conditions were found to occur in more scattered locations with more occurring on the engine front-end and rear-end sides. These results indicate that the in-cylinder fuel-air mixing process may have a significant impact on the knock occurrence spots under DI conditions. The knock positions of the engine with different excessive air ratios, injection timings, and intake-valve timings were also detected, indicating that engine operating parameters have complex influences on the knock-region distribution in a DI engine. In addition, experiments were also carried out in two different cylinders to verify the cylinder-to-cylinder variations in knock regions which may be caused by the engine cooling design. Furthermore, no apparent correlations were observed between the knock position and the knock intensity by analysis of the experimental data.

Analysis of Performance Parameters of Engines with Spark Ignition with Variable Regulations of the Fuel-Injection System, Powered by E100 Fuel

Emission limits imposed on gas-powered vehicles, which have gradually been introduced by the European Commission, as well as the exhaustibility of the planet’s natural resources involve the need to search for alternative solutions and restore renewable fuel markets. In terms of ecology, using biofuels for powering spark-ignition engines has a positive impact on the natural environment. This kind of fuel, however, has a negative effect on the drive unit performance parameters, such as power and torque. This study presents test results of performance parameters of a spark-ignition engine fueled by E100 (pure ethanol). Parameters that have been analyzed are power, torque, exhaust emission components (oxygen, carbon dioxide, hydrocarbons), solid particles included in exhaust gases and emission of noise generated by the drive unit. The vehicle control system software adjustments have also been tested. Twelve regulations have been tested to evaluate performance parameters of a spark-ignition engine powered by E100 fuel. An analysis of the test results has confirmed the advisability of the introduction of control system software regulation. The aim of the work was to develop a model that will help select the appropriate software adjustment for an engine powered by E100 fuel. Due to the introduced emission restrictions, there is an important issue that concerns users of combustion vehicles. The research presented in the manuscript concerns a joint analysis of the engine’s fueling with alternative fuel and the introduction of changes to its software in order to reduce emissions.

Alcohol-diesel fuel blends and their effect in performance and exhaust emissions

The growing demand of fossil fuel and the rising of its price strengthen the incessant search for energy alternatives. The use of alcohol-diesel fuel blends in diesel engines has recently received interest as an alternative fuel for use in spark ignition (SI) engine. However, little research concerning diesel fuel has been found. Moreover, alcohols can improve the combustion phase due to an increase of the oxygen content and reduce exhaust emissions as soot and particulate matter, besides knock. The most used alcohols in blends with diesel fuel are methanol and ethanol, butanol added recently. In contrast, there are very few studies about propanol and pentanol blended with diesel fuel, although engine results are remarkable. Some of them could be even produced via biorefinery, thus being better to the environment than the petroleum-based fuels. Nevertheless, the main challenge is to overcome disadvantages of alcohols including low lubricity, difficulty of vaporization and high auto ignition temperature and definitely, their well-know immiscible problem with diesel fuel being required co-solvents or emulsifiers. Besides, these additives are used to enhance the properties of the fuel, like the increase of the cetane number or the production of a stable blend.

Effects of exhaust gas recirculation on nitrogen oxides, brake torque and efficiency in a hydrogen direct injection spark ignition engine

This study investigated the effects of exhaust gas recirculation (EGR) on emission and efficiency in a hydrogen direct injection spark ignition engine. EGR was supplied as the low-pressure (LP)-EGR system by controlling EGR valve from zero to 18.7% in terms of mass fraction. The result showed that EGR effect on nitrogen oxides (NOx) reduction became enlarged as higher engine speed due to increasing residual gas fraction. Also, under the same excessive air ratio (λ:2.2), EGR addition made NOx reduction from 89.9 to 98.7 % as varying engine speed. As NOx limit was low, the maximum brake torque was also reduced. However, by using appropriate EGR, NOx margin could be converted to increasing brake torque under the same NOx concentration level from 1.9% to 18.2% as varying engine speeds. From this result, to achieve the maximum output when reaching the turbocharger’s limit in a hydrogen engine and effectively reduce nitrogen oxide emissions, it is not only dependent on lean combustion but also effective to incorporate approximately 20% EGR into the operating strategy.

Characteristics and evolution of bioethanol from Manila Tamarind (Pithecellobium dulce) leaf through fermentation

<p>This study's two primary goals are to synthesize bioethanol from biowaste and examine its thermal characteristics. Bioethanol must first undergo a comprehensive assessment of its thermal characteristics in order to be approved for usage in spark-ignition engines. A multi-step procedure comprising extraction, pretreatment, enzymatic hydrolysis, and fermentation was used to manufacture the bioethanol. The raw material was put through a preliminary screening using thermogravimetric analysis to find the mass loss rate as a function of temperature before to starting this process. Remarkably, the Manila tamarind leaves exhibited the highest mass loss, up to 34%. Enzymatic cellulose conversion to fermentable sugars was a critical step in the production of cellulosic ethanol. Following hydrolysis, Saccharomyces cerevisiae was employed in the fermentation process, leading to the bioethanol synthesis phase. The Manila Tamarind leaves yielded the most, around 29% by weight, which is amazing. In order to assess the thermal properties of the extracted ethanol, a variety of parameters were carefully examined, including the viscosity, density, cetane number, and calorific value. In each of these areas, mixtures of tire oil, gasoline, and bioethanol consistently outperformed the others. Furthermore, Fourier Transform Infrared Spectrometry spectra were utilized to validate the concentrations of potential groups, including alcohol, aromatic, alkyne, amide, and carbonyl groups. Clear objectives guide the fermentation process, aiming for consistent quality, safety, and functionality in the end product.</p>

An experimental investigation on the lean-burn characteristics of a novel hydrogen fueled spark ignition engine: Hydrogen injection via a micro-hole on the spark plug

Hydrogen addition in SI engines has been a subject of extensive research over the years, primarily owing to its environmentally friendly attributes and its potential to optimize combustion, especially in lean-burn conditions. However, the use of hydrogen as a gaseous fuel presents challenges due to its high mass-to-volume ratio, which can substantially reduce engine power density, whether in direct injection (DI) or port injection PI conditions. Thus, how to maximum hydrogen's benefits on combustion while minimizing its consumption has become a topic worthy to be studied. In this research, a novel concept where hydrogen direct injected through an aperture on edge of the spark plug (SHDI) was proposed and experimentally investigated on a 1.5 L turbocharged gasoline direct injection (GDI) engine under lean-burn condition. Experiments were conducted at 1600 rpm and medium load conditions with hydrogen injection ratios φH2 varying from 0 % to 5.5 % and excess air coefficients (λ) up to 1.5. Hydrogen port injection (HPI) strategy was also employed as a reference to gauge the performance enhancement achieved through SHDI. The experimental results reveal that, in comparison to HPI, SHDI exhibited more pronounced effects in enhancing initial flame propagation and assisting to formation of stable flame nucleus which, in turn, extended the lean-burn limit substantially. Moreover, SHDI strategy also resulted in a more substantial improvement in mean effective pressure (IMEP) and brake thermal efficiency (BTE) compared to the HPI. However, emissions of NOX, HC and CO were higher in the SHDI mode as opposed to the HPI mode This disparity may be attributed to the elevated local temperatures in the vicinity of the spark plug and the interference caused by the hydrogen jet flow, which disrupted the in-cylinder flow pattern, consequently leading to increased levels of unburnt mixture.