SI Engine Research Articles

Improvement of combustion and emission by combined combustion of ethanol premix and gasoline direct injection in SI engine

In this paper, a test platform for ethanol port injection plus gasoline direct injection was built to explore the effects of different ethanol-gasoline ratios (Re), direct injection timing (DIT) and ignition timing (IT) on the combustion and emissions of a SI engine. Results clearly show that when the total fuel contains more ethanol, the ignition timing corresponding to the maximum torque is smaller than the ignition timing when the total fuel contains more gasoline. Compared with the sole ethanol port injection (EPI) mode and gasoline direct injection (GDI) mode, G25 with EPI + GDI is the best mode for high-efficiency combustion and G25 with IT = 20°CA BTDC and DIT = 120°CA BTDC can be regarded as the optimal operating condition for highest torque output, braking thermal efficiency and lowest BSFC. As for exhaust emissions, CO and HC reach the lowest at G25 while NOx has an opposite trend. Delayed ignition within the range of 10-30°CA BTDC reduces HC and NOx emissions. As for particle number emissions, the size of peak particle number gradually decreases from G100 to G0, the accumulation particle number (APN) is further oxidized and shows a significant downward trend with the increase of ethanol. The lowest TPN was obtained at G25 in which the TPN has dropped by 9% and 85% respectively compared with sole EPI and GDI mode. When Re ≥ 50%, the nucleation mode particle number (NPN) in the total particle distribution is higher than the accumulation mode particle number, while there is an opposite result when Re＜50%. Overall, the findings of this paper make contributions to the development of high-efficiency and low-pollution combined engines and further promote the application of clean alternative fuels.

Effect of ethanol-gasoline blends on SI engine performance and emissions

Negative effects of using traditional engine fuels on climate change and global warning have produced a scenario of high competition to find an alternative fuel more friendly and unharmful to the environment. Alcohol fuel was found very practical to be mixed with engine designed fuel. In the present work, ethanol was mixed with gasoline in different proportions (10% ethanol + 90% gasoline, 20% ethanol + 80% gasoline, 30% ethanol +70% gasoline, 40% ethanol + 60% gasoline) by utilizing ultrasonic bath to ensure perfect mixing which in turn will increase the fuel energy content.A one-cylinder, four-stroke and spark ignition engine was used to study and analyze the effect of ethanol's/gasoline blend on power, efficiency and exhaust gases. Results showed that power, brake specific fuel consumption and thermal efficiency are improved with the increase of ethanol concentration. On the other hand, ethanol was found to have negative effect on volumetric efficiency.Furthermore, adding ethanol reduce harmful exhaust gasses. It is found that more ethanol is an accompanied with less exhaust gasses. Finally, research octane number and motor octane number are found to be much with ethanol blends. Although lower heating value was found to be higher for pure gasoline, it's found that all other parameters are enhanced with adding ethanol to the engine fuel.

The effect of sweet orange peel addition into premium gasoline on fuel consumption and flue gas emissions

This study offered an investigation as to how the use of sweet orange peel oil as an additive for premium gasoline can increase octane performance which influence combustion. Sweet orange peel oil-acting as a RON booster-contains monoterpene compounds and oxygenated hydrocarbons which can improve the quality of combustion. The study also aimed to analyze the combustion characteristics of premium gasoline mixture affected by sweet orange peel additives on SI engines. This study carried out tests on an engine fuel consumption and HC emissions. The cyclic rings and methyl groups of monoterpene compounds in sweet orange peel additives contribute to the increase of electronegativity of additives, therefore being able to interfere with the premium gasoline’s compounds which are dominated by aromatics hydrocarbons. It has an impact on the branches of single-bond molecules series of premium gasoline. This makes the premium gasoline cannot be ignited at low temperatures, which results in perfect combustion. In addition, the polarity of triacetin and eugenol, which includes oxygenated hydrocarbons, is able to reduce CO as the avoided gas in combustion. Sweet orange peel additives—processed by maceration extraction method—are added to premium gasoline. There are 3 ratios of additives in this study; orange peel essential oil extracted with a concentration ratio of dried orange peels simplicial to n-hexane (v / v) of 1% (EO A); 0.75% (EO B); and 0.6% (EO C). To determine the effect of the additive, exhaust gas emission testing and fuel consumption measurement were carried out on the 2013 Honda Absolute Revo motorcycle 4-step, SOHC, 1 cylinder, 109.17 cc engine. The exhaust gas, i.e. CO, HC, CO2, and O2 were analyzed using a Stargas-898-type gas analyzer. Furthermore, fuel consumption measurement was carried out at 3500 rpm engine speed. The results show that CO could be reduced by 37.7%, while the remaining O2 was reduced by 17%. The addition of sweet orange peel additives could increase CO2 levels in exhaust gases when compared to premium gasoline combustion without additives. However, the premium gasoline with additive A (EO A) blend tends to produce higher hydrocarbon emissions compared to other types of premium additive proportions. In conclusion, adding sweet orange peel additives to premium gasoline can reduce fuel consumption by 3.3%; 3.2%; and 3.4% for each blend, respectively.

The impact of using pure ethanol additives on gasoline fuel with respect to SI engine emissions

A major problem in the gasoline engine operation process under heavy-duty conditions is the knocking phenomenon, noises produced in the combustion chamber during the combustion procedure as a consequence of the pre-ignition process. These occur effect of the high temperature of the air, which causes fuel to ignite without additional activation energy (spark). The octane number for gasoline fuel measures the resistance of the fuel to such auto-ignition. Experimental work was done in this study to study the influence of adding pure ethanol to conventional Iraqi gasoline fuel at percentages varying from 10% to 90% in 10% increments by volume, with various fuel properties like density, octane number, viscosity, fuel vapour pressure, and flash point temperature, measured and compared. Ethanol additives were found to increase fuel density, flash point temperature, viscosity, and octane number while reducing fuel vapour pressure. The engine utilised in the trials was a single-cylinder, gasoline engine, naturally aspirated and air-cooled. The experimental outcomes for specific fuel consumption showed decreases of up to 29% at the 90% volumetric percentage of ethanol in conventional gasoline fuel, and emissions of engine NOX, CO, and HC decreased by 67. 7%, 69%, and 61%, respectively, However, CO2 emissions increased.

Performance and Emission Characteristics of SI Engine with Standard and Modified Piston with Turmeric Leaf Oil as Biofuel

Turmeric leaves are waste products after removing turmeric rhizome. In the present work, the oil was extracted from the leaves of curcuma longa by hydro distillation method. The extracted oil was studied for preliminary physicochemical and phytochemical tests. The phytochemical evaluation of the turmeric leaf oil indicates the presence of terpenes which was used to run two stroke and four stroke engines. Engine emits less harmful product with turmeric oil as compared to petrol. Hence, it has been concluded that the turmeric leaf oil can be used as an alternative biofuel for petrol. Theoretically, turmeric leaf oil properties are similar to that of petrol. By performing practical experiments on this oil using different types of piston head shapes and varying parameters, we came to know that this will fulfil all capabilities as a biofuel in IC engines. In the second part, the characteristics fuel properties of turmeric leaf oil and their blends with petrol in the proportion of 40:60 (B40) have been studied. In the third part, engine tests have been conducted on turmeric leaf oil blends with petrol oil and brake thermal efficiency, engine gas temperature and air fuel ratio were evaluated. The next part consists of exhaust emission tests such as CO and HC emission measurement with a five gas analyser.

The effects of photocatalytic activity with titanium dioxide on the performance and emission characteristics of SI engine

This study aimed to improve the properties of gasoline fuel with the help of the photocatalysis method. Accordingly, a 100 ml volume photocapsule was designed and manufactured. UV radiation was applied on gasoline in the photocapsule. If no reductor is used, no change can be obtained. When water was mixed with the fuel, the changes were below the experimental error. However, in the case of ethanol mixing there have been significant improvements in terms of combustion. Distillation test and FTIR analysis were applied to the fuel samples. As a result of FTIR analysis, it was determined that the alcohol content increased and the fuel storage life was extended. The experiments were carried out for constant throttle opening as 4 speed in the range of 1200–1800 rpm (200 rpm increments) for performance and emissions of the engine. As a result of photocatalysis; unification, conversion to alkane, ether, and alcohol groups were determined. Photocatalysis reduces the emissions of HC and CO by a ratio of 6.68% and 20.5% on average and increases the emissions of CO2 emissions and NOX by a ratio of 19.9% and 34.8% respectively. On the other hand, this method reduces BSFC by a ratio of 9% and increases BTE by a ratio of 10% on average.This research proves that photocatalysis can be used with an improving effect on hydrocarbon mixtures.

Modelling the performance and emissions of ethanol–gasoline blend on a gasoline engine using ANFIS

ABSTRACT This research investigates the importance of the adaptive neuro-fuzzy inference method (ANFIS) to model the gasoline engine's performance and exhaust emissions using various fuels. To collect data for the creation of the planned ANFIS model, an experiment was performed on a SI engine using gasoline-ethanol blends at varying engine loads. The ANFIS model was designed to provide an association between all parameters using specific gasoline-ethanol blends and different engine loads. Then, using experimental data, engine performance parameters, and emissions were forecasted by the ANFIS model. The model findings were then contrasted with experimental values to determine the accuracy of the ANFIS predictions. The maximum correlation coefficient (R) of 0.9900–0.9999 and 95.3594% accuracy for both performance and exhaust emissions values were generated by the ANFIS model. The Mean relative errors (MRE) ranged from 0.055 to 8.396% whereas the root mean square errors (RMSE) values were small. The findings confirmed that the ANFIS is competent enough to forecast the performance and emissions of gasoline engines very efficiently.

Beta distribution-based knock probability map learning and spark timing control for SI engines

In gasoline engines, the spark timing is often advanced to increase fuel economy under certain heavy load engine operating conditions. As a compromise between the risk of knock and the power output, spark timing is regulated at the boundary where a low knock probability is tolerated. Due to the stochasticity of binary knock events, it is necessary to have a large number of engine cycles for probability estimations, which can slow down the response speed of a controller to operating condition changes. To speed up the spark timing regulation and to reduce the spark timing variance, in this article, a knock probability feedforward map learning method and a spark timing control method are proposed under a unified framework. A learning method that applies the beta distribution is the key contribution of this work. The beta distribution in the map learning part is used to describe knock probabilities with uncertainties and to determine the next engine operating condition for sampling and map learning. In the spark timing method, the beta distribution is applied in the conventional control method to adjust the control gains. The proposed methods are experimentally validated on a test bench equipped with a production Toyota 1.8 L, 4-cylinder SI engine.

Thermodynamic and experimental analysis of turbocharger for a downsized LPG fuelled automotive SI engine

There has been extensive research on efficient energy conversion systems which also includes turbocharging the automotive SI engine. This research focuses on comparing the thermodynamic aspects of the turbine at different boost pressures at maximum engine torque and speed regions. A naturally aspirated CNG SI engine developing 15.5 kW at 3400 rpm was converted to a turbocharged LPG engine at the compression ratio of 8.5:1. The turbine performance was evaluated using ANSYS CFX numerical simulation tool and results were validated. The simulation study reveals that 1.3 bar boost pressure has a higher enthalpy generation and also has minimal Mach number than 1.5 bar signifying the effects of exhaust blowdown. Further, the experimental study was carried out at different boost pressures. The results show that at 1.3 bar, the turbine efficiency was higher with reduced heat transfer rate to the compressor which was due to reduced friction work compared to 1.5 bar which altogether improved the engine performance. This is also evident from the minimal COV of IMEP for 1.3 bar. On the whole, the turbine exhibited better performance for 1.3 bar and resulted in reduced thermal loading.

End-Gas Autoignition Mechanism in a Downsized Spark-Ignition Engine: Effect of Inhomogeneity

ABSTRACT It is generally accepted that knock in spark-ignition engines is caused by end-gas autoignition. However, limited studies regarding to the effect of the inhomogeneity of temperature and composition on end-gas autoignition are presented. The major objective of this paper is to quantitatively understand the flame propagation velocity and the end-gas autoignition mechanism affected by the reactivity gradient formed by thermal stratification and composition stratification in the combustion chamber of a downsized SI engine. The conclusions were obtained based on a knock combustion case under an initial condition of high temperature and high pressure. In the present work, fuel stratification has a significant influence on the propagation velocity of the main flame. The flame propagation velocity declined with an increase in the level of fuel stratification. However, the temperature stratification had little effect on the flame propagation velocity. It was found that the onset of autoignition advanced with increasing the level of temperature stratification, which demonstrated an approximately linear relationship. It can be found that a high level of fuel stratification induced deflagration because of multi-spot spontaneous combustion. On the contrary, a very intense knock with detonation wave was observed under a slight level of temperature stratification. Under this condition, the temperature gradient near the nascent AI kernel was small and contributed to sequential spontaneous combustion. In fact, both the fuel stratification and temperature stratification are essentially the reactivity stratification. Therefore, similar results also can be conducted from fuel stratification. This work will give a new insight into suppressing knock mechanisms by different strategies.

Evaluation of a novel strategy, based in Coolant Flow Rate Control, for avoiding Knock in a SI engine

An experimental study is carried out for investigating the possibility to limit knock occurrence on a SI engine by proper engine thermal management. The control of the wall temperature is realized by means of an electrically driven water pump. The coolant flow rate can be varied regardless of the engine speed. Preliminarily, an experimental campaign aimed at evaluating the effects of the coolant flow rate on the in-cylinder pressure fluctuations, under steady state engine operation, namely WOT@1500 rpm, is presented. In the experiments, the spark advance and the equivalence ratio are controlled by the ECU according to the production engine map and the coolant flow rate is varied from 1500 up to 4500 dm3/h. In a subsequent set of tests, a variation on spark advance is operated and, for each value of the spark advance, different coolant flow rates are enforced with the aim of evaluating the possibility to increase the spark advance as close as possible to the maximum brake torque condition and of mitigating knock occurrence with increased coolant flow rates. The benefits in terms of fuel economy and increase engine performance, in comparison to the traditional approaches for knock mitigation, are evaluated.

Application of ANN to predict performance and emissions of SI engine using gasoline-methanol blends.

The deployment of methanol like alternative fuels in engines is a necessity of the present time to comprehend power requirements and environmental pollution. Furthermore, a comprehensive prediction of the impact of the methanol-gasoline blend on engine characteristics is also required in the era of artificial intelligence. The current study analyzes and compares the experimental and Artificial Neural Network (ANN) aided performance and emissions of four-stroke, single-cylinder SI engine using methanol-gasoline blends of 0%, 3%, 6%, 9%, 12%, 15%, and 18%. The experiments were performed at engine speeds of 1300-3700 rpm with constant loads of 20 and 40 psi for seven different fractions of fuels. Further, an ANN model has developed setting fuel blends, speed and load as inputs, and exhaust emissions and performance parameters as the target. The dataset was randomly divided into three groups of training (70%), validation (15%), and testing (15%) using MATLAB. The feedforward algorithm was used with tangent sigmoid transfer active function (tansig) and gradient descent with an adaptive learning method. It was observed that the continuous addition of methanol up to 12% (M12) increased the performance of the engine. However, a reduction in emissions was observed except for NOx emissions. The regression correlation coefficient (R) and the mean relative error (MRE) were in the range of 0.99100-0.99832 and 1.2%-2.4% respectively, while the values of root mean square error were extremely small. The findings depicted that M12 performed better than other fractions. ANN approach was found suitable for accurately predicting the performance and exhaust emissions of small-scaled SI engines.

Comparison of performance and combustion analysis of a VCR SI engine using audio transducers

The world today mostly relies on four-stroke gas engines as its primary mover for automotive applications and specifically prefers gasoline engine as it provides more comfort, ease of starting. Some of the most common combustion parameters responsible for the loss of efficiency in an SI engine is Knock, fluctuations load, misfiring, cycle by cycle fluctuations etc. In this experiment, an effort has been made to sense engine combustion with help of audio technology, microphone sensor, and a few android software combined together to capture the fine the behaviour of engine combustion with petrol fuel. Earlier researchers have made the same efforts using engine pressure sensors located inside the engine cylinder head which is also an effective method to sense pressure variations however complicated in practical engines and a poor lifetime of sensors.In this work an SI engine is retrofit in order to increase its compression ratio by modifying the engine head & gasket. The retrofitting is done in such a way that the highest compression ratio induces a forced knock in the cylinder. The performance parameters of this VCR engine have been studied for five different loadings both with petrol as the fuel and combustion analysis has been done by using audio technology. For identifying and measurement of knock, a novel arrangement using Audio transducers were made and fixed on the engine cylinder, many different audio transducers were experimented such as round piezo, straight piezo and the electret of which the electret condenser-based condenser showed better performance. The signals are modified & interpreted by the intermediate software’s which have been analysed for various compression ratios, it was found that the Audio technology can efficiently pick up engine sounds which can be processed by interfaces for identification of Knock.

CFD-guided development of a pre-chamber ignition system for internal combustion engines

In the present paper, the development of a non-fuelled pre-chamber ignition system is introduced. 3D combustion CFD has been employed to guide the design change. Based on the combustion performance of different pre-chamber designs, one design (B4) is identified as the best one among several designs. Design B4 is selected for detailed evaluations. The results of Design B4 are compared with the baseline SI engine. The fuel economy has been improved by using the pre-chamber ignition system. However, NOx emission is higher than the baseline engine, due to higher in-cylinder pressure and temperature. The combustion process in the pre-chamber is separated into three steps characterised with its heat release, temperature and pressure. Based on the pressure difference between the main chamber and pre-chamber, a four-stage mechanism is proposed to describe the gas exchange between them.

Feasibility Study on Model Predictive Control for an EGR-Air Path System in a Turbocharged SI Engine

Abstract The purpose of this study is to develop model predictive control (MPC), which addresses MIMO system optimization control problem under constrains while providing efficient engine calibration process, and to be applied to an intake system control in a turbocharged spark ignition engine. Extended Kalman filter, which was based on an air flow sensor and a pressure sensor, was employed to achieve robustness against actual variations and MPC plant model reduction. The control methodology was demonstrated in MILS through its application to torque and EGR cooperative control using throttle and EGR valves. The results show the control outputs are in good agreement with reference trajectories under various transient operations without large amount of calibration efforts associated with the target valve position.

Potential of hydrogen addition to natural gas or ammonia as a solution towards low- or zero-carbon fuel for the supply of a small turbocharged SI engine

Nowadays there is an increasing interest in carbon-free fuels such as ammonia and hydrogen. Those fuels, on one hand, allow to drastically reduce CO2 emissions, helping to comply with the increasingly stringent emission regulations, and, on the other hand, could lead to possible advantages in performances if blended with conventional fuels. In this regard, this work focuses on the 1D numerical study of an internal combustion engine supplied with different fuels: pure gasoline, and blends of methane-hydrogen and ammonia-hydrogen. The analyses are carried out with reference to a downsized turbocharged two-cylinder engine working in an operating point representative of engine operations along WLTC, namely 1800 rpm and 9.4 bar of BMEP. To evaluate the potential of methane-hydrogen and ammonia-hydrogen blends, a parametric study is performed. The varied parameters are air/fuel proportions (from 1 up to 2) and the hydrogen fraction over the total fuel. Hydrogen volume percentages up to 60% are considered both in the case of methane-hydrogen and ammonia-hydrogen blends. Model predictive capabilities are enhanced through a refined treatment of the laminar flame speed and chemistry of the end gas to improve the description of the combustion process and knock phenomenon, respectively. After the model validation under pure gasoline supply, numerical analyses allowed to estimate the benefits and drawbacks of considered alternative fuels in terms of efficiency, carbon monoxide, and pollutant emissions.

Analysing the effect of weight reduction of Crankshaft on the pressure parameter inside cylinder of single cylinder SI engine

This work presents the analysis of the pressure inside the combustion chamber of a spark-ignition engine, with the help of Pressure Gauge. The pressure gauge measures the maximum pressure during compression stroke of an internal-combustion engine. The measured pressure depends on the crankshaft’s position and the Inertia force on the Piston. This Inertia force is the result of the counter weights present on the crankshaft. If weight is reduced from these counterweights how does the Pressure inside the cylinder is affected is analysed in the present research.

Improved knock detection method for lean burn SI engines

The purpose of this study was to improve the accuracy of knock detection for lean burn SI engines. In this study, we conducted an experiment to observe autoignition in an engine cylinder using a borescope and a high-speed camera under an air excess ratio of 2.1. In addition, the resonance frequency of each vibration mode by knocking and the knock intensity were also calculated from the in-cylinder pressure history. Autoignition was optically observed in all cycles with a knock intensity of more than 20 kPa or more, and in some cycles with that of less than 20 kPa. We compared the vibration caused by combustion and it caused by autoignition. As a result, by distinguishing between the vibration caused by combustion and it caused by autoignition using window functions, a knocking cycle that could not be detected by the conventional index was detected.

Chemical Kinetic Investigation on Nox Emission of Si Engine Fueled with Gasoline-Ethanol Fuel Blends

Chemical Kinetic Investigation on Nox Emission of Si Engine Fueled with Gasoline-Ethanol Fuel Blends

Comprehensive studies on alcohol using port fuel injection facilitated with spark plug engine

Abstract The spark ignition engines are universally used for automobile applications as a result of their consistent performance and economy. Regarding SI engine utilization in such applications global issues are concerned like NOx, HC, CO. Alternative fuels are the fuels of present and future. More and more vehicles are switching to alternative fuels worldwide. Usage of different fuels also reduces emissions which has further pushed demand for eco-friendly fuels. during this direction interest is concentrated on reducing formation of NOx & PM.Exhaust Gas Recirculation (EGR) may be a technique to attenuate NOx and smoke emission. the foremost reliable alternative possibility to deal with critical emissions is to use oxygenated fuels like ethanol, butanol and ether etc. which are renewable. Experimental investigations are performed out on one cylinder four stroke petrol engine producing an influence output of 5.2 kw In this experiment ethanol blends are used alongsideconventional gasoline. The blends used are 75% Ethanol 25% petrol, 50% Ethanol 50% petrol, 75% petrol 25% Ethanol alongsidethis performance parameters like ignition timing, Brake thermal efficiency and Emissions like HC, CO, NOx are monitored.