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It is widely argued that use of petroleum is one of the biggest contributors to environment degradation. In this study, burning of oxygenated fuel blends in diesel and gasoline engines is investigated with particular attention to emissions. The study focus was twofold; firstly, to determine the extent by which emissions of NOx, uHC and CO are increased or reduced for various loads in BMEP. And secondly to compare the emissions between the two engines. In the gasoline engine, 20% methanol was blended with 80% gasoline (M20), while a blend of 20% n-butanol and 80% diesel (B20) was considered in the diesel engine. The gasoline engine was a naturally aspirated Suzuki RS-416 1.6L engine type and the diesel engine was a 1Z type, 1.9L Turbo-Direct injection (TDI). Results showed that NOx emissions increased with an increasing brake mean effective pressure (BMEP) for diesel fuel (DF) but was slightly lower than the blend B20 at 50 and 75% load; whereas using M20, NOx reduced in reference to gasoline fuel (GF) but was four times higher than that obtained in diesel engine. Firing B20 diminished the quality of unburned hydrocarbons (uHC) emissions in diesel engine based on the reference fuel DF. The range of emissions of uHC however was far less in the diesel engine than in the gasoline engine: 10-60 ppm and 600 to 700 ppm respectively. M20 reduced uHc concentration more than the GF above 25% BMEP. The concentration of carbon monoxide (CO) increased more for M20 than GF. Similarly, emission concentration of CO in B20 increased relative to DF. Exhaust gases temperature (EGT) was lower for all oxygenated blends, M20 and B20, than for GF and DF.

Vibration analysis is used to detect faults and anomalies in machinery and other mechanical systems that produce vibrations during operation. The study aimed to develop an algorithm that can detect and locate engine faults in automobiles by analyzing vibrational data produced during engine operation. Analysis was done on one type of engine fault - Spark Ignition Engine misfire. To detect anomalies in the vibrational pattern (waveform), analysis was carried out in both time and frequency domains. To obtain vibrational data an A VR - 32 (Arduino) based data acquisition device was built, and analysis was carried out in MA TLAB using scripts and functions. The developed algorithm isolates frequency components in the waveform that corresponds to engine faults and converts them into numerical quantities that are then compared with computed ranges. The algorithm was able to identify the presence of a misfire in the engine and could locate the cylinder in which the misfire occurs with significant accuracy.

The worldwide decarbonisation movement has turned ammonia into one of the attractive alternative fuel for power generation. This paper reviews the progress of ammonia combustion technologies in spark ignition engine, compression ignition engine, and gas turbine. Relevant publications from prominent academic journals were acquired from credible scholarly databases and analysed. Ammonia dissociation and separate hydrogen supply were typically employed to deliver hydrogen to enhance ammonia reaction in the spark ignition engine. To achieve satisfactory engine performances with thermal efficiency of around 30%, a hydrogen mass fraction of roughly 10% is required for the ammonia/hydrogen engine. Engine parameters optimisation may be needed to increase hydrogen mass fraction further. Aqueous ammonia elevates heat release rate of full load compression ignition engine by almost 10%. However, prolonged ignition delay could potentially lead to higher engine noise levels. Multiple fuel injection optimisation is seemingly a more promising solution for improving ammonia compression ignition engine performances. In recent years, partial premixed combustion has gained considerable interest in hydrogen/ammonia gas turbine combustion research. This is mainly due to its ability to operate at equivalence ratio as low as 0.4, and in the slight fuel-rich regime. For operation at equivalence ratio 1.05, the nitric oxide concentration was decreased by a factor of approximately 5.9 when compared with that of stoichiometric condition. In all, ammonia offers a practical opportunity for sustainable power generation via internal combustion engines and gas turbine. Ground-breaking combustion technologies are crucial to boost the adoption of ammonia in these engines.

This article presents a detailed analysis of the potential of dimethyl ether (DME) fuel applications in SI engines. This paper presents the tests results completed on an 1.6-dm3 Opel Astra engine fueled by gaseous fuel as a mixture of LPG and DME. Dimethyl ether is a fuel with properties similar to liquid LPG fuel. In addition, DME is very well miscible with LPG, hence the possibility of creating a mixture with any DME divisions. The assessment of the possibility of using DME as a component of the mixture was carried out with the use of a chassis dynamometer and equipment, enabling an analysis of the changes taking place inside the cylinder. The results of the analyses are the parameters of the thermodynamic processes describing changes in the engine cylinder.

The use of biofuels for spark ignition engines is proposed to diversify fuel sources and reduce fossil fuel consumption, optimize engine performance, and reduce pollutant emissions. Additionally, when these biofuels are produced from low-grade wastes, they constitute valorisation pathways for these otherwise unprofitable wastes. In this study, ethanol and pyrolysis biogasoline made from low-grade wastes were evaluated as additives for commercial gasoline (RON95, RON98) in tests performed in a spark ignition engine. Binary fuel mixtures of ethanol + gasoline or biogasoline + gasoline with biofuel incorporation of 2% (w/w) to 10% (w/w) were evaluated and compared with ternary fuel mixtures of ethanol + biogasoline + gasoline with biofuel incorporation rates from 1% (w/w) to 5% (w/w). The fuel mix performance was assessed by determination of torque and power, fuel consumption and efficiency, and emissions (HC, CO, and NOx). An electronic control unit (ECU) was used to regulate the air–fuel ratio/lambda and the ignition advance for maximum brake torque (MBT), wide-open throttle (WOT)), and two torque loads for different engine speeds representative of typical driving. The additive incorporation up to 10% often improved efficiency and lowered emissions such as CO and HC relative to both straight gasolines, but NOx increased with the addition of a blend., This work was supported by FCT-Fundação para a Ciência e Tecnologia within the R&D Units, MEtRICs Project Scope: UIDP/04077/2020. Joaquim da Costa was supported through a PhD Grant from Fundo de Desenvolvimento Capital Humano of the Government of Timor Leste.

The exhaust emissions from Internal Combustion Engines (ICE) are currently one of the main sources of air pollution. This research presented a method for improving the exhaust gases and the performance of a Spark-Ignition (SI) engine using a water vapor injection system and a Non-Thermal Plasma (NTP) system. These two systems were installed on the intake manifold to investigate their effects on the engine’s performance and the characteristics of exhaust emission using different air/fuel (A/F) ratios and engine speeds. The temperatures of the injected water were adjusted to 5 and 25 °C, using a thermoelectric cooler (TEC) temperature control device. The total hydrocarbons (HC), nitrogen oxide (NOx), and engine torque were measured at different A/F ratios and engine speeds. The results indicated that the adaptation of the water vapor injection system and NTP system increased the content of the combustibles and combustion-supporting substances while achieving better emissions and torque. According to the test results, while the engine torque under 25 °C water+NTP was raised to 7.29%, the HC under 25 °C water+NTP and the NOx under 25 °C water were reduced to 16.31% and 11.88%, respectively. In conclusion, the water vapor injection and the NTP systems installed on the intake manifold could significantly reduce air pollution and improve engine performance for a more sustainable environment.

Currently, global warming has been a serious issue, which is closely related to anthropogenic emission of Greenhouse Gas (GHG) in the atmosphere, particularly Carbon Dioxide (CO2). To help achieve carbon neutrality by decreasing CO2 emissions, Oxy-Fuel Combustion (OFC) technology is becoming a hot topic in recent years. However, few findings have been reported about the implementation of OFC in dual-injection Spark Ignition (SI) engines. This work numerically explores the effects of Water Injection (WI) strategies on OFC characteristics in a practical dual-injection engine, including GDI (only using GDI), P50-G50 (50% PFI and 50% GDI) and PFI (only using PFI). The findings will help build a conceptual and theoretical foundation for the implementation of OFC technology in dual-injection SI engines, as well as exploring a solution to increase engine efficiency. The results show that compared to Conventional Air Combustion (CAC), there is a significant increase in BSFC under OFC. Ignition delay (θF) is significantly prolonged, and the spark timing is obviously advanced. Combustion duration (θC) of PFI is a bit shorter than that of GDI and P50-G50. There is a small benefit to BSFC under a low water-fuel mass ratio (Rwf). However, with the further increase of Rwf from 0.2 to 0.9, there is an increment of 4.29%, 3.6% and 3.77% in BSFC for GDI, P50-G50 and PFI, respectively. As WI timing (tWI) postpones to around −30 °CA under the conditions of Rwf ≥ 0.8, BSFC has a sharp decrease of more than 6 g/kWh, and this decline is more evident under GDI injection strategy. The variation of maximum cylinder pressure (Pmax) and combustion phasing is less affected by WI temperature (TWI) compared to the effects of Rwf or tWI. BSFC just has a small decline with the increase of TWI from 298 K to 368 K regardless of the injection strategy. Consequently, appropriate WI strategies are beneficial to OFC combustion in a dual-injection SI engine, but the benefit in fuel economy is limited.

Increasingly stringent regulations to reduce vehicle emissions have made it important to study emission mitigation strategies. Highly accurate control of the air-fuel ratio is an effective way to reduce emissions. However, a less accurate sensor can lead to reduced engine stability and greater variability in engine efficiency and emissions. Additionally, internal combustion engines (ICE) are moving toward higher compression ratios to achieve higher thermal efficiency and alleviate the energy crisis. The objective of this investigation was to analyze the significance of the accuracy of air-fuel ratio measurements at different compression ratios. In this study, a calibrated 1D CFD model was used to analyze the performance and emissions at different compression ratios. The results showed that carbon monoxide (CO) and nitrogen oxides (NOx) were sensitive to the equivalence ratio regardless of the compression ratio. With a slight change in the equivalence ratio, a high compression ratio had little effect on the change in engine performance and emissions. Moreover, with the same air-fuel ratio, an excessively high compression ratio (CR = 12) might result in knocking phenomenon, which increases the fluctuation of the engine output parameters and reduces engine stability. Overall, for precise control of combustion and thermal efficiency improvement, it is recommended that the measurement accuracy of the equivalence ratio is higher than 1% and the recommended value of the compression ratio are roughly 11.

In this study, bench tests of a heavy-duty turbocharged natural gas spark ignition (NGSI) engine were conducted with intake air injection at full load and different engine speeds. The flow characteristic of the compressor was revealed. The flow capacity of the compressor is reduced with air injection, and the reduction range increases gradually with the air injection pressure increasing at a constant speed, which would likely lead the compressor to surge. But the decrease extent of the compressor flow rate is improved as the speed increases, which reduces the tendency of surge. Based on those, prediction models for safe air injection pressure which can avoid compressor surge during various operations were proposed and then validated with experimental data. In addition, the influence of air injection on the pumping loss was also analyzed. The turbocharger efficiency is reduced therefore the pumping loss of the engine is increased during the air injection process. At 1200 rpm, the pumping loss efficiency of the engine without air injection is 0.25%, while it is increased to 1.83% with an air injection pressure of 400kPa at the same load.

This paper presents a numerical study of swirl flow effects on the combustion and emissions in single-cylinder spark ignition engine. First, a three-dimensional (3D) computational fluid dynamics (CFD) simulation was performed at two engine operating points to obtain the reference results of in-cylinder flow quantities required for the verification of a new K-k-ε turbulence model integrated with a cycle simulation. Then a zero-dimensional (0D) (quasi- dimensional) combustion model was used to analyze the swirl flow variations on the combustion and emissions where experimental results of 6 operating points were used to calibrate combustion and emission submodels in a cycle simulation. The coupling of the new turbulence and combustion model enabled the reconstruction of ordered in-cylinder swirl flow and the application of velocity operators on flame particles. The double swirl ratio increased the peak cylinder pressure by approximately 20%, and nitrogen oxide emissions were approximately 44% higher, while hydrocarbon (HC) emissions decreased by 44%. The twice lower swirl ratio decreased peak pressure by approximately 6%, and nitrogen oxide emissions were around 15% lower, while HC emissions were increased by 28%. If knock-limited spark advance is found for a double swirl ratio, the engine indicated that efficiency can be increased by 8.7% while HC emissions can be reduced by 20%.

We describe the external and internal hydrogen interaction on contacting surfaces in the “cylinder–piston rings” friction coupling. Under the influence of high temperatures and pressure, the oil in the combustion chamber at a temperature up to 1473 K decomposes and forms small amounts of water. External hydrogen (H2) is subsequently formed. Hydrogen removal from the piston rings reduces the heterogeneity of the structure, residual stresses, and uneven physical and chemical properties of the near-surface layers, which reduces the stress concentration and, as a consequence, results in an improvement in the performance characteristics of the surface layers of the friction couple “cylinder-piston rings” of the spark ignition engine.

In this paper, the effects of external supercharger application on in-cylinder combustion, performance parameters, fuel efficiency and environmental-economic indicators are discussed together regarding a hydrogen-fueled spark ignition engine operating under a lean mixture. The engine was operated at an engine speed of 1600 rpm, under four different boosting pressures (between 10 kPa and 40 kPa), by optimized ignition timing and being compared to a normally aspirated condition. Hydrogen was injected at five bars into the inlet-air. The results show that the indicated mean effective pressure and thermal efficiency increased by 38.9% and 14.2%, respectively, with a 40 kPa boosting pressure under an optimized ignition timing condition according to the normally aspirated engine, and that the cyclic variation decreased by 15.5%. In addition, under 40 kPa boosting pressure, NOx emissions increased by 45.2% and its environmental-social cost increased by 21.8%, while specific fuel consumption and fuel cost were reduced by approximately 18.5%. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Location of the peak cylinder pressure and the crank angle associated with half of the energy releases during the combustion process are generally used to define the engine combustion phasing and control the engine efficiency. To accelerate the optimization of a natural gas spark ignition internal combustion engine, this study proposes a black box modeling approach that will reduce the experimental or computational time needed to estimate the high efficient operating conditions at a particular engine speed and load via combustion phasing information. Specifically, a k-nearest neighbors (KNN) algorithm applied key engine operating variables such as the spark timing, air-fuel ratio, and engine speed as inputs to predict combustion phasing parameters such as the crank angles associated with peak cylinder pressure and 50% energy release. After training the correlative model, the selected engine variables produced acceptable errors for most operating conditions investigated. The results showed that the KNN algorithm predicted much better the location of the peak pressure than the location of the 50% energy release, as evidenced by the larger R2 values and smaller prediction errors. In addition, the regression model built in this study produced larger errors in the sparse-distributed region. Therefore, a more uniformly distributed training dataset is suggested for KNN algorithm, at least for the situations investigated in this research.

Partial conversion of the large inventory of compression-ignition engines to natural-gas (NG) spark-ignition lean-burn operation can reduce U.S. dependence on imported petroleum and enhance national energy security. This paper describes some of the observations made during such an engine conversion and proposes some solutions to alleviate some of the potential issues. The engine conversion in this study consisted from replacing the diesel injector with a spark plug and adding a port fuel injection system for NG delivery. The results indicated that the retrofitted engine performed reliably at lean-burn conditions, despite the different combustion characteristics compared to conventional SI engines. However, the squish region will trap an important fuel fraction (∼30%) and experience less-optimal burning conditions, hence a slower burning rate. This affected the engine efficiency and increased the unburned hydrocarbon and carbon monoxide emissions. From a combustion point of view, the operation of such converted engines can be optimized by increasing the bowl-to-squish volume ratio, optimizing the piston shape (e.g., by removing the central protrusion and avoiding 90-degree edges inside the bowl). The original compression ratio may also need to be reduced to avoid knocking. Moreover, direct gas injection and/or intake charging will increase the volumetric efficiency, which will benefit engine efficiency and emissions.

[EN] Hydrogen is one of the most promising alternative fuels for the transportation industry. The use of hydrogen to enable lean burn in internal combustion engines is an attractive solution for reducing CO2 emissions from two points of views: the substitution of carbon-based fuels and the increased thermal efficiency due to lean operation. Combining this strategy with the passive pre-chamber ignition system with gasoline/hydrogen blends is even more interesting. The main limitations of the passive pre-chamber concept in a high compression ratio spark-ignition engine were shown through engine experiments. A numerical study was then performed to evaluate the chance of extending the dilution limit by using hydrogen along with this technology. Results show how the use of hydrogen provides considerable benefits in the main chamber combustion process by enhancing the thermo-chemical properties of the mixture, increasing the flame speed, and improving the flame structure. Using an adequate gasoline-hydrogen blend proved to enable optimum burning rates at lean conditions, leading to a relevant thermal efficiency gain., Ministerio de Economia, Industria y Competitividad, Gobierno de Espana, Grant/Award Number: TRA2017-89139-C2-1-R; Universitat Politecnica de Valencia, Grant/Award Number: FPI-S1-2019-0033

İçten yanmalı motorlarda güç bir milden alınmakta ve motor hareketi bu milin açısal hareketi ile tanımlanmaktadır. Bu hareket krank mekanizmalı motorlarda krank açısı adını alırken rhombic mekanizmalı motorlarda dişli açışını ifade etmektedir. Bu çalışmada, buji ile ateşlemeli dört zamanlı tek silindirli bir motor için krank hareket mekanizması ile buna alternatif olabilecek rhombic hareket mekanizmasının termodinamik olarak karşılaştırılması yapılmıştır. Hem rhombic hem de krank mekanizmasında maksimum silindir basıncı 371o’de elde edilmiştir. Krank mekanizmalı motorda maksimum silindir basıncı 63,1 bar iken rhombic mekanizmalı motorda maksimum silindir basıncının 64,5 bar olduğu görülmektedir. Rhombic mekanizmalı motorda bir çevrimde silindir duvarından kaybedilen ısı miktarı 15,27 J iken bu değer krank mekanizmalı motorda bir çevrim için 13,68 J olarak hesaplanmıştır.

In this article Authors present the continuation of the calculations for theoretical ACC engine cycle, considering additionally “VCR function” – changeable compression level. For this purpose the self-acting volume change, realized by ACC system, was used. The ACC system was adjusted appropriately to control the compression level. The analysis is based on three cases, representing delayed, premature and optimal reaction of ACC system. Reactions are presented in form of plots with indicated pressure in the combustion chamber. As the result of the conducted analysis and interpretation of obtained graphs, the calculation approach of compression ratio for ACC presented in previous article is being challenged. For the optimal reaction of ACC system, the theoretical operation schematics are devised and presented in the key points of the work. Based on the schematics, the values of theoretical efficiency were calculated for different cycles of theoretical ACC engine, in which regulation of compression ratio takes place. Moreover, the presented analysis includes graphs with optimal courses of indicated pressure for significantly different work parameters of ACC engine, showing its regulation possibilities. Also the time scaled graphs (with millisecond as basic time unit) are presented to show the possibilities of dynamic ACC systems, which are comparable with the combustion time (from 3 to 0,5 ms). In this paper the general discussion is started about the compression ratio in more complex kinematic systems including ACC.

Lean operation of Spark-Ignition engines can provide higher thermal efficiency compared to standard stoichiometric operation. However, for a homogeneous lean mixture, the associated reduction of flame speeds becomes an important issue from the perspective of robust ignition and fast flame spread throughout the charge. This study is focused on the use of a lean partial fuel stratification strategy that can stabilize the deflagration, while sufficiently fast combustion is ensured via the use of end-gas autoignition. The engine has a spray-guided Direct-Injection Spark-Ignition combustion system and was fueled with either a high-octane certification gasoline or E85. Partial fuel stratification was achieved using several fuel injections during the intake stroke in combination with a small pilot-injection concurrent with the Spark-Ignition. The results reveal that partial fuel stratification enables very stable combustion, offering higher thermal efficiency for parts of the load range in comparison to well-mixed lean and stoichiometric combustion. The heat release and flame imaging demonstrate that the combustion often has three distinct stages. The combustion of the pilot-injected fuel, ignited by the normal spark, acts as a “super igniter,” ensuring a very repeatable initiation of combustion, and flame incandescence reveals locally rich conditions. The second stage is mainly composed of blue flame propagation in a well-mixed lean mixture. The third stage is the compression autoignition of a well-mixed and typically very lean end-gas. The end-gas autoignition is critical for achieving high combustion efficiency, high thermal efficiency, and stable combustion. Partial fuel stratification enables very effective combustion-phasing control, which is critical for controlling the occurrence and intensity of end-gas autoignition. Comparing the gasoline and E85 fuels, it is noted that achieving end-gas autoignition for the higher octane E85 requires a more aggressive compression of the end-gas via the use of a more advanced combustion phasing or higher intake-air temperature.

The six-stroke spark ignition engine has the potential to be developed as a new alternative to future motor fuel technology. The development of motor vehicles will be directly proportional to the use of rising fossil fuels. It is, therefore, necessary to have renewable alternative fuel, in which one of them is using ethanol fuel. Characteristics of the ethanol fuel are different from fossil fuels so the ignition timing is needed to be modified. The purpose of this study was to determine the effect of the ignition degree on the performance of a 6-stroke spark-ignition engine fuel using ethanol. This research is worked out directly by experimental and testing on the intended object. The test was carried out on an ethanol-fueled 6-step spark ignition engine with variations in the ignition angle at 24 0 ,26 0 and 28 0 . Each variation was tested for a rotation interval of 600 rpm from 2400 rpm to 7200 rpm. The results show that ignition degree greatly affects performance. The ignition angle of 28 0 produced better torque, effective power, effective specific fuel consumption and effective thermal efficiency than those of the ignition degrees at 24 0 and 26 0 (standard angle ). This is due to the use of ethanol fuel which has a slower combustion speed. Based on this fact, it is necessary to advance the ignition angle so that the explosive power of the air-fuel mixture is increasing. Low fuel consumption and better effective thermal efficiency were observed for 28 0 ignition degrees compared to 24 0 and 26 0 ignition degrees.

The aim of this experimental investigation is to analyse the performance and emission characteristics of spark ignition engine running on petrol doped with various additives. Additives used in this...

One of the objectives of this study is to elaborate an engine cycle simulation program in FORTRAN language to analyze the influence of operating parameters on the performance (theeffective power, torque and specific fuel consumption) of a four-stroke gasoline engine (Ford ZSG 416 gasoline engine) for different engine operating parameters. The GT-Powerengine simulation software was used to compare the results obtained with the developed computer program and to improve it. In this program, a single-zone thermodynamicmodel was considered, which describes each phase of the engine cycle. In order to validate the developed program, a comparison of the experimental results with those obtainedusing GT-Power software was carried out. The other objective of this paper is to investigate the influence of a number of significant engine parameters such as compression ratio, cylinder wall temperature, cylinder diameter, stroke-bore ratio and ignition angle on the performance of the chosen engine. Examining the experimental results and those obtained with the developed program, it was observed that the power difference was in the order of ± 3%, the torque difference was ± 6%, while the BSFC difference was about ± 10%. It has been noted that the most significant parameters in improving the performance of the gasoline engine are the compression ratio, the fuel/air ratio, the engine geometry and the ignition begin. The variation of these parameters was not arbitrary, the knock criteria, in other words, the achievement of normal combustion were taken into account.

Backfire, an abnormal combustion phenomenon, in a hydrogen fuelled spark ignition (SI) engine was analyzed using computational fluid dynamics (CFD) and experimental tests. One of the main causes of backfire origin is the presence of any high temperature heat source including hot spot in the combustion chamber of the engine during intake process. A CFD based parametric study was carried out by varying the temperature of hot spot and its location in the combustion chamber of the engine in order to analyze their effects on backfire origin and its propagation in the intake manifold of the engine. The temperature of hot spot was varied from 800 K to till the temperature of backfire occurrence. The minimum temperature of hot spot at which backfire occurred was observed as 950 K and beyond. The probability of backfire occurrence increases with increase in hot spot temperature. The CFD simulations were also carried out by varying the location of hot spot (spark plug tip and exhaust valve) and the results indicate that the location of hot spot does not influence the characteristics of backfire but it affects the timing of its origin. The average backfire velocity is 230 m/s based on the average turbulent flame velocity during backfire propagation in the intake manifold and the value agreed reasonably well with the experimental observations of backfire propagation on the engine with the transparent intake manifold. Backfire propagation is under the category of deflagration based on its velocity (subsonic), and the maximum pressure gradient (

Biogas is a renewable energy fuel (which can also be upgraded to biomethane), and it has the potential to substitute fossil fuels. In the present study, the effect of various biogas compositions on...

Developing more energy-efficient and environmentally friendly transportation technologies, that can enable to use significantly less petroleum and to reduce regulated emissions while meeting or exceeding drivers’ performance expectations, has always been one of the main challenges in automotive technology. Therefore, based on an experimental dataset, metamodels were generated using design of computer experiments and central composite design technique in order to accurately predict carbon monoxide (CO), oxides of nitrogen ($$\text {NO}_{x}$$), hydrocarbon (HC) and carbon dioxide ($$\text {CO}_{2}$$) emissions, mean effective pressure and exergy destruction due to heat transfer and combustion process. Combustion metamodels was evaluated varying air–fuel ratio, ignition timing [($$^{\circ }$$CAD) Crank Angle Degrees], compression ratio, and combustion duration ($$^{\circ }$$) on the performance of a Spark Ignition (SI) engine at constant speed of 750 rpm. Because SI gasoline engines always encounter the decreased thermal efficiency and increased toxic emissions at idle (Jurgen in Automotive electronics handbook, McGraw-Hill, New York, 1995). The Akaike information criterion was applied to automatically select the best metamodel for each case.

The development and production of modern spark-ignition engines are very important to market and regulations requirements which demand low cost, high-performance engines with low fuel consumption and reduced emissions of pollutant. Because these parameters are directly related to the combustion process in an engine cylinder, many kinds of research have been achieved to identify these parameters which affect combustion efficiency and pollutant formation in this engine cylinder. In this study, a thermodynamic cycle model has been developed and used to predict the effects of Exhaust Gas Recirculation (EGR), which is used to reduce the Nitrogen Oxide (NO) in exhaust gas, on emission levels and performance of a spark-ignition engine. The model simulates full thermodynamic cycle of a spark-ignition engine and includes heat transfer, combustion, gas exchange process, thermal dissociation of water and carbon dioxide, and chemical equilibrium in engine cylinder., Çağdaş buji ile ateşlemeli motorların geliştirilmesi ve üretimi, düşük maliyet, düşük yakıt tüketimi ile yüksek performanslı motorlar ve azaltılmış kirletici emisyonları talep eden pazar ve mevzuat gereksinimleri için çok önemlidir. Bu parametreler buji ile ateşlemeli bir motor silindiri içindeki yanma işlemi ile doğrudan ilişkili olduğu için, buji ile ateşlemeli bir motor silindiri içerisindeki yanma verimini ve kirletici emisyonlarını etkileyen bu parametrelerin tanımlamasını yapan birçok araştırma başarıyla yapılmıştır. Yapılan bu çalışmada, bir termodinamik çevrim modeli geliştirilerek, egzoz gazındaki azot oksit (NO) yüzdesini azaltmak amacı ile kullanılan Egzoz Gazı Geri Verilmesi Yönteminin buji ile ateşlemeli bir motorun egzoz emisyon değerleri ve performansı üzerine etkilerini tahmin etmek için kullanılmıştır. Kurulan model, buji ile ateşlemeli bir motorun tüm termodinamik çevrimini yansıtmakta ve motor silindiri içindeki yanma olayını, ısı transferini, gaz değişimini, yanma ürünlerinin ısıl ayrışmasını ve kimyasal dengeyi içermektedir.

This study analyzes the influence of ethanol as gasoline blend on a spark ignition engine and a mathematical tool is proposed based on multi attribute decision making approach to select optimal combination of operating parameters of a variable compression ratio multi fuel engine considering objective, subjective and integrated weights of attributes. Test fuels used were ethanol-gasoline blends having ethanol in proportions of 10, 20, 30 and 40 vol %. The compression ratio was varied as 6, 7, 8 and 9. The load was varied as 25, 50, 75 and 100%. A series of 16 experiments were conducted by adopting Taguchi based design of experiments resulting in L16 orthogonal array. The result of proposed method shows that the combination of compression ratio 6, ethanol-gasoline blend 30 vol% at a load of 75% is found to the best choice from among other trails and was validated using graph theory matrix approach