The Experts below are selected from a list of 114 Experts worldwide ranked by ideXlab platform
Stanislaw Szwaja - One of the best experts on this subject based on the ideXlab platform.
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Dual nature of hydrogen Combustion Knock
International Journal of Hydrogen Energy, 2013Co-Authors: Stanislaw Szwaja, Jeffrey NaberAbstract:Abstract Combustion Knock is abnormal Combustion taking place in an internal Combustion spark ignited engine. It might be particularly observed in the engine at the end of Combustion when the air–fuel mixture residue can be self-ignited due to exceeding auto-ignition temperature of this mixture. However, while hydrogen is combusted the Knock can also occur as a result of non-auto-ignited Combustion events. Investigation on Knock, presented in the manuscript, was conducted in a hydrogen fueled spark ignited single cylinder engine with variable compression ratio. To express in numbers intensity of the Combustion Knock the in-cylinder pressure pulsations were used as a credible metrics. On the basis of analysis of these pulsations the hydrogen Knock was distinguished as light and heavy one depending on its origin. The light Knock is generated by Combustion instabilities, which are a source for generating pressure waves inside the engine cylinder. The heavy Knock results from hydrogen auto-ignition at the end of Combustion. Its intensity is several times higher in comparison to the light Knock. These observations were additionally confirmed by analysis of heat release rate. Finally, the light and the heavy Knock were characterized by average amplitude of the pulsations from the entire test series of hundreds and several thousands kPa, respectively.
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Knock and Combustion rate interaction in a hydrogen fuelled Combustion engine
Journal of KONES, 2011Co-Authors: Stanislaw SzwajaAbstract:The paper describes correlation between Combustion Knock intensity and Combustion rate calculated as the heat release rate from Combustion pressure traces of a hydrogen fuelled spark ignited engine. Unlike a gasoline spark ignited (SI) engine, the hydrogen fuelled engine can easily generate Knock during Combustion at working conditions similar to a gasoline engine. However, the hydrogen Knock does not necessarily come from hydrogen auto-ignition at the end phase of spark-controlled Combustion process as it is typical at the gasoline fuelled engine. The phenomenon of hydrogen Knock significantly differs from the gasoline Knock due to different Combustion mechanisms and different fuel thermo-chemical properties. The Knock can be generated during hydrogen Combustion itself as result of Combustion instabilities. Intensity of this Knock, expressed here by intensity of Combustion pressure fluctuations, is several times lower in comparison with the Combustion Knock by fuel self-ignition process. This „light Knock“ is a matter of this paper. The tests of hydrogen Combustion in the IC engine has been conducted at air to hydrogen stoichiometric ratio at various compression ratios with spark timing sweep from -10 to 4 crank angle degrees referring to top dead centre of the engine piston. Obtained results show, that there is a positive correlation between the Knock intensity and the Combustion rate. This correlation is particularly observed at tests taken on the engine with compression ratio of 10. The conclusions should provide good premises for Combustion Knock modelling and its prediction.
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Combustion of n-butanol in a spark-ignition IC engine
Fuel, 2010Co-Authors: Stanislaw Szwaja, Jeffrey NaberAbstract:Abstract Alcohols, because of their potential to be produced from renewable sources and because of their high quality characteristics for spark-ignition (SI) engines, are considered quality fuels which can be blended with fossil-based gasoline for use in internal Combustion engines. They enable the transformation of our energy basis in transportation to reduce dependence on fossil fuels as an energy source for vehicles. The research presented in this work is focused on applying n -butanol as a blending agent additive to gasoline to reduce the fossil part in the fuel mixture and in this way to reduce life cycle CO 2 emissions. The impact on Combustion processes in a spark-ignited internal Combustion engine is also detailed. Blends of n -butanol to gasoline with ratios of 0%, 20%, and 60% in addition to near n -butanol have been studied in a single cylinder cooperative fuels research engine (CFR) SI engine with variable compression ratio manufactured by Waukesha Engine Company. The engine is modified to provide air control and port fuel injection. Engine control and monitoring was performed using a target-based rapid-prototyping system with electronic sensors and actuators installed on the engine [1] . A real-time Combustion analysis system was applied for data acquisition and online analysis of Combustion quantities. Tests were performed under stoichiometric air-to-fuel ratios, fixed engine torque, and compression ratios of 8:1 and 10:1 with spark timing sweeps from 18° to 4° before top dead center (BTDC). On the basis of the experimental data, Combustion characteristics for these fuels have been determined as follows: mass fraction burned (MFB) profile, rate of MFB, Combustion duration and location of 50% MFB. Analysis of these data gives conclusions about Combustion phasing for optimal spark timing for maximum break torque (MBT) and normalized rate for heat release. Additionally, susceptibility of 20% and 60% butanol–gasoline blends on Combustion Knock was investigated. Simultaneously, comparison between these fuels and pure gasoline in the above areas was investigated. Finally, on the basis of these conclusions, characteristic of these fuel blends as substitutes of gasoline for a series production engine were discussed.
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hydrogen Combustion in a compression ignition diesel engine
International Journal of Hydrogen Energy, 2009Co-Authors: Stanislaw Szwaja, Karol GrabrogalinskiAbstract:Abstract The investigation presented in this paper concerns both pure hydrogen Combustion under HCCI (homogeneous charge compression ignition) conditions and hydrogen–diesel co-Combustion in a compression ignition (CI) engine. The investigation on the simultaneous Combustion of hydrogen and diesel fuel was conducted with various hydrogen doses in the range from 0% to 17% with respect to energy percentage. With hydrogen of 17% the hydrogen–diesel–air mixture was stoichiometric and provided favorable conditions for generating Combustion Knock. Small amounts of hydrogen (about 5%) when added to a diesel engine shorten the diesel ignition lag and, in this way, decrease the rate of pressure rise. It provides better conditions for soft run of the engine and can increase engine durability. The final conclusions concerning hydrogen impact on Combustion Knock intensity, mass fraction burned (MFB) and heat release rate of the engine are detailed.
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Impact of leaning hydrogen-air mixtures on engine Combustion Knock
Journal of KONES, 2008Co-Authors: Stanislaw Szwaja, Jeffrey NaberAbstract:Combustion of lean hydrogen-air mixtures in an internal Combustion (IC) spark ignited (SI) engine in respect of Combustion Knock effect is presented in this paper. It is known that making the combustible mixture leaner leads to both decreasing in-cylinder peak temperature of Combustion and lengthening ignition lag. It also increases Combustion duration. Having these issues on mind it could be concluded that Combustion Knock intensity decreases as well. It is reported that such a hypothesis is also correct when hydrogen based fuels are combusted in the IC engine, although hydrogen as an engine fuel, on the contrary to gasoline, is very susceptible to Knock generation throughout the entire Combustion duration. At the beginning the paper examines the Combustion Knock intensity on the basis of incylinder pressure traces. Next, a test-bed and obtained experimental results of hydrogen Combustion in the IC single cylinder CFR engine are showed. Finally, analysis of Knock intensity referring to lean hydrogen-air mixture ratio, expressed by the excess air number so-called lambda, is carried out. Significant conclusion from the analysis is that there is strong negative correlation between the hydrogen Knock intensity and the excess air number lambda. In the end, comparison with exhaust gas recirculation as alternative way to reduce Combustion Knock, and constraints for leaning the hydrogen-air combustible mixture for the IC engine are discussed in the paper.
Jeffrey Naber - One of the best experts on this subject based on the ideXlab platform.
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Experimental Investigation of Water Injection Technique in Gasoline Direct Injection Engine
Volume 1: Large Bore Engines; Fuels; Advanced Combustion, 2017Co-Authors: Niranjan Miganakallu, Jeffrey Naber, Sandesh Rao, William Atkinson, Sam BarrosAbstract:This paper experimentally investigates the effect of water injection in the intake manifold on a naturally aspirated, single cylinder, Gasoline Direct Injection engine to determine the Combustion and emissions performance with Combustion Knock mitigation. The endeavor of the current study is to use water injection to attain the optimum Combustion phasing without Knocking. Further elevated intake air temperature tests were conducted to observe the effect of water injection with respect to Combustion and emissions. Experiments were carried out at medium load condition (800 kPa NIMEP, 1500 RPM) at intake air temperatures between 30–90° C in 20° C increments. Two fuels, an 87 AKI and a 93 AKI were used in this study. Baseline tests were undertaken with the high-octane fuel (93 AKI) to achieve optimal Combustion phasing corresponding to Maximum Brake Torque (MBT) without water injection. Water injection was utilized for the low octane fuel to achieve Combustion phasing of 8–10° ATDC and within the controlled Knock limit. Combustion phasing was achieved by controlling the ignition timing, water injection quantity and timing to the Knock threshold. The results showed that water injection and the resultant charge cooling mitigates Combustion Knock and an optimum Combustion phasing based on indicated fuel conversion efficiency is achieved with a water to fuel ratio of 0.6. Water injection reduces the NOx emissions while achieving better indicated thermal efficiency compared to the baseline tests. A detailed comparison is presented on the Combustion phasing, indicated thermal efficiency, burn durations, HC, NOx and PN emissions in this paper.
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Dual nature of hydrogen Combustion Knock
International Journal of Hydrogen Energy, 2013Co-Authors: Stanislaw Szwaja, Jeffrey NaberAbstract:Abstract Combustion Knock is abnormal Combustion taking place in an internal Combustion spark ignited engine. It might be particularly observed in the engine at the end of Combustion when the air–fuel mixture residue can be self-ignited due to exceeding auto-ignition temperature of this mixture. However, while hydrogen is combusted the Knock can also occur as a result of non-auto-ignited Combustion events. Investigation on Knock, presented in the manuscript, was conducted in a hydrogen fueled spark ignited single cylinder engine with variable compression ratio. To express in numbers intensity of the Combustion Knock the in-cylinder pressure pulsations were used as a credible metrics. On the basis of analysis of these pulsations the hydrogen Knock was distinguished as light and heavy one depending on its origin. The light Knock is generated by Combustion instabilities, which are a source for generating pressure waves inside the engine cylinder. The heavy Knock results from hydrogen auto-ignition at the end of Combustion. Its intensity is several times higher in comparison to the light Knock. These observations were additionally confirmed by analysis of heat release rate. Finally, the light and the heavy Knock were characterized by average amplitude of the pulsations from the entire test series of hundreds and several thousands kPa, respectively.
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Combustion of n-butanol in a spark-ignition IC engine
Fuel, 2010Co-Authors: Stanislaw Szwaja, Jeffrey NaberAbstract:Abstract Alcohols, because of their potential to be produced from renewable sources and because of their high quality characteristics for spark-ignition (SI) engines, are considered quality fuels which can be blended with fossil-based gasoline for use in internal Combustion engines. They enable the transformation of our energy basis in transportation to reduce dependence on fossil fuels as an energy source for vehicles. The research presented in this work is focused on applying n -butanol as a blending agent additive to gasoline to reduce the fossil part in the fuel mixture and in this way to reduce life cycle CO 2 emissions. The impact on Combustion processes in a spark-ignited internal Combustion engine is also detailed. Blends of n -butanol to gasoline with ratios of 0%, 20%, and 60% in addition to near n -butanol have been studied in a single cylinder cooperative fuels research engine (CFR) SI engine with variable compression ratio manufactured by Waukesha Engine Company. The engine is modified to provide air control and port fuel injection. Engine control and monitoring was performed using a target-based rapid-prototyping system with electronic sensors and actuators installed on the engine [1] . A real-time Combustion analysis system was applied for data acquisition and online analysis of Combustion quantities. Tests were performed under stoichiometric air-to-fuel ratios, fixed engine torque, and compression ratios of 8:1 and 10:1 with spark timing sweeps from 18° to 4° before top dead center (BTDC). On the basis of the experimental data, Combustion characteristics for these fuels have been determined as follows: mass fraction burned (MFB) profile, rate of MFB, Combustion duration and location of 50% MFB. Analysis of these data gives conclusions about Combustion phasing for optimal spark timing for maximum break torque (MBT) and normalized rate for heat release. Additionally, susceptibility of 20% and 60% butanol–gasoline blends on Combustion Knock was investigated. Simultaneously, comparison between these fuels and pure gasoline in the above areas was investigated. Finally, on the basis of these conclusions, characteristic of these fuel blends as substitutes of gasoline for a series production engine were discussed.
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ionization signal response during Combustion Knock and comparison to cylinder pressure for si engines
SAE International Journal of Passenger Cars - Electronic and Electrical Systems, 2008Co-Authors: Abhijit Abhijit, Jeffrey NaberAbstract:In-cylinder ion sensing is a subject of interest due to its application in spark-ignited (SI) engines for feedback control and diagnostics including: Combustion Knock detection, rate and phasing of Combustion, and mis-fire On Board Diagnostics (OBD). Further advancement and application is likely to continue as the result of the availability of ignition coils with integrated ion sensing circuitry making ion sensing more versatile and cost effective. In SI engines, Combustion Knock is controlled through closed loop feedback from sensor metrics to maintain Knock near the borderline, below engine damage and NVH thresholds. Combustion Knock is one of the critical applications for ion sensing in SI engines and improvement in Knock detection offers the potential for increased thermal efficiency. This work analyzes and characterizes the ionization signal in reference to the cylinder pressure signal under Knocking and non-Knocking conditions. Combustion data including cylinder pressure and ionization signals from a 2.0L I4 and a 5.4L V8 engine are collected at varying operating conditions. The ion and pressure signals are characterized and compared through the use of frequency analysis, correlation, and coherence. The results show that the correlation and coherence are low as a result of both the ion and pressure signals being point measurements and the stochastic aspects of Combustion Knock and characteristics of the in-cylinder pressure waves. Using additional statistical analysis however, the results show a high correlation of Knock levels between the ion and cylinder pressure measurements.
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Impact of leaning hydrogen-air mixtures on engine Combustion Knock
Journal of KONES, 2008Co-Authors: Stanislaw Szwaja, Jeffrey NaberAbstract:Combustion of lean hydrogen-air mixtures in an internal Combustion (IC) spark ignited (SI) engine in respect of Combustion Knock effect is presented in this paper. It is known that making the combustible mixture leaner leads to both decreasing in-cylinder peak temperature of Combustion and lengthening ignition lag. It also increases Combustion duration. Having these issues on mind it could be concluded that Combustion Knock intensity decreases as well. It is reported that such a hypothesis is also correct when hydrogen based fuels are combusted in the IC engine, although hydrogen as an engine fuel, on the contrary to gasoline, is very susceptible to Knock generation throughout the entire Combustion duration. At the beginning the paper examines the Combustion Knock intensity on the basis of incylinder pressure traces. Next, a test-bed and obtained experimental results of hydrogen Combustion in the IC single cylinder CFR engine are showed. Finally, analysis of Knock intensity referring to lean hydrogen-air mixture ratio, expressed by the excess air number so-called lambda, is carried out. Significant conclusion from the analysis is that there is strong negative correlation between the hydrogen Knock intensity and the excess air number lambda. In the end, comparison with exhaust gas recirculation as alternative way to reduce Combustion Knock, and constraints for leaning the hydrogen-air combustible mixture for the IC engine are discussed in the paper.
Luigi Teodosio - One of the best experts on this subject based on the ideXlab platform.
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A Modelling Study to Analyse the Compression Ratio Effects on Combustion and Knock Phenomena in a High-Performance Spark-Ignition GDI Engine
International Review on Modelling and Simulations (IREMOS), 2018Co-Authors: Fabio Bozza, Luigi Teodosio, Vincenzo De Bellis, Diego Cacciatore, Fabrizio Minarelli, Antonio AlipertiAbstract:The modern internal Combustion engines show complex architectures in order to improve their performance in terms of brake torque and fuel consumption. Among the different solutions, a compression ratio (CR) increase represents a well assessed path to achieve the above result. However, CR has to be limited in order to comply with the mechanical and thermal engine safety and to avoid Knocking Combustion. In the present work, a 10-cylinder naturally aspirated spark ignition engine is investigated to evaluate the effects of an increased CR on the performance. In a preliminary stage, the engine is experimentally tested under full load operation for a base CR of 12.6. The main performance parameters and the in-cylinder pressure cycles are measured. The engine is schematized in a one-dimensional model (GT-Power™), where “user routines” are implemented to simulate the turbulence, Combustion, Knock and heat transfer phenomena. The 1D model is validated against experimental data at full load, denoting a good accuracy. The model is then used to estimate the engine performance variations passing from the base CR up to an increased CR value of 13.3. The results underline a reduced improvement of the engine performance for the higher CR configuration, mainly deriving from a higher thermodynamic efficiency. The proposed methodology shows the capability to predict the effects of a partial engine re-design on a completely theoretical basis and presents the potential to be very helpful in reducing the related experimental costs and time-to-market.
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impact of intake valve strategies on fuel consumption and Knock tendency of a spark ignition engine
Applied Energy, 2018Co-Authors: Luigi Teodosio, Vincenzo De Bellis, Dino Pirrello, Fabio Berni, R Lanzafame, Alessandro DadamoAbstract:Abstract Nowadays various technical solutions have been proposed in order to improve the performance of spark-ignition internal Combustion engines both at part and full load operations, especially in terms of Brake Specific Fuel Consumption (BSFC). Among the most advanced technical solutions, a fully flexible valve control system (VVA – Variable Valve Actuation) appears a very robust and reliable approach to attain the above aim. In fact advanced valve strategies, such as Early Intake Valve Closure (EIVC) and Late Intake Valve Closure (LIVC), proved to be an effective way to decrease the fuel consumption: at part load through a reduction of the pumping work and, at high load, through a Knock mitigation and an over-fueling reduction. In this paper, a comparative numerical study is realized to evaluate the influence of the intake valve strategy on the performance of a small-size turbocharged spark-ignition engine. The analyzed engine is equipped with a fully flexible VVA on the intake side, based on the “lost motion” principle and able to realize both EIVC and Full Lift strategies, while the virtual modification of the intake cam profile allows for the actuation of LIVC profiles. First, a 1D model of the tested engine is developed in GT-Power™ framework. It is integrated with in-house developed sub-models for the description of in-cylinder phenomena, including turbulence, Combustion, Knock and heat transfer. The adopted approach is validated against 3D turbulence results, measured global performance parameters and in-cylinder pressure cycles. The consistency of the proposed approach, without requiring any case-dependent tuning, is demonstrated at various speeds, loads and intake valve strategies. The validated engine model is used to perform a parametric analysis for different intake valve closure angles in two representative operating points at full and part load. The results point out that both EIVC and LIVC induce an improved fuel consumption with respect to a conventional Full Lift valve strategy. EIVC proves to be more effective at part load than LIVC, while similar BSFC advantages are obtained at high load. The proposed approach, based on refined sub-models for in-cylinder phenomena description, shows the capability to predict the effects of advanced valve strategies, making the implementation of a “virtual” calibration of a VVA engine possible.
Ciaran Branney - One of the best experts on this subject based on the ideXlab platform.
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A review of water injection applied on the internal Combustion engine
Energy Conversion and Management, 2019Co-Authors: Sipeng Zhu, Sam Akehurst, Colin Copeland, Andrew Lewis, Hao Yuan, Ian Kennedy, Johan Bernards, Ciaran BranneyAbstract:Abstract As a promising technique to reduce the in-cylinder temperature and exhaust temperature, mitigate Combustion Knock, improve Combustion phasing and decrease NOx emissions, water injection applied on different types of engines has attracted extensive attention in recent years to further improve fuel economy and fulfill stricter emission regulations. Since mechanisms of water injection with different aims are distinct, benefits on engine performances and emissions are also varied. This paper intends to give a comprehensive review of water injection applied on the internal Combustion engine. First, different implementations of water injection are introduced, followed by a detailed description of water evaporation processes. Second, mechanisms of the in-cylinder Combustion process with water addition are discussed with respect to the heat release rate, Knock tendency and emission formations. Next, recent works of water injection applied on different kinds of engines are reviewed with special attentions given to the comparisons of different implementations and injection parameters. Furthermore, comparisons and combinations of water injection with other advanced engine techniques are summarized. Finally, critical issues of current research on the water injection technique are discussed.
Baigang Sun - One of the best experts on this subject based on the ideXlab platform.
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inducing factors and frequency of Combustion Knock in hydrogen internal Combustion engines
International Journal of Hydrogen Energy, 2016Co-Authors: Qinghe Luo, Baigang SunAbstract:Abstract Hydrogen is a promising energy carrier, and the port fuel injection (PFI) is a fuel-flexible, durable, and relatively cheap method of energy conversion. However, Combustion Knock as an abnormal Combustion phenomenon does not only limit the brake torque and thermal efficiency, but also breaks the piston or engines. This paper uses a four-stoke cycle, displacement of 2.0 L PFI hydrogen internal Combustion engine and a calculated model to study the inducing factors and frequency of Combustion Knock. Results showed that Combustion Knock occurs at relatively higher engine speed (more than 3000 r/min) than the engine speed occurring Knock of gasoline engine. The calculated average temperatures of air–fuel mixture at the end of Combustion using thermodynamics dual zone model fall in the range of 1000–1100 K for hydrogen engines, which are higher than gasoline ones (about 200 K). Knock and the other abnormal Combustion phenomena (backfire and pre-ignite) interact with each other. When the backfire generates, the components in the cylinder will be heated. In the next cycle, the components of the cylinder will release heat to the intake, which can increase the initial temperature at ignition. The high initial temperature will lead to the Combustion Knock. Otherwise, because of the Combustion Knock, the temperatures of cylinder components will increase, which generates hot spots and ultimately causes pre-ignite and backfire. Through the figures of Fast Fourier Transform (FFT) amplitude, the frequency of hydrogen engines is higher than gasoline ones for every kind of mode. The pressure waves of Combustion Knock spread with radial direction for light Combustion Knock and with circumferential direction for heavy Combustion Knock. These conclusions can be used to explore the working conditions close to Combustion Knock to achieve higher thermal efficiency and provide a guidance to detect the Knock in hydrogen engine.