Combustion Process In Engine Research Articles

Effect of natural gas injection timing on performance and emission characteristics of marine low speed two-stroke natural gas/diesel dual-fuel engine at high load conditions

The scavenging mode, injector position and combustion chamber type of marine low-speed two-stroke dual-fuel engines are different from those of small and medium-sized engines. The combustion process and emission laws of marine low-speed two-stroke dual-fuel engines cannot fully replicate small and medium-sized engines. The aim of this paper is to numerically investigate combustion process and emissions of marine low-speed two-stroke dual-fuel engine with different natural gas injection timings (NGIT). Four NGIT (8 BTDC, 6BTDC, 4BTDC and 2BTDC) were employed. The results showed that the advance of NGIT increased the power, thermal efficiency and NO emission, but decreased methane (CH4) emission. Each combustion stage was affected by the NGIT in different rules. The combustion process had two unstable periods, a stable period and a long tail heat release. The NGIT had an optimal value (6°CA BTDC ∼ 4°CA BTDC) to reduce CH4 and NO emissions. With the NGIT advanced ahead every 2°CA, the power increased by 117 kW, the thermal efficiency increased by 0.7%, the peak cylinder pressure increased by 7%, the peak high temperature volume increased by 0.8%, the peak radial flame propagation velocity increased by 3.7 m/s, the peak axial flame propagation velocity increased by 2.7 m/s, and NO emission increased by 15.4%, while the combustion interruption factor decreased by 1.18%, and CH4 emission decreased by 7.6%.

Effect analysis of the forward flow fuel injection angle on stratified combustion process in a high-pressure direct injection diesel Wankel engine (HPDI-DWE)

High-pressure direct injection (HPDI) combined with stratified combustion technology can further enhance the combustion performance of the diesel Wankel engine (DWE). Consequently, based on our experimentally validated three-dimensional (3D) dynamic simulation model, this study proposes to adopt the fine-designed forward flow fuel injection angle (FIA) to realize mixture distribution in the front region of the rotary combustion chamber (RCC). Then the stratified fuel movement and combustion processes under different FIAs of a high-pressure direct injection diesel Wankel engine (HPDI-DWE) are investigated. The numerical results show that for mixture formation, the ideal distribution rule should make the fuel distribute near the spark ignition chamber (SIC) and avoid excessive mixture concentration since flame presents forward propagation characteristics. During the combustion process, combustion reaction occurs in the front zone of the RCC, while flame front shapes show symmetry structure due to the stratified distribution of fuel and generation of symmetric vortexes in this region. Increasing FIA, better power performance is obtained overall, meanwhile, mixture combustion rate and heat release process are accelerated. Considering the trade-off between power and emission, the preferred FIA is 65°. Compared to FIA of 60° (original scheme), its peak pressure (Pmax) is increased by 1.8%, total combustion duration (TCD), central heat release angle (CA50) and flame propagation period (CA10-90) are shortened by 11.1%, 20.4% and 14.1%, respectively. Moreover, soot and carbon dioxide (NO) are significantly reduced by 39.5% and 52.5%, respectively.

Effect of In-Cylinder Low-Pressure Direct Injection Strategy on the Atomization and Combustion Process of a Small-Scaled Gasoline Wankel Rotary Engine

Effect of In-Cylinder Low-Pressure Direct Injection Strategy on the Atomization and Combustion Process of a Small-Scaled Gasoline Wankel Rotary Engine

The effect of using different Biodiesel fuels on jet development in a Diesel engine

The fuel properties and the injection rate-shape play an important role in the improvement of the combustion process of Diesel engines. In this work, the influences of using the forthcoming renewable biodiesel fuels on fuel jet development utilizing a computer simulation model created with the AVL Hydsim software were studied. Biodiesel fuels B20, B30 and B100 were considered and compared with the original pure Diesel fuel D100. The injection system behaviour under research was that one existing on a tractor engine equipped with Delphi DP200 pump and Delphi injectors. Two engine speeds of 1400 rpm and 2400 rpm were considered representative for the engine operation. For these speeds, the fuel jet characteristics as penetration, spray cone angle and Sauter mean diameter were analyzed. It can emphasize that in similar conditions of needle lift and injection rate-shape variation the usage of biodiesel fuels does not significantly alter the injection pressure and the Sauter mean diameter. However, the specific physical properties of biodiesel fuels affect substantially the spray penetration and its cone angle.

Boosting the Combustion Process in an Ejector Bypass Pulsating Airbreathing Jet Engine

Boosting the Combustion Process in an Ejector Bypass Pulsating Airbreathing Jet Engine

Simulation study on the influence of fuel injection strategy on the soot emission of dual-injection engine

A 2.0T gasoline engine was modified to a dual-injection engine. Numerical simulation method is used to study the influence of fuel type and fuel injection strategy on the in-cylinder mixture formation process, combustion process and soot emission of dual-injection gasoline engine. The simulation results show that an appropriate increase in the intake port fuel injection ratio can improve the uniformity of the air-fuel mixture. Increasing the fuel injection ratio in the intake port of the dual-injection system, the proportion of fuel directly injected into the cylinder decreases and the oil film distribution in the cylinder is reduced. Among the three injection schemes, the flame front of the D85 injection scheme reaches the cylinder wall earliest, and the flame spreads faster; the soot mass fraction generation decreases with the decrease of the GDI injection ratio. In particular, the amount of soot generated under the D65GDI injection ratio is significantly reduced.

Sustainable aviation fuel from the perspective of long-term sustainability and development

The aim of the article is to create a SWOT analysis of the position of sustainable aviation fuels (SAF) as an innovative available product on the aviation fuel market and to evaluate its development and application in the coming years. The motivation for the analysis and subsequent creation of this work is the fact that the topic of sustainable aviation fuels is currently extremely actual and also relevant for the future of air transport, as well as the future of the ecosystem from the point of view of reducing the emission load caused by the emissions of aircraft engines, which have a non-negligible share of the ecological load our planet. Because the combustion process in aircraft engines is the main factor in the creation of emissions, alternative aviation fuels from sustainable sources have been developed in order to reduce them. Thanks to the analysis of the goals of the influential aviation manufacturers, we found that the attention paid to the implementation of sustainable fuel is currently and will be given increased attention in the future. Achieving this goal will be made possible through technological advances and governance adjustments in many companies affecting aviation, from aircraft and fuel manufacturers to institutions dealing with administrative matters affecting aviation.

Benzin-metanol (M5-M10) karışımlarının SI motorundaki performans üzerine deneysel bir araştırması

Methanol is one of the promising alternative fuels for spark-ignition engines. It has a high octane number, increasing the octane number of gasoline that influence engine setting parameters. Ignition timing and injection duration are two engine setting parameters that influence the combustion process and emission of spark-ignition engine, which are therefore fascinating to be studied. The main objective of this work was to improve the performance of gasoline-methanol blends in a spark-ignition engine, which was carried out by optimization of engine operational parameters, which were ignition timing and injection duration. Performance parameters measured in this study were engine torque, power, and specific fuel consumption. An emission parameter such as carbon dioxide, carbon monoxide, and unburnt hydrocarbons was measured to evaluate the combustion process. Test results were analyzed by comparing performance and emission parameters of the engine on its standard and optimized settings. The result obtained that optimized ignition timing and injection duration sets products in an increase in engine torque and power, which are up to 12.99% and 1.72%, respectively, and 7.29% decrease in specific fuel consumption than engine with standard-setting using the same fuel blend. In addition, there was a decrease of carbon monoxide in exhaust emission, and unburnt hydrocarbon was slightly increased.

Mathematical Modeling of the Working Process of a Two-Stroke Engine with Countermoving Pistons

Simulation of the working process of an internal combustion engine is the basis for all further calculations and studies of the engine. Of particular relevance is the availability of an adequate mathematical model of the engine process due to the fact that due to the trend of continuous improvement of engine performance, it is necessary to take into account many influencing factors to obtain a satisfactory result. The most complex and dependent on many physicochemical parameters is the process of combustion of fuel in the engine. Models of combustion in diesel engines can be divided into three groups: detailed models; empirical and semipemirical models. The analysis of world experience in research and mathematical modeling of combustion process in internal combustion engines is performed in the work. The advantages and disadvantages of different mathematical models are indicated. It is proposed to use a semi-empirical mathematical model of combustion which describes the differential characteristic of the combustion rate by two curves corresponding to the periods of the first flash and diffusion combustion. Use of such model simplifies performance of calculations and at the same time allows to receive qualitative results considering many factors of influence.

Pengaruh laju aliran biogas dan waktu penyalaan Terhadap kinerja motor bakar menggunakan sistem dual fuel pertamax-biogas

Fuels such as oil, coal and gas are non-renewable energy sources. For this reason, renewable energy sources are needed to replace these non-renewable energy sources. The use of biogas as a renewable energy source for gasoline motor fuel can be done using a dual fuel system (pertamax-biogas). Combustion on a gasoline engine with a dual fuel system will affect the resulting performance. The combustion process in the combustion engine is influenced by several factors including the biogas flow rate and ignition time. The purpose of this study was to determine the effect of biogas flow rate and ignition timing on the performance of a motorcycle engine with a dual fuel system. The method used in this study is an experimental study by testing the performance of a motorcycle engine using a dual fuel system with variations in the flow rate of biogas fuel 1 lpm, 2 lpm and 3 lpm and variations in ignition time of 11°, 13° and 15°. before TDC. From the results of the study it can be concluded that the biogas flow rate and ignition timing affect the performance of the motor. The highest power was obtained by varying the biogas flow rate of 2 lpm and ignition time of 15° before TDC, while the best specific fuel consumption was obtained at variation of the biogas flow rate of 3 lpm and ignition time of 15° before TDC.

Diesel exhaust particulate emissions and in vitro toxicity from Euro 3 and Euro 6 vehicles

Incomplete combustion processes in diesel engines produce particulate matter (PM) that significantly contributes to air pollution. Currently, there remains a knowledge gap in relation to the physical and chemical characteristics and also the biological reactivity of the PM emitted from old- and new-generation diesel vehicles. In this study, the emissions from a Euro 3 diesel vehicle were compared to those from a Euro 6 car during the regeneration of a diesel particulate filter (DPF). Different driving cycles were used to collect two types of diesel exhaust particles (DEPs). The particle size distribution was monitored using an engine exhaust particle sizer spectrometer and an electrical low-pressure impactor. Although the Euro 6 vehicle emitted particulates only during DPF regeneration that primarily occurs for a few minutes at high speeds, such emissions are characterized by a higher number of ultrafine particles (<0.1 μm) compared to those from the Euro 3 diesel vehicle. The emitted particles possess different characteristics. For example, Euro 6 DEPs exhibit a lower PAH content than do Euro 3 samples; however, they are enriched in metals that were poorly detected or undetected in Euro 3 emissions. The biological effects of the two DEPs were investigated in human bronchial BEAS-2B cells exposed to 50 μg/mL of PM (corresponding to 5.2 μg/cm2), and the results revealed that Euro 3 DEPs activated the typical inflammatory and pro-carcinogenic pathways induced by combustion-derived particles, while Euro 6 DEPs were less effective in regard to activating such biological responses. Although further investigations are required, it is evident that the different in vitro effects elicited by Euro 3 and Euro 6 DEPs can be correlated with the variable chemical compositions (metals and PAHs) of the emitted particles that play a pivotal role in the inflammatory and carcinogenic potential of airborne PM.

Development of a combustion reaction model for lubricant synthetic base oil by experimental and numerical methods

The synthetic base oil (SyBO) is the main component of lubricant oil, determining its basic physical and chemical properties, as well as impacting the pre-ignition, in-cylinder combustion and emission characteristics during the engine applications. Yet the involvement of SyBO in the engine combustion process is rarely investigated, primarily due to the lack of a proper combustion reaction model. The objective of the present study was to develop a fundamentally based combustion reaction model for SyBO, through the joint experimental and theoretical methods. A comprehensive set of experimental techniques was used to characterize the physicochemical properties of SyBO. Results showed that SyBO consisted of 13 large hydrocarbon molecules, ranging from C21 to C54, with mostly linear or lightly branched alkanes. A kinetic modeling approach was developed to systematically construct the reaction model for each component, which were then combined to create the full-component reaction model of SyBO. The accuracy of the thus-developed combustion reaction model was verified by a theoretically calculated ignition delay (ID) data and experimental measurements. The full-component model of SyBO was then reduced by the directed relation graph with error propagation (DRGEP) method to contain 87 species and 647 reactions. To further reduce the size of kinetic model as well as predict the physiochemical properties of SyBO, one surrogate molecule, i-C39H80, through the quantitative structure-property relationship (QSPR) of functional groups in SyBO, as well as one surrogate component, n-C54H110, were proposed. Again, the reaction model for the surrogate molecule was developed, verified, and then reduced to contain 73 species and 530 reactions, which might be applicable to computational fluid dynamics (CFD) simulations for practical engine systems.

Experimental study on the effect of water port injection on the combustion and emission characteristics of diesel/methane dual-fuel engines

In this study, the effect of water port injection on the combustion and emission characteristics of diesel/methane dual-fuel combustion was studied experimentally. Conventional dual-fuel engine combustion was extended and explored as tri-fuel combustion by introducing a water port injection. The experiments were conducted on a four-cylinder engine at 1600 r/min and low load with a brake mean effective pressure of 0.42 MPa. Six methane substitution ratios (MSRs) (0%, 10%, 20%, 30%, 40%, and 50%) were programmed. At each MSR point, five water-to-diesel in pure diesel mode mass ratios (WDMRs) (0%, 25%, 45%, 65%, and 85%) were arranged. The experimental results indicated that methane addition decreased the combustion intensity and retarded the combustion process of the diesel engine. In addition, methane addition and water port injection prolonged the ignition delay of the diesel engine. The larger the MSR, the longer was the ignition delay for the corresponding WDMR. Similarly, the larger the WDMR, the longer was the ignition delay for the corresponding MSR. For emissions, the number concentration of particles decreased owing to methane addition, whereas it increased owing to water injection. Notably, for the maximum MSR (50%) and WDMR (0.85) utilization, the maximum total number concentration was 94474 #/cm3, which is much lower than the minimum total number concentration in a pure diesel engine (118549 #/cm3). Furthermore, both methane addition and water injection significantly decreased the nitrogen oxide (NOx) emissions; however, they increased the CO and HC emissions. In summary, adding methane coupled with water injection is an effective method to decrease NOx and particle emissions simultaneously.

Optimization of multiple-stage fuel injection and optical analysis of the combustion process in a heavy-duty diesel engine

The goals of this study were to optimize multiple-stage fuel injections and optically analyze the effects of multiple injections of fuel on the combustion process in a heavy-duty compressed ignition engine. The engine experiments consisted of pilot injection and post-injection experiments. The pilot injection quantities and timings were varied. The post-injection quantities and number of post injections were analyzed. Combustion images was obtained to calculate the flame temperature and soot density. The results revealed that premixed combustion by a single injection led to engine noise and vibration because of the long ignition delay. The optimal pilot injection strategy improved the engine noise, vibration, thermal efficiency, and nitrogen oxide emissions. However, a pilot injection induced diffusion combustion, and an increase in particulate matter emissions was inevitable. The optimized post-injection promoted the oxidization of incomplete combustion materials and provided a lower peak cylinder pressure, resulting in low nitrogen oxides and particulate matter emissions. The combustion images revealed that the pilot injection caused a moderate increase in flame temperature and high soot production. The post injection, however, effectively reduced the soot density during the late combustion period, resulting in a low soot density at the end of the observation period.

Studies on the effects of bluff body materials in scramjet applications

This paper investigates the flame stabilization and mixing characteristics of non-premixed combustion of scramjet combustor with the trapezoidal bluff body materials. Due to less residence time and small space for the fuel-air mixing inside the combustor, the combustion process of the scramjet engine is incomplete and non-uniform. Stabilizing flames inside the scramjet combustor is difficult due to supersonic airspeeds. Flame holders are employed to stabilize flames inside the scramjet combustor. Bluff body materials flame holders are widely used in gas turbine engines as flame stabilization technique. The bluff body materials will create low-velocity recirculation zones, which will induce proper mixing of fuel-air and stabilize flames inside those recirculation zones. Thus, the combustion of scramjet combustors is enhanced using bluff body materials. The CFD analysis of the two-dimensional scramjet combustor with the trapezoidal bluff body materials is done using ANSYS Fluent. The flow parameters such as velocities, pressure drop, densities, and heat of reaction, turbulence, specific heats, mass fractions, and temperatures are plotted and studied. The combustion of scramjet combustor is enhanced by employing trapezoidal bluff body materials is evident in CFD results.

Analysis of Air Flow, Air and Fuel Induction for Internal Combustion Engine

In an internal combustion engine, performance, efficiency and emission formation depends on the formation of air-fuel mixture inside the engine cylinder. The fluid flow dynamics plays an important role for air-fuel mixture preparation to obtain the better engine combustion, performance and efficiency. This review article discuss the rotating flow (swirl and tumble) in premixed spark-ignition engine and its effect on turbulence generation and flame propagation. Rotating flow can substantially increase turbulence intensity for the duration of the combustion period. This review paper discusses the in-cylinder swirl and tumble flow that affects air induction during the combustion process in internal combustion engine. Alternatively, this study using computer simulation (Computational Fluid Dynamic, CFD) which offer the opportunity to carry out repetitive parameter studies. An integration-type flowmeter (IFM) also has been used which consists of ultrasonic flowmeter, that integrates the flowrate during the intake process, gives accurate measurements regardless of sampling time and frequency. Research parameter in this study was swirl and tumble that represents the fluid flow behavior occurred inside combustion chamber. Fuel injection and air mass also were the important parameters that have been discussed about in air induction process. The results obtain from the numerical analysis can be employed to examine the homogeneity of air-fuel mixture structure for better combustion process and engine performance.

Extreme Miller cycle with high intake boost for improved efficiency and emissions in heavy-duty diesel engines

This study experimentally investigates the impact of extreme Miller cycle strategies paired with high intake manifold pressures on the combustion process, emissions, and thermal efficiency of heavy-duty diesel engines. Well-controlled experiments isolating the effect of Miller cycle strategies on the combustion process were conducted at constant engine speed and load (1160 rpm, 1.76 MPa net IMEP) on a single cylinder research engine equipped with a fully-flexible hydraulic valve train system. Late intake valve closing (LIVC) timing strategies were compared to a conventional intake valve profile under either constant cylinder composition, constant engine-out NOx emission, or constant overall turbocharger efficiency ([Formula: see text]) to investigate the operating constraints that favor Miller cycle operation over the baseline strategy. Utilizing high boost with conventional intake valve closing timing resulted in improved fuel consumption at the expense of sharp increases in peak cylinder pressures, engine-out NOx emissions, and reduced exhaust temperatures. Miller cycle without EGR at constant [Formula: see text] demonstrated LIVC strategies effectively reduce engine-out NOx emissions by up to 35%. However, Miller cycle associated with very aggressive LIVC timings led to fuel consumption penalties due to increased pumping work and exhaust enthalpy. LIVC strategies allowed for increased charge dilution at the baseline NOx constraint of 3.2 g/kWh, resulting in significant fuel consumption benefits over the baseline case without compromising exhaust temperatures or peak cylinder pressures. As Miller cycle implementation was shown to affect the boundary conditions dictating [Formula: see text], the LIVC and conventional IVC cases were studied at an equivalent [Formula: see text] point representative of high boost operation. With high boost, LIVC yielded reduced NOx emissions, reduced peak cylinder pressures, and elevated exhaust temperatures compared to the conventional IVC case without compromising fuel consumption.

Experimental study of the ignition of lean methane/air mixtures using inductive and NRPD ignition systems in the pre-chamber and turbulent jet ignition in the main chamber

The optimization of the combustion process in spark ignition engines has led to novel strategies to ignite lean and low reactivity mixtures, such as the application of turbulent jet ignition and Nanosecond Repetitively Pulsed Discharge (NRPD) ignition systems and Turbulent Jet Ignition (TJI). In the present experimental work, an optically accessible setup was used to investigate the ignition occurrence and early flame development in the pre-chamber and subsequent main chamber ignition of methane/air mixtures at density conditions relevant to engine application. Two schlieren setups coupled with fast recording cameras allow the visualization of both the pre-chamber and main chamber.NRPD ignition with different pulse patterns in terms of pulse number and repetition frequency is applied in the pre-chamber. Conventional inductive ignition and NRPD-assisted ignition are compared for the first time in terms of flame development in the pre-chamber and hot jet ignition in main chamber. The effect of different air to fuel ratios is assessed in both laminar and turbulent pre-chamber conditions.Results show that while NRPD is always advantageous when compared to standard inductive ignition, the higher amount of energy added by increasing the number of pulses only affects the ignition success in very lean conditions, thus showing that increased energy is not the main governing mechanism for successful ignition. Irrespectively of the initial conditions (laminar or turbulent) in the pre-chamber, it is shown that an optimum jet velocity exists that ensures increased ignition probability in the main chamber, thus suggesting that mixing plays a major role in main chamber ignition. The combination of both techniques, NRPD and TJI, allowed assessing the optimum conditions in terms of number and frequency of NRPD pulses for a reliable ignition in lean conditions.

Effects of Different Biodiesel-Diesel Blend Fuel on Combustion and Emission Characteristics of a Diesel Engine

In this paper, biodiesel was used as an alternative fuel to investigate the combustion and emission characteristics of a four-stroke diesel engine, in terms of cylinder pressure, heat release rate, cylinder temperature, brake thermal efficiency, brake specific fuel consumption, nitrogen oxide, soot, carbon monoxide, and hydrocarbon. Firstly, a diesel engine cylinder model was developed by AVL-Fire software coupled with CHEMKIN code to simulate the injection and combustion of biodiesel with a kinetic mechanism with 106 species and 263 reactions. Then, the simulation model was validated by experimental results under 100% and 50% load conditions and used to simulate the combustion process of a diesel engine fueled with pure diesel, biodiesel, and biodiesel–diesel blends with 10%, 20%, 30% biodiesel by volume, respectively. The results showed that the brake specific fuel consumption increased with the increase of mixed biodiesel ratio. The brake specific fuel consumptions of B10, B20 and B30 increased by 1.1%, 2.3% and 3.3%, respectively, compared with that of D100. The combustion and emission characteristics of the diesel engine are improved. Therefore, biodiesel can be used as an alternative fuel for the diesel engine. The diesel–biodiesel fuel can improve the combustion and emission characteristics of the diesel engine.

Numerical study of injection strategy on the combustion process in a peripheral ported rotary engine fueled with natural gas/hydrogen blends under the action of apex seal leakage

To improve the combustion efficiency of the rotary engine fueled with natural gas/hydrogen blends, the effect of the injection strategy of the blended fuel on the combustion process in cylinder was studied. In addition, considering that apex seal leakage (ASL) is difficult to avoid in the actual working process of rotary engines, the action of ASL was considered in the study. Therefore, a 3D dynamic calculation model of a peripheral ported rotary engine considering the ASL was established. Based on the calculation model, the impact of the blended fuel injection position (BFIP) and the blended fuel injection timing (BFIT) on the combustion process was numerically researched. The results showed that when the fuel injection strategy was Case: B-150, whose BFIP was located at the intersection of the cylinder profile and the long axis with the BFIT of 150°CA (BTDC), the blended fuel was more distributed in the front of cylinder (FOC) and the middle of the cylinder (MOC) at the ignition timing, which effectively avoided the problem of the incomplete combustion in the back of the cylinder (BOC). Therefore, to optimize effectively the combustion performance of the rotary engine, the injection strategy of Case: B-150 was recommended in engineering applications.