SI Engine Research Articles

Experimental Investigation of the Influence of Engine Operating Parameters on a Rankine Based Waste Heat Recovery System in a SI Engine

Experimental Investigation of the Influence of Engine Operating Parameters on a Rankine Based Waste Heat Recovery System in a SI Engine

Effect of Fuel-Air Mixture Dilution on Knock Intensity in an SI Engine

Effect of Fuel-Air Mixture Dilution on Knock Intensity in an SI Engine

Computational singular perturbation analysis of super-knock in SI engines

Pre-ignition engine cycles leading to super-knock were simulated with a 48 species skeletal iso-octane mechanism to identify the dominant reaction pathways that are present in super-knock. To mimic pre-ignition, a deflagration front was generated via a hot spot that is placed over the piston at close proximity to the end-wall. Computational singular perturbation (CSP) was used to analyze the chemical dynamics at various in-cylinder locations: a point at the center of the cylinder where the deflagration front consumes the air/fuel mixture and two points located at 3 mm from the end-wall where super-knock and mild knock occur. The CSP analysis of the point at the center of the cylinder reveals weak two-stage ignition-like dynamics with a short second stage. At the other points, a pronounced two-stage ignition is displayed with a long second stage. A distinct contribution of formaldehyde (CH2O) at the second stage of ignition that adds to fast explosive modes in the super-knock points is not observed in the point at the center. A comparison between knock and super-knock analysis indicates that a similar set of reactions is responsible for the abnormal behavior but the fast explosive time scales are comparatively slower for knock, indicating lower reactivity, which results in the reduced intensity of knock. The analyzed results decoded important reactions responsible for the occurrence of super-knock.

Numerical and experimental investigation of post-oxidation of a four-stroke SI engine under fuel-rich conditions

The calibration of high-performance engines is a delicate task. During this procedure certain load points occur when the engine is running on fuel rich mixture. Temperature measurements have shown, that under these conditions the exhaust gas temperature right behind the exhaust valves is lower than in the junction where the separated exhaust pipes merge. This phenomenon is hardly investigated in the state-of-the-art literature and is the purpose of this work. Measurements of the exhaust gas composition at various positions are conducted for further analysis. It can be shown that the amount of hydrocarbon emissions (HC) is reduced significantly with increasing residence time in the exhaust pipes. It can be concluded post-combustion occurs which leads to an additional heat input and a temperature increase of approximately 120 K in the exhaust duct.Numerical methods are used in this work to investigate this effect. Principle studies which focus on premixed combustion models are carried out. For this reason, the experimental results obtained by the Sandia D flame model are used for validation. Finally, the transient flow conditions within the exhaust manifold are investigated. The transient boundary conditions are gained from a 1D GT-Power Simulation and are simplified for the 3D Computational Fluid Dynamics (CFD) Simulation. A very time efficient method is shown to compute the heat release within the exhaust pipes in dependence on the exhaust gas composition.The results point out, that post-combustion occurs at the junction and is strongly influenced by the grade of turbulence. The measured reduction of HC, O2 and CO, as well as the increase of CO2 can be reproduced in the simulation. Moreover, the temperature increase in the numerical simulation is similar as indicated by the measurements.

Research on the reaction progress of thermodynamic combustion based on arc and jet plasma energies using experimental and analytical methods

Plasma energies are a promising technique to increase IC engine performance, expend lean burn flame area, reduce exhaust gas, and enhance engine power. In particular, SI engines using combustion process can obtain the positive air, fuel and ignition sources, and international research organizations are intensively conducting research on new combustion in order to increase the performance for IC engines regarding solution methods that could ensure more stable combustion energies. These authors were conducted on arc and jet plasma energies in order to improve the reaction progress of thermodynamic combustion, where the unburned process in chemical state was changed from plasma signal, density, flame, temperature, and velocity, through experiment and analysis at rarefied mixture values of air and fuel excess ration (ϕ) from air and C3H8 after transmitting with discharge energies based on arc and jet plasma sources. Experimental and analytical methods were transmitted as high 1.2 J energy, where the strength of plasma volume was discharged between positive and negative electrodes to arc plasma, and jet plasma was monitored from reaction progress results as transmitting as 2.03 J energy higher than arc energy in order to have characteristics of directivity. Experimental and analytical conditions were set equally for combustion mixture ratio, which was changed at rarefaction from initial pressure of 4 bar, plasma duration 0.0015 s, plasma plug gap 1 mm, and mass fraction (ϕ) 1.0, 1.2, 1.4 and 1.6. Reaction progress results were noticeable in that jet plasma was influenced more by fast advantages to expend the laminar flame with various waves in an unburned process than arc plasma of combustion response time from thermal diffusion with transient temperature change, plasma volume energy, and jet plasma had more advantages for rarefied combustion state from various energies as changed mass fraction rates (ϕ = 1.0, 1.2, 1.4 and 1.6) by initial jet. Consequentially, density result is noticeable in that jet plasma was quickly changed by a chemical equilibrium of density higher than arc plasma energy.

Kaji Eksperimental Rasio Metanol-Bensin Terhadap Konsumsi Bahan Bakar, Emisi Gas Buang, Torsi Dan Daya

Methanol (CH3OH) is the one of an alternative fuel for SI engine. Methanol has a similiar charakteristic and fisik properties to gasoline. This study using methanol-gasoline fuel blend (M10, M20 and M40). The aim of this study was to determine the effect of using methanol-gasoline fuel blend of fuel consumption, exhaust emission, power and torque. In the experiment, an engine three-cylidre 12 valve with tecnology DOHC Mivec and ECI MPI injection System 1193 cc was used. With a little modification that is using methanol controler to maximize the result of research. The experimental result showed that the fuel consumption decrease with the use of methanol-gasoline ful blend. Each of these reductions in fuel consumption for the M10, M20 and M40 are 1 %, 3% dan 3%. The Power and Torque is increas while using fuel blend than gasoline and it also decrease exhaust emission

An effect of alcohol-plastic oil petrol blends on SI engine performance and exhaust emissions

Energy is becomes a vital and crucial parameter in many technical, commercial and self-development sectors of an individualistic in any countries. In this context, fossil fuels are devaluing and their costs are rises and hovering. While generating energy from the existing fossil fuels not alone economically infeasible but also provoke many sensitive environmental issues. Along with emissions from automobile sector, one of the other culprits in eco system is disposal of waste plastics. To meet the acute energy needs with eco-balance is utilizing plastic oil as functional fuel to run the engines. In the present work experimental investigations are carried out on multi cylinder petrol engine operating with 25 % plastic pyrolysis oil, with and without alcohol additives at 5 % volume basis is blended with petrol. It is noticed from the experimental results that, the engine performance with methanol additive is improved by 8.1 % than petrol and 21.74 % compared to without additive in plastic oil blend. Hydrocarbon emissions are substantially controlled by 54 % compared to petrol and 34.59 % than without additive in plastic oil blend at full load condition.

CFD–CHT calculation method using Buckingham Pi-Theorem for complex fluid–solid heat transfer problems with scattering boundary conditions

A three-dimensional CFD–CHT simulation method is presented and validated with a turbocharged single cylinder SI engine. Various ignition time and lambda strategies as well as variations of boost pressure are investigated with regard to cycle averaged component temperatures. This complements existing published works which experimentally studied crank angle resolved heat fluxes or temperature swings rather than averaged temperatures. Cyclical fluctuations in the pressure curves were measured and processed statistically using probability density functions for the heat transfer coefficient and the cylinder gas temperature. The corresponding joint probability density function considers their strong correlation. The interpretation as random variables enables a time-scale separation with a low-pass filter function. The thermomechanical problem of heat transfer is addressed with simplified models according to Woschni, Eichelberg, and Hohenberg. Previous investigations primarily focused on their predictive quality of instantaneous in-cylinder heat fluxes. In this paper, their effect on cycle averaged component temperatures is investigated and the corresponding different sensitivities to specific engine settings are presented and compared with measurements. It is shown that, by choosing the right model, the suggested simulation approach is an alternative to prevailing experimental methods in temperature analysis: all thermodynamic variations examined are in good agreement with theoretical predictions.

The effect of inlet temperature and spark timing on thermo-mechanical, chemical and the total exergy of an SI engine using bioethanol-gasoline blends

Exergy is a quantity of the work potential of energy from a given thermodynamic condition. Unlike energy, exergy can be destroyed, and for gasoline engines, the major source of this destruction is during the combustion process. Therefore, to assess the quality of gasoline engines, the research team examined the effect of inlet temperature and spark timing on chemical, thermo-mechanical and total exergy of fuel using E0, E20, E40, E60 and E85 fuels. Results showed that by advancing the spark timing (20° bTDC), thermo-mechanical exergy has increased but chemical exergy and total exergy have decreased. In addition, advance or delay in spark timing had no effect on the fuel chemical exergy for the compression and expansion strokes. The effect of temperature on exergy parameters indicated that by reducing inlet temperature (320 K), exergy parameters increased. In other words, the fuel chemical exergy at 320 K for E0, E20, E40, E60 and E85 fuels, increased by 7%, 7.1%, 7.2%, 7.2%, 7.3%, respectively, than 350 K and increased by 14%, 14.3%, 14.4%, 14.4% and 14.5% than 380 K.

Study of Spark-Ignition Engine Fueled with Hydrogen Produced by the Reaction Between Aluminum and Water in Presence of KOH

Hydrogen is seen as one of the important energy vectors of the century. There are several alternatives procedures to produce it in high purity; aluminum corrosion could be considered as one of the most attractive ones. The use of hydrogen derived with this process in spark-ignition engines forms a promising approach to decarbonize hydrogen production and secure domestic energy supply. This study describes the development of an experimental setup for hydrogen production and testing a SI engine in the hydrogen-fueled mode. This paper investigates the effect of aluminum thickness (specific surface) and alkali concentration on the reaction rate. The experimental results show that an increase in alkali concentration and a reduction in aluminum thickness increase hydrogen production rate. The produced hydrogen was used as fuel for a single-cylinder spark-ignition engine. The experiments were conducted under various engine speeds. It is found that hydrogen combustion produces a lower exhaust gas temperature than gasoline, although $$\hbox {NO}_{{x}}$$ emissions decrease about 11 times compared to gasoline. It was expected that CO, $$\hbox {CO}_{2}$$ and HC levels are zero when the engine is supplied with hydrogen, but it is found that there is a slight trace of CO, $$\hbox {CO}_{2}$$ and HC due to combustion and evaporation of lubricant on cylinder walls.

Study on combustion and emission characteristics of a n-butanol engine with hydrogen direct injection under lean burn conditions

The n-butanol fuel, as a renewable and clean biofuel, could ease the energy crisis and decrease the harmful emissions. As another clean and renewable energy, hydrogen properly offset the high HC emissions and the insufficient of dynamic property of pure n-butanol fuel in SI engines, because of the high diffusion coefficient, high adiabatic flame velocity and low heat value. Hydrogen direct injection not only avoids backfire and lower intake efficiency but also promotes to form in-cylinder stratified mixture, which is helpful to enhance combustion and reduce emissions. This experimental study focused on the combustion and emissions characteristics of a hydrogen direct injection stratified n-butanol engine. Three different hydrogen addition fractions (0%, 2.5%, 5%) were used under five different spark timing (10° ,15° ,20° ,25° ,30° CA BTDC). Engine speed and excess air ratio stabled at 1500 rpm and 1.2 respectively. The direct injection timing of the hydrogen was optimized to form a beter stratified mixture. The obtained results demonstrated that brake power and brake thermal efficiency are increased by addition hydrogen directly injected. The BSFC is decreased with the addition of hydrogen. The peak cylinder pressure and the instantaneous heat release rate raises with the increase of the hydrogen addition fraction. In addition, the HC and CO emissions drop while the NOx emissions sharply rise with the addition of hydrogen. As a whole, with hydrogen direct injection, the power and fuel economy performance of n-butanol engine are markedly improved, harmful emissions are partly decreased.

Engine speed and air-fuel ratio effect on the combustion of methane augmented hydrogen rich syngas in DI SI engine

Abstract The main challenge on the fueling of pure hydrogen in the automotive vehicles is the limitation in the hydrogen separation from the product of steam reforming and gasification plants and the storage issues. On the other hand, hydrogen fueling in automotive engines has resulted in uncontrolled combustion. These are some of the factors which motivated for the fueling of raw syngas instead of further chemical or physical processes. However, fueling of syngas alone in the combustion chamber has resulted in decreased power output and increased in brake specific fuel consumption. Methane augmented hydrogen rich syngas was investigated experimentally to observe the behavior of the combustion with the variation of the fuel-air mixture and engine speed of a direct-injection spark-ignition (DI SI) engine. The molar ratio of the high hydrogen syngas is 50% H2 and 50% CO composition. The amount of methane used for augmentation was 20% (V/V). The compression ratio of 14:1 gas engine operating at full throttle position (the throttle is fully opened) with the start of the injection selected to simulate the partial DI (180° before top dead center (BTDC)). The relative air-fuel ratio (λ) was set at lean mixture condition and the engine speed ranging from 1500 to 2400 revolutions per minute (rpm) with an interval of 300 rpm. The result indicated that coefficient of variation of the indicate mean effective pressure (COV of IMEP) was observed to increase with an increase with λ in all speeds. The durations of the flame development and rapid burning stages of the combustion has increased with an increase in λ. Besides, all the combustion durations are shown to be more sensitive to λ at the lowest speed as compared to the two engine speeds.

Knock Phenomena under Very Lean Conditions in Gasoline Powered SI-Engines

Homogeneous lean operation is a well-known strategy for enhancing the thermal efficiency of SI-engines. At higher load points the efficiency is often compromised by the need to suppress knock. Experiments were performed to determine the knock characteristics of SI engines using homogeneous lean operation at λ values of up to 1.8 with various hardware configurations that are commonly used to increase the lean limit. Changing λ altered the eigenfrequencies of the combustion chamber and the highest energy excitation mode. Increasing λ from 1.0 to 1.2 increased the knock tendency and led to an earlier knock onset. However, further increases in λ significantly reduced the knock tendency and retarded the knock onset. The knock signal energy increased for higher λ values and constant knock tendencies. The differences in knock characteristics between the various λ values became more pronounced upon raising the intake temperature from 40 °C to 90 °C. The trends in knock tendency and knock onset largely parallels that observed for engine out NOxemissions and thus the NOxconcentration in the internal EGR. The increased knock signal energy under lean conditions is partly attributed to the change in eigenfrequencies in the combustion chamber.

Exhaust noise, performance and emission characteristics of spark ignition engine fuelled with pure gasoline and hydrous ethanol gasoline blends

The exhaust noise, performance and emission characteristics of a gasoline engine fuelled by hydrous ethanol gasoline with 10%, 20% hydrous ethanol by volume (E10W and E20W) and pure gasoline (E0) were experimentally investigated. The tests were performed at full load and different engine speeds varying from 1500 rpm to 5000 rpm. The results showed that compared with E0, E10W and E20W had much lower exhaust noise at low engine speeds. With the increase of engine speed, E0 showed an advantage in low exhaust noise. However, engine fuelled with three fuels displayed comparable noise emissions at high speed. In addition, better thermal efficiency, significantly decreased CO and HC emissions were achieved by hydrous ethanol gasoline at all tested operating conditions. However, significant NOx emission and slight BSFC were observed for E10W and E20W. Compared with E20W, E10W showed decreased BSFC, HC and NOx emissions with the increase of engine speed, while CO emission was only slightly increased. Hydrous ethanol gasoline was capable of realizing comparable torque and power with E0 at all operating conditions. From the results above, hydrous ethanol gasoline could be considered as a promising alternative for SI engine. What's more, E10W exhibits enhanced performance.

Fuel film thickness measurements using refractive index matching in a stratified-charge SI engine operated on E30 and alkylate fuels

This study shows fuel film measurements in a spark-ignited direct injection engine using refractive index matching (RIM). The RIM technique is applied to measure the fuel impingement of a high research octane number gasoline fuel with 30 vol% ethanol content at two intake pressures and coolant temperatures. Measurements are conducted for an alkylate fuel at one operating case, as well. It is shown that the fuel volume on the piston surface increases for lower intake pressure and lower coolant temperature and that the alkylate fuel shows very little spray impingement. The fuel films can be linked to increased soot emissions. A detailed description of the calibration technique is provided and measurement uncertainties are discussed. The dependency of the RIM signal on refractive index changes is measured. The RIM technique provides quantitative film thickness measurements up to 0.9 µm in this engine. For thicker films, semi-quantitative results of film thickness can be utilized to study the distribution of impinged fuel.

Impact of fusel oil moisture reduction on the fuel properties and combustion characteristics of SI engine fueled with gasoline-fusel oil blends

Abstract In this study, statistical analysis was used to reveal the significant relation between fuel properties and the reduction of moisture contents at a various fraction of fusel oil in the blend. In addition to this, it is also aimed to conduct a comparative study on the effect of the fuel properties on the combustion characteristics before and after moisture extraction from fusel oil. The moisture content of fusel oil was extracted by employing rotary extractor method, and the fuels were tested in an SI engine under different open throttle valve position (load) and 4500 rpm speed of the engine. As a result, the heating value and carbon content improved significantly after extracting the moisture content from fusel oil by 13% and 7% respectively. According to the statistical analysis of test fuel properties results, the heating value, oxygen, and carbon content have statistically significant effects on the test fuels as the fraction of fusel oil increased especially after moisture extraction. Furthermore, the brake power and BSFC observed to be improved by extracting the moisture content with shorter combustion durations. Almost all fusel oil-gasoline blends have lower COV IMEP at all engine loads compared to pure gasoline.

Comparative analysis of the Performance and Emission Characteristics of ethanol-butanol-gasoline blends

Global warming and energy security being the global problems have shifted the focus of researchers on the renewable sources of energy which could replace petroleum products partially or as a whole. Ethanol and butanol are renewable sources of energy which can be produced through fermentation of biomass. A lot of research has already been done to develop suitable ethanol-gasoline blends. In contrast very little literature available on the butanol-gasoline blends. This research focuses on the comparison of ethanol-gasoline fuels with butanol-gasoline fuels with regard to the emission and performance in an SI engine. Experiments were conducted on a variable compression ratio SI engine at 1600 rpm and compression ratio 8. The experiments involved the measurement of carbon monoxide, carbon dioxide, oxides of nitrogen and unburned hydrocarbons emission and among performance parameters brake specific fuel consumption and brake thermal efficiency were recorded at three loads of 2.5kgs (25%), 5kgs (50%) and 7.5kgs (75%). Results show that ethanol and butanol content in gasoline have decreased brake specific fuel consumption, carbon monoxide and unburned hydrocarbon emissions while the brake thermal efficiency and oxides of nitrogen are increased. Results indicate thatbutanol-gasoline blends have improved brake specific fuel consumption, carbon monoxide emissions in an SI engine as compared to ethanol-gasoline blends. The carbon dioxide emissions and brake thermal efficiencies are comparable for ethanol-gasoline blends and butanol-gasoline blends. The butanol content has a more adverse effect on emissions of oxides of nitrogen than ethanol.

“Dedicated EGR”による高効率天然ガスSI エンジンの可能性

“Dedicated EGR”による高効率天然ガスSI エンジンの可能性

Effects of Exhaust Gas Recirculation on Performance and Emission Characteristic of SI Engine using Hydrogen and CNG Blends

This paper shows exhaust gas recirculation (EGR) effects on multi-cylinder bi-fuel SI engine using blends of 0, 5, 10 and 15% hydrogen by energy with CNG. All trials are performed at a speed of 3000, 3500 and 4000 rpm with EGR rate of 0, 5, 10 and 15%, with equal spark timing and injection pressure of 2.6 bar. At specific hydrogen percentage with increase in EGR rate NOx emission reduces drastically and increases with increase in hydrogen addition. Hydrocarbon (HC) and carbon monoxide (CO) emission decreases with increase in speed and hydrogen addition. There is considerable improvement in brake thermal efficiency (BTE) and brake specific energy consumption (BSEC) at 15% EGR rate. At 3000 rpm, 5% EGR rate with 5% hydrogen had shown maximum cylinder pressure. Brake specific fuel consumption (b.s.f.c) increased with increase in EGR rate and decreased with increase in hydrogen addition for all speeds.

Understanding chemistry-specific fuel differences at a constant RON in a boosted SI engine

The goal of the US Department of Energy Co-Optimization of Fuels and Engines (Co-Optima) initiative is to accelerate the development of advanced fuels and engines for higher efficiency and lower emissions. A guiding principle of this initiative is the central fuel properties hypothesis (CFPH), which states that fuel properties provide an indication of a fuel’s performance, regardless of its chemical composition. This is an important consideration for Co-Optima because many of the fuels under consideration are from bio-derived sources with chemical compositions that are unconventional relative to petroleum-derived gasoline or ethanol. In this study, we investigated a total of seven fuels in a spark ignition engine under boosted operating conditions to determine whether knock propensity is predicted by fuel antiknock metrics: antiknock index (AKI), research octane number (RON), and octane index (OI). Six of these fuels have a constant RON value but otherwise represent a wide range of fuel properties and chemistry. Consistent with previous studies, we found that OI was a much better predictor of knock propensity that either AKI or RON. However, we also found that there were significant fuel-specific deviations from the OI predictions. Combustion analysis provided insight that fuel kinetic complexities, including the presence of pre-spark heat release, likely limits the ability of standardized tests and metrics to accurately predict knocking tendency at all operating conditions. While limitations of OI were revealed in this study, we found that fuels with unconventional chemistry, in particular esters and ethers, behaved in accordance with CFPH as well as petroleum-derived fuels.