Alternate Modes Combustion Study: HCCI Fueled With Heptane and Spark Ignition Fueled With Reformer Gas

2005 ◽  
Author(s):  
Vahid Hosseini ◽  
M. David Checkel
Keyword(s):  
Internal Combustion Engines ◽  
Emission Rate ◽  
Spark Ignition ◽  
Nox Emission ◽  
Combustion Stability ◽  
Specific Power ◽  
Si Engine ◽  
Engine Operation ◽  
Trade Offs ◽  
Reformer Gas

Homogenous Charge Compression Ignition (HCCI) combustion is an efficient operating mode for internal combustion engines operating at low specific power and has the further advantage of very low specific NOx emission rate. High Compression Lean Burn (HCLB) spark ignition (SI) provides a more conventional approach to achieving high engine efficiency. Specific NOx emission rates are low though not as low as with HCCI. Compared with HCCI engines, HCLB-SI engines have the advantage of direct combustion control, (through spark timing), and thus are able to start from cold and operate over a wider range of conditions including higher specific power than HCCI. On the other hand HCCI still has the advantage in efficiency and NOx emission rate. These trade-offs makes it desirable to develop an engine which can operate in either mode, hopefully without significantly adding to engine cost or compromising either mode. This paper presents a first exploration of a dual-mode engine which can use either HCCI or HCLB mode by operating on either a base, low-octane liquid fuel or on reformer gas (RG) produced by steam reforming or partial oxidation from the base fuel. Engine experiments with a CFR engine are used to demonstrate engine operation in both HCLB-SI and HCCI operating modes fueled with some combination of n-heptane and reformer gas. The combustion characteristics including combustion stability and cyclic variation are measured and compared for HCCI operation and RG-fueled HCLB-SI engine operation. CNG-fueled SI engine operation is also used as an additional basis for comparison.

Effect of Engine Variables on Combustion Performance of Lean Burn Spark Ignition Engine: An Overview

2002 ◽  
Author(s):  
A. Manivannan ◽  
R. Ramprabhu
Keyword(s):  
Internal Combustion Engines ◽  
Flow Characteristics ◽  
Exhaust Emissions ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Combustion Stability ◽  
Combustion Engines ◽  
Si Engine ◽  
Lean Burn ◽  
Lean Combustion

In the development of internal combustion engines, there has been a continuous effort to reduce fuel consumption and exhaust emissions. Lean combustion is a preferred concept for reducing exhaust emissions for meeting stringent emission standards. However lean combustion is associated with increased cycle-by-cycle combustion variation due to combustion instability. The combustion stability under lean mixture conditions could be improved through enhancement of flow characteristics. Effect of engine variables on lean combustion of Spark Ignition (SI) engine is presented, including combustion chamber and inlet port configuration, and ignition system. Use of pre-chamber for lean combustion is one of the feasible method to achieve stable ignition and quick flame propagation. This paper highlights and compares status of various research works carried out in the area of lean burn engines. A critical analysis of reported experimental data is presented in order to substantiate use of lean combustion in SI engine.

MODELING NANOSECOND-PULSED SPARK DISCHARGE AND FLAME KERNEL EVOLUTION

2021 ◽  
pp. 1-22
Author(s):  
Joohan Kim ◽  
Vyaas Gururajan ◽  
Riccardo Scarcelli ◽  
Sayan Biswas ◽  
Isaac Ekoto
Keyword(s):  
Electrical Discharge ◽  
Internal Combustion Engines ◽  
Initial Conditions ◽  
Fuel Mixture ◽  
Spark Ignition ◽  
Combustion Stability ◽  
Flame Kernel ◽  
Wide Range ◽  
Challenging Environment ◽  
Kernel Growth

Abstract Dilute combustion, either using exhaust gas recirculation or with excess-air, is considered a promising strategy to improve the thermal efficiency of internal combustion engines. However, the dilute air-fuel mixture, especially under intensified turbulence and high-pressure conditions, poses significant challenges for ignitability and combustion stability, which may limit the attainable efficiency benefits. In-depth knowledge of the flame kernel evolution to stabilize ignition and combustion in a challenging environment is crucial for effective engine development and optimization. To date, comprehensive understanding of ignition processes that result in the development of fully predictive ignition models usable by the automotive industry does not yet exist. Spark-ignition consists of a wide range of physics that includes electrical discharge, plasma evolution, joule-heating of gas, and flame kernel initiation and growth into a self-sustainable flame. In this study, an advanced approach is proposed to model spark-ignition energy deposition and flame kernel growth. To decouple the flame kernel growth from the electrical discharge, a nanosecond pulsed high-voltage discharge is used to trigger spark-ignition in an optically accessible small ignition test vessel with a quiescent mixture of air and methane. Initial conditions for the flame kernel, including its thermodynamic state and species composition, are derived from a plasma-chemical equilibrium calculation. The geometric shape and dimension of the kernel are characterized using a multi-dimensional thermal plasma solver. The proposed modeling approach is evaluated using a high-fidelity computational fluid dynamics procedure to compare the simulated flame kernel evolution against flame boundaries from companion schlieren images.

Effect of injection and ignition timing on a hydrogen-lean stratified charge combustion engine

2021 ◽  
pp. 146808742110346
Author(s):  
Sanguk Lee ◽  
Gyeonggon Kim ◽  
Choongsik Bae
Keyword(s):  
Internal Combustion Engines ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Combustion Stability ◽  
Transport Sector ◽  
Injection Timing ◽  
Ignition Timing ◽  
Particulate Emission ◽  
Stratified Charge ◽  
Lean Limit

Hydrogen can be used as a fuel for internal combustion engines to realize a carbon-neutral transport society. By extending the lean limit of spark ignition engines, their efficiency, and emission characteristics can be improved. In this study, stratified charge combustion (SCC) using monofueled hydrogen direct injection was used to extend the lean limit of a spark ignition engine. The injection and ignition timing were varied to examine their effect on the SCC characteristics. An engine experiment was performed in a spray-guided single-cylinder research engine, and the nitrogen oxide and particulate emissions were measured. Depending on the injection timing, two different types of combustion were characterized: mild and hard combustion. The advancement and retardation of the ignition timing resulted in a high and low combustion stability, respectively. The lubricant-based particulate emission was attributed to the in-cylinder temperature and area of the flame surface. Therefore, the results of the study suggest that the optimization of the hydrogen SCC based on the injection and ignition timing could contribute to a clean and efficient transport sector.

scholarly journals Effect of Cylinder-by-Cylinder Variation on Performance and Gaseous Emissions of a PFI Spark Ignition Engine: Experimental and 1D Numerical Study

2021 ◽  
Vol 11 (13) ◽  
pp. 6035
Author(s):  
Luigi Teodosio ◽  
Luca Marchitto ◽  
Cinzia Tornatore ◽  
Fabio Bozza ◽  
Gerardo Valentino
Keyword(s):  
Internal Combustion Engines ◽  
Numerical Study ◽  
Spark Ignition ◽  
Operating Conditions ◽  
Spark Ignition Engine ◽  
Combustion Stability ◽  
Pollutant Emissions ◽  
Gaseous Emissions ◽  
Performance And Emissions ◽  
The Impact

Combustion stability, engine efficiency and emissions in a multi-cylinder spark-ignition internal combustion engines can be improved through the advanced control and optimization of individual cylinder operation. In this work, experimental and numerical analyses were carried out on a twin-cylinder turbocharged port fuel injection (PFI) spark-ignition engine to evaluate the influence of cylinder-by-cylinder variation on performance and pollutant emissions. In a first stage, experimental tests are performed on the engine at different speed/load points and exhaust gas recirculation (EGR) rates, covering operating conditions typical of Worldwide harmonized Light-duty vehicles Test Cycle (WLTC). Measurements highlighted relevant differences in combustion evolution between cylinders, mainly due to non-uniform effective in-cylinder air/fuel ratio. Experimental data are utilized to validate a one-dimensional (1D) engine model, enhanced with user-defined sub-models of turbulence, combustion, heat transfer and noxious emissions. The model shows a satisfactory accuracy in reproducing the combustion evolution in each cylinder and the temperature of exhaust gases at turbine inlet. The pollutant species (HC, CO and NOx) predicted by the model show a good agreement with the ones measured at engine exhaust. Furthermore, the impact of cylinder-by-cylinder variation on gaseous emissions is also satisfactorily reproduced. The novel contribution of present work mainly consists in the extended numerical/experimental analysis on the effects of cylinder-by-cylinder variation on performance and emissions of spark-ignition engines. The proposed numerical methodology represents a valuable tool to support the engine design and calibration, with the aim to improve both performance and emissions.

A Numerical Simulation of Analysis of Backfiring Phenomena in a Hydrogen-Fueled Spark Ignition Engine

2016 ◽  
Vol 138 (10) ◽  
Author(s):  
K. A. Subramanian ◽  
B. L. Salvi
Keyword(s):  
Greenhouse Gas Emission ◽  
Hot Spot ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Intake Manifold ◽  
Injection Timing ◽  
Si Engine ◽  
Engine Operation ◽  
Study Results ◽  
Residual Gas

Hydrogen utilization in spark ignition (SI) engines could reduce urban pollution including particulate matter as well as greenhouse gas emission. However, backfiring, which is an undesirable combustion process of intake charge in hydrogen-fueled SI engine with manifold-based injection, is one of the major technical issues in view of safety of engine operation. Backfiring occurs generally during suction stroke as the hydrogen–air charge interacts with residual gas, resulting in flame growth and propagation toward upstream of engine's intake manifold, resulting in stalling of engine operation and high risk of safety. This work is aimed at analysis of backfiring in a hydrogen-fueled SI engine. The results indicate that backfiring is mainly function of residual gas temperature, start of hydrogen injection timing, and equivalence ratio. Any hot-spot present in the cylinder would act as ignition source resulting in more chances of backfiring. In addition to this, computational fluid dynamics (CFD) analysis was carried out in order to assess flow characteristics of hydrogen and air during suction stroke in intake manifold. Furthermore, numerical analysis of intake charge velocity, flame speed (deflagration), and flame propagation (backfiring) toward upstream of intake manifold was also carried out. Some notable points of backfiring control strategy including exhaust gas recirculation (EGR) and retarded (late) hydrogen injection timing are emerged from this study for minimizing chance of backfiring. This study results are useful for development of dedicated SI engine for hydrogen fuel in the aspects of elimination of backfiring.

Studying the effects of hydrogen addition on the second-law balance of a biogas-fuelled spark ignition engine by use of a quasi-dimensional multi-zone combustion model

2008 ◽  
Vol 222 (11) ◽  
pp. 2249-2268 ◽  
Author(s):  
C D Rakopoulos ◽  
C N Michos ◽  
E G Giakoumis
Keyword(s):  
Combustion Process ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Combustion Model ◽  
Second Law ◽  
Si Engine ◽  
Engine Operation ◽  
Hydrogen Addition ◽  
Cycle Simulation ◽  
Hydrogen Enrichment

Although a first-law analysis can show the improvement that hydrogen addition impacts on the performance of a biogas-fuelled spark-ignition (SI) engine, additional benefits can be revealed when the second law of thermodynamics is brought into perspective. It is theoretically expected that hydrogen enrichment in biogas can increase the second-law efficiency of engine operation by reducing the combustion-generated irreversibilities, because of the fundamental differences in the mechanism of entropy generation between hydrogen and traditional hydrocarbon combustion. In this study, an experimentally validated closed-cycle simulation code, incorporating a quasi-dimensional multi-zone combustion model that is based on the combination of turbulent entrainment theory and flame stretch concepts for the prediction of burning rates, is further extended to include second-law analysis for the purpose of quantifying the respective improvements. The analysis is applied for a single-cylinder homogeneous charge SI engine, fuelled with biogas—hydrogen blends, with up to 15 vol% hydrogen in the fuel mixture, when operated at 1500r/min, wide-open throttle, fuel-to-air equivalence ratio of 0.9, and ignition timing of 20° crank angle before top dead centre. Among the major findings derived from the second-law balance during the closed part of the engine cycle is the increase in the second-law efficiency from 40.85 per cent to 42.41 per cent with hydrogen addition, accompanied by a simultaneous decrease in the combustion irreversibilities from 18.25 per cent to 17.18 per cent of the total availability of the charge at inlet valve closing. It is also illustrated how both the increase in the combustion temperatures and the decrease in the combustion duration with increasing hydrogen content result in a reduction in the combustion irreversibilities. The degree of thermodynamic perfection of the combustion process from the second-law point of view is quantified by using two (differently defined) combustion exergetic efficiencies, whose maximum values during the combustion process increase with hydrogen enrichment from 49.70 per cent to 53.45 per cent and from 86.01 per cent to 87.33 per cent, respectively.

A Numerical Simulation of Analysis of Backfiring Phenomena in a Hydrogen Fuelled Spark Ignition Engine

2015 ◽  
Author(s):  
K. A. Subramanian ◽  
B. L. Salvi
Keyword(s):  
Hot Spot ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Intake Manifold ◽  
Injection Timing ◽  
Ignition Process ◽  
Si Engine ◽  
Engine Operation ◽  
Study Results ◽  
Residual Gas

Hydrogen utilization in spark ignition engines could reduce urban pollution including particulate matter as well as greenhouse gas (carbon dioxide) emission. However, backfiring, which is an undesirable combustion process of intake charge in hydrogen fuelled spark ignition (SI) engine with manifold based injection, is one of the major technical issues in view of safety as well as continuous engine operation as ignition process could proceed instantaneously due to less ignition energy requirement of hydrogen. Backfiring occurs generally during suction stroke as the hydrogen-air charge interacts with residual gas resulting in flame growth and propagation towards upstream of engine’s intake manifold resulting in stalling of engine operation and high risk of safety. This work is aimed at analysis of backfiring in a hydrogen fuelled SI engine. The results indicate that backfiring is mainly function of residual gas temperature, start of hydrogen injection timing and equivalence ratio. Any hot-spot present in the cylinder would act as ignition source resulting in more chances of backfiring. In addition to this, CFD analysis was carried out in order to assess flow characteristics of hydrogen and air during suction stroke in intake manifold. Furthermore, numerical analysis of intake charge velocity, flame speed (deflagration), and flame propagation (backfiring) towards upstream of intake manifold was also carried out. Some notable points of backfiring control strategy including exhaust gas recirculation (EGR) and retarded (late) hydrogen injection timing are emerged from this study for minimizing chance of backfiring. This study results are useful for development of dedicated spark ignition engine for hydrogen fuel in the aspects of elimination of backfiring.

Capturing Cyclic Variability in Exhaust Gas Recirculation Dilute Spark-Ignition Combustion Using Multicycle RANS

2016 ◽  
Vol 138 (11) ◽  
Author(s):  
Riccardo Scarcelli ◽  
James Sevik ◽  
Thomas Wallner ◽  
Keith Richards ◽  
Eric Pomraning ◽  
...  
Keyword(s):  
Internal Combustion Engines ◽  
Initial Conditions ◽  
Exhaust Gas Recirculation ◽  
Spark Ignition ◽  
Operating Conditions ◽  
Combustion Stability ◽  
Exhaust Gas ◽  
Cyclic Variability ◽  
Ignition Characteristics ◽  
Gas Recirculation

Dilute combustion is an effective approach to increase the thermal efficiency of spark-ignition (SI) internal combustion engines (ICEs). However, high dilution levels typically result in large cycle-to-cycle variations (CCV) and poor combustion stability, therefore limiting the efficiency improvement. In order to extend the dilution tolerance of SI engines, advanced ignition systems are the subject of extensive research. When simulating the effect of the ignition characteristics on CCV, providing a numerical result matching the measured average in-cylinder pressure trace does not deliver useful information regarding combustion stability. Typically large eddy simulations (LES) are performed to simulate cyclic engine variations, since Reynolds-averaged Navier–Stokes (RANS) modeling is expected to deliver an ensemble-averaged result. In this paper, it is shown that, when using RANS, the cyclic perturbations coming from different initial conditions at each cycle are not damped out even after many simulated cycles. As a result, multicycle RANS results feature cyclic variability. This allows evaluating the effect of advanced ignition sources on combustion stability but requires validation against the entire cycle-resolved experimental dataset. A single-cylinder gasoline direct injection (GDI) research engine is simulated using RANS and the numerical results for 20 consecutive engine cycles are evaluated for several operating conditions, including stoichiometric as well as exhaust gas recirculation (EGR) dilute operation. The effect of the ignition characteristics on CCV is also evaluated. Results show not only that multicycle RANS simulations can capture cyclic variability and deliver similar trends as the experimental data but more importantly that RANS might be an effective, lower-cost alternative to LES for the evaluation of ignition strategies for combustion systems that operate close to the stability limit.

scholarly journals A New Physics-Based Modeling Approach for a 0D Turbulence Model to Reflect the Intake Port and Chamber Geometries and the Corresponding Flow Structures in High-Tumble Spark-Ignition Engines

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1898 ◽  
Author(s):  
Yirop Kim ◽  
Myoungsoo Kim ◽  
Sechul Oh ◽  
Woojae Shin ◽  
Seokwon Cho ◽  
...  
Keyword(s):  
Turbulence Model ◽  
Large Scale ◽  
Turbulence Models ◽  
Spark Ignition ◽  
New Physics ◽  
Decay Rates ◽  
Operating Conditions ◽  
Combustion Stability ◽  
Spark Ignition Engines ◽  
Engine Operation

Turbulence is one of the most important aspects in spark-ignition engines as it can significantly affect burn rates, heat transfer rates, and combustion stability, and thus the performance. Turbulence originates from a large-scale mean motion that occurs during the induction process, which mainly consists of tumble motion in modern spark-ignition engines with a pentroof cylinder head. Despite its significance, most 0D turbulence models rely on calibration factors when calculating the evolution of tumble motion and its conversion into turbulence. In this study, the 0D tumble model has been improved based on the physical phenomena, as an attempt to develop a comprehensive model that predicts flow dynamics inside the cylinder. The generation and decay rates of tumble motion are expressed with regards of the flow structure in a realistic combustion chamber geometry, while the effects of port geometry on both charging efficiency and tumble generation rate are reflected by supplementary steady CFD. The developed tumble model was integrated with the standard k-ε model, and the new turbulence model has been validated with engine experimental data for various changes in operating conditions including engine speed, load, valve timing, and engine geometry. The calculated results showed a reasonable correlation with the measured combustion duration, verifying this physics-based model can properly predict turbulence characteristics without any additional calibration process. This model can suggest greater insights on engine operation and is expected to assist the optimization process of engine design and operating strategies.

Experimental thermal survey of automotive turbocharger

2018 ◽  
Vol 21 (5) ◽  
pp. 766-780 ◽  
Author(s):  
Seyed Shahabeddin Alaviyoun ◽  
Masoud Ziabasharhagh
Keyword(s):  
Heat Transfer ◽  
Internal Combustion Engines ◽  
Test Bench ◽  
Specific Power ◽  
Engine Test ◽  
Engine Test Bench ◽  
Engine Operation ◽  
Warm Up ◽  
Specific Power Output ◽  
Higher Temperature

Turbochargers are commonly used in the automotive industry due to their ability to increase the specific power output of internal combustion engines. Heat transfer from the turbine to the compressor can strongly influence the turbocharger performance. Therefore, it is essential to consider heat transfer properties of the turbochargers. Existing heat transfer models are generally limited to the specific situations on the turbocharger test rig or the engine test bench, which are different to the real conditions of engine operation in a vehicle. Accurate modeling and calculation of the heat transfer require a more precise measurement study. In this research, we evaluate the temperature distribution of the turbocharger walls using an engine test bench and also a vehicle that are both equipped with the same instrumented turbocharger. Thermocouple measurements and thermography pictures were used to determine the temperature distributions of the turbocharger. Different heat transfer phenomena of turbocharger have been measured and analyzed. In addition, the effect of heat transfer on compressor efficiency is investigated. Several tests have been conducted, including a vehicle on a flat surface and also during an uphill climb with a trailer load hitched. The results of vehicle warm-up test show that the compressor housing has a higher temperature gradient in comparison with the engine test bench. The velocity of the air around the turbocharger is a factor that contributed toward the differences between an engine test bench and typical vehicle conditions.

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