Effect Of Spark Timing Research Articles

Combustion and emissions of an ammonia heavy-duty engine with a hydrogen-fueled active pre-chamber ignition system

Combustion and emission characteristics of a heavy-duty single-cylinder ammonia engine with a hydrogen-fueled active pre-chamber ignition system are investigated experimentally at the condition of IMEP 10 bar, 1000 rpm, where effects of spark timing, excess air ratio (λ), and hydrogen energy ratio are tested. Three distinguishable combustion phases are observed, including pre-chamber combustion, turbulent-jet-controlled combustion, and ammonia-chemical-kinetics-controlled combustion. Advancing spark timing makes combustion phases earlier, increasing pressure rise rate, combustion pressure, and NOx emissions. The optimal spark timing for the highest indicated thermal efficiency (ITE) is −12°CA ATDC in the experiment. λ range for stable combustion is 1.1–1.5 and ITE peaks at λ = 1.3. The hydrogen energy ratio, 7.9%∼10.5%, has little influence on the engine performance. However, a low hydrogen energy ratio could increase the risk of misfire. The optimal hydrogen energy ratio is about 9∼10%.

Technical and economic modeling of a trigeneration system with EF7 engine as a prime mover

In this paper, a comprehensive technical and economic modeling of a trigeneraion system based on a gas engine named EF7 is presented. The innovation is presenting a differential model with high accuracy which considers the effects of spark timing in half-load and full-load modes on the system technical performance, including specific fuel consumption, and the economic performance of the system, including fuel cost savings, investment payback period, net present value and internal rate of return.From economic viewpoint, at half-load condition and optimal spark timing (18° CA BTDC), the system will reach profitability after 8 years. From technical viewpoint, at half-load condition, the spark timing should be more advanced (24° CA BTDC) and the overall specific fuel consumption is 103.24 gr/kWh.But, at full-load mode and optimum ignition timing (18° CA BTDC), the economic performance has improved and with 10% inflation rate, the system can reach profitability after 4 years. Also, after 7 and 10 years, the profit values are $42,300 and $80,500, respectively and internal rate of return values of 22 and 26%, respectively. Also, from technical viewpoint, at full-load condition and optimal spark timing (22° CA BTDC) the minimum amount of overall specific fuel consumption is 110.42 gr/kWh.

Effect of spark timing on the pre-chamber jet ignition in a lean-burn natural gas engine

An enhanced combustion concept, pre-chamber jet ignition can provide high ignition energy and a wide dispersion of ignition sources, thus improving combustion performance and realizing stable lean combustion. However, the ignition performance of the pre-chamber jets depends strongly on the pre-chamber combustion process and is sensitive to many factors. Therefore, this paper will explore the impact of spark timing on the pre-chamber combustion, turbulent jet characteristics, and main chamber combustion performance by CFD simulation based on an active pre-chamber natural gas engine. The in-cylinder flow and combustion processes of the engine are calculated with the fuel-air equivalence ratio of the main chamber maintained at 0.5, and the spark timing varied from 684°CA to 708°CA with a step of 3°CA (compression top dead center is 720°CA). The results show that, in the present engine operating point, the pre-chamber combustion heat release rate is improved when the spark timing is retarded from 696°CA to 705°CA, and the injection velocity of the pre-chamber jet accordingly increases. As the spark timing continues to be delayed until 708°CA, the pre-chamber combustion deteriorates, and the injection velocity of the pre-chamber jet decreases. Under the combustion phase CA50 no more than 725°CA and the combustion duration CA5-90 fixed around 30°CA, the IMEP will maintain a relatively stable value when the spark timing is delayed from 693°CA to 705°CA, in the meantime, the NOx emission decreases with the delay of spark timing. Therefore, on the premise of ensuring engine power performance, it is a feasible scheme to delay spark timing to reduce NOx emission for the natural gas engine with an active pre-chamber.

A Preliminary Study of Spark-Ignition System for Free-Piston Linear Engine

In recent years, the free-piston linear engine (FPLE) has attracted increasing interest from researchers worldwide. With the development of computer control technology, internal combustion engine technology, and material science, there have been significant advances in the aspects of FPLE simulation, experimental techniques, as well as systems FPLE control. This paper presents a model of a two-stroke, spark-ignition free-piston engine converted from two small two-stroke engines. It has a bore size of 34 mm and a maximum stroke of 28 mm. The linear engine uses gasoline fuel that is available on the market. The purposes of the research show a model of the starting system, investigation the effects of spark timing, and effective pressure. A premixed air-fuel charge is conducted by a carburetor then it is directly supplied into each cylinder. The spark timing was varied at 1 mm and 2 mm away from the maximum top dead center with the speed starting at 10 Hz. The model successfully ignited with a maximum pressure of 7.5 kg/cm2 at the ignition of 1 mm before top dead center (TDC) and 9.5 kg/cm2 at the ignition of 2 mm before TDC. The research has completed the initial intentions such as a theoretical investigation, calculation, determination of the engine model, and starting mechanism. Preliminary results have confirmed the feasibility of proposing the FPLE model.

Effects of knock intensity measurement technique and fuel chemical composition on the research octane number (RON) of FACE gasolines: Part 2 – Effects of spark timing

The Research and Motor Octane Number (RON, MON) characterize a fuel’s knock resistance by rating the knock intensity of a sample fuel relative to that of Primary Reference Fuels (PRF) in a Cooperative Fuel Research (CFR) Engine. A fuel’s octane number is regulated to prevent damage from autoignition leading to knocking combustion in spark-ignition engines. The operational differences between the standard RON rating and modern engine operation are explored in a three-part publication series. The previous study focused on the effects of lambda and knock characterization. This second study primarily focuses on the effects of spark timing on RON determination. Following the findings from the first publication, the knock intensity was captured by the knockmeter and by the maximum amplitude of pressure oscillations (MAPO) at the lambda of peak knock intensity and stoichiometry. Knock-limited spark advance tests were conducted for a set of seven Fuels for Advanced Combustion Engines (FACE) from the Coordinating Research Council (CRC) with varying chemical composition, PRFs, and Toluene Standardization Fuels (TSFs). For retarded spark timings, pre-spark low-temperature heat release was found for low RON PRFs. Low RON PRFs also showed knocking characteristics before reaching the center of combustion suggesting that the use of knock-limited spark advance (KLSA) was preferred over the knock-limited combustion phasing. Primarily paraffinic fuels tended towards increased pressure oscillations while dominantly aromatic fuels experienced higher pressure rise rates. A MAPO-based KLSA correlated best to Octane Index at a negative K-factor suggesting beyond RON operation despite being at otherwise RON conditions. At stoichiometry, the MAPO-based KLSA did neither correlate to RON nor Octane Index. Good agreement was found between KLSA-based effective RON from this study to the MAPO-based effective RON from the first study.

Effect of Spark Timing on the Combustion Stages Seen in a Heavy-Duty Compression-Ignition Engine Retrofitted to Natural Gas Spark-Ignition Operation

Effect of Spark Timing on the Combustion Stages Seen in a Heavy-Duty Compression-Ignition Engine Retrofitted to Natural Gas Spark-Ignition Operation

Evaluating Emission Characteristics from Vehicles at Road Test with Different Operating Conditions.(Dept.M)

The present work aims to introduce a new method to evaluate emission characteristics from vehicles al road test condition. The technique is characterized by introducing unique factors representing the equivalent toxic effect of the exhaust species. The method depends on measuring the concentration of exhaust species and calculating a factor called 'conditioned ton taking into consideration the toxic weight of each species relative to CO. For this purpose, a series of measurements were carried out on a specified vehicle to prevent vehicle to-vehicle variation. The vehicle is equipped with an infrared gas analyzer and a magnetic pickup transducer to measure the concentration of exhaust constituents and engine rotational speed, respectively. The measurements were conducted at different vehicle speed and gearshift. The effect of spark timing and tire pressure was also examined. The results indicate that most of the carbon monoxide and unburned hydrocarbons emission appears at higher load as well as near the idling speed, which appears clearly as increase in the relative conditioned ton. The gearshift gives significant effect on the emission considering its analogy with engine load. Retarding the spark timing offers significant reduction in relative conditioned ton in spite of poor engine performance is experienced. It was found also that, the lower tire pressure exhibits significant increase in relative conditioned ton.

Comparison and analysis of the effects of spark timing and lambda on a high-speed spark ignition engine fuelled with n-butanol/gasoline blends

In this study, a four-stroke, high-speed spark ignition (SI) engine was conducted to reflect the effects of n-butanol blend ratio, spark timing and lambda. The experiments were conducted with four types of fuels including B0 (0 vol% n-butanol and 100 vol% gasoline), B10, B20 and B30, two operation conditions including the engine speed of 4000 r/min and 8000 r/min, the throttle position of 35% and 45%, respectively; with the spark timing range from 25° to 48° before top dead center (BTDC), and the lambda range from 0.85 to 1.5. The results demonstrate that with the increasing of n-butanol blend ratio, the fuel mass flow rate is increased when the lambda is fixed. The output power, brake thermal efficiency (BTE) and brake specific fuel consumption (BSFC) increase with increasing n-butanol ratio. The addition of n-butanol to gasoline can decrease nitric oxide (NO) emissions significantly but increase carbon monoxide (CO) emissions slightly. The lambda relative to the maximum BTE, the minimum BSFC and the maximum combustion efficiency become larger with the content of n-butanol increase. The data of engine parameters were normalized, and a calculation formula of weighted analysis for the engine performance was presented. With the n-butanol blend ratio increasing, the test engine has a better performance. Considering the emissions, the spark timing of the highest weighted normalized score (WNS) is retarded relative to maximum brake power (MBP) timing, and the lambda of the highest WNS becomes larger.

Effect of spark timing on laser ignition and spark ignition modes in a hydrogen enriched compressed natural gas fuelled engine

In this experimental study, a prototype laser ignited engine was developed and fuelled with hydrogen enriched compressed natural gas (HCNG; mixture of H2 and CNG). Engine performance, emissions and combustion characteristics were compared for laser ignition (LI) and spark ignition (SI) modes. The maximum brake torque (MBT) timing was employed to reduce cycle-to-cycle variations (CCV) and to improve the engine performance, combustion and emission characteristics. Composition of HCNG mixture was changed by dynamically blending H2 with CNG on a volumetric basis. MBT timing was determined for naturally aspirated engine in conventional SI mode, by varying the spark timing (ST) between 22° CA bTDC to 46° CA bTDC and by varying relative air–fuel ratio (λ) from rich-to-lean. Optimum torque for HCNG mixtures was observed at 31° CA bTDC. The 10% mass fraction burn (MFB10) duration reduced continuously with advancing ignition timing up to 31°CA bTDC, which then increased with further advanced ST. For any particular ST, MFB10 and MFB90 decreased with increasing H2 enrichment of CNG. At high λ (lean mixtures), CCV would be higher due to lower engine efficiency and increased emissions. LI mode exhibited lower coefficient of variation in indicated mean effective pressure (COVIMEP) compared to SI mode. The COVIMEP for all HCNG mixtures were within 2% up to λ = 1.2 and it increased further with increasing λ but the variation was within ± 6%. Lower CCV (< 2% of COVIMEP), reduced emissions and improved brake thermal efficiency (BTE) were observed at 31°CA bTDC MBT timing compared to other spark timings. This experimental study indicated that laser ignition is a suitable technology for deployment in HCNG engines.

Experimental study of the effects of spark timing and water injection on combustion and emissions of a heavy-duty natural gas engine

The growing concern over global warming and stricter emissions regulations (EURO 6 standards) have led to natural gas engines being operated in stoichiometric combustion conditions with three-way catalytic (TWC) and exhaust gas recirculation (EGR) equipment. However, natural gas engines suffer from high thermal load, knock onset, and high turbine inlet temperatures at stoichiometric combustion conditions. Water injection is a promising approach to reduce thermal load and NOx emissions and suppress knock onset. In this study, the effects of water injection on the combustion and performance characteristics of a heavy-duty natural gas engine were experimentally studied. The experiments were conducted with four water to natural gas mass ratios (WNMRs) and various spark timings. The results showed that water injection decreased the burning velocity of natural gas, leading to a decrease in peak in-cylinder pressure, peak heat release rate, and combustion temperature. The flame development period (CA0-10) and the flame propagation period (CA10-90) increased with an increase in WNMR. Compared to pure natural gas, the brake thermal efficiency at the optimum spark timing increased from 27.8% to 28.2% at WNMR = 0.35. BSNOx emissions consistently decreased with an increase in WNMR, while BSTHC emissions and BSCO emissions increased slightly.

Effect of Early and Late Ignition on Combustion and Formation of Emissions in a Natural-Gas Fuelled Spark-Ignited Direct-Injection Engine

Bu çalışmada doğalgazla çalışan direkt enjeksiyonlu benzinli bir motorda ateşleme zamanının yanma ve emisyonlar üzerine etkileri incelenmiştir. Farklı ateşleme zamanları için motorun 3000 devir şartlarında simülasyonlar gerçekleştirilmiştir. Yanma karakteristikleri ve emisyon oluşumlarını incelemek için üç boyutlu hesaplamalı akışkanlar mekaniği kodu olan ANSYS-Forte 19.0 kullanılmıştır. Tüm simülasyonlar farklı ateşleme zamanları için gaz kelebeğinin tam açık konumunda tekrarlanmıştır. Erken ateşleme zamanlamasında silindir içi basıncın yükseldiği görülürken, HC ve CO emisyonlarında düşüş gözlenmiştir. Ayrıca, erken ateşleme şartlarında düşen HC ve CO emisyonlarına rağmen NOx emisyonlarında artış görülmüştür. Sonuç olarak doğalgazlı motorlarda erken ateşleme zamanında daha yüksek yanma verimi elde edilmiştir.

Effects of spark timing and methanol addition on combustion characteristics and emissions of dual-fuel engine fuelled with natural gas and methanol under lean-burn condition

This paper aimed to study the effects of spark timing and methanol addition on the combustion characteristics and emissions of a natural gas/methanol dual-fuel engine. The engine speed is maintained at 1600 rpm and the brake mean effective pressure (BMEP) is maintained at 0.387 MPa with an excess air/fuel ratio of 1.3. The methanol energy substitution ratio (MSR) is set to 0%, 7.5%, and 14.5%. The spark timings are varied from 18 °CA to 38 °CA before the top dead centre, in intervals of 4 °CA. The results demonstrate that for a specific spark timing, the methanol addition increases the peak cylinder pressure, the maximum of the heat release rate, and the peak cylinder mean temperature. Concurrently, it decreases the flame development period (CA0-10) and the flame propagation period (CA10-90) with an increase in the MSR. An improvement in the brake thermal efficiency (BTE), a reduction in the total hydrocarbon (THC) emission, and an increase in the nitrogen oxide (NOX) emission are achieved using methanol enrichment. In addition, the effect of these trends is more pronounced with an increase in MSR. In contrast, for a specific MSR, a spark timing advance increases the peak cylinder pressure and temperature, while decreasing the exhaust temperature under an identical BMEP. Moreover, the spark timing at the maximum BTE retards as MSR increases.

Improvement of a knock model for natural gas SI engines through heat transfer evaluation

Knock is an abnormal combustion phenomena capable of causing serious damage to spark ignition engines, and is a constraint to reach the maximum potential of the engine, since strategies to increase power output and improve efficiency such as turbocharging, increased compression ratio and the advancement of spark timing, also increase the possibility of knock occurrence. Therefore, it is crucial to take into account the limits imposed by knock in the design and operating conditions of the engine when using an engine computational model. In this article a zero-dimensional two-zone engine model, coupled with a chemical kinetic model for knock detection through end-gas auto-ignition is developed and validated, for a natural gas engine. Given the importance of an accurate knock prediction, five heat transfer coefficient correlations are compared to find the most suitable to predict the knock occurrence, through calculation of a knock criterion. Correlations from Sitkei and Annand were the most suitable to predict this knock criterion for the experimental data used, and the Sitkei correlation was later tested in a parametric study to predict the effect of spark timing, compression ratio, equivalence ratio and inlet temperature in knock occurrence and intensity. Results were in accordance with real engine behaviour when knock occurs.

Diesel and Spark Ignition Engines Emissions and After-Treatment Control: Research and Advancements

One of the major risks mankind has encountered during recent years is, without a doubt, the anthropogenic contribution to environmental pollution [...]

Theoretical Study of the Effects of Spark Timing on the Performance and Emissions of a Light-Duty Spark Ignited Engine Running under Either Gasoline or Ethanol or Butanol Fuel Operating Modes

Much research is ongoing to find suitable alternate fuels in order to reduce the exhaust emission levels without deteriorating the basic performance characteristics of conventional spark-ignited (SI) engines. One of the methods to achieve the above problem is the use of alcohols as full supplement fuels to normal gasoline. At the same time, many related research studies have shown that the use of alcohols has a negative impact on some basic engine performance characteristics, e.g., brake power output, etc. On the other hand, spark timing is one of the critical engine operating parameters that significantly influences the combustion mechanism inside the combustion chamber of a SI engine. Therefore, the primary objective of the present work is to investigate the effect of spark timing on the performance and emissions characteristics of a conventional, four-stroke, SI engine running under three different fuel operating modes, viz. with conventional gasoline or ethanol or butanol. The specific investigation is conducted by using an in-house, comprehensive, two-zone phenomenological model. The predictive ability of the model is tested against pertinent experimental data and it is found that the computed results are in good agreement with the respective experimental ones. For all test cases examined herein, the results concern basic engine performance characteristics, i.e., cylinder pressure, power output, specific fuel consumption etc., as well as NO and CO emissions. The main objectives of the work were to record and evaluate the impact that spark timing has on the performance characteristics and emitted pollutants of a conventional SI engine, operating under either conventional gasoline or ethanol or butanol fuel operating modes. Moreover, it deals with the determination of an optimum combination between the type of fuel used and the spark timing, so that probable undesirable effects on engine performance characteristics would be avoided. By comparing this investigation results, it is revealed that the use of alcohols as a full substitute fuel of gasoline accompanied with an appropriate alteration of the spark timing, could be a promising solution to improving both the efficiency and environmental behavior of a light-duty, spark-ignited (SI) engine, without causing any harmful problems to the engine operational lifetime. The conclusions from the study may prove valuable for the application of this technological solution to existing conventional SI engines.

Effect of spark timing on performance of a hydrogen-gasoline rotary engine

This paper aimed to study the effect of spark timing on performance of a hydrogen-gasoline dual-fuel rotary engine. For this aim, a modified rotary engine equipped with a dual-fuel port injection system was developed. An electronic management module (ECM) was specially made to command the fuel injection, excess air ratio and hydrogen volumetric fraction. In this study, the engine was operated at 4500rpm with a manifold absolute pressure (MAP) of 35kPa. Hydrogen volumetric percentage of total intake was kept at 0%, 3% and 6%, severally. When the hydrogen volumetric percentage was changed, the gasoline fraction was also adjusted to keep the mixture at the stoichiometric. For a specified hydrogen volumetric fraction, the ignition timing was varied from 24 to 42°CA BTDC (before top dead center) with a fixed interval of 2°CA. Experimental results showed that for a specific hydrogen volumetric percentage, the peak combustion pressure and chamber temperature were increased, brake thermal efficiency was first increased and then decreased with the increase of spark advance. Advancing spark timing caused the increased flame development period, the decreased flame propagation period and exhaust temperature. Cyclic variation was initially weaken and then deteriorated after raising spark advance. HC and NOx emissions were reduced after retarding spark timing. Spark timing had little effect on CO emission.

Influence of spark timing on the performance and emission characteristics of gasoline–hydrogen-blended high-speed spark-ignition engine

This article experimentally investigates the effect of spark timing on performance and emission characteristics of high-speed spark-ignition (SI) engine operated with different hydrogen–gasoline fuel blends. For this purpose, the conventional carbureted SI engine is modified into an electronically controllable engine, wherein an electronically controllable unit was used to control the ignition timings and injection duration of gasoline. The tests were conducted with different spark timings at the wide open throttle position and 3000 rpm engine speed. The experimental results demonstrated that brake mean effective pressure and engine brake thermal efficiency increased first and then decreased with the increase in spark advance. Peak cylinder pressure, temperature and heat release rate were increased until 20% hydrogen addition and with increased spark timings. NOx emissions were continuously increased with the increment in both spark timings and hydrogen addition, whereas hydrocarbon emissions were increased with spark timings but decreased with hydrogen addition. CO emissions were reduced with the increase in spark timing and hydrogen addition.

Effect of spark timing on combustion and emissions of a hydrogen direct injection stratified gasoline engine

The effect of spark timing on combustion and emissions of a hydrogen direct injection stratified gasoline engine was investigated. The engine was operated at 1500 rpm and excess air ratio at 1.2. It was found that when the hydrogen volume fraction was raised from 0% to 10%, and the hydrogen injection timing was 110 °CA BTDC a good stratified effect was achieved. The spark timing was varied from 4 to 16 °CA BTDC. This test demonstrated that the brake thermal efficiency first rose and then fell with the spark advance angle increased. In addition, it increased with the increase of hydrogen volume fraction. Postponing the spark timing caused the maximum instantaneous heat release rate increase. The peak cylinder pressure and the maximum rate of pressure rise increased with spark advance angle increase. Postponing the spark timing also caused NOx, HC and CO emissions to decrease. When the hydrogen volume fraction increased, the NOx emissions rose and the HC and CO emissions dropped.

PERFORMANCE ANALYSIS OF A BIOGAS ENGINE

A single zone S.I. engine model based on the physical geometries (bore, stroke, crank radius, and connecting rod length), variation of specific heats of gas mixture (air-fuel mixture and combustion products) and chemical equilibrium has been developed in an in-house code to predict the pressure and temperature variation along crank angle, work done, mean effective pressure, power output and other engine parameters suitable for biogas. The intake model has also been incorporated in the developed model. Model has been validated using biogas (methane). Effect of spark timing in spark ignition model have been observed and optimized to obtain maximum work as well as brake mean effective pressure with biogas. It has been observed that at 27° BTDC spark timing give the best performance. The spark ignition model at optimized condition, the brake thermal efficiency is calculated as 24% and brake mean specific fuel consumption is 0.29 m³/kWh.

Effect of spark timing on the performance of a spark ignition engine running on biogas–hydrogen blends

ABSTRACTThe influence of hydrogen addition in small quantities to biogas was studied in a spark ignition (SI) stationary engine at different spark timings at fixed equivalence ratio of 0.92. At this condition the engine operated with good thermal efficiency in the neat biogas mode. A single-cylinder diesel engine modified to operate as a SI engine was employed. The speed was 1500 rpm and the throttle opening was fixed at 100% at a compression ratio of 13:1. The maximum power output and thermal efficiency were achieved at a hydrogen energy share of 10%. Beyond this the engine experienced rough operation due to rapid combustion. However, nitric oxide (NO) emissions were high at this condition. At 5% hydrogen addition the hydrocarbon (HC) emission was significantly reduced with good thermal efficiency. NO levels were also low with 5% hydrogen addition as compared to neat biogas operation as retarded ignition timings could be used. The optimum ignition timings were significantly retarded, as the hydrogen quantity was raised. The best operating condition was 5% hydrogen share with a spark timing of 20°bTDC (before Top Dead Centre). It is concluded that addition of small amounts of hydrogen to biogas can significantly improve biogas engine operation.