Influence of Injection Parameters and Operating Conditions on Ignition and Combustion in Dual-Fuel Engines

2018 ◽  
Vol 140 (10) ◽  
Author(s):  
Marcus Grochowina ◽  
Michael Schiffner ◽  
Simon Tartsch ◽  
Thomas Sattelmayer
Keyword(s):  
Natural Gas ◽  
High Speed ◽  
Measurement Techniques ◽  
Injection Pressure ◽  
Operating Conditions ◽  
Liquid Fuels ◽  
Dual Fuel ◽  
Injection Parameters ◽  
Auto Ignition ◽  
Pilot Fuel

Dual-fuel (DF) engines offer great fuel flexibility since they can either run on gaseous or liquid fuels. In the case of diesel pilot-ignited DF engines, the main source of energy is provided by gaseous fuel, whereas the diesel fuel acts only as an ignition source. Therefore, a proper auto-ignition of the pilot fuel is of utmost importance for combustion in DF engines. However, auto-ignition of the pilot fuel suffers from lower compression temperatures of Miller or Atkinson valve timings. These valve timings are applied to increase efficiency and lower nitrogen oxide (NOx) engine emissions. In order to improve the ignition, it is necessary to understand which parameters influence the ignition in DF engines. For this purpose, experiments were conducted and the influence of parameters, such as injection pressure, pilot fuel quantity, compression temperature, and air–fuel (A/F) equivalence ratio of the homogenous natural gas–air mixture were investigated. The experiments were performed on a periodically chargeable combustion cell using optical high-speed recordings and thermodynamic measurement techniques for pressure and temperature. The study reveals that the quality of the diesel pilot ignition in terms of short ignition delay and a high number of ignited sprays significantly depends on the injection parameters and operating conditions. In most cases, the pilot fuel suffers from too high dilution due to its small quantity and long ignition delays. This results in a small number of ignited sprays and consequently leads to longer combustion durations. Furthermore, the experiments confirm that the natural gas of the background mixture influences the auto-ignition of the diesel pilot oil.

Influence of Injection Parameters and Operating Conditions on Ignition and Combustion in Dual-Fuel Engines

2017 ◽  
Author(s):  
Marcus Grochowina ◽  
Michael Schiffner ◽  
Simon Tartsch ◽  
Thomas Sattelmayer
Keyword(s):  
Natural Gas ◽  
High Speed ◽  
Measurement Techniques ◽  
Injection Pressure ◽  
Operating Conditions ◽  
Liquid Fuels ◽  
Dual Fuel ◽  
Injection Parameters ◽  
Pilot Fuel ◽  
Ignition And Combustion

Dual-Fuel (DF) engines offer great fuel flexibility since they can either run on gaseous or liquid fuels. In the case of Diesel pilot ignited DF-engines the main source of energy is provided by gaseous fuel, whereas the Diesel fuel acts only as an ignition source. Therefore, a proper autoignition of the pilot fuel is of utmost importance for combustion in DF-engines. However, autoignition of the pilot fuel suffers from lower compression temperatures of Miller or Atkinson valve timings. These valve timings are applied to increase efficiency and lower nitrogen oxide engine emissions. In order to improve the ignition, it is necessary to understand which parameters influence the ignition in DF-engines. For this purpose, experiments were conducted and the influence of parameters such as injection pressure, pilot fuel quantity, compression temperature and air-fuel equivalence ratio of the homogenous natural gas-air mixture were investigated. The experiments were performed on a periodically chargeable combustion cell using optical high-speed recordings and thermodynamic measurement techniques for pressure and temperature. The study reveals that the quality of the Diesel pilot ignition in terms of short ignition delay and a high number of ignited sprays significantly depends on the injection parameters and operating conditions. In most cases, the pilot fuel suffers from too high dilution due to its small quantity and long ignition delays. This results in a small number of ignited sprays and consequently leads to longer combustion durations. Furthermore, the experiments confirm that the natural gas of the background mixture influences the autoignition of the Diesel pilot oil.

Ignition of Diesel Pilot Fuel in Dual-Fuel Engines

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Marcus Grochowina ◽  
Daniel Hertel ◽  
Simon Tartsch ◽  
Thomas Sattelmayer
Keyword(s):  
High Speed ◽  
Measurement Techniques ◽  
Injection Pressure ◽  
Operating Conditions ◽  
Dual Fuel ◽  
Spray Formation ◽  
Fuel Concentration ◽  
Injection Parameters ◽  
Pilot Fuel ◽  
Ignition And Combustion

Dual-fuel (DF) engines offer great fuel flexibility combined with low emissions in gas mode. The main source of energy in this mode is provided by gaseous fuel, while the diesel fuel acts only as an ignition source. For this reason, the reliable autoignition of the pilot fuel is of utmost importance for combustion in DF engines. However, the autoignition of the pilot fuel suffers from low compression temperatures caused by Miller valve timings. These valve timings are applied to increase efficiency and reduce nitrogen oxide (NOx) emissions. Previous studies have investigated the influence of injection parameters and operating conditions on ignition and combustion in DF engines using a unique periodically chargeable combustion cell. Direct light high-speed images and pressure traces clearly revealed the effects of injection parameters and operating conditions on ignition and combustion. However, these measurement techniques are only capable of observing processes after ignition. In order to overcome this drawback, a high-speed shadowgraph technique was applied in this study to examine the processes prior to ignition. Measurements were conducted to investigate the influence of compression temperature and injection pressure on spray formation and ignition. Results showed that the autoignition of diesel pilot fuel strongly depends on the fuel concentration within the spray. The high-speed shadowgraph images revealed that in the case of very low fuel concentration within the pilot spray, only the first stage of the two-stage ignition occurs. This leads to large cycle-to-cycle variations and misfiring. However, it was found that a reduced number of injection holes counteract these effects. The comparison of a diesel injector with ten-holes and a modified injector with five-holes showed shorter ignition delays, more stable ignition and a higher number of ignited sprays on a percentage basis for the five-hole nozzle.

Ignition of Diesel Pilot Fuel in Dual-Fuel Engines

2018 ◽  
Author(s):  
Marcus Grochowina ◽  
Daniel Hertel ◽  
Simon Tartsch ◽  
Thomas Sattelmayer
Keyword(s):  
High Speed ◽  
Measurement Techniques ◽  
Injection Pressure ◽  
Operating Conditions ◽  
Dual Fuel ◽  
Spray Formation ◽  
Fuel Concentration ◽  
Injection Parameters ◽  
Pilot Fuel ◽  
Ignition And Combustion

Dual-Fuel (DF) engines offer great fuel flexibility combined with low emissions in gas mode. The main source of energy in this mode is provided by gaseous fuel, while the Diesel fuel acts only as an ignition source. For this reason, the reliable autoignition of the pilot fuel is of utmost importance for combustion in DF-engines. However, the autoignition of the pilot fuel suffers from low compression temperatures caused by Miller valve timings. These valve timings are applied to increase efficiency and reduce nitrogen oxide emissions. Previous studies have investigated the influence of injection parameters and operating conditions on ignition and combustion in DF-engines using a unique periodically chargeable combustion cell. Direct light high-speed images and pressure traces clearly revealed the effects of injection parameters and operating conditions on ignition and combustion. However, these measurement techniques are only capable of observing processes after ignition. In order to overcome this drawback, a high-speed shadowgraph technique was applied in this study to examine the processes prior to ignition. Measurements were conducted to investigate the influence of compression temperature and injection pressure on spray formation and ignition. Results showed that the autoignition of Diesel pilot fuel strongly depends on the fuel concentration within the spray. The high-speed shadowgraph images revealed that in the case of very low fuel concentration within the pilot spray only the first-stage of the two-stage ignition occurs. This leads to large cycle-to-cycle variations and misfiring. However, it was found that a reduced number of injection holes counteracts these effects. The comparison of a Diesel injector with 10-holes and a modified injector with 5-holes showed shorter ignition delays, more stable ignition and a higher number of ignited sprays on a percentage basis for the 5-hole nozzle.

Comparative Evaluation of the Effect of Intake Charge Temperature, Pilot Fuel Quantity and Injection Advance on Dual Fuel Compression Ignition Engine Performance Characteristics and Emitted Pollutants

2009 ◽  
Author(s):  
Roussos G. Papagiannakis ◽  
Theodoros C. Zannis ◽  
Elias A. Yfantis ◽  
Dimitrios T. Hountalas
Keyword(s):  
Diesel Engine ◽  
Natural Gas ◽  
Diesel Fuel ◽  
Diesel Engines ◽  
High Speed ◽  
Engine Performance ◽  
Exhaust Emissions ◽  
Performance Characteristics ◽  
Dual Fuel ◽  
Pilot Fuel

The simultaneous reduction of nitrogen oxide emissions and particulate matter in a compression ignition environment is quite difficult due to the soot/NOx trade off and it is often accompanied by fuel consumption penalties. Thus, fuel reformulation is also essential for the curtailment of diesel pollutant emissions along with the optimization of combustion-related design factors and exhaust after-treatment equipment. Various solutions have been proposed for improving the combustion process of conventional diesel engines and reducing the exhaust emissions without making serious modifications on the engine, one of which is the use of natural gas as a supplement for the conventional diesel fuel (Dual Fuel Natural Gas/Diesel Engines). Natural gas is considered to be quite promising since its cost is relative lower compared to conventional fuels and it has high auto-ignition temperature compared to other gaseous fuels facilitating thus its use on future and existing fleet of small high speed direct injection diesel engines without serious modifications on their structure. Moreover, natural gas does not generate particulates when burned in engines. The most common natural gas/diesel operating mode is referred to as the Pilot Ignited Natural Gas Diesel Engine (P.I.N.G.D.E). Here, the primary fuel is natural gas that controls the engine power output, while the pilot diesel fuel injected near the end of the compression stroke autoignites and creates ignition sources for the surrounding gaseous fuel mixture to be burned. Previous research studies have shown that the main disadvantage of this dual fuel combustion is its negative impact on engine efficiency compared to the normal diesel operation, while carbon monoxide emissions are also increased. The specific engine operating mode, in comparison with conventional diesel fuel operation, suffers from low brake engine efficiency and high carbon monoxide (CO) emissions. The influence becomes more evident at part load conditions. Intake charge temperature, pilot fuel quantity and injection advance are some of the engine parameters which influence significantly the combustion mechanism inside the combustion chamber of a Pilot Ignited Natural Gas Diesel Engine. In order to be examined the effect of these parameters on performance and exhaust emissions of a natural gas/diesel engine a theoretical investigation has been conducted by using a numerical simulation. In order to be examined the effect of increased air inlet temperature combined with increased pilot fuel quantity and its injection timing on performance and exhaust emissions of a pilot ignited natural gas-diesel engine, a theoretical investigation has been conducted by using a comprehensive two-zone phenomenological model. The results concerning engine performance characteristics and NO, CO and Soot emissions for various engine operating conditions (i.e. load and engine speed), comes from the employment of a comprehensive two-zone phenomenological model which had been applied on a high-speed natural gas/diesel engine. The main objectives of this comparative assessment are to record and to comparatively evaluate the relative impact each one of the above mentioned parameters on engine performance characteristics and emitted pollutants. Furthermore, the present investigation deals with the determining of optimum combinations between the parameters referred before since at high engine load conditions, the simultaneous increase some of the specific parameters may lead in undesirable results about engine performance characteristics. The conclusions of the specific investigation will be extremely valuable for the application of this technology on existing DI diesel engines.

Performance of Dual Fuel Engine Running on Jojoba Oil as Pilot Fuel and CNG or LPG

2007 ◽  
Author(s):  
Mohamed Y. E. Selim ◽  
M. S. Radwan ◽  
H. E. Saleh
Keyword(s):  
Methyl Ester ◽  
Natural Gas ◽  
Pressure Rise ◽  
Combustion Noise ◽  
Dual Fuel ◽  
Maximum Pressure ◽  
Injection Timing ◽  
Pressure Rise Rate ◽  
Rise Rate ◽  
Pilot Fuel

The use of Jojoba Methyl Ester as a pilot fuel was investigated for almost the first time as a way to improve the performance of dual fuel engine running on natural gas or LPG at part load. The dual fuel engine used was Ricardo E6 variable compression diesel engine and it used either compressed natural gas (CNG) or liquefied petroleum gas (LPG) as the main fuel and Jojoba Methyl Ester as a pilot fuel. Diesel fuel was used as a reference fuel for the dual fuel engine results. During the experimental tests, the following have been measured: engine efficiency in terms of specific fuel consumption, brake power output, combustion noise in terms of maximum pressure rise rate and maximum pressure, exhaust emissions in terms of carbon monoxide and hydrocarbons, knocking limits in terms of maximum torque at onset of knocking, and cyclic data of 100 engine cycle in terms of maximum pressure and its pressure rise rate. The tests examined the following engine parameters: gaseous fuel type, engine speed and load, pilot fuel injection timing, pilot fuel mass and compression ratio. Results showed that using the Jojoba fuel with its improved properties has improved the dual fuel engine performance, reduced the combustion noise, extended knocking limits and reduced the cyclic variability of the combustion.

scholarly journals Assessment of late pilot injection effect in dual-fuel combustion

2020 ◽  
Vol 197 ◽  
pp. 06010
Author(s):  
Antonio Caricato ◽  
Antonio Paolo Carlucci ◽  
Antonio Ficarella ◽  
Luciano Strafella
Keyword(s):  
Injection Pressure ◽  
Dual Fuel ◽  
Injection Timing ◽  
Pilot Injection ◽  
Compression Ignition Engine ◽  
Engine Load ◽  
Pilot Fuel ◽  
Dual Fuel Combustion ◽  
Cylinder Compression ◽  
Injection Effect

In this paper, the effect of late injection on combustion and emission levels has been investigated on a single cylinder compression ignition engine operated in dual-fuel mode injecting methane along the intake duct and igniting it through a pilot fuel injected directly into the combustion chamber. During the tests, the amount of pilot fuel injected per cycle has been kept constant, while the amount of methane has been varied on three levels. Therefore, three levels of engine load have been tested, while speed has been kept constant equal to 1500rpm. Pilot injection pressure has been varied on three set points, namely 500, 1000 and 1500 bar. For each engine load and injection pressure, pilot injection timing has been swept on a very broad range of values, spanning from very advanced to very late values. The analysis of heat release rate indicates that MK-like conditions are established in dual-fuel mode with late pilot injection. In these conditions, pollutant species, and NOx levels in particular, are significantly reduced without penalization – and in several conditions with improvement – on fuel conversion efficiency.

A Comparative Study of Methane Combustion Characteristics with Different Additions in an Optical SI Engine

2021 ◽  
Author(s):  
Lin Chen ◽  
Xiao Zhang ◽  
Ren Zhang ◽  
Wanhui Zhao
Keyword(s):  
Natural Gas ◽  
Flame Propagation ◽  
Power Output ◽  
High Speed ◽  
Propagation Speed ◽  
Pressure Oscillation ◽  
Methane Combustion ◽  
Natural Gas Engines ◽  
Auto Ignition ◽  
Flame Propagation Speed

Abstract Natural gas is a promising fuel for IC engines with minimal modification, whereas its low power output and slow flame propagation speed remain a challenge for automobile manufacturers. To find a method of improving the natural gas engines, methane combustion with different additions was comparatively studied. High-speed direct photography and simultaneous pressure were performed to capture detailed combustion evolutions. First, the results of pure methane combustion confirm its good anti-knock property, and no pressure oscillation occurs even there is an end-gas auto-ignition, indicating that high compression ratio and high boosting are effective ways to improve the performance of natural gas engines. Second, adding heavy hydrocarbons can greatly improve engines' power output, but engine knock should be considered if low anti-knock fuel was used. Third, as a carbon-free and gaseous fuel, hydrogen addition can not only increase methane flame propagation speed but reduce cyclic variations. However, a proper fraction is needed under different load conditions. Last, oxygen-enriched combustion is an effective way to promote methane combustion. The heat release becomes faster and more concentrated, specifically, the flame propagation speed can be increased by more than 2 times under 27% oxygen concentration condition. The current study shall give insights into improving natural gas engines' performance.

scholarly journals Parametric Knocking Performance Investigation of Spark Ignition Natural Gas Engines and Dual Fuel Engines

2020 ◽  
Vol 8 (6) ◽  
pp. 459 ◽  
Author(s):  
La Xiang ◽  
Gerasimos Theotokatos ◽  
Haining Cui ◽  
Keda Xu ◽  
Hongkai Ben ◽  
...  
Keyword(s):  
Natural Gas ◽  
Compression Ratio ◽  
Engine Performance ◽  
Spark Ignition ◽  
Combustion Model ◽  
Dual Fuel ◽  
Ignition Timing ◽  
Natural Gas Engines ◽  
Study Results ◽  
Pilot Fuel

Both spark ignition (SI) natural gas engines and compression ignition (CI) dual fuel (DF) engines suffer from knocking when the unburnt mixture ignites spontaneously prior to the flame front arrival. In this study, a parametric investigation is performed on the knocking performance of these two engine types by using the GT-Power software. An SI natural gas engine and a DF engine are modelled by employing a two-zone zero-dimensional combustion model, which uses Wiebe function to determine the combustion rate and provides adequate prediction of the unburnt zone temperature, which is crucial for the knocking prediction. The developed models are validated against experimentally measured parameters and are subsequently used for performing parametric investigations. The derived results are analysed to quantify the effect of the compression ratio, air-fuel equivalence ratio and ignition timing on both engines as well as the effect of pilot fuel energy proportion on the DF engine. The results demonstrate that the compression ratio of the investigated SI and DF engines must be limited to 11 and 16.5, respectively, for avoiding knocking occurrence. The ignition timing for the SI and the DF engines must be controlled after −38°CA and 3°CA, respectively. A higher pilot fuel energy proportion between 5% and 15% results in increasing the knocking tendency and intensity for the DF Engine at high loads. This study results in better insights on the impacts of the investigated engine design and operating settings for natural gas (NG)-fuelled engines, thus it can provide useful support for obtaining the optimal settings targeting a desired combustion behaviour and engine performance while attenuating the knocking tendency.

Combustion characteristics of compressed natural gas/diesel dual-fuel turbocharged compressed ignition engine

2003 ◽  
Vol 217 (9) ◽  
pp. 833-838 ◽  
Author(s):  
Liu Shenghua ◽  
Zhou Longbao ◽  
Wang Ziyan ◽  
Ren Jiang
Keyword(s):  
Natural Gas ◽  
Ignition Delay ◽  
Combustion Characteristics ◽  
Operating Conditions ◽  
Dual Fuel ◽  
Compressed Natural Gas ◽  
Delay Effects ◽  
Low Load ◽  
Performance And Emissions ◽  
Ci Engine

The combustion characteristics of a turbocharged natural gas and diesel dual-fuelled compression ignition (CI) engine are investigated. With the measured cylinder pressures of the engine operated on pure diesel and dual fuel, the ignition delay, effects of pilot diesel and engine load on combustion characteristics are analysed. Emissions of HC, CO, NOx and smoke are measured and studied too. The results show that the quantity of pilot diesel has important effects on the performance and emissions of a dual-fuel engine at low-load operating conditions. Ignition delay varies with the concentration of natural gas. Smoke is much lower for the developed dual-fuel engine under all the operating conditions.

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