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.

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.

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.

Parametric Study of Ignition and Combustion Characteristics From a Gasoline Compression Ignition Engine Using Two Different Reactivity Fuels

2016 ◽  
Author(s):  
Khanh Cung ◽  
Toby Rockstroh ◽  
Stephen Ciatti ◽  
William Cannella ◽  
S. Scott Goldsborough
Keyword(s):  
High Speed ◽  
Injection Pressure ◽  
Operating Conditions ◽  
Combustion Stability ◽  
Injection Timing ◽  
Strong Impact ◽  
Boost Pressure ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Ignition And Combustion

Unlike homogeneous charge compression ignition (HCCI) that has the complexity in controlling the start of combustion event, partially premixed combustion (PPC) provides the flexibility of defining the ignition timing and combustion phasing with respect to the time of injection. In PPC, the stratification of the charge can be influenced by a variety of methods such as number of injections (single or multiple injections), injection pressure, injection timing (early to near TDC injection), intake boost pressure, or combination of several factors. The current study investigates the effect of these factors when testing two gasoline-like fuels of different reactivity (defined by Research Octane Number or RON) in a 1.9-L inline 4-cylinder diesel engine. From the collection of engine data, a full factorial analysis was created in order to identify the factors that most influence the outcomes such as the location of ignition, combustion phasing, combustion stability, and emissions. Furthermore, the interaction effect of combinations of two factors or more was discussed with the implication of fuel reactivity under current operating conditions. The analysis was done at both low (1000 RPM) and high speed (2000 RPM). It was found that the boost pressure and air/fuel ratio have strong impact on ignition and combustion phasing. Finally, injection-timing sweeps were conducted whereby the ignition (CA10) of the two fuels with significantly different reactivity were matched by controlling the boost pressure while maintaining a constant lambda (air/fuel equivalence ratio).

scholarly journals Ignition and combustion characteristics of wall-impinged kerosene (RP-3) fuel spray with varying injection parameters

2020 ◽  
Vol 24 (1 Part A) ◽  
pp. 171-181
Author(s):  
Wei Du ◽  
Qiankun Zhang ◽  
Meng Li ◽  
Jinchi Hou
Keyword(s):  
High Speed ◽  
Ignition Delay Time ◽  
Injection Pressure ◽  
Combustion Characteristics ◽  
Fuel Spray ◽  
Injection Parameters ◽  
Combustion Duration ◽  
Main Emphasis ◽  
Ignition And Combustion ◽  
Engine Condition

The fuel quantity and injection pressure are two essential factors to optimize the injection strategy. In this paper, we focus on the investigation for the ignition and combustion characteristics of wall-impinged kerosene (RP-3) fuel spray at different injection quantities and pressures. Experiments are conducted in a constant volume combustion vessel to simulate the Diesel engine condition, adopting a single-hole nozzle with 0.22 mm. The flame images are captured using a high-speed camera, and then the behaviors of ignition and combustion are processed and analyzed. The main emphasis is placed on the variation laws of the ignition position distance, the ignition delay time, the combustion duration, the flame area, spatially integrated natural luminosity and time integrated natural luminosity.

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.

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