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.

Effects of injection strategy on performance and emissions metrics in a diesel/methane dual-fuel single-cylinder compression ignition engine

2019 ◽  
Vol 20 (10) ◽  
pp. 1059-1072 ◽  
Author(s):  
Metin Korkmaz ◽  
Dennis Ritter ◽  
Bernhard Jochim ◽  
Joachim Beeckmann ◽  
Dirk Abel ◽  
...  
Keyword(s):  
Diesel Fuel ◽  
Deep Understanding ◽  
Injection Pressure ◽  
Dual Fuel ◽  
Injection Timing ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Single Cylinder ◽  
Cylinder Compression ◽  
The Impact

In order to counteract the drawbacks of conventional diesel combustion, which can lead to high indicated specific nitric oxide and indicated specific particulate matter emissions, a promising diesel-dual-fuel concept is investigated and evaluated. In this study, methane is used as supplement to liquid diesel fuel due to its benefits like high knock resistance and clean combustion. A deep understanding of the in-cylinder process is required for engine design and combustion controller development. To investigate the impact of different input parameters such as injection duration, injection timing, and substitution rate on varying output parameters like load, combustion phasing, and engine-out emissions, numerous investigations were conducted. Engine speed, global equivalence ratio, and injection pressure were held constant. The experiments were carried out in a modified single-cylinder compression ignition engine. The results reveal regimes with different dependencies between injection timing of diesel fuel and combustion phasing. This work demonstrates the potential of the diesel-dual-fuel concept by combining sophisticated combustion control with the favorable combustion mode. Without employing exhaust gas recirculation, TIER IMO 3 emissions limits are met while ensuring high thermal efficiency.

scholarly journals A Numerical Study on the Pilot Injection Conditions of a Marine 2-Stroke Lean-Burn Dual Fuel Engine

Processes ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1396
Author(s):  
Hao Guo ◽  
Song Zhou ◽  
Jiaxuan Zou ◽  
Majed Shreka
Keyword(s):  
Natural Gas ◽  
Fuel Injection ◽  
Numerical Study ◽  
Pollutant Emissions ◽  
Dual Fuel ◽  
Injection Timing ◽  
Pilot Injection ◽  
Lean Burn ◽  
Injection Duration ◽  
Pilot Fuel

The global demand for clean fuels is increasing in order to meet the requirements of the International Maritime Organization (IMO) of 0.5% global Sulphur cap and Tier III emission limits. Natural gas has begun to be popularized on liquefied natural gas (LNG) ships because of its low cost and environment friendly. In large-bore marine engines, ignition with pilot fuel in the prechamber is a good way to reduce combustion variability and extend the lean-burn limit. However, the occurrence of knock limits the increase in power. Therefore, this paper investigates the effect of pilot fuel injection conditions on performance and knocking of a marine 2-stroke low-pressure dual-fuel (LP-DF) engine. The engine simulations were performed under different pilot fuel parameters. The results showed that the average in-cylinder temperature, the average in-cylinder pressure, and the NOx emissions gradually decreased with the delay of the pilot injection timing. Furthermore, the combustion situation gradually deteriorated as the pilot injection duration increased. A shorter pilot injection duration was beneficial to reduce NOx pollutant emissions. Moreover, the number of pilot injector orifices affected the ignition of pilot fuel and the flame propagation speed inside the combustion chamber.

Combustion and Emission Characteristics of a CI Engine Operating in Diesel-1-Butanol/CNG Dual Fuel Mode With Low and High CNG Substitution Rates in Light Load Operation

2016 ◽  
Author(s):  
Xiangyu Meng ◽  
Yuanxu Li ◽  
Karthik Nithyanandan ◽  
Wuqiang Long ◽  
Chia-Fon F. Lee
Keyword(s):  
Thermal Efficiency ◽  
Substitution Rate ◽  
Fuel Combustion ◽  
Dual Fuel ◽  
Injection Timing ◽  
Combustion Mode ◽  
Substitution Rates ◽  
Low Load ◽  
Pilot Fuel ◽  
Dual Fuel Combustion

Dual-fuel combustion mode with direct injection of diesel as the pilot fuel and port injection of compressed natural gas (CNG) in compression ignition (CI) engines has been widely investigated to comply with the latest emission regulations. The diesel-CNG dual-fuel combustion mode shows some potential to decrease NOx and soot emissions simultaneously, while it reveals a lower thermal efficiency compared to the pure diesel combustion mode under low load condition. The purpose of the current study is to investigate the possibility of using diesel blended with 1-butanol as the pilot fuel to enhance the engine performance and reduce emissions. Three pilot fuels — B0 (pure diesel), B10 (90% diesel and 10% 1-butanol by volume) and B20 (80% diesel and 20% 1-butanol) with the CNG substitution rates of 50% and 80% were compared at an engine speed of 1200 rpm. The experiments were conducted by sweeping the pilot fuel injection timing from −3 to −18 ° CA ATDC with an equivalent total energy (∼5 bar IMEP). The results illustrated that, for the 50% CNG substitution rate, the dual-fuel operation mode revealed a higher indicated thermal efficiency (ITE) under low load conditions, and B10 can significantly improve the ITE due to the shorter combustion duration. The emission results of B10 showed that it obtained lower THC and CO emissions, but a slightly higher NOx emission. For the 80% CNG substitution rate, the results presented lower ITE, higher THC and lower NOx emissions, comparatively.

Effect of Fuelling Control Parameters on Combustion Characteristics of Diesel-Ignited Natural Gas Dual-Fuel Combustion in an Optical Engine

2016 ◽  
Author(s):  
Mahdiar Khosravi ◽  
Jeremy Rochussen ◽  
Jeff Yeo ◽  
Patrick Kirchen ◽  
Gordon McTaggart-Cowan ◽  
...  
Keyword(s):  
Direct Injection ◽  
Injection Pressure ◽  
Fuel Combustion ◽  
Conversion Process ◽  
Dual Fuel ◽  
Pilot Injection ◽  
Fuel Conversion ◽  
Auto Ignition ◽  
Dual Fuel Combustion ◽  
Ci Engines

Its inherent economic and environmental advantages as an internal combustion engine fuel make natural gas (NG) an attractive alternative to diesel fuel as the primary energy source for some compression ignition (CI) engine applications. Diesel pilot-ignition of NG is an attractive fueling strategy as it typically requires minimal modification of existing CI engines. Furthermore, this strategy makes use of the highly developed direct injection (DI) diesel fuel systems already employed on modern CI engines for to control dual-fuel (DF) combustion. Despite the increasing popularity of the dual-fuel NG engine concept, the fundamental understanding of the fuel conversion mechanisms and the impact of the fueling parameters is still incomplete. A conceptual understanding of the relevant physics is necessary for further development of fueling and pilot-ignition strategies to address the shortcomings of dual-fuel combustion, such as low-load emissions and combustion stability. An experimental facility supporting optical diagnostics via a Bowditch piston arrangement in a 2-litre, single-cylinder research engine (Ricardo Proteus) was used in this study to consider the effect of fueling parameters on the fuel conversion process in a dual fuel engine. Fueling was achieved with port injected CH4 and diesel direct injection using a common rail system. Simultaneous, high-speed natural luminosity (NL) and OH* chemiluminescence imaging was used to characterize dual-fuel combustion and the influence of pilot injection pressure (300 bar vs. 1300 bar) and relative diesel-CH4 ratios (pilot ratio, PR), as these have been noted as key operating dual-fuel control metrics. The pilot injection pressure was observed to have a significant impact on the fuel conversion process. At higher pilot injection pressures, the auto-ignition sites were concentrated around the piston bowl periphery and the reaction zone propagated towards the center of the bowl. At lower pilot injection pressures, ignition initiated in the vicinity of the pilot fuel jet structures and resulted in a more heterogeneous fuel conversion process with regions of intense natural luminosity, attributed to particulate matter. An increase in the pilot ratio (i.e., increased diesel fraction) resulted in a more aggressive combustion event, due to a larger fraction of energy released in a premixed auto-ignition event. This was coupled with a decrease in the fraction of the combustion chamber with significant OH* or NL light emission, indicating incomplete fuel conversion in these regions. The insight to the dual-fuel conversion processes presented in this work will be ultimately used to develop dual-fuel injection strategies, as well as provide much needed validation data for modeling efforts.

Studies on Esters of Coconut Oil as Fuel for LPG-Biodiesel Dual Fuel Engine

2003 ◽  
Author(s):  
N. Kapilan ◽  
R. P. Reddy ◽  
P. Mohanan
Keyword(s):  
Diesel Engine ◽  
Coconut Oil ◽  
Poor Performance ◽  
Dual Fuel ◽  
Injection Timing ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Performance And Emission ◽  
Mode Operation ◽  
Pilot Fuel

The rapid depletion in world petroleum reserves and uncertainty in petroleum supply due to political and economical reasons, as well as, the sharp escalation in the petroleum prices, have stimulated the search for alternatives to petroleum based fuels specially diesel and gasoline. Biodiesel is one of the renewable fuels, which will be the good replacement to diesel. But as a sole fuel, it gives poor performance and higher emissions. From the literature survey, it is observed that not much work has been done to use Methyl Ester (ME) of coconut oil as liquid fuel in sole and dual fuel mode of operation. Hence, in the present work, ME of coconut oil is chosen as a sole fuel to run the diesel engine and an alternative pilot fuel to run LPG-Biodiesel dual fuel engine. In dual fuel mode operation, LPG is used as the inducted gaseous fuel. LPG has been chosen as the inducted fuel on account of its easy availability in abundance in the present time. The existing compression ignition diesel engine was modified to work on dual fuel mode. Tests were carried out on a single cylinder, four strokes, water-cooled, direct injection, compression ignition engine using ME of coconut oil as fuel. To study the effect of injection timing, its is advanced and retarded from the standard injection timing recommended for diesel operation. From the results, it is observed that the advanced injection timing results in better performance and lower emissions of the diesel engine. In dual fuel mode operation, first the engine was started with ME of coconut oil as fuel and then the LPG flow rate was increased. With appropriate proportions of the injected (0.45, 0.65 and 0.75 kg/hr) and inducted fuels it is possible to improve the engine performance and reduce its emissions. From the experimental results, it is found that the pilot fuel rate of 0.65 kg/hr is preferred from the point view of brake thermal efficiency, fuel consumption and smooth running. ME of coconut oil were successfully used as sole fuel and pilot fuel. The performance and emission of the engine in sole fuel mode with better injection timing and dual fuel mode with better pilot quantity were compared. From the comparison, it is observed that the ME of coconut oil can be used as pilot fuel in dual fuel engine compared to sole fuel with regard to performance and emissions.

scholarly journals An Investigation of the Effect of Fuel Supply Parameters on Combustion Process of the Heavy-Duty Dual-Fuel Diesel Ignited Gas Engine

Energies ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 2280 ◽  
Author(s):  
Andrey Kozlov ◽  
Vadim Grinev ◽  
Alexey Terenchenko ◽  
Gennady Kornilov
Keyword(s):  
Internal Combustion Engines ◽  
Fuel Injection ◽  
Fuel Efficiency ◽  
Combustion Process ◽  
Injection Pressure ◽  
Dual Fuel ◽  
Injection Timing ◽  
Fuel Supply ◽  
Pilot Fuel ◽  
Fuel Injection Pressure

Modern research in the area of internal combustion engines is focused on researching and investigating the technologies that will improve fuel efficiency and decrease emissions. Application of dual-fuel engines is considered as a potential solution to these problems. In the dual-fuel engine, a natural gas-air mixture is ignited by a small amount of the diesel fuel directly injected into a combustion chamber. Pilot fuel injection parameters can strongly effect the combustion process. The aim of this paper is to investigate the effect of such fuel-supply parameters as pilot fuel mass, pilot fuel injection pressure, pilot fuel injection timing and excess air ratio on the combustion process. Investigation is based on the data obtained during bench tests conducted with the use of measurement equipment. The dependences of engine characteristics from the fuel supply parameters under review were obtained based on the results of the experimental study. Optimal values for every investigated fuel-supply parameter were chosen based on the obtained results. Over the course of the investigation, the coefficient for heat release rate according to the Vibe equation was calculated for each operating point.

Numerical Investigation of the Performance of a High Pressure Direct Injection (HPDI) Natural Gas Engine

2014 ◽  
Author(s):  
Won Geun Lee ◽  
David Montgomery
Keyword(s):  
High Pressure ◽  
Natural Gas ◽  
Direct Injection ◽  
Gas Injection ◽  
Load Condition ◽  
Fuel Combustion ◽  
Dual Fuel ◽  
Injection Timing ◽  
Pilot Injection ◽  
Dual Fuel Combustion

High Pressure Direct-Injection (HPDI) is a technology option for engines used in mobile equipment applications where use of LNG as a fuel is desired. Using the combination of a diesel pilot injection and direct gas injection, HPDI has the potential to deliver low emissions, excellent transient performance, high efficiency, and high gas substitution. When the HPDI program was initially undertaken, in order to aid in initial hardware design, 3-dimensional computational fluid dynamic modeling was conducted to understand the mixing and reaction processes in the combustion chamber of an HPDI engine. Gaining insight into qualitative trends of operation parameters and hardware configurations was a first critical step toward delivering a hardware set to demonstrate HPDI natural gas combustion system capabilities. To model the combustion of multi-component fuel at arbitrary constituent ratios, a combustion model based on a detailed chemical kinetics approach was employed. Several published mechanisms and combinations of established mechanisms were tested by comparing results with existing fumigated dual fuel engine results. The result shows that some of combined mechanisms for n-heptane combustion and methane combustion are capable of adequately predicting combustion behavior in diesel-natural gas dual fuel combustion systems. One of the reduced n-heptane mechanisms (by Patel et al.) also matched dual fuel combustion results reasonably well. This preliminary simulation study was conducted with typical trapped air conditions and fuel quantities matching the energy delivery for a 100 % load condition in existing DI diesel engines. A full 360-degree mesh at intake valve closing was constructed and a detailed geometry of the gas injector nozzle and sac area was modeled in locally refined grids using a Caterpillar proprietary CFD code that accepts industry standard mechanisms. The diesel pilot injection followed by gas injection and resulting combustion inside an HPDI engine was simulated from IVC through the compression and combustion strokes. The operating parameters — such as diesel pilot injection timing, pilot injection amount, and start of gas injection — were varied, and the effect on IMEP, NOx, CO and cylinder pressure were investigated. It was shown that the start of gas injection is the strongest parameter for control of combustion. Subsequent to the work discussed in this paper, the hardware configuration established as optimal during the modeling work was carried forward to the physical engine testing and was successful in delivering the performance and emissions goals without modification, demonstrating the accuracy and value of modern combustion modeling.

Effects of pilot fuel quantity on the emissions characteristics of a CNG/diesel dual fuel engine with optimized pilot injection timing

2013 ◽  
Vol 110 ◽  
pp. 201-206 ◽  
Author(s):  
Jie Liu ◽  
Fuyuan Yang ◽  
Hewu Wang ◽  
Minggao Ouyang ◽  
Shougang Hao
Keyword(s):  
Dual Fuel ◽  
Injection Timing ◽  
Pilot Injection ◽  
Pilot Fuel

Investigation of Dual-Fuel Combustion by Different Port Injection Fuels (Neat Ethanol and E85) in a DE95 Diesel/Ethanol Blend Fueled Compression Ignition Engine

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Habib Gürbüz ◽  
Selim Demirtürk
Keyword(s):  
Combustion Engine ◽  
Experimental Studies ◽  
Exhaust Emissions ◽  
Combustion Efficiency ◽  
Fuel Combustion ◽  
Dual Fuel ◽  
Injection Timing ◽  
Compression Ignition Engine ◽  
Engine Efficiency ◽  
Dual Fuel Combustion

Abstract This paper investigated the effect of different substitution ratios of neat ethanol (E100) and ethanol–gasoline blend E85 on in-cylinder combustion, engine efficiency, and exhaust emissions, in a dual-fuel diesel engine, using the ethanol–diesel blend (DE95). Experimental studies realized at 1400 rpm, 1600 rpm, and 1800 rpm engine speeds under constant engine load of 50% (20 Nm). For each engine speed, the injection timing of diesel and E95 fuels at 24 °CA bTDC kept constant while low-reactivity fuels (i.e., E100 and E85) substitution ratio changed in the range of 59–83%. The results showed that premixed fuels in different SRs have an impact on shaping engine emissions, ignition delay (ID), in-cylinder pressure, and heat-release rate. Also, at the dual-fuel experimental studies in all engine speeds, NOx about 47–67% decrease compared to single fuel conditions of reference diesel and DE95, and smoke opacity remained unchanged around 0.1 FSN, whereas HC and CO increased in the range of 20–50%. However, E85/DE95 and E100/DE95 dual-fuel combustion achieved lower brake thermal efficiency (BTE) and combustion efficiency compared to single diesel fuel combustion. On the other hand, in dual-fuel combustion conditions, despite the low combustion efficiency, premixed E85 fuel offered higher engine efficiency and lower exhaust emissions than E100.

Mapping the combustion modes of a dual-fuel compression ignition engine

2021 ◽  
pp. 146808742110183
Author(s):  
Jonathan Martin ◽  
André Boehman
Keyword(s):  
Direct Injection ◽  
Fuel Combustion ◽  
Dual Fuel ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Combustion Modes ◽  
Si Engines ◽  
Dual Fuel Combustion ◽  
Soot Emissions ◽  
Ci Engines

Compression-ignition (CI) engines can produce higher thermal efficiency (TE) and thus lower carbon dioxide (CO2) emissions than spark-ignition (SI) engines. Unfortunately, the overall fuel economy of CI engine vehicles is limited by their emissions of nitrogen oxides (NOx) and soot, which must be mitigated with costly, resource- and energy-intensive aftertreatment. NOx and soot could also be mitigated by adding premixed gasoline to complement the conventional, non-premixed direct injection (DI) of diesel fuel in CI engines. Several such “dual-fuel” combustion modes have been introduced in recent years, but these modes are usually studied individually at discrete conditions. This paper introduces a mapping system for dual-fuel CI modes that links together several previously studied modes across a continuous two-dimensional diagram. This system includes the conventional diesel combustion (CDC) and conventional dual-fuel (CDF) modes; the well-explored advanced combustion modes of HCCI, RCCI, PCCI, and PPCI; and a previously discovered but relatively unexplored combustion mode that is herein titled “Piston-split Dual-Fuel Combustion” or PDFC. Tests show that dual-fuel CI engines can simultaneously increase TE and lower NOx and/or soot emissions at high loads through the use of Partial HCCI (PHCCI). At low loads, PHCCI is not possible, but either PDFC or RCCI can be used to further improve NOx and/or soot emissions, albeit at slightly lower TE. These results lead to a “partial dual-fuel” multi-mode strategy of PHCCI at high loads and CDC at low loads, linked together by PDFC. Drive cycle simulations show that this strategy, when tuned to balance NOx and soot reductions, can reduce engine-out CO2 emissions by about 1% while reducing NOx and soot by about 20% each with respect to CDC. This increases emissions of unburnt hydrocarbons (UHC), still in a treatable range (2.0 g/kWh) but five times as high as CDC, requiring changes in aftertreatment strategy.

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