Effects of pilot injection timing on the combustion noise and particle emissions of a diesel/natural gas dual-fuel engine at low load

2016 ◽  
Vol 102 ◽  
pp. 822-828 ◽  
Author(s):  
Bo Yang ◽  
Long Wang ◽  
Le Ning ◽  
Ke Zeng
Keyword(s):  
Natural Gas ◽  
Combustion Noise ◽  
Dual Fuel ◽  
Injection Timing ◽  
Pilot Injection ◽  
Particle Emissions ◽  
Low Load

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 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.

scholarly journals Effect of hydrogen addition in diesel/natural gas dual-fuel combustion with late injection

2021 ◽  
Vol 312 ◽  
pp. 08005
Author(s):  
Antonio Caricato ◽  
Antonio Paolo Carlucci ◽  
Antonio Ficarella ◽  
Luciano Strafella
Keyword(s):  
Natural Gas ◽  
Conversion Efficiency ◽  
Early Stage ◽  
Combustion Process ◽  
Pollutant Emission ◽  
Dual Fuel ◽  
Injection Timing ◽  
Pilot Injection ◽  
Fuel Conversion ◽  
Hydrogen Addition

In a previous work, the effectiveness of late pilot injection on improving combustion behaviour – in terms of fuel conversion efficiency and pollutant emission levels – in a diesel/natural gas dual-fuel engine was assessed. Then, an additional set of experiments was performed, aiming at speeding up the combustion process possibly without penalizing NOx levels. Therefore, hydrogen was added to natural gas in a percentage equal to 10%. Results show that hydrogen addition has a significant effect on the combustion development specially during the early stage of combustion: ignition delay is shortened and combustion centre is advanced, while the combustion duration increases when pilot injection timing is set to conventional values, while remains basically unchanged for late timings. Fuel conversion efficiency is only slightly penalized when hydrogen is added. Moreover, it was confirmed that, in general, combustion strategy with late pilot injection timing does not penalize fuel conversion efficiency; indeed, in some cases, it actually increases. Concerning regulated emission levels, it is again proven that late pilot injection does not penalize pollutant production: the hydrocarbons and carbon monoxide reduce as pilot injection is delayed, probably due to the higher temperatures reached into the cylinder during most part of the expansion stroke. Moreover, adding hydrogen always reduces their levels. Concerning NOx, they are drastically reduced delaying pilot injection; as expected, hydrogen addition promotes NOx formation, but the increase, evident with conventional pilot injection timings, becomes marginal with late injection strategy. Therefore, combustion strategy performance with late pilot injection in dual-fuel diesel/natural gas combustion conditions can be further improved with 10% hydrogen addition to natural gas.

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.

scholarly journals A Numerical Study on the Combustion Process and Emission Characteristics of a Natural Gas-Diesel Dual-Fuel Marine Engine at Full Load

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1342
Author(s):  
Van Chien Pham ◽  
Jae-Hyuk Choi ◽  
Beom-Seok Rho ◽  
Jun-Soo Kim ◽  
Kyunam Park ◽  
...  
Keyword(s):  
Natural Gas ◽  
Combustion Process ◽  
Simulation Software ◽  
Dual Fuel ◽  
Injection Timing ◽  
Emission Characteristics ◽  
Cylinder Pressure ◽  
Marine Engine ◽  
Full Load ◽  
Simulation Results

This paper presents research on the combustion and emission characteristics of a four-stroke Natural gas–Diesel dual-fuel marine engine at full load. The AVL FIRE R2018a (AVL List GmbH, Graz, Austria) simulation software was used to conduct three-dimensional simulations of the combustion process and emission formations inside the engine cylinder in both diesel and dual-fuel mode to analyze the in-cylinder pressure, temperature, and emission characteristics. The simulation results were then compared and showed a good agreement with the measured values reported in the engine’s shop test technical data. The simulation results showed reductions in the in-cylinder pressure and temperature peaks by 1.7% and 6.75%, while NO, soot, CO, and CO2 emissions were reduced up to 96%, 96%, 86%, and 15.9%, respectively, in the dual-fuel mode in comparison with the diesel mode. The results also show better and more uniform combustion at the late stage of the combustions inside the cylinder when operating the engine in the dual-fuel mode. Analyzing the emission characteristics and the engine performance when the injection timing varies shows that, operating the engine in the dual-fuel mode with an injection timing of 12 crank angle degrees before the top dead center is the best solution to reduce emissions while keeping the optimal engine power.

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