Experimental Examination of Prechamber Heat Release in a Large Bore Natural Gas Engine

2008 ◽  
Vol 130 (5) ◽  
Author(s):  
Daniel B. Olsen ◽  
Allan T. Kirkpatrick
Keyword(s):  
Natural Gas ◽  
Heat Release ◽  
Equivalence Ratio ◽  
Dynamic Pressure ◽  
Pressure Rise ◽  
Main Chamber ◽  
Lean Burn ◽  
Gas Engine ◽  
Natural Gas Engine ◽  
Common Solution

A common solution in reducing NOx emissions to meet new emission regulations has been lean burn combustion. However, with very lean air∕fuel (A∕F) ratios, both carbon monoxide and hydrocarbon emissions become unacceptably high due to the spark misfiring and combustion instabilities. In order to mitigate this, a prechamber ignition system is often used to stabilize combustion at very lean A∕F ratios. In this paper, the heat release in a retrofit prechamber system installed on a large bore natural gas engine is examined. The heat release analysis is based on dynamic pressure measurements both in the main chamber and prechamber. The Woschni correlation is utilized to model heat transfer. Based on heat release modeling and test data analysis, the following observations are made. Main chamber heat release rates are much more rapid for prechamber ignition compared to spark ignition. During combustion in the prechamber, much of the fuel flows into the main chamber unreacted. About 52% of the mass in the prechamber, at ignition, flows into the main chamber during prechamber combustion. Prechamber total heat release, pressure rise, and maximum jet velocity all increase with increasing prechamber equivalence ratio. Prechamber combustion duration and coefficient of variation of peak pressure are minimized at a prechamber equivalence ratio of about 1.09.

Experimental Examination of Prechamber Heat Release in a Large Bore Natural Gas Engine

2007 ◽  
Author(s):  
Daniel B. Olsen ◽  
Allan T. Kirkpatrick
Keyword(s):  
Natural Gas ◽  
Heat Release ◽  
Equivalence Ratio ◽  
Laminar Flame ◽  
Dynamic Pressure ◽  
Pressure Rise ◽  
Main Chamber ◽  
Lean Burn ◽  
Gas Engine ◽  
Natural Gas Engine

A common solution to reducing NOX emissions to meet new emissions regulations has been lean burn combustion. However, with very lean air/fuel (A/F) ratios, both carbon monoxide and hydrocarbon emissions become unacceptably high due to spark misfiring and combustion instabilities. In order to mitigate this, a prechamber ignition system is often used to stabilize combustion at very lean A/F ratios. In this paper, the heat release in a retrofit prechamber system installed on a large bore natural gas engine is examined. The heat release analysis is based on dynamic pressure measurements both in the main chamber and prechamber. The Woschni correlation is utilized to model heat transfer. Based on heat release modeling and test data analysis the following observations are made. Main chamber heat release rates are much more rapid for prechamber ignition compared to spark ignition. During combustion in the prechamber much of the fuel flows into the main chamber un-reacted. About 52% of the mass in the prechamber, at ignition, flows into the main chamber during prechamber combustion. Prechamber total heat release, pressure rise, and maximum jet velocity all increase with increasing prechamber equivalence ratio. Prechamber combustion duration and coefficient of variation of peak pressure are minimized at a prechamber equivalence ratio of about 1.09, which corresponds roughly to the equivalence ratio of highest laminar flame speed. The above performance optimum does not correspond to the equivalence ratio where the most prechamber energy is released.

Effects of Spark Advance Angle on Combustion and Emission Characteristics of a Compressed Natural Gas Engine

2011 ◽  
Vol 383-390 ◽  
pp. 6085-6090
Author(s):  
Xiao Na Sun ◽  
Hong Guang Zhang ◽  
Xin Wang ◽  
Dao Jing Wang ◽  
Guo Yong Zheng ◽  
...  
Keyword(s):  
Natural Gas ◽  
Pressure Rise ◽  
Emission Characteristics ◽  
Nox Emissions ◽  
Lean Burn ◽  
Compressed Natural Gas ◽  
Gas Engine ◽  
Natural Gas Engine ◽  
Peak Cylinder Pressure ◽  
Co Emission

The effects of spark advance angle on combustion and emission characteristics of a compressed natural gas engine have been investigated experimentally in this paper. The experimental data was conducted under various excessive air coefficient conditions using an electronic ignition system developed self-dependently. The results show that the peak cylinder pressure and peak rate of pressure rise ascends with the increase of spark advance angle in a certain extent, and their corresponding location are advanced. The CO emission keeps almost the same as the spark advance angle varies in the overall mode range. The HC and NOx emissions ascend with the increase of spark advance angle under the condition that excessive air coefficient is near the theoretical value. Under the lean-burn condition, the HC and NOx emissions are almost the same while the spark advance angle varies.

Performance and Combustion Investigation of a Lean Burn Natural Gas Engine Using CFD

2018 ◽  
Author(s):  
Sridhar Sahoo ◽  
Srinibas Tripathy ◽  
Dhananjay Kumar Srivastava
Keyword(s):  
Natural Gas ◽  
Equivalence Ratio ◽  
Spark Ignition Engine ◽  
Engine Fuel ◽  
Lean Burn ◽  
Gas Engine ◽  
Natural Gas Engine ◽  
Spark Timing ◽  
Combustion Duration ◽  
Wide Range

Natural gas is widely used in sequentially port fuel injection engine to meet stringent emission regulation. Lean burn operation is one of the ways to improve spark-ignition engine fuel economy. The instability in the combustion process of the lean burn engine is one of the major challenges for engine research. In this study, the performance and combustion characteristics of a lean burn sequential injection compressed natural gas (CNG) engine were investigated numerically using computational fluid dynamics (CFD) modeling over a wide range of air/fuel equivalence ratio. A detailed chemical kinetic mechanism was used for natural gas combustion along with laminar flame speed model to capture lean burn operating condition within the combustion chamber. Combustion pressure, indicated mean effective pressure (IMEP), and heat release were analyzed for performance analysis, whereas flame development angle (CA 10), combustion duration, thermal efficiency were taken for combustion analysis. The results show that on increasing air/fuel equivalence ratio at a given spark timing, IMEP decreases as the lean burn mixture produces less amount of gross power output due to insufficient available energy. Moreover, lower burning velocity characteristic of natural gas extends the combustion duration, where a substantial amount of total energy released after top dead center. It is also seen that optimum spark timing (MBT) for maximum IMEP advances with an increase in air/fuel equivalence ratio due to late ignition timing under lean burn condition. CFD model successfully captures the effect of dilution to illustrate the considerations to design future combustion engine for spark ignited natural gas engine.

Experimental study of combustion strategy for jet ignition on a natural gas engine

2020 ◽  
pp. 146808742097775
Author(s):  
Ziqing Zhao ◽  
Zhi Wang ◽  
Yunliang Qi ◽  
Kaiyuan Cai ◽  
Fubai Li
Keyword(s):  
Experimental Study ◽  
Natural Gas ◽  
Efficient Points ◽  
Lean Burn ◽  
Gas Engine ◽  
Absolute Value ◽  
Natural Gas Engines ◽  
Natural Gas Engine ◽  
Excess Air ◽  
Lean Limit

To explore a suitable combustion strategy for natural gas engines using jet ignition, lean burn with air dilution, stoichiometric burn with EGR dilution and lean burn with EGR dilution were investigated in a single-cylinder natural gas engine, and the performances of two kinds of jet ignition technology, passive jet ignition (PJI) and active jet ignition (AJI), were compared. In the study of lean burn with air dilution strategy, the results showed that AJI could extend the lean limit of excess air ratio (λ) to 2.1, which was significantly higher than PJI’s 1.6. In addition, the highest indicated thermal efficiency (ITE) of AJI was shown 2% (in absolute value) more than that of PJI. Although a decrease of NOx emission was observed with increasing λ in the air dilution strategy, THC and CO emissions increased. Stoichiometric burn with EGR was proved to be less effective, which can only be applied in a limited operation range and had less flexibility. However, in contrast to the strategy of stoichiometric burn with EGR, the strategy of lean burn with EGR showed a much better applicability, and the highest ITE could achieve 45%, which was even higher than that of lean burn with air dilution. Compared with the most efficient points of lean burn with pure air dilution, the lean burn with EGR dilution could reduce 78% THC under IMEP = 1.2 MPa and 12% CO under IMEP = 0.4 MPa. From an overall view of the combustion and emission performances under both low and high loads, the optimum λ would be from 1.4 to 1.6 for the strategy of lean burn with EGR dilution.

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