The Squish-Jet Combustion Chamber for Ultra-Lean Burn Natural Gas Engines

2011 ◽  
Author(s):  
Eric Kastanis ◽  
Robert L. Evans
Keyword(s):  
Natural Gas ◽  
Combustion Chamber ◽  
Lean Burn ◽  
Natural Gas Engines

Extending the Lean Limit of Natural Gas Engines

2008 ◽  
Author(s):  
R. L. Evans
Keyword(s):  
Natural Gas ◽  
Combustion Chamber ◽  
Lean Burn ◽  
Stratified Charge ◽  
Natural Gas Engines ◽  
Spark Plug ◽  
Charge Mixture ◽  
Cyclic Variations ◽  
Lean Limit ◽  
The Stability

Two different methods to improve the thermal efficiency and reduce the emissions from lean-burn natural gas fuelled engines have been developed, and are described in this paper. One method used a “squish-jet” combustion chamber designed specifically to enhance turbulence generation, while the second method provided a partially stratified-charge mixture near the spark plug in order to enhance the ignition of lean mixtures of natural gas and air. The squish-jet combustion chamber was found to reduce Bsfc by up to 4.8% in a Ricardo Hydra engine, while the NOx – efficiency tradeoff was greatly improved in a Cummins L-10 engine. The partially stratified-charge combustion system extended the lean limit of operation in the Ricardo Hydra by some 10%, resulting in a 64% reduction in NOx emissions at the lean limit of operation. Both techniques were also shown to be effective in increasing the stability of combustion, thereby reducing cyclic variations in cylinder pressure.

Extending the Lean Limit of Natural-Gas Engines

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
R. L. Evans
Keyword(s):  
Natural Gas ◽  
Combustion Chamber ◽  
Lean Burn ◽  
Stratified Charge ◽  
Natural Gas Engines ◽  
Spark Plug ◽  
Charge Mixture ◽  
Cyclic Variations ◽  
Lean Limit ◽  
The Stability

Two different methods to improve the thermal efficiency and reduce the emissions from lean-burn natural-gas fueled engines have been developed and are described in this paper. One method used a “squish-jet” combustion chamber designed specifically to enhance turbulence generation, while the second method provided a partially stratified-charge mixture near the spark plug in order to enhance the ignition of lean mixtures of natural gas and air. The squish-jet combustion chamber was found to reduce brake specific fuel consumption by up to 4.8% in a Ricardo Hydra engine, while the NOx efficiency trade-off was greatly improved in a Cummins L-10 engine. The partially stratified-charge combustion system extended the lean limit of operation in the Ricardo Hydra by some 10%, resulting in a 64% reduction in NOx emissions at the lean limit of operation. Both techniques were also shown to be effective in increasing the stability of combustion, thereby reducing cyclic variations in cylinder pressure.

scholarly journals Emission of Toxic HCN During NO x Removal by Ammonia SCR in the Exhaust of Lean‐Burn Natural Gas Engines

2020 ◽  
Vol 59 (34) ◽  
pp. 14423-14428 ◽  
Author(s):  
Deniz Zengel ◽  
Pirmin Koch ◽  
Bentolhoda Torkashvand ◽  
Jan‐Dierk Grunwaldt ◽  
Maria Casapu ◽  
...  
Keyword(s):  
Natural Gas ◽  
Lean Burn ◽  
Natural Gas Engines

Lean-Burn Characteristics of a Heavy-Duty Diesel Engine Retrofitted to Natural Gas Spark Ignition

2018 ◽  
Author(s):  
Jinlong Liu ◽  
Cosmin E. Dumitrescu
Keyword(s):  
Natural Gas ◽  
Combustion Chamber ◽  
Spark Ignition ◽  
Operating Conditions ◽  
Combustion Stability ◽  
Fuel Injector ◽  
Heavy Duty ◽  
Lean Burn ◽  
Spark Timing ◽  
Heavy Duty Diesel

Increased utilization of natural-gas (NG) in the transportation sector can decrease the use of petroleum-based fuels and reduce greenhouse-gas emissions. Heavy-duty diesel engines retrofitted to NG spark ignition (SI) can achieve higher efficiencies and low NOx, CO, and HC emissions when operated under lean-burn conditions. To investigate the SI lean-burn combustion phenomena in a bowl-in-piston combustion chamber, a conventional heavy-duty direct-injection CI engine was converted to SI operation by replacing the fuel injector with a spark plug and by fumigating NG in the intake manifold. Steady-state engine experiments and numerical simulations were performed at several operating conditions that changed spark timing, engine speed, and mixture equivalence ratio. Results suggested a two-zone NG combustion inside the diesel-like combustion chamber. More frequent and significant late burn (including double-peak heat release rate) was observed for advanced spark timing. This was due to the chamber geometry affecting the local flame speed, which resulted in a faster and thicker flame in the bowl but a slower and thinner flame in the squish volume. Good combustion stability (COVIMEP < 3 %), moderate rate of pressure rise, and lack of knocking showed promise for heavy-duty CI engines converted to NG SI operation.

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.

Phenomenological Modeling of Combustion in Pre-Chamber and the Pilot Flame for Natural Gas Engines

2019 ◽  
Author(s):  
Long Liu ◽  
Xia Wen ◽  
Qian Xiong ◽  
Xiuzhen Ma
Keyword(s):  
Natural Gas ◽  
Combustion Chamber ◽  
Alternative Fuels ◽  
Gas Flow ◽  
Combustion Process ◽  
Clean Energy ◽  
Combustion Model ◽  
Flame Surface ◽  
Flow Process ◽  
Natural Gas Engines

Abstract With energy shortages and increasing environmental problems, natural gas, as a clean energy, has the advantages of cheap price and large reserves and has become one of the main alternative fuels for marine diesel engines. For large bore natural gas engines, pre-chamber spark plug ignition can be used to increase engine efficiency. The engine mainly relies on the flame ejected from the pre-chamber to ignite the mixture of natural gas and air in the main combustion chamber. The ignition flame in the main combustion chamber is the main factor affecting the combustion process. Although the pre-chamber natural gas engines have been extensively studied, the characteristics of combustion in the pre-chamber and the development of ignition flame in the main combustion chamber have not been fully understood. In this study, a two-zone phenomenological combustion model of pre-chamber spark-ignition natural gas engines is established based on the exchange of mass and energy of the gas flow process in the pre-chamber and the main combustion chamber. The basic characteristics of the developed model are: a spherical flame surface is used to describe the combustion state in the pre-chamber, and according to the turbulent jet theory, the influence of turbulence on the state of the pilot flame is considered based on the Reynolds number. According to the phenomenological model, the time when the flame starts to be injected from the pre-chamber to the main combustion chamber, and the parameters such as the length of the pilot flame are analyzed. The model was verified by experimental data, and the results showed that the calculated values were in good agreement with the experimental values. It provides an effective tool for mastering the law of flame development and supporting the optimization of combustion efficiency.

scholarly journals Lean-Burn Natural Gas Engines: Challenges and Concepts for an Efficient Exhaust Gas Aftertreatment System

2020 ◽  
Author(s):  
Patrick Lott ◽  
Olaf Deutschmann
Keyword(s):  
Natural Gas ◽  
Carbon Dioxide Emissions ◽  
Rational Design ◽  
Catalytic Converter ◽  
Pollutant Emissions ◽  
Exhaust Gas ◽  
Lean Burn ◽  
Aftertreatment System ◽  
Natural Gas Engines ◽  
Exhaust Gas Aftertreatment

AbstractHigh engine efficiency, comparably low pollutant emissions, and advantageous carbon dioxide emissions make lean-burn natural gas engines an attractive alternative compared to conventional diesel or gasoline engines. However, incomplete combustion in natural gas engines results in emission of small amounts of methane, which has a strong global warming potential and consequently makes an efficient exhaust gas aftertreatment system imperative. Palladium-based catalysts are considered as most effective in low temperature methane conversion, but they suffer from inhibition by the combustion product water and from poisoning by sulfur species that are typically present in the gas stream. Rational design of the catalytic converter combined with recent advances in catalyst operation and process control, particularly short rich periods for catalyst regeneration, allow optimism that these hurdles can be overcome. The availability of a durable and highly efficient exhaust gas aftertreatment system can promote the widespread use of lean-burn natural gas engines, which could be a key step towards reducing mankind’s carbon footprint.

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