Gas Engine Combustion Principles and Applications

Chen, Simon K.; Beck, N.

doi:10.4271/2001-01-2489

Cited by 24 publications

(8 citation statements)

References 3 publications

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“…With the greater percentage of EGR, the increased inert gas in the combustion decreases engine combustion temperature and NO X emissions (Mahla et al, 2010). Previous studies have found that engine-out hydrocarbon emissions increase as EGR percentage increases due to increased exhaust in the air to fuel mixture, which can also cause incomplete combustion (Chen and Beck, 2001;Pirouzpanah and Sarai, 2003;Einewall et al, 2005). The significant emission reduction observed in stoichiometric engines is mostly achieved by TWC (Einewall et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

“…In a lean-burn engine operating around 1.6 lambda (the ratio of actual air/fuel to stoichiometric air/fuel), control of the air-fuel ratio was critical to avoid misfiring and knocking. An air-fuel ratio close to the lean limit could produce higher performance and possibly reduce NO X emissions (Chen and Beck, 2001), but a slight excess air-fuel ratio beyond the lean limit would cause misfiring and result in high emissions and poor performance due to incomplete combustion (Cho and He, 2007). Since fuel injection with carburetor fuel metering technology was based on a predefined engine operation map, it was very difficult to precisely control the air-fuel ratio close to the lean limit.…”

Section: Introductionmentioning

confidence: 99%

“…While improving engine performance, the increased air-fuel ratio resulted in high hydrocarbon emissions due to incomplete hydrocarbon combustion. For lean-burn engines, as an engine operates with leaner conditions, particularly lambda higher than 1.6, a linear increase of hydrocarbon emissions is expected due to slower flame initiation and propagation (Chen and Beck, 2001;Cho and He, 2007). To reduce HC emissions, engine manufacturers have applied an oxidation catalyst (OxC) to lean-burn engines as an exhaust control technology.…”

Section: Introductionmentioning

confidence: 99%

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Criteria pollutant and greenhouse gas emissions from CNG transit buses equipped with three-way catalysts compared to lean-burn engines and oxidation catalyst technologies

Yoon

Collins

Thiruvengadam

et al. 2013

Journal of the Air & Waste Management Association

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Engine and exhaust control technologies applied to compressed natural gas (CNG) transit buses have advanced from lean-burn, to lean-burn with oxidation catalyst (OxC), to stoichiometric combustion with three-way catalyst (TWC). With this technology advancement, regulated gaseous and particulate matter emissions have been significantly reduced. Two CNG transit buses equipped with stoichiometric combustion engines and TWCs were tested on a chassis dynamometer, and their emissions were measured. Emissions from the stoichiometric engines with TWCs were then compared to the emissions from lean-burn CNG transit buses tested in previous studies. Stoichiometric combustion with TWC was effective in reducing emissions of oxides of nitrogen (NO X ), particulate matter (PM), and nonmethane hydrocarbon (NMHC) by 87% to 98% depending on pollutants and test cycles, compared to lean combustion. The high removal efficiencies exceeded the emission reduction required from the certification standards, especially for NO X and PM. While the certification standards require 95% and 90% reductions for NO X and PM, respectively, from the engine model years 1998-2003 to the engine model year 2007, the measured NO X and PM emissions show 96% and 95% reductions, respectively, from the lean-burn engines to the stoichiometric engines with TWC over the transient Urban Dynamometer Driving Schedule (UDDS) cycle. One drawback of stoichiometric combustion with TWC is that this technology produces higher carbon monoxide (CO) emissions than lean combustion. In regard to controlling CO emissions, lean combustion with OxC is more effective than stoichiometric combustion. Stoichiometric combustion with TWC produced higher greenhouse gas (GHG) emissions including carbon dioxide (CO 2 ) and methane (CH 4 ) than lean combustion during the UDDS cycle, but lower GHG emissions during the steady-state cruise cycle.Implications: Stoichiometric combustion with three-way catalyst is currently the best emission control technology available for compressed natural gas (CNG) transit buses to meet the stringent U.S. Environmental Protection Agency (EPA) 2010 heavy-duty engine NO X emissions standard. For existing lean-burn CNG transit buses in the fleet, oxidation catalyst would be the most effective retrofit technology for the control of NMHC and CO emissions.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Criteria pollutant and greenhouse gas emissions from CNG transit buses equipped with three-way catalysts compared to lean-burn engines and oxidation catalyst technologies

Yoon

Collins

Thiruvengadam

et al. 2013

Journal of the Air & Waste Management Association

View full text Add to dashboard Cite

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“…The challenges with lean charge involve engine stability, as a result of reduced burning rate [9,200,202], and suitability only for part-load conditions and low-MEP operation [8]. Even though gaseous fuels are known for their lower emission of THC, lean-burn CNG has relatively higher emissions of THC, resulting from the unburned mixture in the end zone [205]. The effect of the air-fuel ratio on the combustion efficiency and emissions is shown in Figure 13.…”

Section: Effect Of Lean Charge Strategymentioning

confidence: 99%

Natural Gas Engine Technologies: Challenges and Energy Sustainability Issue

2018

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Energy sustainability and environmental issues pose greater challenges on different primary energy sectors as the global energy demand increases and it is projected to further increase with an upsurge in population. On the other hand, energy sources from conventional fossil-based fuels are depleting, forcing explorations in challenging and difficult locations. As a result, the use of alternative fuels received dramatic consideration to substitute these conventional fuels, of which natural gas took the significant share. However, the share of natural-gas vehicles in the current vehicle market is quite small, and it is estimated to be below 5%. This paper reviews the current resource scenarios including proven and potential reserves, current production, and consumption, along with the fueling infrastructure, distribution, and storage. It also provides summary of the development of fuel-injection technologies aimed to enhance the performance of gas engines. More attention was also given to natural-gas engines and their limitations. Parameters affecting the performance and combustion of compressed natural gas (CNG) in spark-ignition (SI) engines are thoroughly assessed, among which compression ratio and injection timing play major roles in the optimization of CNG-fueled engines. Furthermore, different technologies that help close the performance gap between conventional liquid-fuel and natural-gas engines and future directions of the research are presented.

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“…In general, lean conditions increase both the time needed for initial flame development and the duration of the rapid flame development period. Dilute fuel mixtures produce lower flame propagation speeds and reduce the rate of heat release, and misfires are more likely under very lean conditions [68,69].…”

Section: Combustion Stability Analysismentioning

confidence: 99%

Experimental Investigation of Methane Direct Injection with Stratified Charge Combustion in Optical SI Single Cylinder Engine

Melaika

Dahlander

2016

SAE Technical Paper Series

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N atural gas, biogas, and biomethane are attractive fuels for compressed natural gas (CNG) engines because of their beneficial physical and chemical characteristics. This paper examines three combustion modes-homogeneous stoichiometric, homogeneous lean burn, and stratified combustion-in an optical single cylinder engine with a gas direct injection system operating with an injection pressure of 18 bar. The combustion process in each mode was characterized by indicated parameters, recording combustion images, and analysing combustion chemiluminescence emission spectra. Pure methane, which is the main component of CNG (up to 98%) or biomethane (> 98 %), was used as the fuel. Chemiluminescence emission spectrum analysis showed that OH* and CN* peaks appeared at their characteristic wavelengths in all three combustion modes. The peak of OH* and broadband CO 2 * intensities were strongly dependent on the air/fuel ratio conditions in the cylinder. Lower OH* and CO 2 * intensities were observed with lean air/fuel mixtures because under these conditions, more air was present, the combustion reactions were slower, and the cylinder pressure was higher. CN* was formed by the spark plasma and was detected over a particularly long period when using a dual coil ignition system. The intensities of the OH* and CN* signals correlated when using this ignition system. Combustion image analysis showed that the flame had a wrinkled boundary in stoichiometric and lean burn modes and was especially distorted in stratified mode. No yellow soot luminescence was observed during homogeneous combustion. However, the emission spectra and combustion images acquired during stratified combustion showed that soot formation occurred due to the presence of fuel-rich areas with inadequate mixing in the cylinder. The difficulty of maintaining stable fuel injection, achieving proper air/fuel mixing, and ensuring stable flame propagation in lean air/fuel mixtures increased cycle-to-cycle variations. However, the homogeneous lean burn and stratified combustion modes achieved significantly lower indicated specific fuel consumption values than stoichiometric combustion.

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Gas Engine Combustion Principles and Applications

Cited by 24 publications

References 3 publications

Criteria pollutant and greenhouse gas emissions from CNG transit buses equipped with three-way catalysts compared to lean-burn engines and oxidation catalyst technologies

Criteria pollutant and greenhouse gas emissions from CNG transit buses equipped with three-way catalysts compared to lean-burn engines and oxidation catalyst technologies

Natural Gas Engine Technologies: Challenges and Energy Sustainability Issue

Experimental Investigation of Methane Direct Injection with Stratified Charge Combustion in Optical SI Single Cylinder Engine

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