Low pressure direct injection strategies effect on a small SI natural gas two-stroke engine’s energy distribution and emissions

Darzi, Mahdi; Johnson, Derek; Ulishney, Chris; Clark, Nigel N.

doi:10.1016/j.apenergy.2018.09.091

“…The significantly large proven reserves of natural gas (200 trillion cubic meters worldwide) combined with the capability to operate a cleaner and more efficient cycle make it an attractive alternative fuel [5]. The use of natural gas as a standalone fuel, or as a blend with diesel or hydrogen, has been extensively studied in traditional spark ignition engines [6][7][8][9] and more advanced cycles such as homogeneous charge compression ignition (HCCI) [10][11][12][13][14] and reactivity controlled compression ignition (RCCI) [15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Implementing Natural Gas in a Compression Ignition Cycle Using Noble Gas Addition

Shahsavan¹,

Morovatiyan²,

Baghirzade³

et al. 2019

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Natural gas is known as a relatively clean fossil fuel due to its low carbon to hydrogen ratio compared to other transportation fuels, which yields a reduction of carbon monoxide, carbon dioxide, and unburned hydrocarbons emissions. However, it has a low cetane number, which makes it a difficult fuel for use in compression ignition engines. A potential solution for this issue can be adding small amounts of argon, as a noble gas with a low specific heat to modify the intake conditions. In this numerical study, a commercial compression ignition engine has been modeled to evaluate the auto-ignition of natural gas with the modified intake conditions. Different amounts of argon added to the intake air are examined in order to attain the optimal operating conditions. A detailed chemistry solver is implemented on a 53-species chemical kinetics mechanism to calculate the rate constants. The results show that compression ignition of natural gas can be achieved by adding small amounts of argon to the intake air. It drastically increases the in-cylinder temperature and pressure near TDC, which enables the auto-ignition of the injected natural gas. Moreover, it leads to the reduction in ignition delay and heat release rate, and expands the combustion duration. Emissions analysis indicates that NOx and CO2 can be significantly diminished by increasing the amount of argon in the intake composition. This study introduces an efficient and clean compression ignition engine fueled with natural gas running in optimal operating conditions using argon addition to the intake.

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“…The significantly large proven reserves of natural gas (200 trillion cubic meters worldwide) combined with the capability to operate a cleaner and more efficient cycle make it an attractive alternative fuel [5]. The use of natural gas as a standalone fuel, or as a blend with diesel or hydrogen, has been extensively studied in traditional spark ignition engines [6][7][8][9] and more advanced cycles such as homogeneous charge compression ignition (HCCI) [10][11][12][13][14] and reactivity controlled compression ignition (RCCI) [15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Implementing Natural Gas in a Compression Ignition Cycle Using Noble Gas Addition

Shahsavan

¹

,

Morovatiyan

²

,

Baghirzade

³

et al. 2019

ASME 2019 Internal Combustion Engine Division Fall Technical Conference

0

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Natural gas is known as a relatively clean fossil fuel due to its low carbon to hydrogen ratio compared to other transportation fuels, which yields a reduction of carbon monoxide, carbon dioxide, and unburned hydrocarbons emissions. However, it has a low cetane number, which makes it a difficult fuel for use in compression ignition engines. A potential solution for this issue can be adding small amounts of argon, as a noble gas with a low specific heat to modify the intake conditions. In this numerical study, a commercial compression ignition engine has been modeled to evaluate the auto-ignition of natural gas with the modified intake conditions. Different amounts of argon added to the intake air are examined in order to attain the optimal operating conditions. A detailed chemistry solver is implemented on a 53-species chemical kinetics mechanism to calculate the rate constants. The results show that compression ignition of natural gas can be achieved by adding small amounts of argon to the intake air. It drastically increases the in-cylinder temperature and pressure near TDC, which enables the auto-ignition of the injected natural gas. Moreover, it leads to the reduction in ignition delay and heat release rate, and expands the combustion duration. Emissions analysis indicates that NOx and CO2 can be significantly diminished by increasing the amount of argon in the intake composition. This study introduces an efficient and clean compression ignition engine fueled with natural gas running in optimal operating conditions using argon addition to the intake.

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“…For LPDI operation with SOI of 180 CAD BTDC, a COV of less than 10% was achieved for λ* less than 1.7. Some literature recommends an acceptable threshold of 10% for the COV of IMEP [19], while recently this criteria has been reduced to 5% by industry [61]. In line with combustion instability, combustion duration increased for unstable combustion cases as shown in Figure 37.…”

Section: Lpdimentioning

confidence: 93%

“…To overcome deficiency of PI, a direct injection strategy was evaluated in a small NG two-stroke engine which resulted in a more than 60% relative improvement in BTE [61]. A study conducted in Japan investigated the effects of low-pressure CNG injection into the transfer (scavenging) ports of a two-stroke SI engine.…”

Section: State-of-the-artmentioning

confidence: 99%

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A Framework for Energy Optimization of Small, Two-Stroke, Natural Gas Engines for Combined Heat and Power Applications

Darzi¹

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A Framework for Energy Optimization of Small, Two-Stroke, Natural Gas Engines for Combined Heat and Power Applications Mahdi Darzi This research was focused on the development of a framework for the energy optimization a natural gas engine for small combined heat and power (CHP) applications operating with lowpressure natural gas (NG) available at homes. The required targets of the ARPA-E GENSETS program for 1 kW electric power generation and previous GENSETS simulation at West Virginia University, suggested a design space for the engine which is currently dominated by simple twostroke designs. Hence this research focused on screening, modeling, and experimentally evaluation of cost-effective technologies to achieve a system design that maximized thermal efficiency and utilization factor, while reducing emissions. A baseline engine was selected which started with 8% brake thermal efficiency (BTE) on natural gas operation. By implementing intake and exhaust optimization BTE increased up to around 12% and with head design optimization and exhaust backpressure, the engine reached 15% BTE. Though the initial optimization methods almost doubled efficiency, it was realized that further increases in BTE must be achieved for a commercially competitive design. The engine was redesigned to utilize modified porting for enhanced breathing and scavenging and a method to deploy low-pressure direct injection (LPDI) was developed. With these enhancements, BTE increased to around 24%. A second round of optimization was performed then, by modeling the whole system in a 1D platform and using a genetic algorithm and experimental data to further optimize scavenging which increased the efficiency up to around 26%. Finally, a 3D computational fluid dynamics (CFD) was developed to investigate the stratification effects of LPDI and determine the optimal spark plug location. This effort increased the BTE to around 27.5%. To assess issues with commercial deployment, three different NG compositions and propane operation were investigated. With an energy balance and exergy distribution analysis for each fuel, fuel quality effects on the CHP system performance were determined. At the end, with combination literature review, experiments, 1D and 3D simulations, a framework for optimization of micro-CHP systems operating on gaseous fuels was developed that can serve industry to highlight methods that can more than triple brake thermal efficiency of small two-stroke engines while improving the energy distribution for CHP systems. iii Acknowledgment Special thanks to Dr. Johnson for his support and mentorship throughout my PhD program. I thank my dedicated PhD committee members for their guidance and valuable feedback to improve this dissertation. I would like to thank Mr.

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Low pressure direct injection strategies effect on a small SI natural gas two-stroke engine’s energy distribution and emissions

Cited by 31 publications

References 33 publications

Implementing Natural Gas in a Compression Ignition Cycle Using Noble Gas Addition

Implementing Natural Gas in a Compression Ignition Cycle Using Noble Gas Addition

Implementing Natural Gas in a Compression Ignition Cycle Using Noble Gas Addition

A Framework for Energy Optimization of Small, Two-Stroke, Natural Gas Engines for Combined Heat and Power Applications

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