Spark-Ignition and Combustion Characteristics of High-Pressure Hydrogen and Natural-Gas Intermittent Jets

2008 ◽  
Vol 130 (6) ◽  
Author(s):  
Ali Mohammadi ◽  
Masahiro Shioji ◽  
Yuki Matsui ◽  
Rintaro Kajiwara
Keyword(s):  
High Pressure ◽  
Natural Gas ◽  
Ambient Pressure ◽  
Direct Injection ◽  
Injection Pressure ◽  
Spark Ignition ◽  
Constant Volume Combustion Chamber ◽  
Si Engines ◽  
Ignition And Combustion ◽  
Combustion Processes

Recently, an in-cylinder injection method has been considered for the improvement of thermal efficiency in natural-gas and hydrogen spark-ignition (SI) engines. However, the SI and combustion processes of gaseous jets are not well understood. The present study aims to provide fundamental data for the development of direct-injection SI gas engines. The ignition, combustion, and flame behavior of high-pressure and intermittent hydrogen and natural-gas jets in a constant volume combustion chamber were investigated. The effects of injection pressure, nozzle size, ambient pressure, and spark location were also investigated for various spark timings and equivalence ratios.

The Effects of High-Pressure Injection on a Compression-Ignition, Direct Injection of Natural Gas Engine

2005 ◽  
Author(s):  
G. P. McTaggart-Cowan ◽  
H. L. Jones ◽  
S. N. Rogak ◽  
W. K. Bushe ◽  
P. G. Hill ◽  
...  
Keyword(s):  
High Pressure ◽  
Natural Gas ◽  
Direct Injection ◽  
Injection Pressure ◽  
Operating Conditions ◽  
Heavy Duty ◽  
Substantial Impact ◽  
Single Cylinder ◽  
Particulate Matter Emissions ◽  
And Performance

The use of pilot-ignited, direct-injected natural gas fuelling for heavy-duty on-road applications has been shown to substantially reduce NOx and particulate matter emissions. The fuelling process involves the injection of pilot diesel near top-dead-center, followed shortly afterwards by the injection of natural gas at high pressure. The injection pressure of the gas and diesel will substantially affect the penetration of the fuel into the combustion chamber, the break-up and atomization of the diesel spray, and the mixing and nature of the turbulent gas jet. To investigate these influences, a series of experiments were performed on a single-cylinder heavy-duty engine over a range of engine operating conditions (exhaust gas recirculation fraction, engine speed, engine load). Due to the unique nature of the single-cylinder engine, it was possible to hold all other parameters constant while only varying injection pressure. The results indicated that injection pressure had a substantial impact on emissions and performance at high loads, where substantial reductions in PM and CO were observed, with only minor increases in NOx and no significant effect on tHC or fuel consumption. At low loads, no significant impact on either emissions or performance was detected. The effects of injection pressure, while still significant, were found to be reduced at increased engine speeds. Higher injection pressures were found to consistently reduce both the number density and the size of particles in the exhaust stream.

Parametric study of pilot-ignited direct-injection natural gas combustion in an optically accessible heavy-duty engine

2019 ◽  
Vol 21 (3) ◽  
pp. 497-513 ◽  
Author(s):  
Jeremy Rochussen ◽  
Gordon McTaggart-Cowan ◽  
Patrick Kirchen
Keyword(s):  
Natural Gas ◽  
Heat Release ◽  
Internal Combustion Engines ◽  
Direct Injection ◽  
Injection Pressure ◽  
Gas Combustion ◽  
Gas Ignition ◽  
Partially Premixed ◽  
Natural Gas Combustion ◽  
Combustion Processes

Natural gas is an attractive fuel for internal combustion engines in light of its potential for reduced greenhouse gas and particulate emissions, and significant reserves. To facilitate natural gas use in compression ignition engines, pilot-ignited direct-injection natural gas combustion uses a small pilot injection of diesel to ignite a more significant direct injection of natural gas. Compared to modern diesel combustion, this strategy is a promising technology for the reduction of CO2 emissions while retaining diesel-like efficiency without a significant CH4 emission penalty. To further develop this technology, investigation of in-cylinder combustion processes is needed to identify the primary fuel conversion processes. The objective of this work was to provide a framework of conceptual understanding by identifying key processes in a typical pilot-ignited direct-injection natural gas combustion event and characterizing their sensitivity to fuel injection parameters. A parametric sweep of injection pressure, natural gas injection duration, and relative timing of the diesel pilot and natural gas injections was performed in an optically accessible 2 L single-cylinder engine. Combined heat release rate and OH*-chemiluminescence reaction zone analysis was used to demarcate the transition from ignition reactions to primary natural gas heat release. Five distinct combustion processes were identified: (1) pilot auto-ignition; (2) natural gas ignition; (3) rapid, distributed partially premixed natural gas combustion; (4) non-premixed combustion; and (5) late-cycle oxidation. While natural gas ignition was found to be insensitive to injection pressure, it was strongly affected by the time between pilot and natural gas injections. Reducing the relative injection timing from +8° to −6° resulted in the primary natural gas heat release transitioning from non-premixed, to distributed partially premixed, to stratified premixed flame propagation as a result of increasing natural gas premixing. The presented measurements and analysis serve to refine an initial conceptual model of the combustion process and lay the groundwork for future, more focused studies of pilot-ignited, direct-injection natural gas combustion.

Fundamental insights on ignition and combustion of natural gas in an active fueled pre-chamber spark-ignition system

2021 ◽  
Vol 232 ◽  
pp. 111561
Author(s):  
Rajavasanth Rajasegar ◽  
Yoichi Niki ◽  
Jose Maria García-Oliver ◽  
Zheming Li ◽  
Mark P.B. Musculus
Keyword(s):  
Natural Gas ◽  
Spark Ignition ◽  
Ignition System ◽  
Ignition And Combustion

scholarly journals Phenomenological model for determining velocity field of LPG jet in combustion chamber of direct injection S.I. engine

2004 ◽  
Vol 26 (2) ◽  
pp. 83-92
Author(s):  
Bui Van Ga ◽  
Phung Xuan Tho ◽  
Nhan Hong Quang ◽  
Nguyen Huu Huong
Keyword(s):  
Combustion Chamber ◽  
Phenomenological Model ◽  
Direct Injection ◽  
Spark Ignition ◽  
Velocity Profiles ◽  
Gas Jet ◽  
Liquefied Petroleum Gas ◽  
Si Engine ◽  
Si Engines ◽  
Stratified Combustion

A phenomenological model has been established to predict the velocity distribution of LPG (Liquefied Petroleum Gas) jet in combustion chamber of spark ignition (SI) engine. A shaped coefficient \(\beta\) governing the similarity of velocity profiles of LPG jets has been defined based on the theoretical and experimental analyses of turbulent diffusion jets. The results show that \(\beta\) is constant for steady jet but it is not the case for unsteady one. The model will enable us to calculate the velocity profiles of LPG jet after ending injection. This is necessary for research of stratified combustion in direct injection LPG SI engines.

Assessment of Turbulent Combustion Models for Simulating Pre-Chamber Ignition in a Natural Gas Engine

2021 ◽  
Author(s):  
Joohan Kim ◽  
Riccardo Scarcelli ◽  
Sibendu Som ◽  
Ashish Shah ◽  
Munidhar Biruduganti ◽  
...  
Keyword(s):  
Natural Gas ◽  
Turbulent Combustion ◽  
High Efficiency ◽  
Turbulent Flame ◽  
Spark Ignition ◽  
Cylinder Wall ◽  
Gas Engine ◽  
Natural Gas Engine ◽  
Combustion Models ◽  
Combustion Processes

Abstract Lean combustion in an internal combustion engine is a promising strategy to increase thermal efficiency by leveraging a more favorable specific heat ratio of the fresh mixture and simultaneously suppressing the heat losses to the cylinder wall. However, unstable ignition events and slow flame propagation at fuel-lean condition lead to high cycle-to-cycle variability and hence limit the high-efficiency engine operating range. Pre-chamber ignition is considered an effective concept to extend the lean operating limit, by providing spatially distributed ignition with multiple turbulent flame-jets and enabling faster combustion rate compared to the conventional spark ignition approach. From a numerical modeling perspective, to date, still the science base and available simulation tools are inadequate for understanding and predicting the combustion processes in pre-chamber ignited engines. In this paper, conceptually different RANS combustion models widely adopted in the engine modeling community were used to simulate the ignition and combustion processes in a medium-duty natural gas engine with a pre-chamber spark-ignition system. A flamelet-based turbulent combustion model, i.e., G-equation, and a multi-zone well-stirred reactor model were employed for the multi-dimensional study. Simulation results were compared with experimental data in terms of in-cylinder pressure and heat release rate. Finally, the analysis of the performance of the two models is carried out to highlight the strengths and limitations of the two formulations respectively.

scholarly journals An Investigation of the Influence of Gas Injection Rate Shape on High-Pressure Direct-Injection Natural Gas Marine Engines

Energies ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2571 ◽  
Author(s):  
Jingrui Li ◽  
Jietuo Wang ◽  
Teng Liu ◽  
Jingjin Dong ◽  
Bo Liu ◽  
...  
Keyword(s):  
High Pressure ◽  
Natural Gas ◽  
Fuel Consumption ◽  
Direct Injection ◽  
Gas Injection ◽  
Injection Rate ◽  
Emission Characteristics ◽  
Nox Emissions ◽  
Indicated Mean Effective Pressure ◽  
Marine Engines

High-pressure direct-injection (HPDI) natural gas marine engines are widely used because of their higher thermal efficiency and lower emissions. The effects of different injection rate shapes on the combustion and emission characteristics were studied to explore the appropriate gas injection rate shapes for a low-speed HPDI natural gas marine engine. A single-cylinder model was established and the CFD model was validated against experimental data from the literature; then, the combustion and emission characteristics of five different injection rate shapes were analyzed. The results showed that the peak values of in-cylinder pressure and heat release rate profiles of the triangle shape were highest due to the highest maximum injection rate, which occurred in a phase close to the top dead center. The shorter combustion duration of the triangle shape led to higher indicated mean effective pressure (IMEP) and NOx emissions compared with other shapes. The higher initial injection rates of the rectangle and slope shapes had a negative effect on the ignition delay periods of pilot fuel, which resulted in lower in-cylinder temperature and NOx emissions. However, due to the lower in-cylinder temperature, the engine power output was also lower. Otherwise, soot, unburned hydrocarbon (UHC), and CO emissions and indicated specific fuel consumption (ISFC) increased for both rectangle and slope shapes. The trapezoid and wedge shapes achieved a good balance between fuel consumption and emissions.

Kinetic Study of the Ignition Process of Methane/n-Heptane Fuel Blends under High-Pressure Direct-Injection Natural Gas Engine Conditions

2020 ◽  
Vol 34 (11) ◽  
pp. 14796-14813
Author(s):  
Jingrui Li ◽  
Xinlei Liu ◽  
Haifeng Liu ◽  
Ying Ye ◽  
Hu Wang ◽  
...  
Keyword(s):  
High Pressure ◽  
Natural Gas ◽  
Kinetic Study ◽  
Direct Injection ◽  
Ignition Process ◽  
Gas Engine ◽  
Natural Gas Engine ◽  
Fuel Blends
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