The scavenging timing of pre-chamber on the performance of a natural gas engine

2020 ◽  
pp. 146808742096087
Author(s):  
Xue Yang ◽  
Yong Cheng ◽  
Pengcheng Wang
Keyword(s):  
Natural Gas ◽  
Combustion Process ◽  
Injection System ◽  
Maximum Pressure ◽  
Ignition Process ◽  
Main Chamber ◽  
Ignition Timing ◽  
Gas Engine ◽  
Natural Gas Engines ◽  
Natural Gas Engine

The pre-chamber ignition system scavenged with natural gas can effectively improve the in-cylinder combustion process and extend the lean-burn limit of natural gas engines. The scavenging process affects the flow field and fuel-air mixture concentration distribution in the pre-chamber and affects the combustion process in the pre-chamber as well as the ignition process in the main chamber. This has a significant influence on the performance of natural gas engines. It is supposed that the ratio of natural gas remaining in the mixture inside the pre-chamber at the ignition timing affects the combustion process in the pre-chamber. To verify this suppose, an independent injection system for injecting natural gas into the pre-chamber is designed and experiments are carried out on a single-cylinder natural gas engine. The ratio of natural gas remaining in the mixture inside the pre-chamber at the ignition timing is adjusted by changing the injection start angle of the scavenging process. The combustion process in the pre-chamber and the main chamber are analyzed using the in-cylinder pressures. The results indicate that, with the delay of the injection start angle, the ratio of natural gas remaining in the mixture inside the pre-chamber at the ignition timing increases, the combustion process in the pre-chamber is enhanced, the maximum pressure difference between two chambers increases and appears earlier. The energy of the hot jets and the penetration of the jets increase, which enhances the combustion process in the main chamber.

CFD Modeling of the Performance of a Prechamber for Use in a Large Bore Natural Gas Engine

2005 ◽  
Author(s):  
Allan Kirkpatrick ◽  
Gi-Heon Kim ◽  
Daniel Olsen
Keyword(s):  
Natural Gas ◽  
Fuel Injection ◽  
Combustion Process ◽  
Three Dimensional ◽  
Cfd Modeling ◽  
Main Chamber ◽  
Gas Engine ◽  
Natural Gas Engines ◽  
Natural Gas Engine ◽  
Cfd Models

The topic of this paper is the performance of a prechamber for use in a large bore two stroke natural gas engine. With increased regulation of emissions from stationary natural gas engines, there has been interest in modification of the combustion process, such as extending the lean limit, to reduce NOx emissions. One promising combustion technique uses an ignition prechamber. CFD models of a prechamber and the cylinder were developed in order to simulate the performance of a prechamber ignition system. The modeling included a full three dimensional transient analysis with scavenging, moving piston, and main chamber fuel injection. The CFD analysis included the fuel injection into the prechamber, pressurization by the inflowing main chamber gases, spark ignition, combustion, and flame propagation into the main combustion chamber. The computations indicated that the prechamber is more well mixed than the main engine chamber, with the prechamber mixture close to stoichiometric for better ignition. There is a strong, well-organized vortex in the prechamber induced by the incoming jet from the main chamber. The combustion flame in the prechamber travels in the direction of the gas vortex along lines of increasing equivalence ratio. The flame then propagates across the main cylinder in a very uniform fashion, indicating that there is sufficient energy to ignite the lean, partially mixed mixture in the main chamber. The orientation of the prechamber nozzle was also investigated, and an orientation of twenty degrees relative to the main chamber was found to produce a flame that did not impinge on the piston.

Selective NOx Recirculation for Stationary Lean-Burn Natural Gas Engines

2004 ◽  
Author(s):  
Chamila A. Tissera ◽  
Matt M. Swartz ◽  
Emre Tatli ◽  
Ramprabhu Vellaisamy ◽  
Nigel N. Clark ◽  
...  
Keyword(s):  
Natural Gas ◽  
Combustion Process ◽  
Injection System ◽  
Lean Burn ◽  
Desorption Process ◽  
Gas Engine ◽  
No Conversion ◽  
Natural Gas Engine ◽  
Fuel Ratio ◽  
Conversion Rates

NOx control in a lean burn natural gas engine is typically achieved with appropriate management of air/fuel ratio and ignition timing. A novel approach for further reduction involves the capture of NOx by first adsorbing the NOx from the exhaust stream, followed by the periodic desorption of NOx from an aftertreatment medium. Then, by passing the desorbed NOx gas into the intake air stream and back through the engine, a percentage of the NOx will be converted to harmless gases during the combustion process. The objective of this paper is to report the NOx conversion phenomenon during a lean combustion process. The results of this testing will be used to develop an optimal system for the conversion of NOx with a NOx adsorber. A 1993 Cummins L10-G spark ignited natural gas engine was used to conduct the experiments. Commercially available nitric oxide (NO, 98.8% purity) was injected into the engine intake to mimic the NOx stream from the desorption process to obtain NO conversion rates at various steady-state engine operating points. The NO injection system was capable of injecting NO at varying flow rates and time intervals. NO was injected into the intake manifold for ten and twenty second periods, and the conversion rates were calculated. When the injected NO amount increased from 0.22 g/s to 1.2 g/s and engine loads varied from 200ft-lb to 400ft-lb at 800 RPM, the NO conversion rates increased from 5% to 47%. It was observed that the air/fuel ratio, injected NO quantity and the engine load greatly effected the NO conversion rates. It was also noted that engine speed had a negligible affect when the intake NO concentration was held constant.

Numerical Simulation of Marine Diesel Ignited Natural Gas Engine Based on the Finite Volume Method

2014 ◽  
Vol 926-930 ◽  
pp. 3124-3127
Author(s):  
Hong Liang Yu ◽  
Feng Shuo Xing ◽  
Shu Lin Duan
Keyword(s):  
Numerical Simulation ◽  
Natural Gas ◽  
Finite Volume ◽  
Combustion Process ◽  
Combustion Model ◽  
Emission Characteristics ◽  
Gas Engine ◽  
Natural Gas Engines ◽  
Natural Gas Engine ◽  
Marine Diesel

Currently, the research of marine natural gas engine is rare, while the combustion and emission characteristics of natural gas engine are affected greatly by the diesel ignition. This paper built a finite volume combustion model of diesel ignited natural gas engine by AVL FIRE software, and compared experimental data to prove the accuracy of the model, and numerical simulation of the combustion process that the diesel ignited natural gas was carried, analyzed the combustion and emission characteristics of natural gas engines, provided a theoretical basis for the further optimize and design of marine natural gas engine.

Formaldehyde Characterization Utilizing In-Cylinder Sampling in a Large Bore Natural Gas Engine

2000 ◽  
Vol 123 (3) ◽  
pp. 669-676 ◽  
Author(s):  
D. B. Olsen ◽  
J. C. Holden ◽  
G. C. Hutcherson ◽  
B. D. Willson
Keyword(s):  
Natural Gas ◽  
Combustion Process ◽  
Critical Time ◽  
Sampling Techniques ◽  
Test Results ◽  
Gas Engine ◽  
Natural Gas Engines ◽  
Natural Gas Engine ◽  
Future Work ◽  
Stroke Cycle

This research addresses the growing need to better understand the mechanisms through which engine-out formaldehyde is formed in two-stroke cycle large bore natural gas engines. The investigation is performed using a number of different in-cylinder sampling techniques implemented on a Cooper-Bessemer GMV-4TF four-cylinder two-stroke cycle large bore natural gas engine with a 36-cm (14-in.) bore and a 36-cm (14-in.) stroke. The development and application of various in-cylinder sampling techniques is described. Three different types of valves are utilized, (1) a large sample valve for extracting a significant fraction of the cylinder mass, (2) a fast sample valve for crank angle resolution, and (3) check valves. Formaldehyde in-cylinder sampling data are presented that show formaldehyde mole fractions at different times during the engine cycle and at different locations in the engine cylinder. The test results indicate that the latter part of the expansion process is a critical time for engine-out formaldehyde formation. The data show that significant levels of formaldehyde form during piston and end-gas compression. Additionally, formaldehyde is measured during the combustion process at mole fractions five to ten times higher than engine-out formaldehyde mole fractions. Formaldehyde is nearly completely destroyed during the final part of the combustion process. The test results provide insights that advance the current understanding and help direct future work on formaldehyde formation.

Effects of Natural Gas Compositions on Engine In-Cylinder Process

2015 ◽  
Vol 1092-1093 ◽  
pp. 498-503
Author(s):  
La Xiang ◽  
Yu Ding
Keyword(s):  
Natural Gas ◽  
Alternative Fuels ◽  
Combustion Process ◽  
Engine Performance ◽  
Maximum Temperature ◽  
Maximum Pressure ◽  
Test Bed ◽  
Promising Alternative ◽  
Natural Gas Engines ◽  
Lower Maximum

Natural gas (NG) is one of the most promising alternative fuels of diesel and petrol because of its economics and environmental protection. Generally the NG engine share the similar structure profile with diesel or petrol engine but the combustion characteristics of NG is varied from the fuels, so the investigation of NG engine combustion process receive more attentions from the researchers. In this paper, a zero-dimensional model on the basis of Vibe function is built in the MATLAB/SIMULINK environment. The model provides the prediction of combustion process in natural gas engines, which has been verified by the experimental data in the NG test bed. Furthermore, the influence of NG composition on engine performance is investigated, in which the in-cylinder maximum pressure and temperature and mean indicated pressure are compared using different type NG. It is shown in the results that NG with higher composition of methane results in lower maximum temperature and mean indicated pressure as well as higher maximum pressure.

Railplug Design Optimization to Improve Large-Bore Natural Gas Engine Performance

2005 ◽  
Author(s):  
Hongxun Gao ◽  
Matt J. Hall ◽  
Ofodike A. Ezekoye ◽  
Ron D. Matthews
Keyword(s):  
Natural Gas ◽  
High Energy ◽  
Parameter Study ◽  
Transfer Model ◽  
High Speed Photography ◽  
Discharge Process ◽  
Ignition System ◽  
Gas Engine ◽  
Natural Gas Engines ◽  
Natural Gas Engine

It is a very challenging problem to reliably ignite extremely lean mixtures, especially for the low speed, high load conditions of stationary large-bore natural gas engines. If these engines are to be used for the distributed power generation market, it will require operation with higher boost pressures and even leaner mixtures. Both place greater demands on the ignition system. The railplug is a very promising ignition system for lean burn natural gas engines with its high-energy deposition and high velocity plasma jet. High-speed photography was used to study the discharge process. A heat transfer model is proposed to aid the railplug design. A parameter study was performed both in a constant volume bomb and in an operating natural gas engine to improve and optimize the railplug designs. The engine test results show that the newly designed railplugs can ensure the ignition of very lean natural gas mixtures and extend the lean stability limit significantly. The new railplug designs also improve durability.

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

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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