Laser Ignition of Natural Gas Engines Using Fiber Delivery

2005 ◽  
Author(s):  
Azer P. Yalin ◽  
Morgan W. Defoort ◽  
Sachin Joshi ◽  
Daniel Olsen ◽  
Bryan Willson ◽  
...  
Keyword(s):  
Natural Gas ◽  
Past Research ◽  
Spark Ignition ◽  
Laser Source ◽  
Laser Ignition ◽  
Ignition System ◽  
Gas Engine ◽  
Natural Gas Engines ◽  
Natural Gas Engine ◽  
Design Concepts

A practical impediment to implementation of laser ignition systems has been the open-path beam delivery used in past research. In this contribution, we present the development and implementation of a fiber-optically delivery laser spark ignition system. To our knowledge, the work represents the first demonstration of fiber coupled laser ignition (using a remote laser source) of a natural gas engine. A Nd:YAG laser is used as the energy source and a coated hollow fiber is used for beam energy delivery. The system was implemented on a single-cylinder of a Waukesha VGF 18 turbo charged natural gas engine and yielded consistent and reliable ignition. In addition to presenting the design and testing of the fiber delivered laser ignition system, we present initial design concepts for a multiplexer to ignite multiple cylinders using a single laser source, and integrated optical diagnostic approaches to monitor the spark ignition and combustion performance.

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.

Development of an Open Path Laser Ignition System for a Large Bore Natural Gas Engine: Part 1 — System Design

2005 ◽  
Author(s):  
David L. Ahrens ◽  
Azer P. Yalin ◽  
Daniel B. Olsen ◽  
Gi-Heon Kim
Keyword(s):  
Natural Gas ◽  
Pollutant Emissions ◽  
Electrode Erosion ◽  
Laser Ignition ◽  
Ignition System ◽  
Gas Engine ◽  
Natural Gas Engine ◽  
Spark Plug ◽  
Engine Part ◽  
Beam Delivery

Using a laser, as opposed to a conventional (electrical) spark plug, to create a combustion initiating spark is potentially advantageous for several reasons: flexibility in choosing and optimizing the spark location, in particular to move the spark away from solid heat sinks; production of a more robust spark containing more energy; and obviation of electrode erosion problems. These advantages may lead to an extension of the lean limit, an increase in engine thermal efficiency, and the concomitant benefits of reduced pollutant emissions. This paper presents the design of a laser ignition system appropriate for a large bore natural gas engine. Design considerations include: optimization of spark location, design of beam delivery system and optical plug, and mitigation of vibration and thermal effects. Engine test results will be presented in the second paper of this two-paper series.

Development of an Open Path Laser Ignition System for a Large Bore Natural Gas Engine: Part 2 — Single Cylinder Demonstration

2005 ◽  
Author(s):  
David L. Ahrens ◽  
Daniel B. Olsen ◽  
Azer P. Yalin
Keyword(s):  
Natural Gas ◽  
Combustion Stability ◽  
Electrode Erosion ◽  
Laser Ignition ◽  
Engine Test ◽  
Test Results ◽  
Ignition System ◽  
Gas Engine ◽  
Natural Gas Engine ◽  
Spark Plug

Using a laser, as opposed to a conventional (electrical) spark plug, to create a combustion initiating spark is potentially advantageous for several reasons: flexibility in choosing and optimizing the spark location, in particular to move the spark away from solid heat sinks; production of a more robust spark containing more energy; and obviation of electrode erosion problems. In this paper we present the on-engine test results of the laser ignition system on a large bore natural gas engine. Test results include: mass fraction burn duration, hydrocarbon emissions data, and combustion stability comparisons to the conventional spark plug ignition system. Design and spark location considerations for the laser ignition system were presented in the first paper of this two-paper series.

Ignition System Designed to Extend the Plug Life, and the Lean Limit in a Natural Gas Engine

2003 ◽  
Author(s):  
A. K. Chan ◽  
S. H. Waters
Keyword(s):  
Natural Gas ◽  
Engine Performance ◽  
Ignition System ◽  
Gas Engine ◽  
Natural Gas Engine ◽  
Dc System ◽  
Spark Plug ◽  
Long Duration ◽  
Discharge Duration ◽  
Lean Limit

An ignition system that is based on the alternating (AC) rather than the traditional direct (DC) current in the spark plug discharge has been developed at the Caterpillar Technical Center. This system can generate a long duration discharge with controllable power. It is believed that such an ignition system can provide both a leaner operating limit and a longer spark plug life than a traditional DC system due to the long discharge duration and the low discharge power. The AC ignition system has successfully been tested on a Caterpillar single cylinder G3500 natural gas engine to determine the effects on the engine performance, combustion characteristics and emissions. The test results indicate that while the AC ignition system has only a small impact on engine performance (with respect to a traditional DC system), it does extend the lean limit with lower NOx emissions. Evidences also show the potential of reduce spark plug electrode erosions from the low breakdown and sustaining discharge powers from the AC ignition system. This paper summarizes the prototype design and engine demonstration results of the AC ignition system.

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.

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.

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

2019 ◽  
Author(s):  
Joohan Kim ◽  
Riccardo Scarcelli ◽  
Sibendu Som ◽  
Ashish Shah ◽  
Munidhar S. 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.

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.

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