Laser Spark Ignition: Laser Development and Engine Testing

Author(s):  
Michael H. McMillian ◽  
Steven D. Woodruff ◽  
Steven W. Richardson ◽  
Dustin L. McIntyre

Evermore demanding market and legislative pressures require stationary lean-burn natural gas engines to operate at higher efficiencies and reduced levels of emissions. Higher in-cylinder pressures and leaner air/fuel ratios are required in order to meet these demands. Contemporary ignition systems, more specifically spark plug performance and durability, suffer as a result of the increase in spark energy required to maintain suitable engine operation under these conditions. This paper presents a discussion of the need for an improved ignition source for advanced stationary natural gas engines and introduces laser spark ignition as a potential solution to that need. Recent laser spark ignition engine testing with natural gas fuel including NOx mapping is discussed. A prototype laser system in constructed and tested and the results are discussed and solutions provided for improving the laser system output pulse energy and pulse characteristics.

Author(s):  
Dustin L. McIntyre ◽  
Steven D. Woodruff ◽  
Michael H. McMillian ◽  
Steven W. Richardson ◽  
Mridul Gautam

To meet the ignition system needs of large bore lean burn stationary natural gas engines a laser diode side pumped passively Q-switched laser igniter was developed and used to ignite lean mixtures in a single cylinder research engine. The laser design was produced from previous work. The in-cylinder conditions and exhaust emissions produced by the miniaturized laser were compared to that produced by a laboratory scale commercial laser system used in prior engine testing. The miniaturized laser design as well as the combustion and emissions data for both laser systems was compared and discussed. It was determined that the two laser systems produced virtually identical combustion and emissions data.


2004 ◽  
Author(s):  
Michael McMillian ◽  
Steven Richardson ◽  
Steven D. Woodruff ◽  
Dustin McIntyre

1975 ◽  
Vol 189 (1) ◽  
pp. 139-147 ◽  
Author(s):  
G. A. Karim ◽  
I. A. Ali

For various fuel-air mixtures and different compression ratios, the intake temperature was varied over the entire range of ***200°F (366K) down to − 100°F (200K) when employing a single cylinder spark ignited research engine fuelled with natural gas. Performance data such as knock and ignition limits the nature and extent of exhaust emission and chamber pressure cyclic variation were obtained. Means were then suggested for the interpretation of the above mentioned data in terms of engine operation on liquefied natural gas. The experimental work confirmed in general the attractive features of the use of natural gas as a fuel in a spark ignition engine operated under extremely cold intake temperature conditions and that emissions of pollutants were not significantly increased.


2004 ◽  
Author(s):  
S. R. Munshi ◽  
C. Nedelcu ◽  
J. Harris ◽  
T. Edwards ◽  
J. Williams ◽  
...  

Author(s):  
Marc E. Baumgardner ◽  
Daniel B. Olsen

Due to current and future exhaust emissions regulations, oxidation catalysts are increasingly being added to the exhaust streams of large-bore, 2-stroke, natural gas engines. Such catalysts have been found to have a limited operational lifetime, primarily due to chemical (i.e. catalyst poisoning) and mechanical fouling resulting from the carry-over of lubrication oil from the cylinders. It is critical for users and catalyst developers to understand the nature and rate of catalyst deactivation under these circumstances. This study examines the degradation of an exhaust oxidation catalyst on a large-bore, 2-stroke, lean-burn, natural gas field engine over the course of 2 years. Specifically this work examines the process by which the catalyst was aged and tested and presents a timeline of catalyst degradation under commercially relevant circumstances. The catalyst was aged in the field for 2 month intervals in the exhaust slipstream of a GMVH-12 engine and intermittently brought back to the Colorado State Engines and Energy Conversion Laboratory for both engine testing and catalyst surface analysis. Engine testing consisted of measuring catalyst reduction efficiency as a function of temperature as well as the determination of the light-off temperature for several exhaust components. The catalyst surface was analyzed via SEM/EDS and XPS techniques to examine the location and rate of poison deposition. After 2 years on-line the catalyst light-off temperature had increased ∼55°F (31°C) and ∼34 wt% poisons (S, P, Zn) were built up on the catalyst surface, both of which represent significant catalyst deactivation.


Author(s):  
A. Ramesh ◽  
Mohand Tazerout ◽  
Olivier Le Corre

This work deals with the nature of cycle by cycle variations in a single cylinder, lean burn, natural gas fuelled spark ignition engine operated at a constant speed of 1500 rev/min under variable equivalence ratio, fixed throttle conditions. Cycle by cycle variations in important parameters like indicated mean effective pressure (IMEP), peak pressure, rate of pressure rise and heat release characteristics were studied. At the lean misfire limit there was a drastic increase in combustion duration. With mixtures leaner than the lean limit, good cycles generally followed poor cycles. However, the vice versa was not true. Cycles that had a high initial heat release rate lead to more complete combustion. A high rate of pressure rise led to a high IMEP. The IMEP of cycles versus their frequency of occurrence was symmetric about the average value when the combustion was good.


2017 ◽  
Vol 139 (10) ◽  
Author(s):  
Bader Almansour ◽  
Subith Vasu ◽  
Sreenath B. Gupta ◽  
Qing Wang ◽  
Robert Van Leeuwen ◽  
...  

Lean-burn operation of stationary natural gas engines offers lower NOx emissions and improved efficiency. A proven pathway to extend lean-burn operation has been to use laser ignition (LI) instead of standard spark ignition (SI). However, under lean conditions, flame speed reduces, thereby offsetting any efficiency gains resulting from the higher ratio of specific heats, γ. The reduced flame speeds, in turn, can be compensated with the use of a prechamber to result in volumetric ignition and thereby lead to faster combustion. In this study, the optimal geometry of PCLI was identified through several tests in a single-cylinder engine as a compromise between autoignition, NOx, and soot formation within the prechamber. Subsequently, tests were conducted in a single-cylinder natural gas engine comparing the performance of three ignition systems: standard electrical spark ignition (SI), single-point laser ignition (LI), and PCLI. Out of the three, the performance of PCLI was far superior compared to the other two. Efficiency gain of 2.1% points could be achieved while complying with EPA regulation (BSNOx < 1.34 kWh) and the industry standard for ignition stability (coefficient of variation of integrated mean effective pressure (COV_IMEP) < 5%). Test results and data analysis are presented identifying the combustion mechanisms leading to the improved performance.


2003 ◽  
Author(s):  
A. Manivannan ◽  
P. Tamil Porai ◽  
S. Chandrasekaran ◽  
R. Ramprabhu

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