scholarly journals Lean-Burn Stationary Natural Gas Reciprocating Engine Operation With a Prototype Miniature Diode Side Pumped Passively Q-Switched Laser Spark Plug

2008 ◽  
Author(s):  
Dustin L. McIntyre ◽  
Steven D. Woodruff ◽  
Michael H. McMillian ◽  
Steven W. Richardson ◽  
Mridul Gautam
Keyword(s):  
Natural Gas ◽  
Laser System ◽  
Lean Burn ◽  
Engine Operation ◽  
Natural Gas Engines ◽  
Spark Plug ◽  
Laser Spark ◽  
Laser Systems ◽  
Laser Design ◽  
Engine Testing

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.

Laser Spark Ignition: Laser Development and Engine Testing

2004 ◽  
Author(s):  
Michael H. McMillian ◽  
Steven D. Woodruff ◽  
Steven W. Richardson ◽  
Dustin L. McIntyre
Keyword(s):  
Natural Gas ◽  
Laser System ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Lean Burn ◽  
Engine Operation ◽  
Natural Gas Engines ◽  
Laser Spark ◽  
Engine Testing ◽  
Laser Spark Ignition

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.

Lean-Burn Stationary Natural Gas Reciprocating Engine Operation With a Prototype Fiber Coupled Diode End Pumped Passively Q-Switched Laser Spark Plug

2009 ◽  
Author(s):  
Dustin L. McIntyre ◽  
Steven D. Woodruff ◽  
John S. Ontko
Keyword(s):  
Natural Gas ◽  
Optical Fiber ◽  
Optical Power ◽  
Boost Pressure ◽  
Lean Burn ◽  
Engine Operation ◽  
Pump Source ◽  
Spark Plug ◽  
Spark Timing ◽  
Laser Spark

An end pumped passively Q-switched laser igniter was developed to meet the ignition system needs of large bore lean burn stationary natural gas engines. The laser spark plug used an optical fiber coupled diode pump source to axially pump a passively Q-switched Nd:YAG laser and transmit the laser pulse through a custom designed lens. The optical fiber coupled pump source permits the excitation energy to be transmitted to the spark plug at relatively low optical power, less than 250 watts. The Q-switched laser then generates as much as 8 millijoules of light in 2.5 nanoseconds which is focused through an asymmetric biconvex lens to create a laser spark from a focused intensity of approximately 225 GW/cm2. A single cylinder engine fueled with either natural gas only or hydrogen augmented natural gas was operated with the laser spark plug for approximately 10 hours in tests spanning 4 days. The tests were conducted with fixed engine speed, fixed boost pressure, no exhaust gas recirculation, and laser spark timing advance set at maximum brake torque timing. Engine operational and emissions data were collected and analyzed.

Lean-Burn Stationary Natural Gas Engine Operation With a Prototype Laser Spark Plug

2010 ◽  
Vol 132 (7) ◽  
Author(s):  
Dustin L. McIntyre ◽  
Steven D. Woodruff ◽  
John S. Ontko
Keyword(s):  
Natural Gas ◽  
Optical Fiber ◽  
Optical Power ◽  
Boost Pressure ◽  
Lean Burn ◽  
Engine Operation ◽  
Pump Source ◽  
Spark Plug ◽  
Spark Timing ◽  
Laser Spark

An end pumped passively Q-switched laser igniter was developed to meet the ignition system needs of large bore lean burn stationary natural gas engines. The laser spark plug used an optical fiber coupled diode pump source to axially pump a passively Q-switched Nd:YAG laser and transmit the laser pulse through a custom designed lens. The optical fiber coupled pump source permits the excitation energy to be transmitted to the spark plug at relatively low optical power, less than 250 W. The Q-switched laser then generates as much as 8 mJ of light in 2.5 ns, which is focused through an asymmetric biconvex lens to create a laser spark from a focused intensity of approximately 225 GW/cm2. A single cylinder engine fueled with either natural gas only or hydrogen augmented natural gas was operated with the laser spark plug for approximately 10 h in tests spanning 4 days. The tests were conducted with fixed engine speed, fixed boost pressure, no exhaust gas recirculation, and laser spark timing advance set at maximum brake torque timing. Engine operational and emissions data were collected and analyzed.

Poison Build-up and Performance Degradation of an Oxidation Catalyst in 2-Stroke Natural Gas Engine Exhaust

2017 ◽  
Author(s):  
Marc E. Baumgardner ◽  
Daniel B. Olsen
Keyword(s):  
Natural Gas ◽  
Catalyst Deactivation ◽  
Catalyst Surface ◽  
Oxidation Catalyst ◽  
Lean Burn ◽  
Gas Field ◽  
Natural Gas Engines ◽  
Engine Testing ◽  
And Performance ◽  
Carry Over

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.

Extending the Lean Limit of Natural Gas Engines

2008 ◽  
Author(s):  
R. L. Evans
Keyword(s):  
Natural Gas ◽  
Combustion Chamber ◽  
Lean Burn ◽  
Stratified Charge ◽  
Natural Gas Engines ◽  
Spark Plug ◽  
Charge Mixture ◽  
Cyclic Variations ◽  
Lean Limit ◽  
The Stability

Two different methods to improve the thermal efficiency and reduce the emissions from lean-burn natural gas fuelled engines have been developed, and are described in this paper. One method used a “squish-jet” combustion chamber designed specifically to enhance turbulence generation, while the second method provided a partially stratified-charge mixture near the spark plug in order to enhance the ignition of lean mixtures of natural gas and air. The squish-jet combustion chamber was found to reduce Bsfc by up to 4.8% in a Ricardo Hydra engine, while the NOx – efficiency tradeoff was greatly improved in a Cummins L-10 engine. The partially stratified-charge combustion system extended the lean limit of operation in the Ricardo Hydra by some 10%, resulting in a 64% reduction in NOx emissions at the lean limit of operation. Both techniques were also shown to be effective in increasing the stability of combustion, thereby reducing cyclic variations in cylinder pressure.

Use of Railplugs to Extend the Lean Limit of Natural Gas Engines

2004 ◽  
Author(s):  
Hongxun Gao ◽  
Ron Matthews ◽  
Sreepati Hari ◽  
Matt Hall
Keyword(s):  
Natural Gas ◽  
Stability Limit ◽  
High Energy ◽  
Lean Burn ◽  
Ignition System ◽  
Natural Gas Engines ◽  
Natural Gas Engine ◽  
Spark Plug ◽  
Lean Mixtures ◽  
Ignition Characteristics

Ignition of extremely lean mixtures is a very challenging problem, especially for the low speed, high load conditions of large-bore natural gas engines. This paper presents initial results from testing a high energy ignition system, the railplug, which can assure ignition of very lean mixtures by means of its high energy deposition and high velocity jet of the plasma. Comparisons of natural gas engine tests using both a spark plug and a railplug are presented and discussed in this paper. The preliminary engine test show that the lean stability limit (LSL) can be extended from an equivalence ratio, φ, of ∼0.63 using a spark plug down to 0.56 using a railplug. The tests show that the railplug is very promising ignition system for lean burn natural gas engines and potentially for other engines that operate with very dilute mixtures. The ignition characteristics of different railplug geometric and circuit designs are also discussed.

Extending the Lean Limit of Natural-Gas Engines

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
R. L. Evans
Keyword(s):  
Natural Gas ◽  
Combustion Chamber ◽  
Lean Burn ◽  
Stratified Charge ◽  
Natural Gas Engines ◽  
Spark Plug ◽  
Charge Mixture ◽  
Cyclic Variations ◽  
Lean Limit ◽  
The Stability

Two different methods to improve the thermal efficiency and reduce the emissions from lean-burn natural-gas fueled engines have been developed and are described in this paper. One method used a “squish-jet” combustion chamber designed specifically to enhance turbulence generation, while the second method provided a partially stratified-charge mixture near the spark plug in order to enhance the ignition of lean mixtures of natural gas and air. The squish-jet combustion chamber was found to reduce brake specific fuel consumption by up to 4.8% in a Ricardo Hydra engine, while the NOx efficiency trade-off was greatly improved in a Cummins L-10 engine. The partially stratified-charge combustion system extended the lean limit of operation in the Ricardo Hydra by some 10%, resulting in a 64% reduction in NOx emissions at the lean limit of operation. Both techniques were also shown to be effective in increasing the stability of combustion, thereby reducing cyclic variations in cylinder pressure.

Analysis of the Rotating Arc Spark Plug in a Natural Gas Engine

2005 ◽  
Author(s):  
Jim Tassitano ◽  
James E. Parks
Keyword(s):  
Natural Gas ◽  
Fuel Efficiency ◽  
Cost Effective ◽  
Combustion Stability ◽  
Engine Operation ◽  
Gas Engine ◽  
Natural Gas Engines ◽  
Natural Gas Engine ◽  
Spark Plug ◽  
Rotating Arc

Large natural gas engines are durable and cost-effective generators of power for distributed energy applications. Fuel efficiency is an important aspect of distributed generation since operating costs associated with fuel consumption are the major component of energy cost on a life-cycle basis; furthermore, higher fuel efficiency results in lower CO2 emissions. Leaner operation of natural gas engines can result in improved fuel efficiency; however, engine operation becomes challenging at leaner air-to-fuel ratios due to several factors. One factor in combustion control is ignition. At lean air-fuel mixtures, reliable and repeatable ignition is necessary to maintain consistent power production from the engine, and spark plug quality and durability play an important role in reliability of ignition. Here research of a novel spark plug design for lean natural gas engines is presented. The spark plug is an annular gap spark plug with a permanent magnet that produces a magnetic field that forces the spark to rotate during spark discharge. The rotating arc spark plug (RASP) has the potential to improve ignition system reliability and durability. In the study presented here, the RASP plug was operated in a small natural gas engine, and combustion stability (measured by the coefficient of variation of indicated mean effective pressure (IMEP)) was measured as a function of air-to-fuel ratio to characterize the ignition performance at lean mixtures. Comparisons were made to a standard J-plug spark plug.

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