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Title: Natural Gas Engine Performance Ignited by a Passively Q-Switched Microlaser

Abstract

A robust end pumped, passively Q-switched, air-cooled, microlaser was designed and prototyped to yield a 1064 nm pulsed laser output of 21 mJ/P with a pulse width of 4.2 ns FWHM. This microlaser was coupled to a standard laser plug carrying a sapphire lens with 13 mm back focal length. This assembly was tested in a natural gas fueled single-cylinder engine, and in one cylinder of a turbocharged 6-cylinder engine. Single cylinder engine tests showed extension of the lean ignition limit which enabled an efficiency improvement of 0.2% while meeting emission regulations. The tests conducted in the 6-cylinder engine showed highly improved ignition stability.

Authors:
; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE) - Advanced Manufacturing Office
OSTI Identifier:
1335938
DOE Contract Number:
AC02-06CH11357
Resource Type:
Conference
Resource Relation:
Conference: 3rd Laser Ignition Conference, 04/27/15 - 04/30/15, Argonne, IL, US
Country of Publication:
United States
Language:
English
Subject:
Laser Ignition

Citation Formats

Bihari, Bipin, Biruduganti, Munidhar, and Gupta, Sreenath. Natural Gas Engine Performance Ignited by a Passively Q-Switched Microlaser. United States: N. p., 2015. Web. doi:10.1364/LIC.2015.T5A.5.
Bihari, Bipin, Biruduganti, Munidhar, & Gupta, Sreenath. Natural Gas Engine Performance Ignited by a Passively Q-Switched Microlaser. United States. doi:10.1364/LIC.2015.T5A.5.
Bihari, Bipin, Biruduganti, Munidhar, and Gupta, Sreenath. Wed . "Natural Gas Engine Performance Ignited by a Passively Q-Switched Microlaser". United States. doi:10.1364/LIC.2015.T5A.5.
@article{osti_1335938,
title = {Natural Gas Engine Performance Ignited by a Passively Q-Switched Microlaser},
author = {Bihari, Bipin and Biruduganti, Munidhar and Gupta, Sreenath},
abstractNote = {A robust end pumped, passively Q-switched, air-cooled, microlaser was designed and prototyped to yield a 1064 nm pulsed laser output of 21 mJ/P with a pulse width of 4.2 ns FWHM. This microlaser was coupled to a standard laser plug carrying a sapphire lens with 13 mm back focal length. This assembly was tested in a natural gas fueled single-cylinder engine, and in one cylinder of a turbocharged 6-cylinder engine. Single cylinder engine tests showed extension of the lean ignition limit which enabled an efficiency improvement of 0.2% while meeting emission regulations. The tests conducted in the 6-cylinder engine showed highly improved ignition stability.},
doi = {10.1364/LIC.2015.T5A.5},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Apr 01 00:00:00 EDT 2015},
month = {Wed Apr 01 00:00:00 EDT 2015}
}

Conference:
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  • 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 twomore » laser systems produced virtually identical combustion and emissions data.« less
  • Optical firing sets need miniature, robust, reliable pulsed laser sources for a variety of triggering functions. In many cases, these lasers must withstand high transient radiation environments. In this paper we describe a monolithic passively Q-switched microlaser constructed using Cr:Nd:GSGG as the gain material and Cr{sup 4+}:YAG as the saturable absorber, both of which are radiation hard crystals. This laser consists of a 1-mm-long piece of undoped YAG, a 7-mm-long piece of Cr:Nd:GSGG, and a 1.5-mm-long piece of Cr{sup 4+}:YAG diffusion bonded together. The ends of the assembly are polished flat and parallel and dielectric mirrors are coated directly onmore » the ends to form a compact, rugged, monolithic laser. When end pumped with a diode laser emitting at -807.6 nm, this passively Q-switched laser produces -1.5-ns-wide pulses. While the unpumped flat-flat cavity is geometrically unstable, thermal lensing and gain guiding produce a stable cavity with a TEM{sub 00} gaussian output beam over a wide range of operating parameters. The output energy of the laser is scalable and dependent on the cross sectional area of the pump beam. This laser has produced Q-switched output energies from several {micro}J per pulse to several 100 {micro}J per pulse with excellent beam quality. Its short pulse length and good beam quality result in high peak power density required for many applications such as optically triggering sprytrons. In this paper we discuss the design, construction, and characterization of this monolithic laser as well as energy scaling of the laser up to several 100 {micro}J per pulse.« less
  • Market demands for lower fueling costs and higher specific powers in stationary natural gas engines has engine designs trending towards higher in-cylinder pressures and leaner combustion operation. However, Ignition remains as the main limiting factor in achieving further performance improvements in these engines. Addressing this concern, while incorporating various recent advances in optics and laser technologies, laser igniters were designed and developed through numerous iterations. Final designs incorporated water-cooled, passively Q-switched, Nd:YAG micro-lasers that were optimized for stable operation under harsh engine conditions. Subsequently, the micro-lasers were installed in the individual cylinders of a lean-burn, 350 kW, inline 6-cylinder, open-chamber,more » spark ignited engine and tests were conducted. To the best of our knowledge, this is the world’s first demonstration of a laser ignited multi-cylinder natural gas engine. The engine was operated at high-load (298 kW) and rated speed (1800 rpm) conditions. Ignition timing sweeps and excess-air ratio (λ) sweeps were performed while keeping the NOx emissions below the USEPA regulated value (BSNOx < 1.34 g/kW-hr), and while maintaining ignition stability at industry acceptable values (COV_IMEP <5 %). Through such engine tests, the relative merits of (i) standard electrical ignition system, and (ii) laser ignition system were determined. In conclusion, a rigorous combustion data analysis was performed and the main reasons leading to improved performance in the case of laser ignition were identified.« less