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UBC Theses and Dissertations

Development and application of in-cylinder fuel concentration and pyrometry optical diagnostic tools in diesel-ignited dual-fuel natural gas engines Yeo, Jeff


In recent years, government policies have mandated significant reductions in emissions of greenhouse gases (GHG) and particulate matter (PM) from heavy-duty, on-highway transportation applications. This has necessitated the development of clean engine technologies such as dual-fuel combustion of natural gas (NG) in compression ignition (CI) engines. With these new engine developments, the need to understand and optimize these technologies to meet emission regulations becomes crucial. Traditional engine research relies on thermodynamic methods and exhaust analysis to examine performance and emission trends present across real-world operating conditions – more recently, optical tools have become increasingly accessible and are providing new methods of understanding combustion phenomena. Interpretation however, is often not directly translatable between optical and thermodynamic engines due to the many mechanical differences between the two. This work aims to provide the foundations for a new “thermo-optical” approach which combines conventional thermodynamic analysis with optical insight into combustion phenomenon to bridge the gap between thermodynamic and optical engine studies. The development and application of an optical probe performing line of sight pyrometry for in-cylinder soot concentration and temperature measurements, as well as the implementation of a probe for in-cylinder local fuel concentration measurements is detailed. The probes are operated in a 2-litre single-cylinder research engine capable of thermodynamic (“all-metal”) and optical configurations and were utilized under two vastly different operating strategies. These strategies used premixed methane with a diesel pilot (DIDF), and High Pressure Direct Injection (HPDI) for non-premixed NG with a diesel pilot. The pyrometry probe demonstrated the effect of HPDI injection parameters on in-cylinder PM concentration while fuel concentration measurements were used to identify the combustion mode under DIDF conditions, and to provide insight to HPDI injection and combustion characteristics. The probes’ performance and capabilities were evaluated under thermodynamic and optical configurations, with high-speed cameras complementing the probes during optical operation. The framework for interpretation in the “thermo-optical” methodology was developed through analysis of the local fuel concentration, soot concentration and temperature, spatially resolved optical results, and conventional apparent heat release rate (AHRR) analysis.

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