Application of an In-Cylinder Local Infrared Absorption Fuel Concentration Sensor in a Diesel-Ignited Dual-Fuel Engine 2016-01-2310

As global energy demands continue to be met with ever evolving and stricter emissions requirements, natural gas (NG) has become a highly researched alternative to conventional fossil fuels in many industrial sectors. Transportation is one such field that can utilize the benefits of NG as a primary fuel for use in internal combustion engines (ICEs). In the context of heavy-duty on-highway transportation applications, diesel-ignited dual-fuel (DIDF) combustion of NG has been identified as a commercially viable alternative technology. Previous investigations of DIDF have examined the various trends present across the spectrum of DIDF operating space. However, in-cylinder processes are still not well understood and this investigation aims to further understanding in this area.

An in-cylinder, local infrared absorption fuel concentration sensor is used to examine in-cylinder processes by comparison with previous optical and thermodynamic studies. A 2-litre single-cylinder research engine was operated at selected DIDF operating modes with significantly different fuel conversion mechanisms. Fuelling was achieved through port injection of CH₄ and direct injection of diesel. The operating modes were specified by varying the relative pilot diesel injection mass and pressure along with CH₄ injection mass. Additionally, an injection timing sweep of port injected CH₄ was performed at a constant fuelling point. Through analysis of the measured fuel concentration and apparent heat release rate (AHRR), the combustion mode could be identified with greater certainty than using just pressure-based measurements alone.