Dual Fuel Low Temperature Combustion - A Practical Strategy for In-Cylinder Emissions Reduction (PPT)

摘要

Economic, environmental, and strategic interests have refocused IC engines research on increasing efficiencies, reducing pollutant emissions, and identifying renewable alternative fuels. In recent years, advanced combustion strategies grouped under the umbrella termed "low-temperature combustion" (LTC) are being investigated. Of these LTC concepts, dual fuel LTC is a promising strategy that utilizes a combination of two fuels with very different ignition and combustion characteristics. The basic premise in dual fuel LTC is that sustained low temperature combustion can be achieved by direct injection of very small sprays (2-3 percent of total fuel energy) of a high-cetane fuel (e.g., diesel) to ignite a stable, low cetane fuel (e.g., natural gas) that is induced along with the air through the intake manifold. In this mode of combustion, dual fuel LTC provides the opportunity to achieve very low emissions of oxides of nitrogen (NOx < 0.2 g/bhp-hr) and particulate matter, diesel-like fuel efficiencies (> 40%), and high power densities (brake mean effective pressures higher than 10 bar). In this presentation, experimental results from a specific type of dual fuel LTC concept known as Advanced (injection) Low Pilot-Ignited Natural Gas (ALPING) combustion will be discussed. The discussion will also focus on the relative merits of early pilot injection (～60° BTDC) and late pilot injection (near TDC) strategies on the performance and emissions with ALPING LTC.