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In order to take advantage of different properties of fuel components or fractions, a new concept of fuel stratification has been proposed by the authors. This concept requires that two fractions of standard gasoline (e.g., light and heavy fractions) or two different fuels in a specially formulated composite be introduced into the cylinder separately through two separate intake ports. The two fuels will be stratified into two regions in the cylinder by means of strong tumble flows. In order to verify and optimize the fuel stratification, a two-tracer Laser Induced Fluorescence (LIF) technique was developed and applied to visualize fuel stratification in a three-valve twin-spark SI engine. This was realized by detecting simultaneously fluorescence emissions from 3-pentanone in one fuel (hexane) and from N,N-dimethylaniline (DMA) in the other fuel (iso-octane).

A quantitative relationship between diesel soot oxidation rate and oxidation temperature and oxygen partial pressure was investigated by burning the diesel exhaust soot particles in a controlled flat flame supplied with methane/air/oxygen/nitrogen mixtures. The oxidation temperature and the oxygen partial pressure were controlled in the ranges of 1530 to 1820 K and 0.01 to 0.05 atm (1atm = 1.01325 bar) respectively. Soot particle size distribution measurements were achieved with transmission electron microscopy (TEM) for particle samples that were collected on copper grids at different positions along the flame centerline. Oxidation periods were determined by means of laser Doppler anemometry (LDA). The experimental results showed that the experimental oxidation rates fall between the values predicted by the Nagle and Strickland-Constable formula and those by the Lee formula.

This study aims to improve the dual fuel combustion for low/zero carbon fuels. Seven cases were tested in a single cylinder optical engine and their ignition and combustion characteristics are compared. The baseline case is the conventional diesel combustion. Four cases are diesel-gas (compressed natural gas) dual-fuel combustion operations, and two cases are diesel-hythane combustion. The diesel fuel injection process was visualized by a high-speed copper vapour laser. The combustion processes were recorded with a high-speed camera at 10000 Hz with an engine speed of 1200 rpm. The high-speed recordings for each case included 22 engine cycles and were postprocessed to create one spatial overlapped average combustion image. The average combustion cycle images were then further thresholded and these images were then used in a new method to analyze the cycle-to-cycle variation in a dimensionless, for all cases comparable value.

The increasing concern about CO2 emissions and energy prices has led to new CO2 emission and fuel economy legislation being introduced in world regions served by the automotive industry. In response, automotive manufacturers and Tier-1 suppliers are developing a new generation of internal combustion (IC) engines with ultra-low emissions and high fuel efficiency. To further this development, a better understanding is needed of the combustion and pollutant formation processes in IC engines. As efficiency and emission abatement processes have reached points of diminishing returns, there is more of a need to make measurements inside the combustion chamber, where the combustion and pollutant formation processes take place. However, there is currently no good overview of how to make these measurements.