Combustion characteristics of droplets composed of light cycle oil and diesel light oil in a hot-air chamber☆

Development of gas turbines fueled with light cycle oil (LCO) and oil mixture of LCO and diesel light oil (LO) requires an understanding of the droplet burning and vaporization characteristics of those oils. The present study is devoted to comparing the burning characteristics of isolated fuel droplets composed of an LCO and an LO. The tests were conducted in an atmospheric hot-air chamber preset at 1173 K, and the examined LCO had a lower cetane number but higher volatility and aromatics content compared to LO. It was demonstrated that the burning of the LCO droplet was sootier, while that of the LO droplet was more disruptive. At the tested temperature, coke formation was indistinct for both the oils, whereas slightly higher ignition delay time was shown for the LO droplet. The microexplosive burning more or less complicated the time-series droplet size d, an explicit burning rate constant, however, was still definable according to the d2-law to show the overall regression speed of the droplet surface area d2 with burning time t. The rate constant exhibited little difference for smaller LCO and LO droplets but was greater for LO when the droplet was larger. The rate constant also gradually increased with increasing the initial droplet diameter d0, which caused the relative size d/d0 to be unified (normalized) into a single curve by a burning time t/d0n (1.0<n<2.0). Analysis revealed that this unification resulted from the respective overlaps of the unsteady and quasi-steady burning phases for differently sized droplets. Further, it was clarified that the unification and analysis are generally valid to isolated liquid fuel droplet burning in hot ambiences.