Ignition and Combustion of a Coal-Oil Mixture Drop in a Microgravity Environment

Abstract

Ignition and combustion characteristics of a coal-oil mixture drop have been measured under normal and micro gravity conditions in order to get fun-damental understandings on combustion processes of a coal slurry spray. The experi-ment were conducted in a drop tower, which has a fall of 710 m and a duration of 10 seconds of the microgravity condition. In this study, Taiheiyo Coal and n-Dodecane were used for coal-oil mixture which has a 50 % mixing ratio. The Taiheiyo Coal had a fixed coal mass percentage of 43.03 %, a volatility mass percentage of 40.97 % and an ash mass percentage of 16.00 %.
A mass percentage of the Taiheiyo Coal with a diameter smaller than 75 mm was 85.74%. Comparison of the experimental results between under the microgravity condi-tion andunder the normal gravity condition clarifies differences in combustion charac-teristics between the two. The minimum ignition temperature under microgravity is more than 380 K lower than that under normal gravity, and the ignition delay of the COM drop under microgravity is shorter than that under normal gravity.