Experimental study on coal combustion at microgravity

Abstract

Coal is the primary energy supply worldwide and will remain dominant in energy consumption structure in China for a long period. The fundamental studies on coal combustion are still of great demand due to the increasing pursuit of the higher efficiency and lower emission. Microgravity (μg) environment minimizes the buoyancy effect that the coal particles are subjected to during the combustion under normal gravity, and thus provides an ideal environment to discover new phenomena and obtain more accurate data. The results are useful to explore the basic combustion principles and the strength of the buoyancy effect to coal combustion, and to validate and develop coal combustion models for the ground coal utilization. The paper reviews the experimental studies on the coal combustion at microgravity conducted using drop towers. Furthermore, it introduces the state-of-art coal combustion study using Chinese SJ-10 satellite. With the careful design of the microgravity experimental system, space experiments on both single coal particles and pulverized coals were conducted in the first time. The entire burning process for coal particles, including the high volatile content bituminous coal and low volatile content anthracite coal were observed. The differences in volatile release mode, ignition temperature and delay time, volatile flame evolution, flame shape, and char burnout time for the coal particles burning at microgravity from counterparts at normal gravity were reported. With the new observation and data from drop tower and SJ-10 satellite experiments, more accurate models could be developed for the ground coal utilization.