This U.S.-Bulgaria Research award is to Dr. Martin Hertzberg of the American University in Bulgaria, to work with the U.S. Bureau of Mines, in cooperation (on the Bulgarian side) the Bulgarian Academy of Sciences, the University of Mining and Geology, and the Mining Research and Technology, and the Mining Research and Technology Institute, to work on "Combustion Experiments and Numerical Modelling of Dust Explosions and Spontaneous Self-Heatings." The researchers will perform experimental studies of the explosability of dusts and the spontaneous self-heating of coals, complemented by theoretical numerical modelling of those combustion processes. The combustion of phase-heterogeneous systems plays a critical role in modern technology. The objective of the explosability part of this research program is to study the fundamental physical processes responsible for the existence of flammability limits. The need to solve the problem of spontaneous combustion of low rank coals presenting severe hazards in underground Bulgarian mines provides a strong incentive to reevaluate the fundamentals of the spontaneous ignition process formulated in the classical theory of Semenov and Frank-Kamenetskii, which theory requires substantial modifications in order to include the processes of natural convection and gas transport into (and out of) the self-heating mass. In addition, the exothermic/endothermic moisture transport process must be added to the exothermic surface oxidation rate of coals, and the numerical modelling of those processes must be three-dimensional. This project in combustion research fulfills the program objective of advancing scientific knowledge by enabling leading experts in the United States and Eastern Europe to combine complementary talents and pool resources in areas of strong mutual interest and competence.
