Numerical simulation of the dynamic formation process of fog-haze and smog in transport tunnels of a hot mine

Abstract

Fog-haze and smog can be formed in transport tunnels during artificial cooling by air-conditioner, under hot and high humidity conditions inside a coal mine. The processes of coagulation, condensation, nucleation, crushing and evaporation, which can occur at the same time, can be simulated by a dynamic model. The relationship between the particle size distribution over time and environmental parameters such as wind speed, temperature and relative humidity, during smog formation in transport tunnels in a coal mine was characterised by our numerical modelling and in-situ study of a coal mine in Hunan Province, China. The development and dissipation of fog-haze and smog when under cooling inside a deep coal mine were modelled using multiple Monte Carlo algorithm method validated by our experiment using a 1 m3 wooden chamber. Our numerical modelling was confirmed by our in-situ measurement results, indicating that (1) the bigger the condensation coefficient would lead to a faster formation of aerosol particles giving larger number and sizes of particles; (2) faster wind speed would reduce the number of aerosol particles and increase the geometric mean of the particle diameter. (3) When cooling in the tunnels, 2 m/s would be the lowest wind speed that could disperse the haze in the transport tunnels in the mine. The findings of our research should provide the theoretical basis for artificial cooling and controlling of the formation of haze in transport tunnels for mining.