CFD simulations of the effect of wind on the spontaneous heating of coal stockpiles

Abstract

A commercial CFD software program, fluent, was used to study the effect of wind on the spontaneous heating process of a coal stockpile. A two-domain model was developed to simultaneously solve the governing equations of an open porous medium (coal stockpile domain) situated in a homogeneous atmosphere (wind flow domain). Simulations with air blowing from a fixed direction as well as real fluctuations of the airflow both in velocity and direction were performed.

Numerical calculations confirmed the promoting role of wind on the dynamics of the development of spontaneous heating. Under the conditions of the simulations, three possible shifts of the hot spot in the stockpile were distinguished when coal undergoes the self-heating process:

(1)

Shift of the hot spot to the pile surface when spontaneous heating of coal is in progress. (2)

Movement of the hot spot inwards the stockpile as the wind speed increases. (3)

Transfer of the hot spot from the upper part of the stockpile to the lower part when the self-heating process progresses. Such movement was found for wind speeds ⩽3 m s−1 and clearly is mainly connected with the effect of buoyancy.