Model predictions on self-heating and prevention of stockpiled coals

In the paper, we present a mathematical model including a detailed radiation balance of the coal stockpile surface. Our aim was to describe the radiation balance in more detail even on the oriented slopes of a stockpile. Here, the periodic boundary condition differs from that applied on the horizontal surface. The energy from the Sun has a strong influence on the temperature profile in a coal stockpile. It would not be suitable to describe it by a constant, because it represents day and year cycles. The model is flexible enough to be applied to any part of the world since it uses meteorological input data obtained experimentally. Four types of coal were studied with different reactivity. We observed the influence of several factors (coal reactivity, coal matrix porosity, meteorological conditions, coal reactivity (two-dimensional model), coal matrix porosity (two-dimensional model)) on the temperature profile in two types of coal stockpiles. One-dimensional model can be applied on a situation when coal is being stored under ground. In this case only the topside is exposed to the ambient conditions. A two-dimensional model is necessary when describing a commonly used heap-like stockpile. Here, the changing boundary conditions must be applied on the topside as well as on both slopes. Finally, a long-term simulation for average meteorological conditions at a certain place was studied. (C) 2004 Elsevier Ltd. All rights reserved.