MODELING TEMPERATURE DISTRIBUTION DUE TO UNDERGROUND COAL FIRES-A Study in Jharia Coal Field

Abstract

Numerous coal fires, both surface and sub-surface, have been reported from the Jharia coalfield. Coal fires cause severe environmental and economic problems worldwide. Underground coal fires (UCF) heat up the surface to give temperature anomalies on TIR image. Using these temperature anomalies an attempt has been made to model the temperature distribution due to a UCF in the sub surface and to understand the effects of various variables on the temperature distribution.For simplicity, only conductive heat transfer has been assumed in the study. Also, the temperature anomaly is taken along the dip direction of the coal bed; hence temperature distribution in a 2 dimensional space is modeled. The heat equation is a partial differential equation giving temperature distributionin 2-dimensions, x (along the surface) and z (below the surface). PDE toolbox of MATLAB 2009b was used to solve the equation. Modeling is done for three fire regions for three different coal fire temperatures. The asymmetrical distribution of surface temperatures about the hottest point is well reflected in underground temperatures as well. And for two out of three cases the fire seems to be progressing in upward dip direction. The third case is peculiar and needs further examination.