On the effects of temperature-dependent diffusion of carbon dioxide from underground coal fires

Abstract

This study offers a physics-based model for the assessment of the CO2 emission through the overburden above underground coal fires. It was developed by coupling simultaneous porous media subsurface flow, heat transfer, and solute transport phenomena to create an accurate underground coal fire/overburden model. Parametric studies were conducted by varying coal fire and overburden temperatures, soil type and void ratios. The results show that as the overburden and the coal fire temperatures increased, a lower CO2 concentration at the top surface of the overburden was observed due to increased CO2 storage in the overburden and reduced temperature-dependent diffusivity.