Electron heat transport in low-rank lignite: combining experimental and computational methods

Coal fire combustion has been known for a long time to be a complicated physical and chemical process, and finding hidden coal fires has always been a challenge. With the arrival of an advanced quantum detection method, such fires can be accurately identified. Before applying the method to detect hidden coal fires, researchers must develop a better understanding of the transport properties of heat carriers in coal. An examination of a lignite sample taken from a typical coal fire region (Tunbao, Xinjiang, China) was conducted using experimental and computational methods. The molecular structure of Tunbao coal was clarified using methods such as 13 C-NMR, XPS, and elemental analysis. A model of Tunbao coal’s molecular structure was generated, and its chemical formula was C 311 H 209 N 3 O 68 . Moreover, ab initio molecular dynamics was used to compute the heat carriers in coal molecules. As revealed by calculations, this coal is a semiconductor with metallic characteristics and is capable of transporting electrons. Naphthalene and pyrrole contribute to this metallicity, and coals with larger amounts of naphthalene and pyrrole may have stronger electrical conductivity. In accordance with the AIMD results, when the temperature rose, the electron transport of coal molecules became more frequent and powerful, resulting in increased electrical conductivity.