Prospects for the use of underground structures as a source of thermal energy

Abstract

Purpose. The paper is intended to pay attention of scientific community and technical community to the application prospects of underground permanent mine workings (andnot only them) as a source of distributed energy required to heat both surficial and underground facilities. Methodology.Theoretical studies,concerninggeothermalprocesses with the use of analytical mathematical methods, have been carried out. The results of the theoretical studies and experiments have been analyzed and generalized. Findings. It has been demonstrated that use of underground mine workings as an artificial medium, within which thermal pump manifold (or manifolds) is placed, makes it possible to generate such an amount of thermal energy which can be compared minimally with the energy generated in the process of combustion of the coal extracted from the mine working. In this context, a problem of reuse of mine working, excluded from a production chain but remained to keep their long-lasting stable state, can be solved partially. Scientific novelty. A new approximate solution of specific problem, concerning heat exchange between a flat-plain manifold and a rock, has been obtained. The following has been determined: the thermal energy, extracted from earth interior, is proportional directly to the temperature within the location of a manifold of thermal pump as well as square root of production of conductive heat transfer coefficient per rock density, and its heat capacity; velocity of the thermal energy extraction from the subsoil in the context of constant rock temperature within the area of its extraction decreases with the course of time; and satisfactory correspondence between experimental values and analytical values of specific capacities as for the heat extraction from a subsoil takes place. Under otherwise equal conditions, the amount of the thermal energy, extracted from the mined-out working by means of thermal pump, can be comparable with the energy generated during combustion of coal which was extracted from the mine working. Practical relevance.The theoretical results, obtained by the paper authors, make it possible to forecast efficient use of mine workings as thermal energy sources.