Evaluation of heat supply with maintaining a safe mine water level during operation of open geothermal systems in post-coalmining areas

Abstract

Purpose. Evaluation of the efficiency of open geothermal systems in flooded and drained mines of the Donetsk basin for heat supply of buildings with maintaining a safe mine water level. Methods. Both circulation and non-return geothermal systems for the mine water heat recovery are analyzed. We proposed the energy and cost criteria for evaluating the effectiveness of open geothermal systems based on a comparison of the produced thermal energy with the energy costs for its production. The criteria use the relationships of thermodynamics, hydraulics, analytical formulas for calculation of ground water flow and methods to calculate the heat demand of indoor spaces. Findings. The estimated ranges of thermal capacity from a few tens kW to a few MW and a coefficient of performance (COP) conversion factor of 3.5-6.8 achievable by geothermal systems for the studied closed mines of Donbas correlate well with the values of these indicators at open geothermal systems operated in different countries, which shows the technical and economic feasibility of the installation to cover local heat demands. The possibility to fully cover the needs for thermal energy is shown on the example of buildings with office spaces for staying of a few hundred people. We demonstrate how to preliminary calculate the parameters of mine water circulation with maintaining the safe level in terms of keeping the ground water quality in the areas adjacent to the mine. Originality. The developed criteria and calculation methodology allow to realistically evaluate the parameters of the efficiency of operation for open non-return and circulation geothermal systems, taking into account mining, geological and technology conditions, to prioritize the exploration of geothermal resources in mines and to evaluate the parameters of mine water circulation with maintaining the safe mine water level. Practical implications. The study showed the feasibility of installation and effective operation of open geothermal systems at the mines of the Donetsk basin for heat supply of buildings located in the adjacent areas with maintaining a safe mine water level.

Multisource working condition recognition via nonlinear kernel learning and p-Laplacian manifold learning

“…According to Ref. [ 21 ] and based on the mechanism analysis, the wellhead temperature signal features are extracted from the heat loss during a stroke. Specifically, three features are obtained from the wellhead temperature signal.…”

“…Moreover, semi-supervised learning (SSL) schemes based on p -Laplacian manifold regularization and loss function significantly enhance the classification performance by utilizing richer unlabeled data efficiently in fewer labeled data [ 19 , 20 ]. Other studies have shown that in practical engineering, data feature analysis combined with expert knowledge and mechanism analysis contributes to more efficient and practical model building [ 21 ]. In summary, combined with the actual operation of the oil well, a working condition recognition method based on measured multisource nonlinear kernel learning and p -Laplacian manifold learning is proposed in this paper.…”

CO2 Storage and Geothermal Extraction Technology for Deep Coal Mine

“…Hai Pu et al proposed a method to develop mine geothermal resources with the use of water storage and heat storage in abandoned mines [42]. Rudakov D et al evaluated the efficiency of open geothermal systems in flooded and drained mines for the heat supply of buildings and proved the good effect of the system [43].…”

Grouting Effect Detection within the Floor of a Coal Seam Using 3D Electric Resistivity Tomography (ERT) with Arbitrary Electrode Positions

“…The water inrush coefficient method [27,28] is used to predict whether the floor of the working face is prone to water inrush events [29]. A water inrush coefficient less than 0.06 indicates that the working face is safe; relatively, water inrush may occur when the water inrush coefficient exceeds 0.06 [30,31]. The water inrush coefficients T1max and T2max of the NO.…”