The study aims to develop a method of effectiveness evaluation for geothermal heat recovery in closed mines of Donbas using relations of heat transfer theory in rocks and fluids. Geothermal heat is proposed to recover using coaxial geothermal probes to be installed in flooded closed mines. As a result of evaluation and ranking, five top promising sites with the highest expected performance indicators among 27 closed mines located in Donbas have been identified. The evaluation method takes into account geological settings, mine condition, and heat exchange parameters of the probe with mine water. The locations of the most promising sites were found to correlate with the areas of higher geothermal flux and the deeper mines. The results obtained can be used in feasibility studies on installation and operation of geothermal probes in closed mines.
Objective of the paper is to substantiate and implement the integrated approach aimed at the studies of filtration and mass-transfer processes within roof rocks of coal seams in the context of their underground gasification. Integrity of the studies is substantiated by the use of analytical calculations as well as physical and numerical modeling. Zones with different permeability have been determined and values of specific water inflow have been identified basing upon the performed numerical modeling and involving multicomponent transformations within roof formation. The research data actuality is in the studies of spatial and temporal dynamics of rock technogenic rock permeability above gasification channel depending upon their geological structure which will favour the substantiation of efficient engineering solutions to control a process of underground coal gasification under difficult hydrogeological conditions.
The aim of the paper is justification of the economically efficient technological scheme for development of a thermal resource of “Stashkov” mine after its closure, ensuring the maintenance of a favorable energy and ecological-hydrogeological regime in the region. A geotechnological scheme of environmentally safe usage of mine water was justified, involving water pumping up to the surface, heat removal and water reverse pumping into the seams. The suggested circulation system is characterized by an increased energy balance, since it is used to extract almost all the groundwater heat, as well as part of the heat of host rocks. In order to estimate the effectiveness of usage of this technology, calculations of usage of mine water as a source of low-potential energy in heat pumps in comparison with other alternatives (groundwater and surface water streams) using Mathcad software were performed, and it was established that this gives great conversion coefficients of mine water. A geotechnological scheme of usage of mine water was developed, which considers heat transfer, filtration direction, velocity and temperature of groundwater during pumping and removal of heat-transfer fluid from an aquifer for heating and cooling of buildings. The mechanism of heat removal in a flooded rock massif of amine during liquidation was studied with justification of environmentally safe usage of mine water.
In 2004, the total installed capacity of geothermal plants located in 24 countries of the world still amounted to 8.91 GW with an annual power generation of 56.8 TWh; in 2009, these indices grew up to 10.71 GW and 67.2 TWh, respectively; in 2014 these indices reached 12.64 GW and 73.55 TWh (Erdlac et al. 2006; Bertani 2015; Shulyupin and Chernev 2015). Details of installed capacity distribution over the world and development trends were reported by Gehringer and Loksha (2012). In the same period, the annual electricity generation based on geothermal energy increased from 56.8 to 73.55 TWh. In recent years, geothermal energy use was growing most rapidly in Kenya (+ 392 MW), USA (+ 352 MW), Turkey (+ 306 MW), New Zealand (+ 243 MW),
Purpose. Theoretical and technological substantiation of parameters and schemes related to formation and use of natural and man-made volumetric and thermal resources of abandoned coal deposits using complex of geo-modules providing their activation, selection and storage in keeping with uneven seasonal energy consumption. Methods. Analytical and numerical methods for solving equations of hydrogas dynamics and heat-mass transfer; mathematical modeling by means of special software; statistical methods; stabilometrical testing of aqueous rocks samples by triaxial compression tool. Findings.The system of models presenting gas-dynamic, filtration and heat processes occurring in disturbed rocks as a result of natural and man-made resources development while shutting down mining works has been developed. The studied patterns of water and gases movement in low-permeable coal-bearing rocks, reservoir beds and flooded mines allowed to evaluate the technological parameters of extraction, accumulation, and utilization of these heat transfer fluids for heating and cooling of buildings. The paper proposes and justifies technological options serving to utilize the thermal resource of water in a flooded mine and to activate this resource by underground combustion of residual coal reserves.Originality. The mechanism of heat transfer in the flooded rock mass of the abandoned mine with periodic pumping and selection of mine waters from different horizons and their heating by natural geothermal heat and underground combustion of residual coal reserves has been studied.Practical implications. The developed models have been implemented in real mines which allowed to evaluate the ranges of flow and heat transfer parameters related to the conditions for heat transfer fluid extraction and utilization at the final stage of mining. The developed models and obtained dependences allowed to justify the parameters of technological schemata aimed at the development of natural and man-made resources of coal deposits.
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