Study on the heat transfer characteristics of cemented backfill heat exchangers with a horizontally penetrating rough fracture under groundwater advection
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引用次数: 0
Abstract
One of the most effective methods for geothermal energy extraction in deep mine stopes is the installation of heat exchange tubes within cemented backfill bodies. However, the complex underground environment can cause fracture in the backfill, which may negatively affect the geothermal extraction performance, especially in the presence of groundwater flow. This study establishes a three-dimensional seepage and heat transfer coupling model of cemented backfill heat exchangers with horizontal penetrating rough fractures via a finite element software platform. The model employs the Monte Carlo method combined with linear filtering to generate a rough fracture. The findings demonstrate that for fracture apertures ranging from 0 to 0.3 mm, the predominant mechanism of heat transfer is thermal conduction, with a negligible contribution from groundwater flow. However, as apertures expand from 0.3 mm to 2 mm, groundwater flow significantly enhances heat transfer, stabilizing beyond 2 mm. Increased fracture roughness at a 0.2 mm aperture does not enhance the heat recovery performance of the heat exchange tubes, but at a 4 mm aperture, a strong positive correlation between roughness and heat transfer is observed. Thus, narrow fractures can be treated as smooth, whereas roughness must be considered for wider fractures. The interaction between fracture flow and Darcy seepage increases with increasing groundwater hydraulic head, resulting in a notable improvement in the heat extraction performance of the heat exchange tube. When the relative position transitions from 0.75 °C to 0 °C, the outlet water temperature of the heat exchanger tube increases by approximately 9 °C.
期刊介绍:
The use of computers is firmly established in geotechnical engineering and continues to grow rapidly in both engineering practice and academe. The development of advanced numerical techniques and constitutive modeling, in conjunction with rapid developments in computer hardware, enables problems to be tackled that were unthinkable even a few years ago. Computers and Geotechnics provides an up-to-date reference for engineers and researchers engaged in computer aided analysis and research in geotechnical engineering. The journal is intended for an expeditious dissemination of advanced computer applications across a broad range of geotechnical topics. Contributions on advances in numerical algorithms, computer implementation of new constitutive models and probabilistic methods are especially encouraged.