Geothermics最新文献_第4页

Effect of Ethylenediaminetetraacetate (EDTA) on the polymerization and adsorption of silicic acid in the presence of iron: Implication to the prevention of silica scale formation from acidic geothermal water

IF 3.5 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2025-01-31 DOI: 10.1016/j.geothermics.2025.103267

Saefudin Juhri , Kotaro Yonezu , Takushi Yokoyama

As conventional geothermal energy resources are increasingly explored and exploited, there is a need to explore non-conventional geothermal energy resources for future development of geothermal energy, such as using acidic geothermal water. However, studies have shown that simple neutralization of the acidic water might bring a risk of silica scaling due to the metal contents, such as iron (Fe). Therefore, in this study, the chelating effect of ethylenediaminetetraacetate (EDTA) on Fe was examined to prevent the polymerization of silicic acid, its precipitation, and its adsorption on the surface of silica gel. Results of laboratory experiments showed that adding Fe(III) accelerated the polymerization of silicic acid when NaOH was used to adjust the pH of acidic geothermal water. On the contrary, the acceleration effect of Fe(III) was not observed when EDTA·4Na was used to adjust the pH. The concentration of monomeric Fe(III) immediately decreased to almost 0 after adding EDTA·4Na, suggesting effective Fe(III) trapping by EDTA. The results of onsite adsorption experiments agreed with the laboratory experiment, where Fe(III) accelerated silicic acid's adsorption rate on the silica gel's surface, and EDTA effectively prevented its acceleration effect. The consistent result of the onsite experiment suggests the applicability of this method to prevent the precipitation of siliceous deposits and the formation of silica scale from Fe-bearing geothermal water.

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引用次数: 0

Impact of groundwater flow on thermal response tests in heterogeneous geological settings

IF 3.5 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2025-01-31 DOI: 10.1016/j.geothermics.2025.103266

Alberto Previati, Giovanni Crosta

This study investigates thermal response tests (TRTs) in heterogeneous geological settings to assess the impact of groundwater flow on TRT interpretation and borehole heat exchanger (BHE) performance. Traditional TRT analysis relies on the infinite line source (ILS) model, which assumes homogeneous ground and negligible groundwater flow. However, these assumptions are often lacking in natural environments, resulting in an overestimation of the thermal conductivity. The analysis of four distributed thermal response tests (DTRTs) in high groundwater flow regimes reveals apparent thermal conductivities up to 40 times higher than expected, highlighting the limitations of the ILS method in such settings. To address this issue, a comparison between the ILS model and the moving infinite line source (MILS) model, which accounts for advective heat transfer due to groundwater flow, was conducted. Model fitting and parameter optimization were performed on 84 temperature perturbation time series distributed along four BHEs used for TRT. The MILS model (global RMS = 0.25 °C) outperforms the ILS model (global RMS = 0.48 °C) in TRT data fitting and better reflects actual thermal conductivity values obtained from laboratory tests and literature. The MILS model also estimates groundwater flow velocities up to 3.0 × 10^–5 m/s. Considering the estimated thermal conductivity and groundwater flow velocity, it was found that advective heat transfer contributes to 35–44 % of the total thermal exchange potential for all BHEs. A correction procedure for the apparent thermal conductivity derived from the ILS model, considering Darcy flow velocity, is presented using nomograms. This correction is crucial for accurate BHE design in areas with significant groundwater flow, ensuring a better understanding of BHE performance and its implications for shallow geothermal energy applications.

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引用次数: 0

A novel multi-level and multi-branch geothermal well system for synergetic geothermal energy exploitation and mine heat hazard prevention: numerical investigation

IF 3.5 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2025-01-30 DOI: 10.1016/j.geothermics.2025.103264

Baiyi Li , Luwei Ding , Jixiong Zhang , Meng Li , Hengfeng Liu , Junmeng Li

With the increasing of mining depth, heat hazard faced by deep coal mines is increasingly prominent. The inability to carry out mining work in high-temperature environments limits the exploitation of high-quality coal resources in deep areas. In this research, the idea of a synergetic geothermal exploitation method and mine heat hazard prevention was proposed to liberate the high temperature coal resources. The key of this study is to exploit geothermal resources while achieving efficient cooling of coal seams and ensure the safety of water inrush in this process. Therefore, based on actual conditions of mines in eastern China, the multilevel directional branch layout modes of channels were proposed and the parametric range of water injection-endangering safety was determined. Numerical Fluid Mechanics and heat transfer models of underground mining areas were developed in COMSOL Multiphysics by taking single channels as examples. Thereafter, influences of pressure, temperature, and level spacing of water injection on the temperature reduction effect of the model and heat adsorption effect were revealed. The results showed that higher water injection pressure, lower water injection temperature, and small-interference level spacing in a safety range can well demonstrate the temperature reduction effect of the model. On this basis, the optimal scheme can be determined to help obtain the number of channel branches in a full range. The developed intact numerical model in the application zone has three channel branches and the average temperature of coal seams in the case of 1.8 years is reduced below 26 °C. The results proved that this scheme delivers efficient temperature-reduction performance.

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引用次数: 0

Impact of land cover and climate change on Aquifer Thermal and Energy Storage (ATES) system performance

IF 3.5 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2025-01-30 DOI: 10.1016/j.geothermics.2025.103262

Godinaud Jérémy , Pryet Alexandre , Bayer Peter , Larroque François

This study investigates the impact of climate change and intense urbanization on Low-Temperature Aquifer Thermal Energy Storage (LT-ATES) systems. A synthetic groundwater model was developed to consider transient thermal boundary conditions due to climate change, urbanization, and evolving building thermal demands. Four scenarios were analyzed, showing potentially significant influences on subsurface thermal conditions, leading to distinct aquifer temperature profiles. The results for conditions with strong ground heat gain indicate pronounced subsurface warming and imbalanced thermal plume extensions and decreasing ATES performance over time. Recommendations include incorporating realistic surface boundary conditions in ATES modeling and strategies to mitigate adverse thermal impacts from urbanization.

引用次数: 0

Delineation of the thermal plume associated with a standing column well system in a fractured aquifer using numerical modeling

IF 3.5 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2025-01-27 DOI: 10.1016/j.geothermics.2025.103260

Laurence Champagne-Péladeau , Philippe Pasquier , Denis Millette , J. Christian Dupuis

Standing column wells mostly recirculate groundwater in uncased wells. To enhance their thermal performance, a fraction of the flow can be diverted into one or more nearby injection well, which promotes advective heat transfer and can lead to the development of a thermal plume. The thermal plume may affect the capacity of the ground to supply heat and thereby impact the sustainability of a ground-source heat pump system. The effect of fractures on a thermal plume, as well as the potential conflicts of use arising from the operation of a standing column well system, were assessed for a fractured geological environment. A 3D finite-element model was used to simulate the thermal plume of a real ground-source heat pump system consisting of five standing column wells and one injection well at an elementary school located in Mirabel, Canada. The horizontal extent of the thermal plume is approximately 40 m by 45 m over a surface area of 1600 m

^{2}

and the temperature anomalies are more prominent between the standing column wells and the injection well. The study also reveals that permeable fractures are associated with the maximum horizontal extent of the thermal plume and are therefore particularly important to consider in dense and urban areas, where the risk of interference is higher. Moreover, it is shown that productive fractures control thermal feedback and ground temperature recovery and, hence, need to be taken into account to properly design and evaluate the actual performance and sustainability of a standing column well system.

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引用次数: 0

Constraints of hydrochemical and geological controls in deep-circulation geothermal systems: Insights from Chengde, Dehua, and Tashkorgan geothermal fields in China

IF 3.5 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2025-01-26 DOI: 10.1016/j.geothermics.2025.103265

Xiao Wang , Guiling Wang , Haonan Gan , Yu Zhang , Zhijuan Gao

Controlled by the collision of the Indian–Eurasian Plate and the subduction of the Pacific–Philippine Plate into the Eurasian Plate, deep-circulation geothermal resources are widely developed on the Tibetan Plateau in western China, the Yanshan Mountains in northern China, and the coastal region in southeastern China. However, the hydrochemical and lithospheric thermal–structural responses under different geological and tectonic background conditions are currently unknown, which constrains our understanding of the factors controlling the genesis of low- to medium-temperature deep-circulation geothermal systems. In this study, the deep-circulation geothermal systems of Chengde in Northern China, Dehua in Southern China, and Tashkorgan on the Pamir Plateau in Northwestern China were investigated. Geothermal systems in the Pacific tectonic domain at the eastern margin of the Eurasian Plate have similar elemental geochemistry and hydroxide isotopic characteristics with differences in major anion types and reservoir temperatures, which may be attributed to differences in fluid circulation depths along the fracture networks in the geothermal systems. The geothermal systems in the Tethys tectonic domain, caused by the collision of the Indian and Eurasian Plates, differ significantly from those in the Pacific tectonic domain, with more complex hydrochemical types, higher crustal and reservoir temperatures, and hydroxide isotopes showing more significant magma–water drifts. These differences indicate that the regional tectonic domain may have first-order control over deep-circulation geothermal systems. Under the same tectonic domain, the background heat flow acts as a secondary controlling factor, affecting the reservoir temperatures and circulation depths of the geothermal system.

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引用次数: 0

Appraisal of geothermal setup using magnetic spectral analysis and 3D gravity inversion for the southern part of Mahanadi geothermal province within Eastern Ghats Mobile Belt, Odisha, India

IF 3.5 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2025-01-23 DOI: 10.1016/j.geothermics.2025.103261

Ananya Parthapradip Mukherjee, Animesh Mandal

The study aims to establish possible linkages between the occurrence of four hot springs of the Mahanadi geothermal province, lying in the central part of the Eastern Ghats Mobile Belt, and the prevalent structural setup, by deciphering the crustal configuration as well as the thermal regime of the area. The centroid method is used for estimating Curie point depths (CPD) utilizing the EMAG2v3 magnetic anomaly data, thereby to obtain the corresponding geothermal gradient, and heat flow values for the study area. The CPD, geothermal gradient, and heat flow values range from 19.5 km to 32 km, 26.6 K/km to 43.6 K/km, and 66.5 mW/m² to 109.1 mW/m², respectively. The CPD results are shallower than the Moho depth variations obtained from the 3D inversion of global gridded gravity data and the CRUST1.0 model. The surface heat flow due to radiogenic heat production (RHP) of the major rock types within the study area is calculated and compared with that obtained from the CPD estimates. The average heat flow estimates from the CPD calculations (i.e., 77.5 mW/m²) and from the RHP estimates (i.e., 70.2 mW/m²) are both higher than the global mean value, implying a combined influence of radiogenic heat sources of the thin magnetic crust as well as heat from the deeper part. The shallower CPD and higher heat flow around the Mahanadi Shear zone region, indicate its role as the pathway for the thermally heated fluids from both deeper sources and near-surface radioelement-rich areas to the geothermal systems of Deulajhari, Atri, and Tarabalo. The Taptapani hot spring corresponds with a relatively deeper CPD, and lower heat flow values, where thermal water is possibly transported to it from a far-away source by the nearby shear zones and associated fracture/fault systems. Thus, the study suggests that the shear zones and the fault/fracture system around the hot springs play a vital role in developing these geothermal systems, along with the contribution of the radiogenic heat.

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引用次数: 0

Two new analytical models for heat transport in ground-coupled heat pump system with heat loss at ground surface: A new meshless treatment of ground heat exchanger for reflecting heat capacity effect

IF 3.5 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2025-01-20 DOI: 10.1016/j.geothermics.2025.103258

Chenyang Tang , Hund-Der Yeh , Ching-Sheng Huang

Existing boundary conditions or source terms specified at cylindrical ground heat exchangers (GHEs) in ground-coupled heat pump (GCHP) systems neglect the effect of GHE heat capacity. This study modifies a governing equation as a new meshless GHE treatment reflecting the effect by the product of a coefficient and temperature time derivative. Two new analytical models are developed for depicting heat transport in a GCHP system with heat loss at the ground surface. The two-zone model adopts two coupled governing equations describing heat transport in the GHE and soil formation zones. The single-zone model applies the new GHE treatment for the GHE zone with the governing equation for the formation zone. Analytical solutions of the models are derived; finite element solutions are built to release analytical solutions’ assumption of the same thermal property of the GHE and formation below the GHE. Results suggest the coefficient equals the half product of the GHE density, specific heat, and square of its radius divided by its thermal conductivity. Both analytical solutions agree to temperature within 6.2 % relative difference and 5 % for most time of a heating or cooling season, applicable to most GHEs. One finite element solution with the new meshless GHE treatment takes about 1 % of the computing time of acquiring the other finite element solution based on the governing equation and fine GHE discretization. The assumption causes 10.6 % relative error in temperature at the GHE bottom, but the error dramatically decreases below 5 % elsewhere. The present solution applies to a field GCHP experiment. In conclusion, this study may provide a better understanding of GCHP systems and useful approach for field applications.

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引用次数: 0

Findability of geothermal energy websites in seven EU countries and Iceland

IF 3.5 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2025-01-20 DOI: 10.1016/j.geothermics.2025.103252

M. Macut , D.F. Bruhn , J.M. Chicco , G. Götzl , T. Marković , A. Nádor , J.A. Newson , P.G. Ramsak , N. Rman

Obtaining information on scientific topics and access to websites with multidimensional data is a crucial part of any geothermal project development. Using the Internet to publish information according to the FAIR principles (Findability, Accessibility, Interoperability and Reusability) on topics that are not yet well known to stakeholders could improve not only general knowledge but also public acceptance for increased use of geothermal in the future. This research lists 90 geothermal websites from eight countries: nine in Austria, 13 in Croatia, eight in Hungary, 17 in Italy, seven in Germany, 16 in Iceland, 13 in the Netherlands and seven in Slovenia, and classifies them based on findability and content criteria. It is an issue that only 41 % of these national-relevant websites are easy to find using a browser and keywords, while for the rest an expert advice is needed. The user-impression by searching these websites was checked, for example, on language, graphical presentation, type of information, content, and references. It was expected that Iceland, Italy and Germany, as the countries with the largest geothermal utilization, have the most information available. Iceland has the most findable and quality websites, while Italy has the most listed websites but only a few are easy to find. Germany is not ranked as high as expected. The Netherlands and Croatia do not stand out but have few very good websites. Hungary and Austria show similar results while Slovenia needs most improvements.

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引用次数: 0

Stepwise multi-objective framework for decoupling multi-parameter estimation of ground heat exchangers

IF 3.5 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2025-01-17 DOI: 10.1016/j.geothermics.2025.103249

Min Li , Haoxin Peng

It is a great challenge to estimate multiple parameters of ground heat exchangers (GHEs) from a thermal response test (TRT) with high reliability. This study proposed a stepwise framework involving the lexicographic multi-objective optimization method to increase the identifiability of multi-parameter estimation of GHEs. Three ideas constitute the foundation of the framework: 1) using a temperature derivative objective-function to complement the temperature objective function, 2) using the lexicographic method for solving the involved multi-objective minimization problem, 3) using an analytical short-time solution for addressing the time-varying features of parameter sensitivity. This framework was illustrated by two variant algorithms for five-parameter estimation (four thermal properties plus borehole thermal resistance). The two variant algorithms were validated by an independent sandbox experiment, and the results show that these algorithms yield estimates for borehole thermal resistance, soil thermal conductivity, grout thermal diffusivity, grout thermal conductivity, and soil thermal diffusivity with relative errors smaller than 2.0 %, 4.0 %, 14 %, 20 %, and 36 %, respectively.

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引用次数: 0