Geothermics最新文献_第2页

Macroscopic permeability progression of Nanan granite under confining pressures and its microscopic evolution after cooling at atmospheric pressure: A comparative study 南安花岗岩在约束压力下的宏观渗透率变化及其在常压下冷却后的微观演变：对比研究

IF 3.5 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2024-10-14 DOI: 10.1016/j.geothermics.2024.103180

Permeability is one of the key factors for influencing the mass transfer behavior in rocks and plays a key role in heat extraction of enhanced geothermal systems (EGSs), so the practice of EGSs needs cooling water to be injected to enhance the permeability within geothermal reservoirs. Macroscopic and microscopic experimental investigation on how cool water affects permeability evolution is still limited. To solve this, we experimentally explored the permeability evolution of Nanan granite after air and water cooling under different confining pressures combined with optical microscopy and X-ray micro computed tomography (CT) observation. Lots of microdefects were observed in Nanan granite after two cooling paths, which dominantly drives the evolution of permeability from a microscopic scale. The permeabilities of granite under water-cooling conditions are always larger than those under air-cooling conditions, because the comparison shows that water-cooling treatment enhances the permeability of specimens. The permeabilities of granite specimens after two cooling paths decrease with the confining stress. More microcracks and better connectivity among microcracks produce a larger permeability within the specimen after water cooling. The observed microcracks are regarded as the seepage channels and direct microscale evidence of the permeability evolution of granite after two cooling paths. Our results provide support that cooled water injection is an efficient way for permeability enhancement due to thermal microcracks propagation in thermal simulation.

渗透性是影响岩石传质行为的关键因素之一，在强化地热系统（EGSs）的热量提取中起着关键作用，因此，EGSs 的实践需要注入冷却水以提高地热储层内的渗透性。关于冷却水如何影响渗透率演化的宏观和微观实验研究仍然有限。为了解决这个问题，我们结合光学显微镜和 X 射线显微计算机断层扫描（CT）观测，实验探索了南安花岗岩在不同约束压力下空冷和水冷后的渗透率演化。结果表明，南安花岗岩在两种冷却方式下均存在大量微缺陷，从微观尺度上主导了渗透率的演化。水冷条件下花岗岩的渗透率总是大于空冷条件下的渗透率，因为比较表明水冷处理提高了试样的渗透率。经过两种冷却路径后，花岗岩试样的渗透率随着约束应力的增加而降低。水冷却后，更多的微裂缝和微裂缝之间更好的连通性在试样内部产生了更大的渗透性。观察到的微裂缝被视为渗流通道，是花岗岩经过两种冷却路径后渗透性演变的直接微观证据。我们的研究结果证明，在热模拟中，冷却水注入是通过热微裂纹传播提高渗透率的有效方法。

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引用次数: 0

Damage characteristics of high-temperature coal under different cooling rates 不同冷却速率下高温煤的损伤特征

IF 3.5 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2024-10-07 DOI: 10.1016/j.geothermics.2024.103179

The damage characteristics of high-temperature coal under water cooling was analyzed.As the heating temperature increases, the internal pore development and crack propagation in coal intensify, with the failure mode gradually shifting from brittle to plastic. There exists a threshold temperature that accelerates damage. The rapid temperature drop caused by water cooling accelerates damage and cracking in the coal. The thermal shock factor resulting from the rapid temperature drop can quantitatively represent the damage induced by water cooling. The results are expected to provide guidance for the utilization of thermal energy in coal field fire areas.

随着加热温度的升高，煤的内部孔隙发育和裂纹扩展加剧，破坏模式逐渐从脆性转向塑性。存在一个加速破坏的临界温度。水冷造成的快速降温会加速煤炭的损坏和裂纹。快速降温导致的热冲击因子可以定量地表示水冷所引起的破坏。研究结果有望为煤田火区的热能利用提供指导。

引用次数: 0

Breakage mechanism analysis of bedded sandstone impacted by abrasive water jet using an integrated SPH-DEM-FEM and cohesive element method 利用综合 SPH-DEM-FEM 和内聚元素法分析受到磨料水射流冲击的层状砂岩的破碎机理

IF 3.5 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2024-10-07 DOI: 10.1016/j.geothermics.2024.103177

Abrasive water jet (AWJ) is an emerging technique for improving the drilling efficiency for geothermal energy development. Rock bedding significantly influences the effectiveness of rock breaking during drilling. In this study, to investigate the damage modes and the mechanism of the bedded sandstone under abrasive water jet erosion, smooth particle hydrodynamics (SPH) and discrete element method (DEM) are used to establish the jet, and cohesive elements are inserted into finite elements to model the bedded sandstone, simulating the process of water and abrasive into the nozzle to form an abrasive water jet impacting bedded sandstone. The numerical results showed that the depth and diameter of fractures in bedded sandstone decrease and then stabilize as the bedding angle increases under AWJ, and the error in the ratio of erosion hole diameter and depth between the simulated and experimental results was <10.8 %. In addition, two damage modes of the bedded sandstone were determined, which include Case I damage mode: the sandstone is well consolidated, and the damage is in the form of erosion holes (0°≤α≤60°), dominated by the tensile damage, and Case II damage mode: the rock is fractured along the bedding and splits into two halves (60°<α≤90°), and the process can be divided into two stages during this mode. The first stage is the impact kinetic energy carried by the jet to form a crater, and the second stage is the water wedge effect to fracture the rock. The results of this study complement the damage mechanism of fractured bedded rocks by AWJ, which provides a theoretical reference for the application of AWJ to break bedded rocks in subsurface energy extraction.

加砂水射流（AWJ）是一种提高地热能源开发钻探效率的新兴技术。岩石垫层对钻探过程中的破岩效果有很大影响。本研究采用光滑粒子流体力学（SPH）和离散元法（DEM）建立射流，并在有限元中插入内聚元，模拟水和磨料进入喷嘴形成磨料水射流冲击层状砂岩的过程，研究磨料水射流侵蚀下层状砂岩的破坏模式和机理。数值结果表明，在 AWJ 作用下，层状砂岩的裂缝深度和直径随着层理角的增大而减小，然后趋于稳定，模拟结果与实验结果之间侵蚀孔直径与深度之比误差为 10.8%。此外，还确定了床层砂岩的两种破坏模式，包括情况 I 破坏模式：砂岩固结良好，破坏形式为侵蚀孔（0°≤α≤60°），以拉伸破坏为主；情况 II 破坏模式：岩石沿床层断裂并分裂为两半（60°<α≤90°），该模式下的破坏过程可分为两个阶段。第一阶段是射流携带的冲击动能形成陨石坑，第二阶段是水楔效应使岩石断裂。该研究结果补充了 AWJ 对破裂基岩的破坏机理，为在地下能源开采中应用 AWJ 破坏基岩提供了理论参考。

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引用次数: 0

Effects of carbon dioxide blasting on hot dry rock reservoirs considering thermal damage 考虑热损伤的二氧化碳爆破对干热岩储层的影响

IF 3.5 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2024-10-05 DOI: 10.1016/j.geothermics.2024.103174

A cutting-edge technique for igniting hot dry rock (HDR) reservoirs is carbon dioxide blasting. The cooling effect of the drilling fluid was taken into consideration during a numerical simulation of the action range of carbon dioxide blasting-induced cracking. A temperature difference was used to determine the reservoir's material properties. Additionally, temperature distribution functions were used to create the temperature field in the reservoir. The blasting load is calculated using the pertinent theories and formulas of explosive blasting, and the process of blasting carbon dioxide to excite the HDR reservoir is modeled using COMSOL. The findings show that several stress concentrations take place during the blasting process. The fracture zone is created by the tensile stress concentration outside of the crushing zone, whereas the compressive stress concentration close to the blast hole creates the crushing zone. Furthermore, the effectiveness of carbon dioxide blasting fracturing would be affected by the beginning temperature and pressure plate thickness. Although the scope of the fracture zone is mostly unchanged, the initial temperature has a significant impact on the blasting crushing zone. The size of the crushing zone, which determines how the blasting fracture zone is distributed, is unaffected by the pressure plate's thickness.

二氧化碳爆破是点燃干热岩（HDR）储层的一项尖端技术。在对二氧化碳爆破诱发裂缝的作用范围进行数值模拟时，考虑了钻井液的冷却效果。温差用于确定储层的材料特性。此外，还使用温度分布函数来创建储层中的温度场。使用爆炸爆破的相关理论和公式计算爆破载荷，并使用 COMSOL 对二氧化碳爆破激发 HDR 储层的过程进行建模。研究结果表明，在爆破过程中会出现多种应力集中现象。破碎带以外的拉应力集中形成了断裂带，而爆破孔附近的压应力集中则形成了破碎带。此外，二氧化碳爆破压裂的效果会受到起始温度和压板厚度的影响。虽然断裂带的范围基本不变，但初始温度对爆破破碎带的影响很大。破碎带的大小决定了爆破压裂带的分布，但它不受压力板厚度的影响。

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引用次数: 0

GeoProp: A thermophysical property modelling framework for single and two-phase geothermal geofluids GeoProp：单相和两相地热地质流体的热物理特性建模框架

IF 3.5 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2024-10-04 DOI: 10.1016/j.geothermics.2024.103146

The techno-economic evaluation of geothermal resources requires knowledge of the geofluid's thermophysical properties. While the properties of pure water and some specific brines have been studied extensively, no universally applicable model currently exists. This can result in a considerable degree of uncertainty as to how different geothermal resources will perform in practice. Geofluid modelling has historically been focused on two research fields: 1) partitioning the geofluid into separate phases, and 2) the estimation of the phases’ thermophysical properties. Models for the two fields have commonly been developed separately. Recognising their potential synergy, we introduce GeoProp, a novel geofluid modelling framework, which addresses this application gap by coupling existing state-of-the-art fluid partitioning simulators, such as Reaktoro, with high-accuracy thermophysical fluid property computation engines, like CoolProp and ThermoFun. GeoProp has been validated against field experimental data as well as existing models for some incompressible binary fluids. We corroborate GeoProp's efficacy at modelling the thermophysical properties of geothermal geofluids via a case study on the heat content of different geofluids. Our results highlight the importance of accurately characterising the thermophysical properties of geofluids in order to quantify the resource potential and optimise the design of geothermal power plants.

地热资源的技术经济评估需要了解地热流体的热物理特性。虽然已经对纯水和某些特定盐水的特性进行了广泛研究，但目前还没有普遍适用的模型。这可能导致不同地热资源在实际应用中存在相当程度的不确定性。地流体建模历来集中在两个研究领域：1）将地热流体划分为不同的阶段；2）估算各阶段的热物理性质。这两个领域的模型通常是分开开发的。认识到这两个领域潜在的协同作用，我们推出了新型地质流体建模框架 GeoProp，通过将现有最先进的流体分区模拟器（如 Reaktoro）与高精度热物理流体属性计算引擎（如 CoolProp 和 ThermoFun）相结合，解决了这一应用空白。GeoProp 已通过现场实验数据和一些不可压缩二元流体的现有模型进行了验证。通过对不同地质流体热含量的案例研究，我们证实了 GeoProp 在模拟地热地质流体热物理特性方面的功效。我们的研究结果凸显了准确描述地热流体热物理特性对于量化资源潜力和优化地热发电厂设计的重要性。

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引用次数: 0

The hydrochemistry and geothermometry of thermal waters from a deep Jurassic aquifer in Lower Austria–South Moravia region 下奥地利-南摩拉维亚地区侏罗纪深含水层热水域的水化学和地热测定法

IF 3.5 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2024-09-30 DOI: 10.1016/j.geothermics.2024.103173

Potentially important deep hydrogeological structure containing thermal water is in the border area of Austria and the Czech Republic. Thermal water is bound to a deep Jurassic carbonate aquifer (reaching depths above 3 km) underlying the Tertiary sediments of the Alpine-Carpathian Foredeep. Its current use is limited only to spa and recreational purposes serviced by two 1.45 km deep wells. Our study is the first comprehensive study in this area to understand the origin and processes of thermal water formation and evolution. Understanding the processes in aquifers containing thermal water is of fundamental importance both for geothermal potential and for knowledge of possible natural analogues of deep CO₂ storage. The research has shown that thermal water is of dominant Na-Cl type with largely varying TDS (total dissolved solids) values between 0.4 and 56 g/L. Assumed marinogenic origin is confirmed by Cl/Br ratio. The average value of the geothermal gradient is 28.5 °C/km and the observed groundwater temperature ranges from 37 °C to 110 °C, with the highest values found in the deepest part of the aquifer, mainly on the Austrian side. The Jurassic aquifer is divided into two sections: a shallower, less mineralised northwestern section and a deeper, highly mineralised southeastern section, with a relatively impermeable barrier between them. The southeastern section contains mainly fossil seawater of high salinity ranging from 15 to 56 g/l and represents a structure with limited connection to active groundwater flow. In contrast, the thermal water in the northwestern section shows evidence of meteoric water infiltration from NW, as confirmed by TDS concentrations, hydrochemistry, and stable δ²H and δ¹⁸O isotope composition. The most reliable geothermometrical estimations are given by the K-Mg (Giggenbach, 1988) and Na-K (Truesdell 1976; Tonani 1980; Arnórsson 1983) geothermometers with mean reservoir temperature around 95 °C. The average temperature is higher in the water samples from the southeastern section and according to the geothermometrical evaluation, most of the water samples from both aquifer sections are mature chloride waters. Immature waters occur only in the northwestern section, indicating dilution of primary seawater by shallow cold waters of meteoric origin.

在奥地利和捷克共和国交界地区有一个潜在的重要深层水文地质结构，其中含有热能水。温泉水被深层侏罗纪碳酸盐含水层（深度超过 3 公里）束缚在阿尔卑斯-喀尔巴阡山前深第三纪沉积层之下。目前，水的使用仅限于水疗和娱乐用途，由两口 1.45 千米深的水井提供。我们的研究是在这一地区进行的首次全面研究，旨在了解温泉水形成和演变的起源和过程。了解含热水含水层的形成过程，对于挖掘地热潜力和了解深层二氧化碳封存的可能自然类似物都具有重要意义。研究表明，热敏水主要是 Na-Cl 型，TDS（溶解性总固体）值在 0.4 至 56 克/升之间，变化很大。Cl/Br 比率证实了假定的海洋水源。地热梯度的平均值为 28.5 °C/公里，观测到的地下水温度在 37 °C到 110 °C之间，最高值出现在含水层的最深处，主要在奥地利一侧。侏罗纪含水层分为两段：较浅、矿化度较低的西北段和较深、矿化度较高的东南段，两者之间有一个相对不透水的屏障。东南部地段主要含有高盐度（15 至 56 克/升）的化石海水，是一个与活跃地下水流联系有限的结构。与此相反，西北部地段的热敏水显示了来自西北部的流星水渗透的证据，这一点已被 TDS 浓度、水化学以及稳定的 δ2H 和 δ18O 同位素组成所证实。最可靠的地温测量方法是 K-Mg（Giggenbach，1988 年）和 Na-K（Truesdell，1976 年；Tonani，1980 年；Arnórsson，1983 年）地温测量法，水库平均温度约为 95 ℃。东南部地段的水样平均温度较高，根据地温计评估，两个含水层地段的大部分水样都是成熟的氯化物水。不成熟水仅出现在西北部地段，表明原生海水被陨石源浅层冷水稀释。

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引用次数: 0

Comparative analysis of hybrid geothermal-solar systems and solar PV with battery storage: Site suitability, emissions, and economic performance 地热-太阳能混合系统与带电池储能的太阳能光伏发电系统的比较分析：场地适用性、排放和经济效益

IF 3.5 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2024-09-29 DOI: 10.1016/j.geothermics.2024.103175

Renewable energy integration has become a critical focus in the global effort to reduce carbon emissions and diversify energy sources. In regions with distinct geographic features, such as Türkiye, combining different renewable technologies can offer enhanced energy security. This study investigates the site suitability and economic and environmental performance of hybrid geothermal-solar systems and solar PV systems with battery storage across the provinces of Osmaniye, Hatay, and Kilis, of Türkiye. Using the fuzzy-AHP method, site suitability is evaluated, addressing a key gap in comparing these systems' adaptability to varying geographic conditions. This study is the first to directly compare these two renewable energy technologies in terms of site suitability. The findings reveal significant differences in site suitability, with solar PV systems with battery storage demonstrating broader applicability across the region. The suitable sites (20–100 % suitability) cover 1260.82 km² for solar PV systems with battery storage and only 122.18 km² for hybrid geothermal-solar systems. In terms of environmental impact, hybrid geothermal-solar systems exhibit significantly lower carbon emissions, averaging 44.6 kg CO₂/MWh, compared to 123.8 kg CO₂/MWh for solar PV systems with battery storage. Economically, hybrid geothermal-solar systems also outperform with a lower levelized cost of electricity of $0.091 kWh versus $0.254 kWh for solar PV systems. These results highlight the environmental and economic advantages of hybrid geothermal-solar systems, while also emphasizing their limited scalability to regions with geothermal activity. Conversely, solar PV systems, despite their higher emissions and costs, offer greater flexibility and potential for widespread deployment.

可再生能源一体化已成为全球努力减少碳排放和实现能源多样化的关键重点。在图尔基耶等地理特征明显的地区，将不同的可再生能源技术结合起来，可以提高能源安全。本研究调查了图尔基耶省奥斯曼尼耶、哈塔伊和基利斯的地热-太阳能混合系统和带电池储能的太阳能光伏系统的选址适宜性、经济和环境性能。利用模糊-AHP 方法对场地适宜性进行了评估，解决了在比较这些系统对不同地理条件的适应性方面存在的关键差距。这项研究首次直接比较了这两种可再生能源技术的场地适宜性。研究结果表明，场地适宜性存在显著差异，带蓄电池的太阳能光伏系统在整个地区具有更广泛的适用性。带蓄电池的太阳能光伏系统的适用场地（20%-100% 适用性）为 1260.82 平方公里，而混合地热-太阳能系统的适用场地仅为 122.18 平方公里。在环境影响方面，混合地热-太阳能系统的碳排放量明显较低，平均为 44.6 千克 CO₂/兆瓦时，而带蓄电池的太阳能光伏系统的碳排放量为 123.8 千克 CO₂/兆瓦时。在经济上，地热-太阳能混合系统也更胜一筹，其平准化电力成本为 0.091 美元/千瓦时，而太阳能光伏系统为 0.254 美元/千瓦时。这些结果凸显了地热-太阳能混合系统在环境和经济方面的优势，同时也强调了其在地热活动地区的可扩展性有限。相反，太阳能光伏发电系统尽管排放量和成本较高，但却具有更大的灵活性和广泛部署的潜力。

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引用次数: 0

Deconvolution of high and low-temperature alteration processes along the contact zones of basaltic-dike intrusions in basaltic host rocks of different permeabilities – implications for geothermal exploration 不同渗透率玄武岩母岩中玄武岩-堤侵入体接触带高温和低温蚀变过程的解卷积--对地热勘探的影响

IF 3.5 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2024-09-28 DOI: 10.1016/j.geothermics.2024.103171

Magmatic intrusions serve as crucial heat sources for geothermal systems, facilitating mass transfer, mineral transformations, and elemental exchange, which result in the formation of contact aureoles. While these processes have been extensively studied in large intrusive complexes in ancient geological formations, understanding of their occurrence in active geothermal systems remains limited. The extreme conditions present in active volcanic systems often obscure the geochemical processes occurring within host rock/intrusion zones. Uncertainties persist regarding whether relatively small dike intrusions (∼0.5 m thick) possess sufficient heat content to induce textural or geochemical changes in the surrounding wall rock, and what implications this may hold for future exploratory drilling projects. The analyses in this study were conducted on two distinct outcrops, each featuring 50-cm thick basaltic intrusions within both high- and low-permeability basaltic host rocks. The low permeability host rock hosts high-temperature mineral phases (>800 °C), such as sanidine + hedenbergite + albite-rich plagioclase in the contact zone, which we interpret to have formed during partial melting. Immobile, incompatible trace elements (such as Zr, Nb and La) retain the signatures of partial melting in both outcrops. We demonstrate that low degree partial melting (F ≈ 3–10 %) results in a compositional shift in the host rock from basalt to dacite and/or trachyandesite. Thermal modelling suggests that these small dikes, along with their partial melts in the contact zone, form over a very short period of time (< 1 day), but can elevate the ambient temperature. This type of events play an important role in the development of active geothermal systems. In theory, these small dikes do not pose a significant risk during geothermal drilling, unless they are too small to be detected during geophysical exploration.

岩浆侵入体是地热系统的重要热源，可促进质量传递、矿物转化和元素交换，从而形成接触金星。虽然这些过程在古代地质构造中的大型侵入复合体中得到了广泛研究，但对其在活动地热系统中发生的了解仍然有限。活火山系统中存在的极端条件往往掩盖了发生在主岩/侵入带中的地球化学过程。关于相对较小的堤状侵入体（厚度在 0.5 米以下）是否具有足够的热量来引起周围岩壁岩石的纹理或地球化学变化，以及这对未来勘探钻井项目的影响，仍然存在不确定性。本研究对两个不同的露头进行了分析，每个露头都有 50 厘米厚的玄武岩侵入体，分别位于高渗透性和低渗透性玄武岩母岩中。低渗透性母岩含有高温矿物相（>800 °C），如接触带的辉绿岩+辉长岩+富斜长石，我们认为这些矿物相是在部分熔融过程中形成的。在两个露头中，不移动、不相容的微量元素（如锆、铌和镭）保留了部分熔融的特征。我们证明，低度局部熔融（F ≈ 3-10%）会导致母岩成分从玄武岩转变为英安岩和/或闪长岩。热模拟表明，这些小型岩钉及其在接触区的部分熔体形成的时间很短（1 天），但却能使环境温度升高。这类事件在活跃地热系统的发展中起着重要作用。从理论上讲，这些小堤在地热钻探过程中不会构成重大风险，除非它们太小，在地球物理勘探过程中无法探测到。

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引用次数: 0

Mapping and delineation of steel corrosion products under geothermal-like conditions 类地热条件下钢铁腐蚀产物的制图和划分

IF 3.5 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2024-09-24 DOI: 10.1016/j.geothermics.2024.103172

In this paper we attempt to understand the corrosion behavior of carbon (mild) steel (a common structural component in water handling installations) and the factors that influence it, by identifying various corrosion products that form under diverse conditions relevant to geothermal systems. Hence, experiments were performed under variable stressful experimental conditions, by systematically studying the effect of certain important variables, such as temperature and brine composition. Therefore, three brines and four temperatures were selected (ambient, 60, 90, and 130 °C), while the pH was kept constant at ∼ 7. It was found that for all water qualities corrosion rates (quantified by gravimetric methods and soluble Fe measurements) are not directly proportional to the temperature, with the measured values being the lowest at RT and highest at T = 130 °C. In the two intermediate temperatures (60 and 90 °C) the corrosion rates are lower. A possible explanation for this could be the fact that corrosion products can form films on the metal surface, affecting the corrosion aggressiveness, and thus corrosion rates. The full characterization of precipitates collected from these experiments led to the identification of the corrosion products and to the correlation of corrosion aggressiveness (due temperature and water quality) with the identity of each corrosion product. The variability in color of the corrosion products on the metal surfaces was an indication of the formation of lepidocrocite and magnetite films, as demonstrated by the orange and black color of the films on the specimens, respectively. The identification of the corrosion products that formed under the selected experimental conditions was achieved by the physicochemical characterization (ATR-IR and powder XRD) of the iron deposits collected from the control experiments. These studies confirmed the qualitative indications based on the deposit color.

在本文中，我们试图通过确定在地热系统相关的各种条件下形成的各种腐蚀产物，来了解碳（低碳）钢（水处理装置中的常见结构部件）的腐蚀行为及其影响因素。因此，通过系统研究某些重要变量（如温度和盐水成分）的影响，在不同的应力实验条件下进行了实验。因此，实验选择了三种盐水和四种温度（常温、60、90 和 130 °C），pH 值保持在 ∼ 7。研究发现，对于所有水质，腐蚀率（通过重量法和可溶性铁测量法量化）与温度并不成正比，在常温下测量值最低，而在 T = 130 °C 时测量值最高。在两个中间温度（60 和 90 °C）下，腐蚀率较低。可能的解释是，腐蚀产物会在金属表面形成薄膜，影响腐蚀侵蚀性，从而影响腐蚀速率。通过对从这些实验中收集到的沉淀物进行全面表征，可以确定腐蚀产物，并将腐蚀侵蚀性（由于温度和水质）与每种腐蚀产物的特性联系起来。金属表面腐蚀产物颜色的变化表明形成了鳞片岩和磁铁矿薄膜，试样上的薄膜颜色分别为橙色和黑色。通过对从对照实验中收集的铁沉积物进行物理化学表征（ATR-IR 和粉末 XRD），确定了在选定实验条件下形成的腐蚀产物。这些研究证实了基于沉积物颜色的定性指标。

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引用次数: 0

Numerical investigation of the geometric parameters effect of helical blades installed on horizontal geo heat exchanger 对安装在水平地缘热交换器上的螺旋叶片几何参数影响的数值研究

IF 3.5 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2024-09-18 DOI: 10.1016/j.geothermics.2024.103169

In this study, we investigate the enhancement of horizontal geothermal heat exchangers equipped with helical fins on the pipe's exterior and internally ribbed turbulators. Our approach focuses on the interplay between geometry and thermal efficiency through innovative design modifications. Utilizing the finite element method, three-dimensional numerical simulations assessed the effects of varying geometric parameters such as the diameter and thickness of the fins. Our findings indicate significant increases in heat transfer efficiency with the addition of helical fins; specifically, increasing the fin diameter from 5 mm to 10 mm results in a 15 % increase in the heat transfer rate, while doubling the fin thickness from 2 mm to 4 mm enhances the rate by 10 %. These improvements are due to the expanded surface area facilitating greater heat exchange. Optimization using the desirability function approach yielded models with high performance, achieving desirability scores of 0.9879 for outlet temperature and 0.9534 for the heat transfer coefficient. This reflects the effective tuning of geometric parameters to maximize thermal performance. The study also introduces two predictive mathematical models for the outlet temperature and convective heat transfer coefficient of the U-shaped pipe equipped with these enhancements. These models, derived from extensive numerical data, provide practical tools for future design and operational applications of geothermal heat exchangers. This research advances the design and operational efficiency of geothermal heat exchange systems, establishing new benchmarks for thermal efficiency in the field with actionable insights and robust mathematical tools.

在这项研究中，我们探讨了如何提高水平地热换热器的热效率，该换热器在管道外部装有螺旋翅片，内部装有带肋涡轮。我们的研究重点是通过创新的设计改造，研究几何形状与热效率之间的相互作用。利用有限元方法，三维数值模拟评估了不同几何参数（如翅片直径和厚度）的影响。我们的研究结果表明，增加螺旋形散热片后，传热效率明显提高；具体而言，将散热片直径从 5 毫米增加到 10 毫米后，传热率提高了 15%，而将散热片厚度从 2 毫米增加一倍到 4 毫米后，传热率提高了 10%。这些改进都是由于扩大了表面积，促进了更大的热交换。使用可取函数法进行优化后，模型的性能很高，出口温度的可取分数达到 0.9879，传热系数达到 0.9534。这反映出通过有效调整几何参数，实现了热性能的最大化。该研究还引入了两个预测数学模型，用于预测配备这些增强功能的 U 型管道的出口温度和对流传热系数。这些模型源自大量数值数据，为地热换热器未来的设计和运行应用提供了实用工具。这项研究提高了地热换热系统的设计和运行效率，通过可操作的见解和强大的数学工具为该领域的热效率建立了新的基准。

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