共查询到20条相似文献，搜索用时 38 毫秒
1.
A mathematical model is developed for simulating the thermal energy transfer in a confined aquifer with different geological properties in the underlying and overlying rocks. The solutions for temperature distributions in the aquifer, underlying rock, and overlying rock are derived by the Laplace transforms and their corresponding time-domain solutions are evaluated by the modified Crump method. Field data adopted from the literature are used as examples to demonstrate the applicability of the solutions in modeling the heat transfer in an aquifer thermal energy storage (ATES) system. The results show that the aquifer temperature increases with time, injection flow rate, and water temperature. However, the temperature decreases with increasing radial and vertical distances. The heat transfer in the rocks is slow and has an effect on the aquifer temperature only after a long period of injection time. The influence distance depends on the aquifer physical and thermal properties, injection flow rate, and injected water temperature. A larger value of thermal diffusivity or injection flow rate will result in a longer influence distance. The present solution can be used as a tool for designing the heat injection facilities for an ATES system. 相似文献
2.
分布热源作用下裂隙岩体渗流-传热的拉氏变换-格林函数半解析计算方法 总被引：1，自引：0，他引：1
以裂隙岩体高放射性核废物地下处置库性能评估为目标,提出了分布热源作用下单裂隙岩体渗流-传热的简化概念模型、控制微分方程和拉氏变换-格林函数半解析法,为进一步采用半解析法计算分布热源作用下多裂隙岩体的渗流-传热问题奠定了基础。针对单裂隙岩体的渗流-传热问题,建立考虑岩石内热源和二维热传导的控制微分方程,利用拉氏变换域微分方程的基本解建立格林函数积分方程,采用解析法处理其中的奇点,通过数值积分和拉氏数值逆变换求解,计算任意时刻裂隙水和岩石的温度分布。通过算例,与基于岩石一维热传导假定的解析解进行了对比,并计算分析了分布热源作用下单裂隙岩体的渗流-传热特征及其对裂隙开度、岩石热传导系数和热流集度的敏感度。算例表明,（1）就裂隙水温度而言,由于考虑了岩石的二维热传导,拉氏变换-格林函数半解析解小于基于岩石一维热传导假定的解析解;（2）裂隙水温度和岩石温度对裂隙开度和热流集度的敏感度较大,对岩石热传导系数的敏感度较小。 相似文献
3.
An analytical solution to describe the transient temperature distribution in a geothermal reservoir in response to injection of cold water is presented. The reservoir is composed of a confined aquifer, sandwiched between rocks of different thermo-geological properties. The heat transport processes considered are advection, longitudinal conduction in the geothermal aquifer, and the conductive heat transfer to the underlying and overlying rocks of different geological properties. The one-dimensional heat transfer equation has been solved using the Laplace transform with the assumption of constant density and thermal properties of both rock and fluid. Two simple solutions are derived afterwards, first neglecting the longitudinal conductive heat transport and then heat transport to confining rocks. Results show that heat loss to the confining rock layers plays a vital role in slowing down the cooling of the reservoir. The influence of some parameters, e.g. the volumetric injection rate, the longitudinal thermal conductivity and the porosity of the porous media, on the transient heat transport phenomenon is judged by observing the variation of the transient temperature distribution with different values of the parameters. The effects of injection rate and thermal conductivity have been found to be profound on the results. 相似文献
4.
针对高放射性核废物地下处置库近场饱和裂隙岩体环境,提出一种由分布热源、饱和单裂隙和两侧无限大岩石构成的三维水流-传热简化模型,建立了控制微分方程和基于拉氏变换域格林函数的积分方程;采用矩形单元把裂隙面域离散化,利用极坐标下的解析方法计算包含奇点的单元积分,利用数值方法计算分布热源和不包含奇点的单元积分,建立拉氏变换域的线性代数方程组,求解后,利用拉氏数值逆变换,计算任意时刻裂隙水和岩石的温度分布。对两个无内热源、流场确定的计算模型进行了计算,与仅考虑岩石沿裂隙面法向一维热传导的解析解进行了对比。计算分析了分布热源作用下饱和单裂隙岩体的三维水流-传热特征及其对裂隙水流速、岩石热传导系数和热源热流集度的敏感度。计算结果表明：与直接采用高斯数值积分相比,提出的解析法奇异积分精度较高;就裂隙水温度而言,单裂隙岩体三维水流-传热半解析计算方法与解析法得到的结果基本一致,但由于半解析计算方法考虑了岩石的三维热传导,使得裂隙水的上游温度较低,而下游温度较高;无分布热源作用时,岩石热传导系数越大,裂隙水温度越低;裂隙水流速越大,裂隙进水温度对裂隙水和岩石温度分布的影响越明显;由于受到裂隙水流动传热的作用,分布热源对裂隙水温度和岩石温度的影响在裂隙水流的下游区域比较显著。 相似文献
5.
6.
封闭条件下抛石路堤降温效果及机理的试验研究 总被引：22，自引：13，他引：9
在多年冻土地区道路工程的修筑与维护中, 如何保证多年冻土不退化所采取措施的长期可靠度问题日益为人们所关注. 通过室内试验研究了实际工程中半开放半封闭抛石路堤受到风沙或积雪填埋后,在不同温度变幅条件下的降温效果. 实验结果发现: 在满足一定厚度时, 封闭条件下的块石层仍具有良好的降温效果, 具有可变等效导热系数的特性, 在实验中充分体现了"热二极管效应". 在外界温度变幅较大的条件下, 降温速度和降温效率均大于温度变幅较小的情况. 通过对块石层顶底温差与其顶部温度变化关系, 以及块石层内温度场特征的分析, 证实了封闭块石层内自然对流的真实存在和对流的运动发展趋势. 试验结果为抛石路堤降温的长期可靠性提供了依据. 相似文献
7.
The backfilling materials of borehole heat exchangers (BHE), particularly the grout material, must provide a suitable thermal contact and ensure durability to the induced thermal stresses because of the heat loading. In this paper, the thermal stresses that occurred in BHEs because of heat injection or extraction is investigated with an analytical solution of a hollow cylinder model that is adapted for time‐dependent heat loading, the geometry of a BHE, and the thermo‐mechanical properties of surrounding ground conditions. Firstly, the hollow cylinder model is solved with the considered boundary conditions in 2D plane stress. Secondly, the temperature differences at the inner and outer circles of the cylinder are evaluated with the heat line source models for continuous and discontinuous loading to observe the impact of the heat loading schedule. The developed analytical solution for thermal stress investigation is validated with numerical models. It is demonstrated that the analytical solutions agree well with numerical results for two types of BHE configurations (co‐axial and single U‐shaped pipes). Furthermore, the calculated maximum stresses are compared with the tensile strength of grout materials obtained from Brazilian tests. It is predicted that the thermal contraction of the grout, partially constrained by the surrounding rock, generates tensile stresses that may lead to cracking in the BHE. According to the results, the stiffness of rock has a primary role on the developed tensile stresses, and the relationship between the thermal conductivity of the ground and of the grout induces a proportional impact on the magnitude of thermal stresses. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
8.
边界条件对碎石层降温效果及机理的影响 总被引：22，自引：14，他引：8
对平均粒径为22.1 cm, 厚度1.3 m, 边界为开放和封闭的碎石层进行了一系列的实验. 从环境温度为最高和最低时刻封闭碎石层内的温度和速度分布可知: 当碎石层上表面温度低于下表面时,碎石层自下向上的散热由空气对流和碎石间的热传导来完成; 当上表面温度高于下表面时, 自上向下传递的热量由碎石接触面间的热传导完成, 此时, 由于其内部的空气几乎静止, 能阻隔热量的传入, 因此封闭边界的碎石层具有热半导体特性. 而开放边界的碎石层, 当平均温度为 0.5℃的空气从上表面吹过时, 碎石体内的热量传递主要是靠强迫对流来完成, 热半导体效果不明显, 不利于使其下面的冻土降温. 相似文献
9.
Bruno Della Vedova Claudio Vecellio Stefano Bellani Umberta Tinivella 《International Journal of Earth Sciences》2008,97(2):317-332
We present a 3-D thermal model of the Larderello geothermal field (Tuscany) to evaluate (1) the extent and contribution of
the heat transfer mechanisms (conduction vs. convection) at the intermediate-upper crust levels, (2) the variability of the
heat and mass fluxes entering from below and (3) the crucial role of the formation permeability. The model, composed by three
main layers, considers the upper 10 km of the crust to better constrain the simulations with experimental data from borehole,
fluid inclusion studies and hypocentral distributions. Several sets of simulations were carried out with different bottom
boundary temperatures and different formation permeabilities for the two deeper layers. The results indicate that the present
temperature (T) and pressure distributions in the Larderello field require deep reservoir rocks with higher permeability than the overlying
capping units and underlying intermediate crust. Permeability values of 1 mDarcy for the reservoir rocks are enough to allow
fluid convection, if the temperature at 10 km depth is as high as 500 ± 50°C. The presence of localized zones with formation
permeability 50–100 times higher than the surrounding rocks strongly favours the migration of over-pressurized fluids, which
episodically break through the overburden, feeding the presently exploited geothermal fields. 相似文献
10.
This paper proposes a three-dimensional coupled hydrothermal model for fractured rock based on the finite-discrete element method to simulate fluid flow and heat transport. The 3D coupled hydrothermal model is composed of three main parts: a heat conduction model for the rock matrix, a heat transfer model for the fluid in the fractures (including heat conduction and heat convection), and a heat exchange model between the rock matrix and the fluid in the fractures. Four examples with analytical solutions are provided to verify the model. A heat exchange experiment of circulating water in a cylindrical granite sample with one fracture is simulated. The simulation results agree well with the experimental results. The effects of the fracture aperture, fluid viscosity, and pressure difference on the heat exchange between the fluid and rock are studied. Finally, an application concerned with heat transport and fluid flow in fractured rock is presented. The simulation results indicate that the 3D fully coupled hydrothermal model can capture the fluid flow and temperature evolution of rocks and fluids. 相似文献
11.
Stefano Lo Russo Glenda Taddia Paolo Dabove Elena Cerino Abdin Ambrogio Maria Manzino 《Environmental Earth Sciences》2018,77(18):647
Thermal perturbation produced in the subsurface by open-loop groundwater heat pumps (GWHPs) represents a complex transport phenomenon that is affected by several factors, including intrinsic characteristics of the exploited aquifer, abstraction and reinjection well features, and the temporal dynamics of the accessed groundwater. Post-GWHP water may have become warmed or cooled before being reinjected into the aquifer, thereby creating a thermal plume, known as the thermal affected zone (TAZ), which can alter aquifer temperature. The TAZ is propagated mainly by advection, after which the plume tends to degrade via conductive heat transport and convection within moving water. Groundwater monitoring and multiparametric probes are used to check the dynamics of plume propagation and whether a system’s thermal plumes are generating unsuitable interference with wells, subsurface infrastructure, or land use. Analyses of time-series groundwater monitoring data can be used to monitor TAZ movement. In this paper, the thermal plume velocity was calculated by both an analytical solution and cross-correlation. Cross-correlation calculated between temperature measured in the reinjection well and control downstream piezometers can reveal plume dynamics and demonstrate the importance of advective transport in aquifer heat transfer. 相似文献
12.
尹福光 《沉积与特提斯地质》2003,23(4):79-83
康滇地区裂谷作用已得到证实,但形成这种地堑地垒的格局有多种解释,以传统的地质力学分析为主。笔者借以热力学的自由热对流原理来加以论述：攀西巨厚的火山岩体在下覆异常地幔热作用下,发生自由热对流,引起热量散失,使地壳沉降与隆起不均衡,生成地堑地垒的格局。自由对流单元的侧向迁移,使盆地形成非对称性。 相似文献
13.
Measured groundwater temperatures in the surficial zone are dependent on the properties of porous media and vertical flow velocity. Sensitivity analyses, collinear diagnostics and an inverse numerical solution to the one-dimensional heat-transport equation are used to determine which parameters can be estimated from temperature measurements in the surficial zone. This is done for heat transport in the saturated zone considering a constant vertical flow velocity. The use of temperature profiles, temperature time-series and temperature envelopes are considered. There is an important difference between a conduction and a convection dominated system. Sensitivity analysis shows that temperature measurements are sensitive to effective thermal conductivity and heat capacity and are insensitive to effective porosity and thermal dispersivity. In a conduction dominated system, temperature is also insensitive for vertical velocity. Collinear diagnostics show that in a conduction dominated system, only the combination of heat capacity and effective thermal conductivity, the thermal diffusivity, can be derived. In a convection dominated system, both the vertical velocity and the effective thermal conductivity can, theoretically, be derived. 相似文献
14.
Based on the combined finite-discrete element method (FDEM), a two-dimensional coupled hydro-thermal model is proposed. This model can simulate fluid flow and heat transfer in rock masses with arbitrary complex fracture networks. The model consists of three parts: a heat conduction model of the rock matrix, a heat-transfer model of the fluid in the fracture (including the heat conduction and convection of fluid), and a heat exchange model between the fluid and rock at the fracture surface. Three examples with analytical solutions are given to verify the correctness of the coupled model. Finally, the coupled model is applied to hydro-thermal coupling simulations of a rock mass with a fracture network. The temperature field evolution, the effect of thermal conductivity of the rock matrix thermal conductivity and the fracture aperture on the outlet temperature are studied. The coupled model presented in this paper will enable the application of FDEM to study rock rupture driven by the effect of hydro-thermo-mechanical coupling in geomaterials such as in geothermal systems, petroleum engineering, environmental engineering and nuclear waste geological storage.
相似文献15.
Thermal Conductivity of Argillaceous Rocks: Determination Methodology Using In Situ Heating Tests 总被引：1，自引：1，他引：0
Benoit Garitte Antonio Gens Jean Vaunat Gilles Armand 《Rock Mechanics and Rock Engineering》2014,47(1):111-129
This study focuses on the characterisation of thermal conductivity for three potential host rocks for radioactive waste disposal. First, the heat conduction process is reviewed on the basis of an analytical solution and key aspects related to anisotropic conduction are discussed. Then the existing information on the three rocks is summarised and a broad uncertainty range of thermal conductivity is estimated based on the mineralogical composition. Procedures to backanalyse the thermal conductivity on the basis of in situ heating tests are assessed and a methodology is put forward. Finally, this methodology is used to estimate the impact of experimental uncertainties and applied to the four in situ heating tests. In the three potential host rocks, a clear influence of the bedding planes was identified and anisotropic heat conduction was shown to be necessary to interpret the observed temperature field. Experimental uncertainties were also shown to induce a larger uncertainty on the anisotropy ratio than on the equivalent thermal conductivity defined as the geometric mean of the thermal conductivity in the three principal directions. 相似文献
16.
Björn Onno Kaiser Mauro Cacace Magdalena Scheck-Wenderoth 《Environmental Earth Sciences》2013,70(8):3643-3659
Based on a numerical model of the Northeast German Basin (NEGB), we investigate the sensitivity of the calculated thermal field as resulting from heat conduction, forced and free convection in response to consecutive horizontal and vertical mesh refinements. Our results suggest that computational findings are more sensitive to consecutive horizontal mesh refinements than to changes in the vertical resolution. In addition, the degree of mesh sensitivity depends strongly on the type of the process being investigated, whether heat conduction, forced convection or free thermal convection represents the active heat driver. In this regard, heat conduction exhibits to be relative robust to imposed changes in the spatial discretization. A systematic mesh sensitivity is observed in areas where forced convection promotes an effective role in shorten the background conductive thermal field. In contrast, free thermal convection is to be regarded as the most sensitive heat transport process as demonstrated by non-systematic changes in the temperature field with respect to imposed changes in the model resolution. 相似文献
17.
Shunde Yin 《国际地质力学数值与分析法杂志》2013,37(15):2523-2538
Integration of poromechanics and fracture mechanics plays an important role in understanding a series of thermal fracturing phenomena in subsurface porous media such as cold water flooding for enhanced oil recovery, produced‐water reinjection for waste disposal, cold water injection for geothermal energy extraction, and CO2 injection for geosequestration. Thermal fracturing modeling is important to prevent the potential risks when fractures propagate into undesired zones, and it involves the coupling of heat transfer, mass transport, and stress change as well as the fracture propagation. Analytical method, finite element method, and finite difference method as well as boundary element method have been used to perform the thermal fracturing modeling considering different degrees and combinations of coupling. In this paper, extended finite element method is employed for the thermal fracturing modeling in a fully coupled fashion with remeshing avoided, and the stabilized finite element method is employed to account for the convection‐dominated heat transfer in the fracturing process with numerical oscillation circumvented. With the thermal fracturing model, a hypothetical numerical experiment on cold water injection into a deep warm aquifer is conducted. Results show that parameters such as injection rate, injection temperature, aquifer stiffness, and permeability can affect the fracture development in different ways and extended finite element method and stabilized finite element method provide effective tools for thermal fracturing simulation. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
18.
A simple and analytical method of solving the problem of heat extraction from a penny-shaped crack having both inlet and outlet holes is developed by using a two-dimensional flow model when fluid is injected at a constant flow rate. Temperature distributions in both rock and fluid are obtained by taking into account the hydraulic and thermal growth of the crack. The outlet fluid temperature and energy extraction rate versus time are shown by some illustrative examples. Although the effect of thermal, contraction of rock upon the crack width is large, its influence upon flow rate and crack tip stress intensity factor is sufficiently small within the first several years so that the crack radius can be determined mainly by the mechanical deformation of, the rock. 相似文献
19.
A semi‐analytical approach is developed for modeling 3D heat transfer in sparsely fractured rocks with prescribed water flow and heat source. The governing differential equations are formulated, and the corresponding integral equations over the fracture faces and the distributed heat source are established in the Laplace transformed domain using the Green function method with local systems of coordinates. The algebraic equations of the Laplace transformed temperatures of water in the fractures are formed by dividing the integrals into elemental ones; in particular, the fracture faces are discretized into rectangular elements, over which the integrations are carried out either analytically for singular integrals when the base point is involved or numerically for regular integrals when otherwise. The solutions of the algebraic equations are inverted numerically to obtain the real‐time temperatures of water in the fractures, which may be employed to calculate the temperatures at prescribed locations of the rock matrix. Three example calculations are presented to illustrate the workability of the developed approach. The calculations found that water flux in the fractures may decrease the rate of temperature rise in regions close to the distributed heat source and increase the rate of temperature rise in regions downstream away from the distributed heat source and that the temperature distribution and evolvement in a sparsely fractured rock mass may be significantly influenced by water flow exchange at intersection of fractures. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
20.
能量桩是将地源热泵系统中的换热管埋置在桩体内部,桩同时起到承载和换热的作用,是一种新型的基础型式。为了合理分析黏土地基中能量桩的力学特性,需要了解能量桩运行过程中桩和地基土的温度响应,并考虑温度变化对土体力学性能的影响。基于有限元软件ABAQUS建立了能量桩传热分析三维有限元模型,把能量桩的传热简化为换热管内液体与管壁之间的对流传热、桩体中的热传导和地基中的热传导,将计算结果与常规理论和实测数据进行了对比验证。对热力耦合边界面本构模型进行了二次开发,通过算例验证了模型对土体压缩和剪切性状温度效应的模拟能力。利用所提出的能量桩传热分析方法和热边界面模型,考虑不同的桩顶工作荷载水平,对正常固结黏土地基中能量桩单桩的长期性能进行了研究,分析了温度循环对桩顶沉降、桩侧摩阻力和桩身轴力的影响。结果表明,工作荷载越高,温度循环次数越多,桩顶累积沉降越大。 相似文献