干热岩单裂隙渗流—传热实验与数值模拟研究

发布时间：2018-05-15 00:04

本文选题：干热岩 + 单裂隙　；参考：《吉林大学》2017年硕士论文

【摘要】：近年来对能源和环境质量要求越来越高,干热岩由于有巨大的资源储量和清洁性,越来越受到重视。干热岩型地热能提取通常在裂隙中与地热岩体发生热交换来提取,因此研究裂隙的渗流换热机理对干热岩工程具有重要意义。本文采用3D打印技术制备各种粗糙裂隙,利用实验、数值模拟和量化评价的方法对单裂隙粗糙岩体的渗流传热影响因素和传热机理进行探讨。对不同粗糙类型岩样分别进行了渗流实验和渗流换热实验,分析各粗糙裂隙面的渗流换热特征;采用基于平板层流换热理论数值软件模拟进行理论对比;采用全局灵敏度法定量分析,主要结论如下:首先,采用3D打印方法依据巴顿标准粗糙曲线制备了22块渗流方向和垂直渗流方向粗糙裂隙面岩样,在此基础上开展了渗流实验,实验结果显示,随着粗糙度的增加,裂隙流量和等效水力开度均降低;在降低流体流量方面,垂直渗流方向粗糙度作用最小,二维粗糙裂隙作用最大,二维裂隙面中粗糙度高的裂隙面比粗糙度低的裂隙面作用大,渗流方向粗糙度比垂直渗流方向粗糙度作用大。其次,依据巴顿标准粗糙曲线制备的22块渗流方向和垂直渗流方向粗糙裂隙面岩样,开展了渗流换热实验,实验结果显示,各种粗糙裂隙面岩样的对流换热系数随着流量的升高提高越大,随着裂隙面温度的升高对流换热系数逐渐增大;垂直渗流方向粗糙度对提高对流换热系数的作用最小,二维粗糙裂隙对提高对流换热系数的影响作用相对较大;渗流方向粗糙裂隙和垂直渗流方向粗糙裂隙渗流传热机理较为相似,主要是受换热面积和局部紊流影响,二维粗糙裂隙渗流换热机理增加了渗流优势路径的影响;对22种粗糙裂隙面拟合了Nu与Re和Pr的曲线,给出了相应的特征数方程。再次,通过单裂隙岩体渗流传热数值模拟进行了理论对比,平直裂隙、渗流方向不同粗糙度裂隙和垂直渗流方向不同粗糙度裂隙岩样的数值模拟和实验结果误差较小,采用层流换热理论可以近似计算;二维粗糙裂隙岩样的对比误差较大,不适合采用层流换热理论近似计算。最后,采用全局灵敏度评价方法评价渗流换热实验中各实验变量的影响作用。在各类粗糙裂隙面渗流换热实验中,岩石温度对出水口温度的提高起主要作用;粗糙度在渗流方向粗糙裂隙面中作用比垂直渗流方向粗糙裂隙面作用大;在二维粗糙裂隙面实验中,1号裂隙面粗糙度大于2号裂隙面,但是1号裂隙面流量对换热的作用低于2号裂隙面;平直裂隙和一维粗糙裂隙数值模拟评价与渗流换热实验评价接近;二维裂隙面数值模拟评价与渗流换热实验评价差距较大。
[Abstract]:In recent years, the requirements of energy and environmental quality are more and more high, and the dry hot rock has been paid more and more attention because of its huge resource reserves and cleanliness. The extraction of geothermal energy of dry-hot rock type usually takes place in fissure and geothermal rock mass to get heat exchange, so it is very important to study the mechanism of seepage heat transfer of fracture in dry-hot rock engineering. In this paper, 3D printing technique is used to fabricate various rough fractures. By means of experiments, numerical simulation and quantitative evaluation, the factors affecting the seepage heat transfer and the heat transfer mechanism of single fissure rough rock mass are discussed. The seepage experiments and heat transfer experiments on different types of rock samples were carried out to analyze the seepage heat transfer characteristics of each rough fracture surface, and the theoretical comparison was carried out by using the numerical simulation software based on laminar heat transfer theory of flat plate. The main conclusions are as follows: firstly, 22 rock samples with percolation direction and perpendicular percolation direction have been prepared by 3D printing method according to Barton standard rough curve, and seepage experiments have been carried out on the basis of the global sensitivity method. The experimental results show that with the increase of roughness, the fracture flow rate and equivalent hydraulic opening decrease, the vertical percolation direction roughness is the least, and the two-dimensional coarse fracture effect is the greatest. The roughness of the surface with high roughness is greater than that of the surface with low roughness, and the roughness of percolation direction is greater than that of the direction of perpendicular percolation. Secondly, according to 22 rock samples of percolation direction and perpendicular percolation direction prepared by Barton standard rough curve, the seepage heat transfer experiment is carried out. The experimental results show that, The convection heat transfer coefficient of rock samples of various rough fracture surfaces increases with the increase of flow rate and gradually increases with the increase of fracture surface temperature, and the effect of perpendicular percolation direction roughness on the increase of convection heat transfer coefficient is the least. The effect of two-dimensional rough fissure on the increase of convection heat transfer coefficient is relatively large, and the seepage heat transfer mechanism of rough fissure in percolation direction is similar to that in perpendicular direction, which is mainly affected by heat transfer area and local turbulence. The heat transfer mechanism of two-dimensional rough fracture seepage increases the influence of percolation dominant path, and the curves of Nu, re and pr are fitted for 22 kinds of rough fracture surfaces, and the corresponding characteristic number equations are given. Thirdly, through the numerical simulation of seepage heat transfer in single fractured rock mass, the numerical simulation and experimental results of straight fracture, different roughness fissure in percolation direction and different roughness fissure in vertical percolation direction are compared. The laminar heat transfer theory can be used to approximate the calculation, and the contrast error of two-dimensional rough fissure rock samples is large, so it is not suitable to use laminar flow heat transfer theory to approximate calculation. Finally, the global sensitivity evaluation method is used to evaluate the influence of various experimental variables in the seepage heat transfer experiment. In the experiments of seepage heat transfer of various rough fracture surfaces, rock temperature plays a major role in the increase of outlet temperature, and roughness plays a more important role in the percolation direction of rough fracture surface than in the vertical direction of percolation direction. In the experiment of two-dimensional rough fracture surface, the roughness of No. 1 fissure surface is greater than that of No. 2 fissure surface, but the heat transfer effect of No. 1 fissure surface is lower than that of No. 2 fissure surface. The numerical simulation of straight fractures and one-dimensional rough fractures is close to the experimental evaluation of seepage heat transfer, and the gap between the numerical simulation of two-dimensional fracture surface and the experimental evaluation of seepage heat transfer is large.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU45

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