不同地质结构对地埋管换热器的影响研究

发布时间：2018-07-01 10:45

本文选题：均匀单物性地质结构 + 非均匀双层不同物性地质结构　；参考：《重庆大学》2014年硕士论文

【摘要】：土壤源热泵是我国目前比较成熟的一种新能源开发形式，因其污染小可以有效利用地热能源而成为国家的能源利用重点发展方向。对于地埋管换热器，我国根据自身情况对建筑负荷、介质流速、岩土初始温度及埋管换热器的布置等耦合和相互影响均做相当多的研究，但是我国的地源热泵并没有进入完善的发展模式。另一方面我国对于各地区地质缺乏详细的地质构造分析，在地源热泵设计过程中，对岩土物性参数的确定许多地区仅根据个人经验和局部测试，忽视了竖向地质存在着不均匀性的分层构造。本课题以土壤源热泵为研究对象，在查阅众多文献并依据前人提出的三维模型为基础，建立竖向两种不同地质结构的三维模型，一种为均匀单物性地质结构模型，另一种为非均匀双层不同物性地质结构模型。根据建模需要定义地质类型，，为非均匀双层不同物性地质结构模型的不同地质分析提供基础；根据数值分析需要定义岩土类型，为非均匀双层不同物性地质结构模型的不同岩土物性分析提供基础。再根据数值分析需要定义平均换热系数的概念，并将平均换热系数作为判断换热器性能的评价参数。对于均匀单物性地质结构模型，主要分析在不同单物性地质物性、不同加热功率、不同介质流速及岩土初始平均温度对换热器性能参数的影响。分析结果发现均匀单物性地质结构中不同加热功率、介质流速及岩土初始平均温度均对换热器平均换热系数没有影响，与理论分析一致；根据固定工况下不同岩土参数类型对应的平均换热系数的变化，得出岩土参数类型中导热系数越大平均换热系数越大，并拟合得到相互关联式。对于非均匀双层不同物性地质结构模型，分析主要分为两方面,一方面研究不同加热功率、介质流速及岩土初始平均温度对换热器性能参数的影响并以实验测试得到加热功率和介质流速的变化对平均换热系数不产生影响，与均匀单物性地质结构形成对比，从而提出等效导热系数概念。另一方面，根据已经定义的地质类型和岩土参数类型，分别研究在六种岩土参数类型下地质类型对换热器换热性能参数的影响；研究在相同地质类型下两种岩土物性对换热器换热性能参数的影响；最后根据平均换热系数K与下层岩土深度h，及上层岩土导热系数λ和下层岩土导热系数λ之间关系拟合关联式。通过该课题的研究，不仅可以得到利用平均传热系数来评价地埋管的换热性能的合理意义，而且找到了平均传热系数与岩土导热系数的关系以及其非影响参数。同时，可以通过竖向不同地质结构的导热系数以及竖向分层深度，定量得到非均匀性物性参数条件下的平均换热系数。这对于评价复杂地层下的地埋管换热性能以及弥补热响应测试的不足，具有一定的参考价值。
[Abstract]:Ground-source heat pump (GSHP) is a mature new energy development form in our country at present. Because of its small pollution, it can effectively utilize geothermal energy, so it has become the key direction of energy utilization in our country. For ground buried tube heat exchangers, our country has done quite a lot of research on the coupling and mutual influence of building load, medium velocity, initial temperature of rock and soil and arrangement of buried tube heat exchangers according to our own situation. But our country ground source heat pump has not entered the perfect development mode. On the other hand, there is a lack of detailed geological structure analysis in our country. In the design process of ground-source heat pump, the determination of geophysical parameters in many areas is only based on personal experience and local test. It is neglected that the vertical geology has inhomogeneous stratified structures. In this paper, taking the ground source heat pump as the research object, based on the many literatures and based on the three dimensional model proposed by the predecessors, a three-dimensional model of vertical two different geological structures, one of which is a homogeneous single physical geological structure model, is established. The other is a non-uniform double-layer geological model with different physical properties. The geological type is defined according to the need of modeling, which provides the basis for the different geological analysis of heterogeneous double-layer different physical geological structure model, and defines the geotechnical type according to the need of numerical analysis. It provides a basis for the analysis of different geophysical properties of heterogeneous double layer models with different physical properties. Then the concept of average heat transfer coefficient is defined according to the need of numerical analysis, and the average heat transfer coefficient is taken as the evaluation parameter to judge the performance of heat exchanger. For homogeneous single physical geological structure model, the effects of different single physical properties, different heating power, different velocity of medium and initial average temperature of rock and soil on the performance parameters of heat exchanger are analyzed. The results show that different heating power, medium velocity and initial average temperature have no effect on the average heat transfer coefficient of the heat exchanger in homogeneous single physical geological structure, which is consistent with the theoretical analysis. According to the change of average heat transfer coefficient corresponding to different geotechnical parameter types under fixed working conditions, the larger the average heat transfer coefficient of geotechnical parameter type is, the greater the average heat transfer coefficient is, and the correlation formula is obtained. For the non-uniform double-layer models of different physical properties, the analysis is mainly divided into two aspects. On the one hand, the different heating power is studied. The effects of medium velocity and initial average temperature of rock and soil on the performance parameters of heat exchangers are studied. The experimental results show that the change of heating power and velocity of medium has no effect on the average heat transfer coefficient, which is in contrast to the homogeneous single physical geological structure. Thus, the concept of equivalent thermal conductivity is proposed. On the other hand, according to the defined geological types and geotechnical parameter types, the influence of geological types on heat transfer performance parameters of heat exchangers under six types of geotechnical parameters is studied respectively. The effects of two kinds of geotechnical properties on the heat transfer properties of heat exchangers under the same geological type are studied. Finally, according to the relationship between the average heat transfer coefficient K and the depth of the lower rock and soil, as well as the relationship between the thermal conductivity coefficient 位 of the upper rock and soil and the thermal conductivity coefficient of the lower rock and soil. Through the research of this subject, we can not only get the reasonable meaning of using average heat transfer coefficient to evaluate the heat transfer performance of buried pipe, but also find the relationship between average heat transfer coefficient and thermal conductivity of rock and soil and its non-influence parameters. At the same time, the average heat transfer coefficient under the condition of non-uniformity physical parameters can be quantitatively obtained by means of the thermal conductivity and vertical delamination depth of different vertical geological structures. It has some reference value for evaluating the heat transfer performance of buried pipes in complex strata and making up for the deficiency of thermal response test.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU831

【参考文献】