不同土壤中地下水渗流速度对单U型垂直埋管换热器性能影响的模拟研究
发布时间：2018-09-19 07:54
【摘要】：在我国现阶段,人口与建筑密度巨大,资源消耗和所需剧增,能源供应越来越紧张,因此,各行各业已经开始关注建筑节能。而地源热泵是一种既节能,又环保,还满足可持续发展要求的系统。它为解决困扰我国发展中遇到的环境污染与能源危机的两大问题带来了契机,因此地源热泵技术的发展前景在中国将十分明朗以及广阔。 地源热泵的应用研究中涉及多种参数条件,这些条件中有浅层地质条件这一项。地源热泵运行过程中,岩土物性担任着决定性的角色,其中包含着地下水渗流这一动态因素,这一因素在地源热泵的理论研究和实际应用中均显现出较大的作用影响,当前研究者认为地下水渗流因素是准确设计地源热泵系统的中心因素之一。 本文首先对地源热泵的工作原理、组成与分类以及系统特点和国内外现状进行了详细的阐述说明,接着给出了传热基础与地埋管换热器的传热理论。随后视土壤为饱和多孔介质,论述了埋管换热器传热过程中考虑地下水渗流的数学模型与渗流模型。使用GAMBIT前处理器建立管内流体、垂直U型管、与周围土壤的热渗耦合物理模型,然后使用FLUENT软件进行数值模拟计算及后处理。 本文首先研究夏季工况中无渗流情况下,埋于五种不同土壤类型(分别为致密砂土、轻质砂土、粉质粘土、卵石(黄冈岩等)、砂岩)中时,U型埋管换热器周围土壤的温度分布情况与埋管进出口温差。其次对五种土壤类型,不同渗流速度(100m/y,200m/y,300m/y,400m/y,500m/y,600m/y,700m/y,800m/y,900m/y,1000m/y)条件下,U型埋管换热器周围土壤温度场分布情况以及进出口温差的变化进行模拟并数据分析。 模拟结果发现,在有渗流情况下,埋管周围土壤温度场将沿着渗流方向发生一定程度的偏移,且U型埋管换热器的换热效果明显好于无渗流情况。通过对比每种类型土壤下的模拟结果,给出各自的最佳渗流速度,致密砂土、轻质砂土、粉质粘土、卵石(黄冈岩等)、砂岩的最佳渗流速度分别为500m/y、600m/y、800m/y,300m/y和300m/y。在最佳渗流速度下的U型埋管换热器的进出口温差最大。卵岩和轻质砂土两种土壤的U型埋管换热器的进出口温差受渗流速度影响较大,变化明显;而砂岩、致密砂土和粉质粘土三种土壤内埋管进出口温差的曲线较为平缓,受渗流速度变化的影响较小。本文的结论对地源热泵U型埋管换热器的工程设计具有一定的指导作用。
[Abstract]:At the present stage of our country, the population and the building density are huge, the resource consumption and the need increases sharply, the energy supply is more and more tight, therefore, the various industries have begun to pay attention to the building energy saving. Ground-source heat pump is a kind of energy-saving, environmental protection, but also meet the requirements of sustainable development. It brings an opportunity to solve the two major problems of environmental pollution and energy crisis that beset the development of our country, so the development prospect of ground-source heat pump technology will be very bright and broad in China. The application of ground source heat pump involves a variety of parameter conditions, such as shallow geological conditions. In the operation of ground-source heat pump (GSHP), geotechnical properties play a decisive role, including the dynamic factor of groundwater seepage, which plays an important role in the theoretical research and practical application of GSHP. Current researchers believe that groundwater seepage is one of the central factors in the accurate design of ground source heat pump system. In this paper, the working principle, composition and classification of ground-source heat pump, the characteristics of the system and the present situation at home and abroad are described in detail, and then the heat transfer theory of the ground source heat exchanger and the heat transfer theory of the ground source heat exchanger are given. Then, considering the soil as saturated porous medium, the mathematical model and seepage model considering groundwater seepage in the heat transfer process of buried tube heat exchanger are discussed. The thermo-osmotic coupling physical model between the fluid and the vertical U-tube in the pipe was established by using the GAMBIT pre-processor, and then the numerical simulation and post-processing were carried out by using the FLUENT software. In this paper, five different types of soil (dense sand, light sand, silty clay) are studied in summer without seepage. The temperature distribution of the soil around the U-type heat exchanger in the pebble (Huanggang rock and sandstone) is different from the temperature difference between the inlet and outlet of the buried pipe. Secondly, the distribution of soil temperature field and the temperature difference between the inlet and outlet of U-type buried tube heat exchangers were simulated and analyzed under the conditions of five soil types, different seepage velocities (100m / yt ~ 300m / yy ~ (300m / y) ~ 400m / y ~ 500m / y ~ 600m / y ~ (-) and temperature difference between the inlet and outlet of U-type buried tube heat exchangers. The simulation results show that the soil temperature field around the buried pipe will deviate to a certain extent along the seepage direction under the condition of seepage, and the heat transfer effect of U-type buried tube heat exchanger is obviously better than that of no seepage. By comparing the simulation results of each type of soil, the optimal seepage velocity of each type of soil is given. The optimum seepage velocity of dense sand, light sand, silty clay, pebbles (Huanggang rock, etc.) and sandstone is 500m / yyr / 600m/ yyyyr ~ 300my and 300m/ yy, respectively. The temperature difference between the inlet and outlet of U-type buried tube heat exchanger is the largest at the optimum seepage velocity. The temperature difference at the inlet and outlet of U-tube heat exchangers in two kinds of soils, ovalite and light sandy soil, is influenced by seepage velocity and changes obviously, while the curve of inlet and outlet temperature difference of sandstone, dense sand and silty clay is relatively smooth. It is less affected by the variation of seepage velocity. The conclusion of this paper is helpful to the engineering design of U-type buried tube heat exchanger of ground source heat pump.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU83
本文编号：2249505
[Abstract]:At the present stage of our country, the population and the building density are huge, the resource consumption and the need increases sharply, the energy supply is more and more tight, therefore, the various industries have begun to pay attention to the building energy saving. Ground-source heat pump is a kind of energy-saving, environmental protection, but also meet the requirements of sustainable development. It brings an opportunity to solve the two major problems of environmental pollution and energy crisis that beset the development of our country, so the development prospect of ground-source heat pump technology will be very bright and broad in China. The application of ground source heat pump involves a variety of parameter conditions, such as shallow geological conditions. In the operation of ground-source heat pump (GSHP), geotechnical properties play a decisive role, including the dynamic factor of groundwater seepage, which plays an important role in the theoretical research and practical application of GSHP. Current researchers believe that groundwater seepage is one of the central factors in the accurate design of ground source heat pump system. In this paper, the working principle, composition and classification of ground-source heat pump, the characteristics of the system and the present situation at home and abroad are described in detail, and then the heat transfer theory of the ground source heat exchanger and the heat transfer theory of the ground source heat exchanger are given. Then, considering the soil as saturated porous medium, the mathematical model and seepage model considering groundwater seepage in the heat transfer process of buried tube heat exchanger are discussed. The thermo-osmotic coupling physical model between the fluid and the vertical U-tube in the pipe was established by using the GAMBIT pre-processor, and then the numerical simulation and post-processing were carried out by using the FLUENT software. In this paper, five different types of soil (dense sand, light sand, silty clay) are studied in summer without seepage. The temperature distribution of the soil around the U-type heat exchanger in the pebble (Huanggang rock and sandstone) is different from the temperature difference between the inlet and outlet of the buried pipe. Secondly, the distribution of soil temperature field and the temperature difference between the inlet and outlet of U-type buried tube heat exchangers were simulated and analyzed under the conditions of five soil types, different seepage velocities (100m / yt ~ 300m / yy ~ (300m / y) ~ 400m / y ~ 500m / y ~ 600m / y ~ (-) and temperature difference between the inlet and outlet of U-type buried tube heat exchangers. The simulation results show that the soil temperature field around the buried pipe will deviate to a certain extent along the seepage direction under the condition of seepage, and the heat transfer effect of U-type buried tube heat exchanger is obviously better than that of no seepage. By comparing the simulation results of each type of soil, the optimal seepage velocity of each type of soil is given. The optimum seepage velocity of dense sand, light sand, silty clay, pebbles (Huanggang rock, etc.) and sandstone is 500m / yyr / 600m/ yyyyr ~ 300my and 300m/ yy, respectively. The temperature difference between the inlet and outlet of U-type buried tube heat exchanger is the largest at the optimum seepage velocity. The temperature difference at the inlet and outlet of U-tube heat exchangers in two kinds of soils, ovalite and light sandy soil, is influenced by seepage velocity and changes obviously, while the curve of inlet and outlet temperature difference of sandstone, dense sand and silty clay is relatively smooth. It is less affected by the variation of seepage velocity. The conclusion of this paper is helpful to the engineering design of U-type buried tube heat exchanger of ground source heat pump.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU83
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